WO2002006766A1

WO2002006766A1 - Method and system for determining a cellular phone's position within a communication network

Info

Publication number: WO2002006766A1
Application number: PCT/US2001/022246
Authority: WO
Inventors: Guoyu He
Original assignee: Alcor Communications Llc
Priority date: 2000-07-17
Filing date: 2001-07-16
Publication date: 2002-01-24
Also published as: AU2001275924A1

Abstract

The present invention relates to a method or a system of using radio frequency signals to determine the position of an electronic apparatus (100, 200), such as a cellphone, within a communication network without affecting its ability to transmit audio and data information within a communication network. In particular, the present invention relates to a method or a system for position or distance (900) measurement using a radio frequency signal's phase change along its transmission pathway.

Description

METHOD AND SYSTEM FOR DETERMINING A CELLULAR PHONE'S POSITION WITHIN A COMMUNICATION NETWORK

BACKGROUND

Distance and position measurement are widely used in various areas. Increasingly, they are used in wireless networks to determine an electronic apparatus' position, for example, determination of a cellular phone's position within a service area. To meet this increasing demand, many different techniques and systems have been developed for distance and position measurement.

Among them is the global positioning system (GPS), which is generally regarded as one of the most accurate techniques. GPS often includes a network of multiple satellites. To measure a receiver's position, signals are transmitted from a number of satellites to the receiver. The receiver can then calculate its position by measuring time difference of arrival signals from each satellite. Other techniques include measurement of a signal's angle-of- arrival, and strength-of-arrival.

Each of these techniques either lacks required accuracy or has its significant drawbacks. For example, in GPS, the signal acquisition process by a receiver usually takes several minutes in order to sort through numerous frequencies. This could significantly affect the accuracy of measuring due to the Doppler effect if the receiver is a mobile apparatus.

Meanwhile, the slow data acquisition process in GPS also makes it difficult to transmit other voice and data information from a satellite to a receiver. As a result, a receiver must store or separately acquire data information regarding its surrounding geographical area. This is not only inconvenient, but may also limit the receiver's location function within a certain range.

Finally, GPS requires a network of multiple satellites, which could be very expensive. In addition, the addition of GPS function to wireless receiver, such as a cellular phone, could also significantly increase its weight and cost, which may not be desirable.

As a result, there is a need for an accurate, fast, and cost-effective system for distance and position measurement.

SUMMARY OF INVENTION The present invention relates to a method of using radio frequency signals to determine a cellular phone's distance or position without affecting its ability to transmit audio or data information within a communication network. In particular, the present invention relates to a method for distance measurement using a radio frequency signal's phase change along its transmission pathway.

One aspect of the present invention is determine a cellular phone's position within a communication network by generating at least one test signal which is used for distance or position measurement. Such a test signal is first modulated with a carrier signal having a higher frequency before being transmitted within the communication network. The test signal's phase change resulted from such transmission may then be used to determine the cellular phone's distance or position within the communication network. All these can be achieved in addition to or together with any transmission of audio or data information between the cellular phone and communication network. It should be emphasized that the present invention should not be limited to cellular phones. It is equally applicable to other electronic communication apparatus, including radio, computer, hand-held device and other wireless communication device.

Another aspect of the present invention is a communication network that includes multiple signal stations. Each signal station is able to transmit at least one test signal having a predetermined frequency after such test signal is modulated with a carrier signal having a higher frequency. A cellular phone can receive such signals transmitting from each station. After receiving such signals, the cellular phone could then compare phase difference of the test signals transmitting from each signal station in order to determine its exact location within the network. The present invention is limited to cellular phone only, and it should also be applicable to other communication apparatus, such as electronic receiver, radio, computer, handheld device, and other wireless communication device. In addition, the position measurement network described in the present invention may be used to communicate audio or data signals.

Another aspect of the present invention is a communication network for measuring a cellular phone's position within the network. Instead of being a receiver, a cellular phone could generate and transmit at least one test signal having a predetermined frequency with such test signal being modulated with a carrier signal having a higher frequency. Such a network may further comprise multiple signal stations with each station receiving the signals transmitting from the cellular phone, and with at least one station measuring phase differences of the test signals received by each signal station to determine the position of the cellular phone within the network. The present invention should not be limited to cellular phone only, and it should also be applicable to other communication apparatus, such as electronic transmitter, radio, computer, handheld device, and other wireless communication device. In addition, the position measurement network described in the present invention may be used to communicate audio or data signals.

Another aspect of the present invention is a position measurement apparatus for measuring an electronic apparatus' position within a communication network. Such apparatus comprises an electronic device that includes at least a memory and a processor. It further includes executable software residing in the memory wherein the software is operative with the processor to perform the function of receiving signals from multiple sources, identifying the sources of the signals, obtaining signal components with a predetermined frequency from the received signals; and measuring phase difference between the received signals at the predetermined frequency. Such apparatus could be radio, laptop computer, cellular phone, hand-held computer, or other wireless audio communication device. Such an apparatus may further include input device and display device. It may also include speaker or other similar device for audio signal communication.

Another aspect of the present invention is a distance measurement apparatus. Such apparatus comprises an electronic device having at least a memory and a processor. It further includes executable software residing in the memory wherein the software is operative with the processor to generate at least one test signal, having a predetermined frequency; modulate the test signal with at least a carrier signal having a higher frequency; receive a modulated signal, containing the same predetermined frequency component; and measure the phase difference between the test signal and the received signal at the predetermined frequency. Such apparatus could be radio, laptop computer, cellular phone, hand-held computer, or other wireless audio communication device. Such an apparatus may further include input device, display device. It may also include speaker or other similar device for audio signal communication.

Another aspect of the present invention is a wireless audio communication apparatus capable of position measurement within a communication network. Such apparatus could include at least one signal channel for processing signals received from different signal stations located within the network. It further includes various means for obtaining predetermined frequency components from the received signals, and signal processor for measuring phase difference of the signals received from different signal stations at the predetermined frequency. Upon obtaining such information, the apparatus may then determine its position within the communication network. Such an apparatus may be selected from a group consisting of radio, laptop computer, cellular phone, and hand-held computer. It should be understood that each signal station as described may provide a discreet carrier signal so that the apparatus could recognize the source of each received signal.

Another aspect of the present invention is a computerized method for measuring a cellular phone' position within a communication network. Such a method include the steps of receiving modulated radio frequency signals from multiple signal sources within the network; identifying the source for each received signal; obtaining at least one predetermined frequency component from each received signal; measuring phase difference of the signals received from different sources; and calculating the cellular phone's position within the network. It should be noted that the present invention should also be applicable to other electronic apparatus, including but not limited to radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

Another aspect of the present invention is a method for measuring the distance between two or more electronic apparatus. Such a method include the steps of transmitting at least one modulated signal between the two apparatus, wherein such modulated signal consists of at least one audio signal and one carrier signal; obtaining at least one frequency component, having a predetermined frequency, from the transmitted signals; measuring the signal's phase change resulted from the transmission between the two apparatus at the predetermined frequency; and determining the distance between the two apparatus. It should be noted that the audio signal as described could be in either analog or digital format, and the apparatus as described could be selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

Another aspect of the present invention is a method for using radio frequency signals to determine relative position between two electronic apparatus. Such a method comprises the steps of generating at least one test signal having a predetermined frequency; modulating the test signal with at least one carrier signal having a higher frequency; transmitting the modulated test signal between the two apparatus; recording the movement of at least one apparatus; and determining distance between the two electronic apparatus by measuring the test signal's phase change resulting from such signal transmission between the two apparatus at multiple points along the movement path of at least one apparatus. It should be noted that one or both apparatus could be installed upon a moving object, such as aircraft, vehicle and ship. A further application of the present invention is to determine one apparatus' exact location when the position of the other apparatus is known. All these may be achieved in addition or together with communication of audio or data signals between the two apparatus.

Another aspect of the present invention is an audio signal communication apparatus that may be used for distance measurement. Such an apparatus comprises at least one signal source for generating test signal having predetermined frequency; one modulator for combining the test signal with at least one carrier signal; one antenna for transmitting and receiving signals; one demodulator for obtaining signal component having the same predetermined frequency from the received signal; and one device for measuring signal phase difference. It should be noted that the modulator as described could be selected from, but not limited to, a group consisting of AM modulator, FM modulator, and digital encoder. The apparatus as described could also be selected from but not limited to a group consisting of local oscillators, crystal-stabilized oscillators, frequency synthesizers, digital frequency synthesizers.

It must be emphasized that the present invention as described herein is not limited to the use of a single test signal, having a predetermined frequency. Rather, multiple test signals may be used and each of these test signals could have its discreet frequency. Therefore, another aspect of the present invention is a method for distance measurement between two electronic apparatus. Such a method includes the steps of comprising generating at least two test signals, each having a discreet and predetermined frequency; combining the two test signals with at least one carrier signal having a higher frequency; transmitting the combined signal between the two apparatus; obtaining a new signal from the combined signal, with such new signal having a frequency that is the frequency difference of the two test signals; and measuring the new signal's phase change resulted from signal transmission between the two electronic apparatus. Finally, the present invention also describes methods how computerized programs may be used for distance or position measurement. Embedded in an electronic apparatus, such as a computer, a computerized program could operatively link memory, processor, as well as other components for distance or position measurement. Using a computerized program, an electronic apparatus, such as cellular phone, may receive signals from different sources, identify the source of each received signal, obtain frequency components having a predetermined frequency from each received signal, and then measure phase difference among each received signals. As a result, such an electronic apparatus could calculate its exact position within the network.

Such a computerized program described in the present invention may also be used for measuring distance between two electronic apparatus. Using such a computerized program, radio frequency signals could be transmitted between the two apparatus. Meanwhile, certain frequency components, having a predetermined frequency, could be obtained from the transmitted signals. One or both apparatus may then be able to measure the signal' phase change resulted from transmission between the two apparatus, and therefore determine the distance between the two apparatus.

Embedded in the present invention could be one or more of the follow advantages. First, the method or the network described in the present invention could be readily used by communicating devices, such as radio, laptop computer, cellular phone, hand-held computer, and other wireless devices, that are currently available without significant change to their components.

Second, beside the distance or position measurement, the signal network or the electronic apparatus described in the present invention may. be used to transmit other signals, such as signals carrying audio and data information. Especially, the distance or position measurement described in the present invention may be achieved in conjunction or simultaneously as other signals are transmitted.

Finally, the method described in the present invention offers great flexibility as to the range and accuracy of the measurement. For example, a test signal's frequency may be selected from a wide frequency range and multiple test signals may be used altogether. As a result, the method described in the present invention could be advantageous to other methods that are currently available.

BRIEF DESCRIPTION OF FIGURE DRAWINGS

FIG. 1 is a block diagram that describes the basic components and signal transmission in one embodiment of present invention, in which two identical electronic apparatus communicate with each other, while also determining the relative distance between them.

FIG. 2 illustrates one example of a modulating circuit, which may be used to combine different signals, such as a carrier signal, a test signal used for distance measurement, and other signals carrying audio, video, and data information, for signal transmission. FIG. 3 illustrates one example of a demodulating circuit, which may be used to separate signals of difference frequencies for further signal processing.

FIG. 4 illustrates two electronic apparatus may determine their relative position by measuring their distance at different positions.

FIG. 5 illustrates one example of how a test signal's frequency may be determined so as to avoid interference with other signals, such as audio signals, to be transmitted

FIG. 6 illustrates one example of a modulating circuit, which may be used to obtain and combine a carrier signal and multiple test signals to be used for distance measurement.

FIG. 7 illustrates one example of a demodulating circuit, which may be used to offset a carrier signal and obtain multiple test signals for distance measurement.

FIG. 8 illustrates one example of a radio frequency signal-receiving device, which may be used to receive multiple test signals from multiple sources so as to enable distance measurement among multiple apparatus.

FIG. 9 illustrates how an APS uses three signal stations of known positions to determine an electronic apparatus' position.

FIG. 10 illustrates one example of an APS and how signals are combined and transmitted within such an APS.

FIG. 11 illustrates one example how an electronic apparatus-may determine its position within a signal network, having multiple signal stations.

FIG. 12 illustrates one example of an electronic receiving device, which may be used for position measurement in a signal network.

FIG. 13 illustrates one example of an electronic receiving device, which maybe used for position measurement in a signal network.

DETAILED DESCRIPTION OF THE FIGURE DRAWINGS

The present invention is described in reference to the figure drawings, some of which may only illustrate one embodiment of the present invention for particular applications. It should be understood that the present invention should not be limited to these particular embodiments as described herein. It should be further emphasized that certain components used in these embodiments may be modified and other components may be added without affecting the practice of the present invention. Referring now to the drawings, like numerals indicate like elements throughout the several drawing figures. FIG. 1 illustrates how radio frequency signals are generated and transmitted between two electronic apparatus, each containing identical components for distance measurement. To better describe FIG. 1, the first apparatus will be called a signal transmitter 100 and the second apparatus will be called a signal receiver 200. Components in the signal transmitter 100 and components in the signal receiver 200 are similarly numbered with each of transmitter's components starts with the number "1", while each of the receiver's components starts with the number "2". However, it should be understood that both the transmitter 100 and the receiver 200 may be used as transceiver for both transmitting and receiving signals. The same should also be applied to other figures, if applicable.

As shown in FIG. 1, the signal transmitter 100 first comprises a signal source 116, which generates at least one radio frequency signal 160, herein also called "test signal", used for distance measurement. A variety of signal sources may be used to generate such a test signal 160, such as local oscillators, crystal-stabilized oscillators, frequency synthesizers, and digital frequency synthesizers, etc.

A test signal 160 usually has a predetermined and relatively low frequency (F_Ω). A test signal's frequency could affect the range and accuracy of measurement. For example, a test signal's frequency (F_Ω) could fall within a range of 100Hz to 500KHz. A test signal of 100Hz may have a longer measurement range; while a test signal of 500KHz may have greater accuracy. Therefore, for different applications of the present invention, it may be desirable to -adjust a test signal's frequency. It should be emphasized that a test signal's frequency (Fn) is not be limited to the frequency range of 100Hz to 500KHz.

The transmitter 100 includes a second signal source 112, which generates a carrier signal 175, having a frequency of Fci. A carrier signal's primary function is to help transmit low or intermediate frequency signals. It usually has a higher frequency. For example, the frequency of carrier signals used in most cellular phone networks falls between 800MHz to 4GHz. This should be applicable in the present invention. Of course, other frequency range may also be used.

The signal source 112 for the carrier signal 175 may also be selected from a variety of sources, including local oscillators, frequency synthesizers, digital frequency synthesizers, as well as other frequency generators. Sometimes, it may be possible for a transmitter 100 to have one signal source, which generates signals of different frequencies, including the test signal 160 and the carrier signal 175. The test signal 160 then passes through a switching device 114, which at the position lb allows the test signal 160 to be transmitted to a modulating circuit 108. Also transmitted to the modulating circuit 108 is the carrier signal 175, as well as other signals 180 that need be transmitted to the receiver 180. A modulating circuit's primary function is to combine these signals together for signal transmission.

Depending upon different communication systems, there are a variety of modulating methods, such as AM, FM, TDMA, PCS, TACS, AMPS, DAMPS and CDMA, that could used to modulate or combine a test signal and a carrier signal for signal transmission. All these methods should be applicable to the present invention. But it should be noted that different modulating methods may require the use of different components.

Briefly described in FIG. 2 is one example of a modulating circuit 108. As shown in FIG. 2, a modulating circuit may include one or multiple modulators, such as modulator a 304 and modulator B 306. A carrier signal 390 and a test signal 385 may be combined in a modulator A 304. If multiple test signals need be used, an additional modulator, such as modulator B 306, may be used. The output signals 380, 375 from each modulator may then be combined in an adder 308 to obtain a combined signal 365 for transmission.

In addition, other audio, video and data information may also be transmitted together with the test signal. These signals 370 could be separately combined with the carrier signal 390 in Modulator B 306 before being further combined with the test signal in an adder 308. It may also be possible to combine the test signal 385 and these other signals 370 first before they are further combined with the carrier signal 390 for signal transmission.

Now referring back to FIG. 1, by way of the modulating circuit 108, the carrier signal (Fci) 175, the test signal (F_Ω) 160 (also 165), as well as other signals 180, maybe combined to provide an output signal 150, which includes different frequency components. For example, as a result of combination, an output signal 150 may include the frequency components, that may be partly represented by the following equation (1):

F_Cι +/- F_Ω (1)

wherein Fci is derived from the carrier signal's frequency (Fci) 175 and F_Ω is derived from the test signal's frequency 160. It should be emphasized that other frequency components may also be included in an output signal 150. This output signal 150 may then pass through a circular 104, which allows the output signal 150 to be transmitted to an antenna 102. The antenna 102 then further transmits the output signal 150 to the signal receiver 200 at a distance of D 900.

As mentioned previously, at different points along its transmission pathway, a signal could have different phase information. And difference in phase usually depends upon the distance a signal has traveled or been transmitted. As a result of signal transmission, the output signal 150 provided by the signal transmitter 100 usually incurs a phase change when received by the receiver 200. This phase change may generally be reflected from the following equation (2), which represents the signal received by the receiver 200:

cos (ωci +/- Ω)(t + Δt) (2)

wherein ωci is derived from the test signal's frequency (Fci), also known as 2πFcι; Ω is derived from the test signal's frequency (F_Ω), also known as 2πF_Ω; Δt, also known as D/c (c is the light of speed), reflects the phase change resulted from its transmission over the distance (D) 900 between the transmitter 100 and receiver 200.

After being collected by the receiver's antenna 202, the signal passes through the receiver's circular 204 before being transmitted to the receiver's demodulating circuit 206. One primary function of a demodulating circuit 206 is to process a combined or modulated signal 206 so as to separate different frequency components. For distance measurement, the demodulating circuit 206 may be used to separate the test signal's frequency component (F_Ω) 160, as transmitted by the signal transmitter 100.

Briefly described in FIG. 3 is one example of a demodulating circuit. As shown in FIG. 3, a signal 490 collected by a receiver is first amplified in an amplifier 402. The amplified signal 480 is then combined with an offset signal 470 in a mixer 404 for signal , downconversion. As well known in the filed, the offset signal may include an intermediate frequency component during downconversion.

The output signal 460 from the mixer 404 is then further amplified in an IF amplifier 406 before being transmitted to a demodulator 408. After demodulation, the output signals 430, 440 may then be transmitted to different band pass filters (BPFs) 412, 414 to obtain signals of different frequencies. For distance measurement purpose, one BPF 412 could be used to select signals 420, having a frequency of F_Ω- Meanwhile, a separate BPF 414 may be used to obtain other signals 410, carrying audio, video, and data information. Referring back to FIG. 1, the signal 295 received by the receiver 200 is first transmitted to a demodulating circuit 206, which in turn provides signals of different frequencies. For distance measurement, the demodulating circuit 206 provides at least one output signal 270, having the test signal's frequency (F_Ω). The output signal 270 may be partly represented by the following equation (3):

cos ( Ωt + ΩΔt) (3) .

wherein Ω relates to the test signal's frequency (FQ), also known as 2πF_Ω; Δt reflects the phase change resulted from signal transmission from the transmitter 100 to the receiver 200.

This output signal 270 will be viewed as the same test signal since it is derived from the test signal generated by the transmitter 100 and has the same frequency (F_Ω). However, it should be noted that, after signal modulation, demodulation and transmission, this output signal 270 may differ from the test signal 160 in other aspects, such amplitude.

In some circumstances, the use of a receiver's demodulating circuit 206, as well as many of its components, may be optional. For example, after receiving the signal transmitted by the transmitter 100, a receiver 200 could simply amplify the signal and transmit it back to the transmitter without demodulating the signal or transmit the signal back to the transmitter after adding its own carrier signal for distinction.

The output signal 270 from the receiver's demodulating circuit 206 may then pass through a switching device 214, which, at the positions of 2a' and 2b', allows the signal 270 to be transmitted to the receiver's modulating circuit 265. Similarly, the receiver 200 also has its own signal source 212 for generating its own carrier signal 275, having a frequency of Fc₂. The output signal 270 (also 265) is then combined with the receiver's carrier signal 275 in the receiver's modulating circuit 208 to provide a combined signal 250. This combined signal 250 then passes through a circular 204 before being transmitted back to the transmitter 100.

The receiver's carrier signal (F_C ) 275 could have the same or a different frequency as the transmitter's carrier signal (Fci) 175. Often, in a complicated communication network, each apparatus should have its own discreet carrier signal for distinction. Of course, other methods, such as the use of digital signal processors, may also be used for this purpose.

As described previously, the transmitter 100 contains an identical demodulating circuit 106 as the receiver 200. The signal transmitted by the receiver 200 could be similarly downconverted and demodulated in the transmitter's demodulating circuit 106. This in turn could give rise one output signal 170, having the frequency of F_Ω.

Meanwhile, as a result of the second transmission from the receiver 200 to the transmitter 100, the test signal now incurs a second phase change. Assuming that the distance between the transmitter 100 and the receiver 200 remains to be D 900, the second phase change should be the same as the phase change resulted from the first signal transmission from the transmitter 100 to the receiver 200. Consequently, the output signal 170 may also be partly represented by the following equation after received by the transmitter may also be represented by the following equation (4):

cos ( Ωt + 2ΩΔt) (4)

wherein 2ΩΔt reflects the accumulated phase change to the test signal resulted from the signal transmission between the transmitter 100 and the receiver 200. Similarly, for the purpose of distance measurement, this output signal 170 could be viewed as the test signal having a phase change resulted from signal transmission between the transmitter 100 and the receiver 200.

It should be noted that both transmitter 100 and the receiver 200 could be moving during distance measurement. As a result, when the signal is transmitted from the receiver 200 back to the transmitter 100, the distance (D) 900 may have changed. This could cause slight error in distance measurement. But because of a high signal acquisition speed, this should not affect the accuracy of distance measurement in the present invention, fn addition, this error could be further minimized by taking into account each apparatus' speed and moving direction.

The output signal 170 then passes through the switching device 114, which, at the position la, allows the signal to be transmitted to a phase detector 118. Meanwhile, the phase detector 118 also receives the test signal 155 as originally generated by the signal source 116. This phase difference (Δφ) between the two signals 170, 155 may then be detected. As explained previously, the phase difference also be represented by the following equation (5)

Δφ = 2ΩΔt (5) wherein ΩΔt is inco orated from the above equation (4). Upon knowing the phase difference (Δφ), the distance (D) 900 between the transmitter 100 and the receiver 200 may then be calculated and represented by the following equation (6)

D = Δφ * λ / 2π (6)

wherein λ refers to the wavelength of the test signal 160, also known as c/2F_Ω. By limiting Δφ to a range of 0 - 2π, the distance (D) 900 between the transmitter 100 and the receiver 200 should fall within a range of 0 - λ.. Since the test signal has a predetermined frequency (F_Ω), the test signal's wavelength (λ) should be known. The distance (D) 900 between a transmitter 100 and a receiver 200 may be calculated in a signal processor.

To increase the range of distance measurement without affecting accuracy, another embodiment of the present invention is the use of two or more test signals, each having a discreet frequency, for distance measurement. For example, a test signal of 150KHz may be used in combination with another test signal of 1KH. The test signal of lKHz may be used to measure the approximate distance within a long range, such as 150 kilometer. Upon knowing the approximate distance and how many 0 - 2π cycles a signal of 150KHz could have been transmitted, the test signal of 150KHz may then be used to measure distance with great accuracy. For example, using the two signals, the accuracy of distance measurement within a range of 150 kilometer may reach an approximate 1.4 meter. Of course, accuracy of measurement may vary when signals of different frequencies are used.

Since both the transmitter 100 and the receiver 200 could include identical components as shown in FIG. 1, distance measurement described above could be performed by both the transmitter 100 and the receiver 200. In other words, the signal receiver 200 may be used as a signal transmitter. By generating its own test signal 260 and carrier signal 275, the signal receiver 200 could also measure the distance between itself and the signal transmitter 100.

A test signal could be or be converted to different types of signals, such as digital and analog signals. For example, a test signal and other signals carrying voice or data information, may be first converted into digital signals through an A D converter. They then may be combined to obtain a combined signal. For further signal transmission, this combined signal could be further combined with a carrier signal using different methods, such as CDMA, TDMA, for signal transmission. Of course, when digital signals are used, devices such as digital encoder, A/D converter, and digital signal processor may be necessary.

In addition, the present invention also enables both the signal transmitter 100 and the signal receiver 200 to measure distance at the same time. For example, the transmitter 100 and the receiver 200 could each generates its own test signal having a discreet frequency. An electronic switching device 114, 214 can be used to allow signals of a particular frequency to be transmitted to the phase detector 118, 218, while simultaneously allowing signals of another frequency to be transmitted to the modulating circuit 108, 208. As a result, both apparatus could engage in distance measurement simultaneously.

Meanwhile, the present invention is not limited to distance measurement only, it may also be used determine the relative position between two apparatus. One example is illustrated in FIG. 4. A first apparatus could be a mobile apparatus having a known movement trajectory, while the second apparatus remains at the fixed position 962. At different positions along the first apparatus' movement pathway, such as Position A 952, Position B 954, Position C 956 and Position D 958, distance between the two apparatus could be measured. Since the relative distance and direction between each position should be known from the first apparatus' movement trajectory, the relative position between the two apparatus could be easily calculated. This embodiment could be particularly useful to - determine one apparatus' position, including its altitude, when the other apparatus' position is already known.

FIG. 1. further describes how other information, for example, audio, video, and data information, may be transmitted between a signal transmitter 100 and a receiver 200. This could be particularly useful for various wireless devices, such as cellular phones, laptop computers, hand-held devices, and other wireless apparatus by adding the distance measurement function.

As shown in FIG. 1, both the transmitter 100 and the receiver 200 could contain a signal processing circuit (P) 110, 210. A signal processing circuit 110, 210 could have multiple functions by including different components. For example, it could serve as a signal source, such as a microphone, amplifier, A/D converter, etc, for obtaining other audio, video, and data information so that they could be transmitted between the transmitter 100 and the receiver 200. These information 180, 280 could be transmitted to the same modulating circuit 108, 208 to be combined with the carrier signal 175, 275, and sometimes test signals 165, 265, as well. A signal processing circuit 110, 210 may also include other components to process these audio, video, and data information. For example, after demodulating process, signals 185, 285 containing these information could be transmitted to the signal process circuit 110, 210 for further processing.

When a test signal or signals carrying these audio, video and data information need to be combined together for transmission, it is sometimes necessary for a test signal to have a different frequency so as to avoid interference. For example, a cellular phone may need to transmit a test signal and voice signals together. As illustrated in FIG. 5, since most audio signals have a frequency range of 20Hz - 20KHz, a test signal's frequency could fall outside this range. This could avoid interference between different signals.

It should be noted that sometimes the same signals carrying audio, video, and data information, may be used as test signals to measure distance. For example, a particular frequency or frequency range of signals carrying this information may be separated for distance measurement. The approach may be especially useful when digital signals are used for transmitting these information. A digital signal processor may be used to process these signals and obtain signals of a particular frequency.

As explained previously, it is sometimes desirable to use multiple test signals of different frequencies for distance measurement. It may also be desirable for multiple test signals' frequencies to fall within a relatively narrow frequency range. Another embodiment of the present invention is to expand the range of distance measurement using two test signals whose frequencies fall within a relatively narrow frequency range.

Briefly illustrated in FIG. 6 and FIG. 7 are examples how two test signals may be used for distance measurement.

As shown in FIG. 6, a signal frequency synthesizer 502 could generate a carrier signal (Fo) 550, and two test signals 545, 540, each having a discreet frequency of Fπ 545 or F₁₂ 540. As mentioned, the two test signals' frequencies could fall within a narrow frequency range, for example, a first test signal (Fu) 545 could have a frequency of 150 KHz, while the second test signal (Fι ) 540 could have a frequency of 151 KHz.

The first test signal (Fu) 545 is first combined with the carrier signal (Fo) 550 in a modulator C 504, which provides an output signal (Fo + Fπ) 535. Similarly, the second test signal (F₁₂) 540 is also combined with the carrier signal (F₀) 550 in a modulator D 506, which provides an output signal (F₀ + F₁₂) 530. The two output signals 535, 530 are then added together in an adder 508, before being transmitted to a receiver. Meanwhile, the frequency synthesizer 502 also provides two signals that will be used as references signals for phase measurement. The first reference signal 510 could be either the first test signal (Fπ) or the second test signal (Fι₂), even though FIG. 5 only shows a reference signal 510, having a frequency of Fi i . The second reference signal 505 is a combined signal between the first test signal (Fj j) 545 and the second test signal (Fι ) 540, and have a frequency of Fπ - Fπ .

As explained previously, different modulating methods should not affect the application of the present invention. With respect to each modulating method, Modulator C 504 and Modulator D 506 should be accordingly adjusted. If more test signals are needed, additional modulators may be used. Also, other signals 520, 515, such as audio, video, digital and analog signals that are not used for distance measurement, may also be combined with the test signals and carrier signals so that they may be transmitted simultaneously.

After receiving the combined signal 525, a receiver could then separate it into different frequency component using a demodulating circuit. One example of such a demodulating circuit is shown in FIG. 3. As a result, a receiver should be able to obtain at least two signals, one derived from the first test signal 545 and having a frequency of Fπ, and another derived from the second test signal 540 and having a frequency of F₁₂. These two signals may then be combined with the receiver's carrier signal (F_L) through a modulating circuit, one example of which is described in FIG. 5. The combined signal is then transmitted back to the transmitter.

Upon receiving this combined signal, the transmitter then uses a demodulating circuit to separate this combined signal and obtain signals of different frequencies. One example of such a demodulating circuit is briefly shown in FIG. 7. It is similar to the example shown in FIG. 3, except some additional components that provide a combined signal having a frequency of F ₂ - Fπ-

As shown in FIG. 7, a combined signal 695 transmitted back from a receiver could be first amplified in an amplifier 602. The amplified signal is then combined with an offset signal 690, having a frequency of Fπ, in a mixer 604 for a conventional signal down- conversion.

To increase signal-to-noise ratio, the offset signal's frequency (F_L!) could include a predetermined intermediate frequency component. For example the offset signal's frequency could be either Fι+ FIF or FL-F_1F, wherein F_L corresponds to the receiver's carrier signal's frequency (F_L) and FIF is a predetermined intermediate frequency component. When a carrier signal has a frequency between 800MHz and 4GHz, the intermediate frequency component could be around 500KHz.

The output signal from the mixer 604 is then further amplified in an IF amplifier 606 before being transmitted to a demodulator 608, whose selection usually depends upon how a signal is modulated before transmission. After demodulation, the output signal from the demodulator 608 is then transmitted to different band pass filters (BPFs) 612, 614, 616, 622, 626, 632, each of which selectively allow signals of different frequencies or frequency ranges to pass through.

A first BPF 616 could be used to select the signal 680, having a frequency of Fπ or F₁₂. A second BPF 614 may be used to select signals 670 that are not related to distance measurement for further processing. A third BPF 612 could be used to select signals of both F_π and Fι₂.

The output signal from the third BPF 612 is then further combined in a mixer 624 with another offset signal 685, having a frequency of F , for a second signal downconversion. The offset signal's frequency (F_L2) 685 could be Fπ or F₁₂, plus or minus a predetermined lower frequency component (F_LF)- The low frequency component (FLF) should be around the frequency difference between Fπ and F₁₂. For example, with Fπ at 150 KHz and F₁₂ at 151 KHz, the lower frequency component (F_LF) could be 5 KHz and F_L2 could be F_n(or F_π) + 5 KHz, or F_n(or F₁₂) - 5 KHz.

The output signal from the mixer 624 is then transmitted to two separate BPFs 622, 626. The first BPF 622 may selectively allow a signal having a frequency of F_LF to pass through, while the second BPF 626 may selectively allow a signal having a frequency of F _F + (F₁ - Fπ) or F _F - (Fj₂ - Fπ)- The output signals from these two BPFs 622, 626 are then combined in a mixer 628. The output signal from the mixer 628 then passes through a low pass band filter 632 which allows the signal 675 having a frequency of F₁₂ - Fπ to pass through. This signal 675, as well as a signal having the frequency of F₁₂ or Fπ may then be compared with the two reference signals 510, 505, as shown in FIG. 6 to measure phase change resulted from signal transmission between the transmitter and the receiver.

Using the distance measurement methods described above, the present invention enables an area positioning system (APS), which allows measurement of an electronic apparatus' exact position within a particular area. An area positioning system usually includes multiple signal stations, each of which has a known position. A signal station could be conventional radio stations, cellular communication station, or even a moving signal station, such as a signal transmitting airplane.

Briefly illustrated in FIG. 8 is the basic scheme of an APS which uses the triangulation method to determine an electronic apparatus' position. An APS may include three signal stations, including signal station A 810, signal station B 820 and signal station C 830. A signal station could be traditional radio stations, cellular transmission stations, satellites, as well as other signals source of known locations. To measure the position of a ground object such as Cl 893 within the area, one may first determine Cl's distance to each signal station using the methods described previously. Upon knowing the distance between an apparatus and each signal station, one can easily measure the apparatus' position. With the addition of a fourth signal station, an apparatus' altitude may also be calculated.

Another example of the APS is shown in FIG. 9 in more details. An APS may comprise four signal stations, signal station A 811, signal station B 821, signal station C 831, and signal station D 841, whose locations are already known. An addition of a fourth signal station is to measure an apparatus' altitude. The use of the fourth signal station may not be necessary for a ground object.

For distance measurement, each signal station may generate at least one test signal, having the same frequency (Ω) and its own carrier signal. For example, signal station A 811 generates a test signal (Ω) 814 and a carrier signal (F_A) 812. As described previously, the test signal and the carrier signal are then combined and transmitted to Cl 893, whose position need be measured.

Upon receiving the signals from each signal station, Cl in turn transmits a responding signal to each signal station without changing the test signal's phase. Each signal station may then determine its distance to Cl 893. This information, as well as information regarding each signal station's exact location, may then be compiled to calculate Cl's position, including its altitude.

Of course, it is also possible for Cl 893 to measure its position by generating a carrier signal and one or multiple test signals. Each signal station may then function as individual signal receiver. Also, it is also possible for each signal station to have a discreet carrier signal as well as discreet test signals. This should not affect the use of present invention.

In addition, a signal station, such as signal station A 811, should also be able to simultaneously communicate with multiple objects, such as Cl 893, C2 895, and C3 897 within a particular area. This enables each object to obtain information regarding not only its own position, but also positions of other objects within the same area. Shown in FIG. 10 is an electronic circuit that a signal station may use to communicate with multiple objects.

As shown in FIG. 10, such an electronic circuit could consist of a sweep frequency synthesizer 704, which is controlled by a digital frequency processor 716 and provides a span of offset signals 770, which are timely controlled. Signals 790 received are first amplified in an amplifier 702 before being transmitted to a mixer 706. These signals are then combined with the span of offset signals 770. The output signals 760 are then further amplified in an IF amplifier 708 whose output signals, are further demodulated in a demodulating circuit 712. The output signal 740 may then be transmitted to a A/D converter 714 before they are further processed by a digital signal processor 716 for phase information. As references, test signals originally generated may also be transmitted to the A/D converter before being used in the digital signal processor.

Sometimes, it may be difficult for an electronic apparatus, especially a relatively small and mobile apparatus, such as a cell-phone or other hand-held communicating devices, to generate a signal strong enough to be transmitted to a distance location. As a result, it is sometimes beneficial for an electronic apparatus to simply receive signals that enable it to determine its position. Another application of the present invention is to measure an electronic apparatus' position by establishing: a network,, in which an electronic apparatus could measure its position by simply receiving signals without the necessity of transmitting signals back.

Illustrated in FIG. 11 is one example of such a signal network. It could comprise four different signal stations, signal station A 905, signal station B 908, signal station C 911, and signal station D 914. The relative distance between each of these signal stations should be known. In addition, the network may also include a main signal station 901. The main signal station's primary role is to serve as a common signal source which generates one or multiple test signals, having one or several discreet frequencies, to be further transmitted to each signal station, such as signal station A 905, signal station B 908, signal station C 911 and signal station D 914. The relative distance between the main station 901 and each signal station should also be known so that any phase change to a test signal resulting from distance signal transmission from the main station 901 to each signal station is known.

It should be emphasized that the main station's primary role is a common signal source for generating test signals, and therefore, the use of the main station 901 maybe optional. Alternatively or additionally, it is also possible to use one of the four signal stations, such as station A 905, station B 908, station C 911 or station D 914, to generate one or more test signals, which are then further transmitted to others for distance or position measurement.

To measure the position of an electronic apparatus, also called "receiver" 916, in this figure, the main station 901 first generates a test signal 903, having a frequency of F_TESτ. As explained previously, a test signal's frequency could be selected from a wide frequency range. Its selection may affect range or accuracy of distance or position measurement. For example, a test signal having a relatively high frequency may be used to measure distance within a short range, while a test signal having a relatively low frequency may be used to measure distance within a wide range. Of course, it is also possible for a main station 901 to generate multiple test signals, each having its discreet frequency, so that combination of multiple test signals could increase range, as well as accuracy, of a measurement. But for the purpose of explaining FIG. 11, a single test signal, having a frequency of F_TE_ST, will be used. But it should be noted that the present invention should not be limited the use of a single test signal.

Meanwhile, the main station 901 could also generate a carrier signal 902, having a frequency of F_M- A carrier signal's frequency (F ) could also be selected from a wide frequency range. The carrier signal 902 and the test signal 903 are then combined before being transmitted to each signal station, such as station A 905, station B 908, station C 909 and station D 915. A variety of methods and apparatus, including examples shown in FIG. 2 and FIG. 6, may be used to combine carrier signal and test signal. Detailed explanation will not be further provided here.

Upon receiving the combined signal transmitted from the main station 901, each signal station may then process the received signal to obtain the frequency component of FTE_ST, corresponding to that of the test signal (F_TEST) 903 generated by the main station 901. Using the station A 905 as an example, a signal component, having a frequency of F_TE_ST, niay be obtained from the received signal 904. Various methods and apparatus, including examples shown in FIG. 1 and FIG. 7, may be used to obtain such a frequency component. This frequency component, having a frequency of F_TEST, is then combined with station A's carrier signal 906, having a frequency of F_A- The combined signal may then be transmitted to the receiver 916 for position measurement.

Similarly, the signal transmitted from the main station 901 may also be received and processed by station B 908, station C 911 and station D 914. Upon obtaining the frequency component corresponding to that of the test signal (F_TEST) 903, each station could add a carrier signal of its own. For example, station B 908 may add a carrier signal 909, having a frequency of F_B; station C 911 may add a carrier signal 912, have a frequency of Fc; and station D 914 may a carrier signal 915, having a frequency of F_D. The combined signals are then transmitted to the receiver 916 for distance or position measurement.

It should be noted that one primary purpose of replacing the main station's carrier signal 902 with a different carrier signal is to help the receiver 916 to recognize the source of the signals it receives. But this does not mean that F_A, F_B, F_C and F_D must each have a discreet frequency, as long as the signals transmitted from each station could be identified. Some of them may not need the replacement of the main station's carrier signal, hi other words, it may also be possible for each signal station to add certain codes, such as digital codes unique to itself, to the signal received from the main station 901 before further transmission.

For example, a variety of modulating methods, such as CDMA, TDMA, etc., are available for marking signals for recognition. As well-known in the field, these methods use digital codes or digital signals to identify signals from different sources. All these should be applicable in the present invention.

It must be pointed out that the use of the term "station" as shown in FIG. 11, does not mean that each signal station, such as station A 905, station B 908, station C 911, station D 914, and main station 901, must have a fixed position. Rather, any or all of them may be mobile devices, such as satellite, airplane or other communication devices, as long as their relative distance or position within the network are known.

As explained previously that the main station 901 may be optional, FIG. 11 generally shows the use of four different signal stations, station A 905, station B 908, and station C 911, and station D 914 in measuring a receiver's position 916, including its altitude. Sometimes, it may also be possible to use three, instead of four, signal stations in measuring a receiver's position. For example, to measure a ground object's position or distance, the use of three stations generally lead to two positions for a receiving device. But by arranging a test signal's frequency range or the location of the three signal stations, it may be possible for one of the position to be located outside the range of the network. In other words, between the two positions, it would be impossible for a receiving device to be at one of the positions since such a position would be out of the range of detection. In addition, there are also other methods that may be used in conjunction with the present invention to further reduce the number of signal stations required for measuring a receiving device's position or distance. For example, a receiving device may detect the strength of signals to determine its relative distance to different signals stations.

Upon receiving signals transmitted from each signal station, such station A 905, station B 908, station C 911 and station D 914, the receiver 916 may then obtain the frequency component(s) that correspond to that of the test signal (F_TEST) from each received signal. Using these frequency components, the receiver 916 could then measure phase difference between each received signal.

As shown in FIG. 11, because the test signal(s) is originally generated by a common signal source, the main station 901, phase difference between each received signal as measured should result from difference in distance each signal has been transmitted, starting from the main station 901 and ending at the receiver 916. In other words, it results from difference in distance that a test signal has been transmitted from the main station 901, to each of the four signal stations, then from each of the four stations to the receiver 916.

Since the test signal's frequency is a predetermined frequency, phase difference as measured by the receiver 916 could be easily converted into difference in distance. As stated previously, the distance between each signal station, as well as distance between the main station 901 and each of the four stations, is already known. With these information, a receiver 916 could easily calculate its position within the network or its distance to each of the signal stations. It should be noted that phase differences measured by a receiver 91 may be due to two different transmissions, first from the main station to each signal station, and then from each signal station, to the receiver. Therefore, during calculation, the receiver should exclude the effect of the first transmission when calculating its distance to each of the four stations, including station A 905, station B 908, station C 911 and station D 914.

Of course, it is also possible for each of the four signal stations, station A 905, station B 908, station C 911 and station D 914, to first adjust a test signal's phase so that the test signal when transmitted out from each of the four stations will have the same starting phase information. In other words, each signal station could provide a phase adjustment to the test signal it has received from the main station 901 so that, after adjustment, the phase of the test signal transmitted from each signal station to the receiver 916, will be the same. For example, assuming the distance between the main station 901 and station A 905 is equivalent to half the wavelength of a test signal, while the distance between the main station 901 and station B 908 is equivalent to one wavelength. Due to the difference in distance, the signal phase of the test signal, received by station A 905, could be different from that received by station B 908 by 180 degree. To make up this difference, station A may use a phase shifter to introduce an additional 180 degree phase change to the test signal before it is further transmitted to the receiver 916. As a result, the distance measurement task may be simplified for the receiver 916 because it need not take into consideration of the transmission between the main station 901 and each of the four signal stations.

There are a variety of apparatus that may be used as a receiver 916 for position measurement in a network shown in FIG. 11. Briefly illustrated in FIG. 12 and FIG. 13 are two examples of such an apparatus. It should be emphasized that the application of the present invention should not be limited to these two examples.

The primary function of a receiving apparatus is to process signals received from different stations. These signals may comprise different frequency components, derived from different sources, such as carrier signals, test signals, as well as other signals carrying audio, video or data information. For the purpose of distance or position measurement, the primary role of the apparatus is to obtain the test signals from the received signals transmitted from different signal stations and then to compare them and calculate the apparatus' position or distance within the network. Of course, an apparatus may also function in other ways, such as receiving audio, video, and data information. .

Shown in FIG. 12 is one example of such a receiving device, which resembles the example shown in FIG. 3 and described previously. Instead of using one signal channel for signal downconversion, the example shown in FIG. 12 comprises two parallel signal channels, which are respectively used to process signals received from two different signal stations, for example, station A and station B. The two signal channels may include similar components, all of which have been described previously and are routinely used for signal downconversion.

A' signal 917 received from station A is first amplified in a signal amplifier 918, before being further transmitted to a mixer 919. Also transmitted to the mixer 919 is an offset signal, having a frequency of F_Lι, generated by a signal frequency synthesizer 924 for signal downconversion. The selection of the offset signal's frequency (F_LI) usually depends on the frequency of the carrier signal used by station A so as to eliminate the carrier signal frequency component for signal downconversion. As explained previously, the offset signal's frequency (Fu) may also include an intermediate frequency component. The output signal from the mixer 919 may then be further amplified in an IF amplifier 920 before being transmitted to a demodulator 921 to be further processed.

Sometimes, a combined signal having a relatively high frequency may undergo multiple steps of signal downconversion. In other words, the output signal from the mixer 919 may be amplified and transmitted to a second or even a third mixer. Within these mixers, the signal is further combined with a second or a third offset signal so that it may be further downconverted. These steps generally are optional and their use depends upon the frequency level of a signal initially received and the accuracy of measurement desired. The process of downconverting signals in multiple steps has been well known in the field and will not be further elaborated herein.

Selection of a demodulator 921 usually depends upon how signals are combined or modulated as the signal source, station A in this case. There are many demodulating devices, readily available in the field, which could be used in the present invention.

The output signal from the demodulator 921 may then be further transmitted to different band pass filters (BPF) 922, 923, each of which is to obtain a discreet frequency or frequency range. For example, one band pass filter may be used to selectively allow the. passage of signals having the same frequency or frequency range as that of the test signal (F_TEST), such as signal of 150KHz, while the other band pass filter may be used to obtain conventional audio frequency signals. Of course, a second band pass filter may also be used to obtain a second test signal when multiple test signals are .used for distance or position measurement. Numbers and types of band pass filters used in the present invention could be adjusted in accordance with different applications of the present invention. The output signals from these band pass filters are then transmitted to a signal processor 932 for measurement or further process. Of course, other components, such as speakers and monitors, may be added.

It should be noted that the distance or position measurement described in the present invention should not affect transmission of signals carrying audio, video and data information. For example, the output signals from the demodulator 921 may be transmitted to a band pass filter, which selectively allows the passage of audio frequency signals, which are further processed.

Similarly, a signal 925 received from station B may also be amplified in an amplifier 926 before being transmitted to a mixer 927. It is then combined with an offset signal (F_L2) provided by the frequency synthesizer 924. The downconverted signal is then further amplified in an IF amplifier 928 before being transmitted to a demodulator 929. The output signal from the demodulator 929 is further separated by different band pass filters (B.P.F.) 930 and 931 for obtaining signals of different frequencies or frequency ranges. The output signals are then transmitted to the signal processor 932.

Upon receiving signals from different signal stations, a signal processor 932 may then compare and measure phase differences among signals transmitted from different stations. Since the test signals' frequencies and wavelengths are already known and the distance between stations, such as the distance between station A and station B, is also known, the signal process 932 may then calculate its distance to each signal station. It should be noted that comparison of signals received from two signal stations, such as station A and station B alone, may not be give rise to the position information between a receiver and each of the signal stations. Rather, as explained previously, to measure a receiving device's position or distance to each signal station, signals from three or four signal stations may be needed. Accordingly, a receiver's geographical location could also be known when information regarding one or more signal stations' geographical position is available.

Another example of the receiving apparatus that: may be used in the present invention is illustrated in FIG. 13. It resembles the example that is illustrated in FIG. 7 and has been described previously in some details, and is particularly applicable, in processing combined signals, having. multiple test signals. Such a device maybe used to extend the range and accuracy of the measurement. Similarly, it also includes two parallel signal channels for receiving and processing signals received from two different signal stations.

As shown in FIG. 13, signal 970 received from station A may be first amplified in an amplifier 971 before being combined with an offset signal generated by a frequency synthesizer 994. The offset signal has a frequency of F_LI which usually relates to the frequency of the carrier signal used by the station A. The output signal is then further amplified in an IF amplifier 973 and then demodulated in a demodulator 974. The output signal from the demodulator 974 is then transmitted to different BPFs, each obtaining signals of a particular frequency of frequency range. For example, one BPF 975 could be used to selectively allow the passage of signals having a frequency of Fπ, which corresponds to that of one test signal.

Meanwhile, another BPF 976 may selectively allow the passage of signals having a particular frequency range, such as both Fπ and F₁₂, which is identical to another test signal. The output signal from this BPF 976 may then be transmitted to another mixer 977 to be further combined with another offset signal (F_L ), equivalent of F_LF in FIG. 7, for signal down conversion. Similar to what has been described previously, the output signal from the mixer 977 is then further processed by different BPFs 978, 979, whose output signals are combined in another mixer 980. The output signal from the mixer 980 further passes through another BPF 981 to obtain a signal, having a frequency of F_] - Fπ or Fπ - Fι , which is then transmitted to a signal processor 995 for phase measurement and process.

Similarly, signals received from station B 982 are also processed in a parallel signal channel. As a result, the signal processor 995 is able to measure phase differences between the signals received from different signal stations, and in turn calculate the distance between the receiver and each signal station.

The examples illustrated in FIG. 12 and FIG. 13 both describe the use of a two parallel signal channel to downconvert or process signals received from different signal stations. Additional signal channels may be added so that an apparatus could process signals transmitted from multiple signal stations. For example, the example described in FIG. 12 may further contain a third signal channel which processes signals received from a third signal station, such as signals from station C or station D.

It may also be possible to use a device having a single signal channel to process signals received from different stations. This could be especially useful in processing digital or other signals transmitted from multiple signal stations. For example, using digital coding methods, each signal station could add its discreet digital codes into the signal that it is going to transmit to a signal receiver. These signals may have identical or similar carry signal frequency. As a result, a receiver could use a single signal downconversion channel, including common components, such as amplifier, mixer, frequency synthesizer, IF amplifier, to process signals from all the signal stations. After the downconversion process, the output signals are then transmitted to multiple signal decoders, such as despreaders. Each of these signal decoders could then recognize and obtain signals from a particular signal station or signals having a particular frequency or frequency range. Their output signals are then further transmitted to a signal processor for comparison and measurement.

It should be noted that, sometimes, signals transmitted from each station may not be received by a receiving device simultaneously. This should not affect the application of the present invention because each signal as received may be first stored or recorded before being further compared or processed. FIG. 11, FIG. 12 and FIG. 13 describe how signals may be transmitted from signal stations to a receiving device in order to measure the device's distance or position. The terms, such as "receiver" and "receiving apparatus", have been used to explain these figures. But it should be noted that this does not mean a receiver may only receive signals. Rather, like what has been described in FIG. 1, if desired, a receiving apparatus may also be able to generate and transmit signals for distance or position measurement, as well as transmitting signals carrying other audio, video and data information.

For example, the "receiver" 916, as shown in FIG. 11, may also generate one or more test signals for distance or position measurement. Upon combining these test signals with its carrier signal, the receiver may then transmit the combined signal to each signal station A, B, C or D. After receiving the signals, each signal station could then communicate with each other, for example, by further relaying the signals received by each station to a single signal station, so as to compare and measure the phase changes resulted from signal transmission for the receiver to each of the signal stations. As a result, the exact position of the "receiver" within the signal network and its distance to each of the signal stations could be determined.

Like what has been described in FIGS. 1 - 10, other signals, such as signals carrying audio, video and data information, may also be transmitted within the network. For example, as shown in FIG. 11, in addition to test signals, a signal station could add signals carrying audio, video and data information into the combined signal so that they could also be transmitted to the receiver. Similarly, a receiver could also generate and transmit these signals to each of the signal stations. All these may be achieved in addition to or together with distance or position measurement.

Meanwhile, signals carrying audio, video and data information may be used to carry out the distance or position measurement. For example, a particular frequency or frequency range of the signals carrying data information may be separated and obtained. Upon measuring phase changes resulted from signal transmission, a receiver could then measure its distance or position from the signal stations where the signals has been transmitted. This should not affect the transmission of signals carrying data information.

The present invention of distance or position measurement may also be implemented through the use of computerized programs, such as computerized codes, software, machine codes, as well as other similar computer-aided methods. These computerized programs may not only be used for distance or position measurement within a signal network, but also be applicable for distance measurement between two or more individual electronic apparatus, such as the example shown in FIG. 1. h particular, such computerized programs should be especially useful for currently existing electronic communicating apparatus, including but not limited to cellular phones, hand-held computing devices, and other mobile communication apparatus. Using the existing components in these apparatus, a computerized program or code could provide the distance or position measurement abilities to these apparatus. Of course, additional components could always be added for the use of computerized program, and the same computerized programs may also be used at the signal stations.

A computerized program or software for position or distance measurement often involves the use of computerized chips or processors, usually embedded in an electronic apparatus. In addition, a storage memory may also be desirable. But it should be noted that, sometimes, the storage memory is physically built into a processor as part of the signal processor. An executable program or software may then reside in such a storage memory or signal processor. By operatively linking and adjusting the processor, the storage memory, as well as other components, such as input and display devices, a computerized program or software may then perform distance or position measurement functions.

Upon receiving signals transmitted from different sources, such as different signal stations as shown in FIG. 11, a computerized program could first identify the source of these signals. This could be achieved through a variety of methods that are currently available. For example, the program could identify the source of a particular signal by matching its codes with what has been stored in the memory. Of course, the information needed for identifying the source of each received signal may also be transmitted through cable, internet, or even together with the signals used for distance or position measurement, whenever necessary. Accordingly, a computerized program could easily identify the source of the signal or signals it received.

Sometimes, it may also be desirable for the computerized program to obtain information regarding each signal source's position within the network. For example, using FIG. 11 as an example, a receiver may need to obtain information regarding each signal station's relative position within the network. This kind of information may be stored in the memory or be transmitted to the receiver through cable, internet, wire, or wirelessly.

After identifying the source of the signals received, the computerized program may then obtain one or more frequency components from the signal received for position or distance measurement. As explained previously, signal transmission often requires the use of carrier signals. As a result, signals as received usually are complex signals comprising different frequency components. For distance or position measurement, a computerized program could select one particular frequency in order to measure a signal's phase change or difference at this particular frequency. Like the selection of a test signal's frequency, a computerized program should be able to select a predetermine frequency or frequency range for distance measurement. Of course, more than one frequency or frequency range may be selected by a computerized program. In addition, the selected frequency could be adjustable for different applications of the present invention.

It should be noted that, sometimes, a computerized program may obtain signal component of a particular frequency or frequencies before identifying the source of the signals. This should not affect the application of the present invention.

Upon obtaining signal component of a particular frequency or frequency range, the computerized program may then further measure the phase change of the signals received at the particular frequency. There are different ways of measuring a signal's phase change. For example, a computerized program could measure the phase difference of the signals received from different signal sources, such as different signal stations shown in FIG. 11. It may also measure a signal's phase change after, transmission between two apparatus. These all depend upon different uses of the present invention. .

Upon obtaining information regarding phase difference between signals received from different sources or phase change resulted from signal transmission, a computerized program may then calculate distance or position information. Depending upon different applications of the present invention, additional information may be needed. For example, when measuring an electronic apparatus' position within a network, such as the example illustrated in FIG. 11, a computerized program may need additional information regarding the relative position of each signal source, or each signal station, within the network. As explained previously, upon obtaining these information, the computerized program could easily calculate an electronic apparatus' exact position within the network. Meanwhile, such information may not be needed if a computerized program is used to measure the distance between two electronic apparatus, such as the example illustrated in FIG. 1.

As mentioned previously, other components may also be used with the application of a computerized program or software for distance or position measurement. These components may include input, output and display devices. An input device could be keyboard, speaker, receiver, and antenna for obtaining signals. An output device could be transmitter and antenna for transmitting signals. A display device could include conventional signal monitors. Variation of these components should not affect the application of the present invention.

Claims

What is Claimed is:

1. A method for determining a cellular phone's position within a communication network, comprising: generating at least one test signal having a predetermined frequency; modulating the test signal with at least one carrier signal having a higher frequency; transmitting the modulated test signal within the communication network; measuring phase change of the test signal resulted from such transmission; and determining the cellular phone's position within the network.

2. The method as described in claim 1, further comprising using two or more test signals, each having a discreet frequency.

3. The method as described in claim 1, further comprising transmitting audio signals between the cellular phone and the communication network.

4. The method as described in claim 1, wherein the cellular phone is an electronic apparatus capable of communicating audio or data signals.

5. The method as described in claim 1, wherein the test signal having a frequency between 100Hz and 500KHz.

6. The method as described in claim 1, wherein the communication network comprising at least three signal stations having known locations.

1. The method as described in claim 1, wherein the test signal is a signal selected from a group consisting of digital and analog signals.

8. The method as described in claim 1, wherein the cellular phone is an electronic apparatus selected from a group consisting of radio, laptop computer, hand-held computer, and other wireless audio communication device.

9. The method as described in claim 1, wherein the carrier signal having a frequency between 800MHz and 4GHz.

10. A communication network for measuring a cellular phone's position within the network, comprising multiple signal stations, with each station transmitting at least one test signal having a predetermined frequency and such test signal being modulated with at least one carrier signal having a higher frequency; and a cellular phone for receiving the signals transmitted from the signal stations, measuring phase difference of the test signals and determining its position within the network.

11. The network as described in claim 10, wherein each signal station transmitting two or more test signals, each having a discreet frequency.

12. The network as described in claim 10, wherein the cellular phone is an electronic apparatus capable of communicating audio or data signals.

13. The network as described in claim 10, wherein the test signal is a signal selected from a group consisting of digital and analog signals.

14. The network as described in claim 10, wherein the cellular phone is an electronic apparatus selected from a group consisting of radio, laptop computer, hand-held computer, and other wireless audio communication device.

15. The network as described in claim 10, wherein each signal station generating a discreet carrier signal.

16. The network as described in claim 10, wherein the carrier signal having a frequency between 800MHz and 4GHz.

17. The network as described in claim 10, wherein the test signal having a frequency between 100Hz and 500KHz.

18. A communication network for measuring a cellular phone's position within the network, comprising a cellular phone which transmits at least one test signal having a predetermined frequency with such test signal being first modulated with at least one carrier signal; multiple signal stations, with each station receiving the test signal transmitted from the cellular phone, with at least one station measuring phase differences of the test signals received by each signal station and determining the position of the cellular phone within the network.

19. The signal network as described in claim 18, wherein multiple test signals, each having a discreet frequency, are transmitted.

20. The network as described in claim 18, wherein the cellular phone is an electronic apparatus capable of communicating audio signals.

21. The network as described in claim 18, wherein the test signal is a signal selected from a group consisting of digital and analog signals.

22. The network as described in claim 18, wherein the cellular phone is an electronic device selected from a group consisting of radio, laptop computer, hand-held computer, and other wireless audio communication device.

23. The network as described in claim 18, wherein the carrier signal having a frequency between 800MHz and 4GHz.

24. The network as described in claim 18, wherein the test signal having a frequency between 100Hz and 500KHz.

25. A position measurement apparatus for measuring an electronic apparatus' position within a communication network, comprising: an electronic device, wherein the device comprises at least a memory and a processor; executable software residing in the memory wherein the software is operative with the processor to: receive signals from multiple sources; identify the sources of the signals; obtain signal components, having a predetermined frequency, from the received signals; and measure phase difference between the received signals at the predetermined frequency.

26. The apparatus as described in claim 25 is an apparatus selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

27. The apparatus as described in claim 25 wherein the executable software is further operative with an input device.

28. The apparatus as described in claim 25 wherein the executable software is further operative with a display device.

29. A distance measurement apparatus, the apparatus comprising: an electronic device, wherein the device comprises at least a memory and a processor; executable software residing in the memory wherein the software is operative with the processor to: generate at least one test signal, having a predetermined frequency; modulate the test signal with at least a carrier signal having a higher frequency; receive a modulated signal, containing the same predetermined frequency component; and measure the phase difference between the test signal and the received signal at the predetermined frequency.

30. The apparatus as described in claim 29 is selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

31. The apparatus as described in claim 29, wherein the executable software is further operative with the processor to generate multiple test signals.

32. The apparatus as described in claim 29, wherein the executable software is further operative with an input device.

33. The apparatus as described in claim 29, wherein the executable software is further operative with a display device.

34. A wireless audio communication apparatus capable of position measurement within a communication network, wherein the apparatus comprising: at least one signal channel for processing signals received from different signal stations located within the network; means for obtaining predetermined frequency components from the received signals; and signal processor for measuring phase difference of the signals received from different signal stations at the predetermined frequency.

35. The apparatus as described in claim 34 is an apparatus selected from a group consisting of radio, laptop computer, cellular phone, and hand-held computer.

36. The apparatus as described in claim 34, further comprising multiple signal channels for processing the received signals from different signal stations.

37. The apparatus as described in claim 34, further comprising a memory for storing information related to the received signals.

38. The apparatus as described in claim 34, further comprising means for obtained multiple frequency components, each having a discreet frequency, from the received signals.

39. A computerized method for measuring a cellular phone' position within a communication network, the method comprising: receiving modulated radio frequency signals from multiple signal sources within the network; identifying the source for each received signal; obtaining at least one predetermined frequency component from each received signal; measuring phase difference of the signals received from different sources; and calculating the cellular phone's position within the network.

40. The method as described in claim 39, further comprising transmitting information regarding each signal source's position to the cellular phone within the network.

41. The method as described in claim 39, wherein the cellular phone is an electronic apparatus capable of transmitting audio signals.

42. A method for measuring the distance between two electronic apparatus, the method_, comprising transmitting at least one modulated signal between the two apparatus, wherein such modulated signal consists of at least audio signal and carrier signal; obtaining at least one frequency component, having a predetermined frequency, from the transmitted signals; measuring the signal's phase change resulted from the transmission between the two apparatus at the predetermined frequency; and determining the distance between the two apparatus.

43. The method as described in claim 42, wherein the audio signal is in digital format.

44. The method as described in claim 42, wherein the apparatus is selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

45. A method for using radio frequency signals to measure distance between two audio communication apparatus, comprising: generating at least one test signal having a predetermined frequency; modulating the test signal with at least one carrier signal having a higher frequency; transmitting the modulated test signal between the two apparatus; and measuring the test signal's phase change resulting from transmission between the two apparatus.

46. The method as described in claim 45, further comprising using two or more test signals, each having a discreet frequency, for measurement.

47. The method as described in claim 45, wherein the apparatus is selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer and other wireless communication device.

48. The method as described in claim 45, wherein the test signal is selected from a group consisting of digital signal and analog signal.

49. The method as described in claim 45, wherein each apparatus provide a discreet carrier signal.

50. The method as described in claim 45, wherein the carrier signal having a frequency between 800MHz and 4GHz.

51. A method for using radio frequency signals to determine relative position between two electronic apparatus, comprising: generating at least one test signal having a predetermined frequency; modulating the test signal with at least one carrier signal having a higher frequency; transmitting the modulated test signal between the two apparatus; recording the movement of at least one apparatus; and determining distance between the two electronic apparatus by measuring the test signal's phase change resulting from such signal transmission between the two apparatus at multiple points along the movement path.

52. The method as described in claim 51, wherein at least two test signals, each having a discreet frequency, are combined with the earner signal.

53. The method as described in claim 51, further comprising determining the first apparatus' location with the second apparatus having known location.

54. The method as described in claim 51, wherein relative position comprising information related to distance, direction, and altitude.

55. The method as described in claim 51, wherein the test signal comprises a frequency between 100Hz and 500MHz.

56. The method as described in claim 51, wherein each apparatus generating its discreet carrier signal.

57. The method as described in claim 51, further comprising transmitting audio and data information between the two apparatus.

58. The method as described in claim 51, further comprising determining relative position between three or more apparatus.

59. An audio signal communication apparatus that may be used for distance measurement, comprising one signal source for generating test signal having predetermined frequency; one modulator for combining the test signal with at least one carrier signal; one antemia for transmitting and receiving signals; one demodulator for obtaining signal component having the same predetermined frequency from the received signal; and one device for measuring signal phase difference.

60. The apparatus as described in claim 59, wherein the modulator is selected from a group consisting of AM modulator, FM modulator, and digital encoder.

62. The apparatus as described in claim 59, wherein the signal source is selected from a group consisting of local oscillators, crystal-stabilized oscillators, frequency synthesizers, digital frequency synthesizers.

63. The apparatus as described in claim 59, further comprising a signal source for generating the carrier signal.

64. A method as described in claim 59, wherein the apparatus comprises a device selected from a group consisting of radio, laptop computer, cellular phone, hand-held computer, and other wireless audio communication device.

65. A method for distance measurement between two electronic apparatus, comprising generating at least two test signals, each having a discreet and predetermined frequency; combining the two test signals with at least one carrier signal having a higher frequency; transmitting the combined signal between the two apparatus; obtaining a new signal from the combined signal, with such new signal having a frequency that is the frequency difference of the two test signals; and measuring the new signal's phase change resulted from signal transmission between the two electronic apparatus.

66. The method as described in claim 65, wherein the two test signals having a frequency between 100Hz and 500KHz.

67. The method as described in claim 65, wherein the new signal having a frequency between 100Hz and 1Hz.

68. The method as described in claim 65, wherein the cany signal having a frequency between 800MHz and 4GHz.

69. The method as described in claim 65, wherein each apparatus providing a discreet carrier signal.

70. The method as described in claim 65, further comprising transmitting signals selected from a group consisting of audio and data signals between the two apparatus.

71. The method as described in claim 65, wherein the test signals are selected from a group consisting of digital and analog signals.

72. A communication network for measuring an electronic apparatus' position within the network, comprising multiple signal stations, with each station transmitting at least one test signal having a predetermined frequency and such test signal being modulated with at least one carrier signal having a higher frequency; and the apparatus for solely receiving the signals transmitted from the signal stations, measuring phase difference of the test signals and detennining its position within the network.

73. The communication network as described in claim 72, wherein the apparatus is installed upon a carrier selected from a group consisting of vehicle, ship, and airplane.

74. A communication network for measuring an electronic apparatus' position within the network, comprising the apparatus for solely generating and transmitting at least one test signal having a predetermined frequency with such test signal being first modulated with at least one carrier signal; multiple signal stations, with each station receiving the test signal transmitted from the apparatus, with at least one station measuring phase differences of the test signals received by each signal station and determining the position of the apparatus within the network.

The communication network as described in claim 74, wherein the apparatus is installed upon a carrier selected from a group consisting of vehicle, ship, and airplane.