WO1995007516A1

WO1995007516A1 - Radio transceiver for the reception and transmission of information

Info

Publication number: WO1995007516A1
Application number: PCT/FR1993/000858
Authority: WO
Inventors: Dominique Bernard Hamel
Original assignee: Dominique Bernard Hamel
Priority date: 1992-04-02
Filing date: 1993-09-07
Publication date: 1995-03-16

Abstract

A radio transceiver for the reception and transmission of information is integrated in a portable object and adapted to exchange information with an information processing station, and comprises information reception and transmission means which are connected to a central processing unit (2), and an electric power supply (1), said transceiver being characterized in that it further comprises means (3) for the periodical activation of means (4) for the detection of the emission of a radioelectric signal by the information processing station whose output is connected to control means (5a) for controlling the supply to the remaining (2) elements of said device in response to the detection of the signal.

Description

'Device for receiving and transmitting information by radio means'.

The present invention relates to a device for receiving and transmitting information by radioelectric means, integrated in a portable object and suitable for exchanging information with an information processing station.

Information exchange systems between portable objects and information processing stations, are already known in the state of the art and have been developed to allow exchange of information between these two bodies, without physical contact. between these.

Indeed, in some applications, this physical contact is relatively restrictive.

We know for example from document FR-A-2 640 830, a device for the remote exchange of information between a portable object and a station.

This device is based on the variation of an electromagnetic signal at the terminals of an inductive frame of a gantry, during a remote inductive coupling with a portable object such as a memory card, which is significant of the presence of this card in the portal. We also know from the request of French patent 91/11621, a device of the type described above which includes means for receiving information transmitted by the station, in frequency modulation, means for demodulating the output signals of the receiving means, a processing unit of information for processing the output information from the demodulation means and an osillator controlled by the information processing unit and connected to means for transmitting information, in amplitude modulation , towards the station. However, all the devices developed in the prior art have a certain number of drawbacks in terms of their relatively limited operating autonomy, since the supply of electrical energy to the various organs of these devices is ensured by for example by a battery or an electric accumulator.

The object of the invention is therefore to solve these autonomy problems. To this end, the subject of the invention is a device for receiving and transmitting information by radioelectric means, integrated into a portable object and suitable for exchanging information with an information processing station, said device comprising reception means and means for transmitting information connected to a central information processing unit, and a source of supply of electrical energy, characterized in that it comprises in addition to means for periodically activating means for detecting the emission of a radioelectric signal by the information processing station, the output of which is connected to means for controlling the supply of the rest of the organs of this device in response to the detection of said signal. Advantageously, the activation means comprise an oscillator, the output of which activates a switch for supplying the detection means, connected between the supply source of electrical energy and the detection means. Advantageously also, the means for receiving the radio signal are formed by the means for receiving information from the device.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

FIG. 1 represents a block diagram of an embodiment of a part of a device according to the invention; FIG. 2 represents a detailed electrical diagram of an embodiment of the part of the device according to the invention, represented in the figure

1;

FIG. 3 represents the pulse delivered by an operational amplifier forming part of a device according to the invention;

FIG. 4 represents the signal supplied by means for receiving a radioelectric signal, forming part of a device according to the invention; and

FIG. 5 illustrates the production of means for detecting an intermediate frequency, entering into the constitution of a device according to the invention. As can be seen in Figure 1, a device for receiving and transmitting information by radio, integrated in a portable object and adapted to exchange information with an information processing station , comprises in a manner known per se a supply source of electrical energy, designated by the general reference 1 in this figure and constituted for example by a battery.

Furthermore, this device also includes a certain number of means for receiving and transmitting information, connected to a central information processing unit, for example with a microprocessor.

This set of means is designated by the general reference 2 in this figure.

For further information concerning devices of this type, reference may be made to the documents mentioned above.

In contrast to the wake-wake functions currently used by remote data transmission systems, which are essentially based on the principle of radiation of the inductive type emitted by a fixed beacon, equipped with specific equipment for this purpose. function and constituted for example by a coil antenna with a diameter of several tens of hundred meters and a low frequency generator for example from 100 to 200 KHz, the device according to the invention does not require d equipment other than that used for data transmission. This comes from the fact that this wake-up call function is fulfilled by means of the device integrated in the portable object itself and it is then this device which will activate on its own initiative to detect the presence a fixed data transmission station.

To perform this function, the device represented in this FIG. 1 further comprises means 3 for periodically activating means 4 for detecting the emission of a radioelectric signal by an information processing station, including the exit tie is connected to means 5a for controlling the supply of the remainder 2 of the organs of this device, in response to the detection of said signal.

In the embodiment shown, these activation means 3 comprise an oscillator 6 connected to the electric power supply source 1 and the output of which periodically activates a switch 7 supplying the detection means 4 mentioned above. This switch 7 is connected between the electrical energy supply source 1 and these means.

As shown, the above-mentioned detection means 4 advantageously comprise means 8 for receiving the radio signal, the output of which is connected to determination means 9 and to detection means 10 of the intermediate frequency of this signal, to activate the switch 5a described above, in response to the reception of this signal.

It will be noted that the means for determining the intermediate frequency advantageously comprise an oscillator 11 connected to an input of a mixer 12 receiving on another input, the output of the reception means 8 constituted for example by an antenna. The output of this mixer 12 is connected to a filter 13 of intermediate frequency. The output of this intermediate frequency filter can be connected to a demodu¬ lator 14 delivering a useful signal to the rest of the organs of this device.

The output of the intermediate frequency filter 13 is also connected to the input of the detection means 10 mentioned above, through an amplifier 15. It can therefore be seen that the part of this arrangement tif integrated in the portable object, makes it possible to periodically test the presence of an HF wave of determined frequency. The scanning period depends on the type of system applications. The longer the scrutiny period, the more the autonomy of the portable object increases as consumption decreases.

It is therefore advantageous to use the same frequency as that used for the exchange of information.

The reception of this HF wave is carried out using a reception circuit of this known type which will be described in more detail below and which is switched on at the end of each scanning period. This circuit is also used by the rest of the organs of this device for the exchange of data, between the information processing station and the portable object.

So as to obtain the information of the presence of a radio signal as quickly as possible, that is to say in order to reduce the time during which the reception and detection means are supplied at the end of each period and in order to obtain a selectivity, that is to say a rejection of the neighboring frequencies, sufficient, the radioelectric signal is analyzed after filtering at the intermediate frequency (IF) and before demodulation, that is to say, it is taken between the intermediate frequency filter 13 and the demodulator 14 to be injected into the detection means 10.

By way of example, it turns out that an activation of 0.2 ms of this part of the device makes it possible to determine without fail the presence or not of the HF wave.

The scanning period can be set, depending on the application, from 0.1 s to several tens born from seconds. The width of the window at the end of the period is not correlated with the duration of this period.

It will be noted that the detection means 10 also control a switch 5b for self-supply of the detection means. This switch is connected in parallel with the switch 7 described above and controlled by the oscillator 6. A reset signal (RESET) of the detection means 10 is applied to these by the central processing unit 2.

It is therefore understandable that the oscillator 6 causes the periodic closing of the switch 7 to supply the detection means 4 of a radioelectric signal emitted by a station. These means, in response to the detection of this signal, trigger the supply of the rest of the organs 2 of the device by means of the switch 5a to allow the exchange of information between the device and station.

In Figure 2, there is shown a detailed embodiment of this part of the device.

We recognize in this figure, the oscillator 6 which is produced around a programmable operational amplifier of the LM 4250 type whose consumption is reduced to lμA by the resistor R4.

When the output of this operational amplifier is at Vcc (or almost), the capacitor Cl charges through the resistor R5 and fixes the period of the oscillations. This resistance is fixed for example at 10 MOhms so as to limit as much as possible the charging current of this capacitor C1.

When the negative input of this operational amplifier reaches the potential of the positive input, namely practically Vcc, the output of this ci switches to 0, modifying the potential of its positive input, determined by the resistors RI and R2.

At the same time, the capacitor C1 discharges rapidly through the diode D3 which has become conductive.

When the negative input of the operational amplifier has gone down to the level of the positive input, the output of this operational amplifier switches to Vcc and a new cycle begins. The discharge time of the capacitor C1 defines the pulse which activates the means 4 for detecting the emission of the radio signal.

This time is determined by the couple of resistances RI and R2. The diode D3 is necessary in this embodiment because it is not possible to obtain the desired duty cycle by playing only on the resistors RI and R2.

However, this diode introduces a drift in the duration of the pulse as a function of the temperature, which is not tolerable, because in one case, when the temperature increases, the pulse has too short a duration. , which does not allow the detection means to provide useful information and in the other case, when the temperature decreases, the pulse is too long, which causes excessive consumption of the device.

In order to compensate for this thermal drift, a diode D2 is added in series with the resistor R2.

Thus, if the resistance of the diode D3 decreases, the capacitor Cl charges more quickly. However, the diode D2 which has the same characteristics as the diode D3, has a resistance which also decreases, c which causes that the positive input ve of the operational amplifier sees its potential decrease and consequently, leads to a faster discharge of the capacitor C1, which results in the fact that the duration of the pulse remains constant. The output of this operational amplifier activates a P-channel MOS-FET transistor of the B-type 5592 which plays the role of the switch 7 mentioned above, for periodic activation, that is to say powering up. periodic, of all the means for receiving and detecting the emission of a radioelectric signal by the information processing station.

A component of the FET type fulfills this function correctly because, given its low bias current, the operational amplifier of oscillator 6, can practically not supply current.

Note that it is possible to operate the oscillator under a lower current, for example 0.1 μA, but the characteristics of the operational amplifier make the output pulse of that -this becomes trapezoidal, as can be seen in Figure 3.

However, there is a significant dispersion on the control voltage of a MOS transistor. This would result in a significant fluctuation in the instant of energization of the rest of the device.

By way of example, the oscillator 6 described above, which is supplied with power throughout the lifetime of the portable object, can generate an activation pulse of 0.2 s every 2 seconds.

The means for detecting the emission of a radio signal are for their part based on the use of a reception circuit of the TDA 7021T type marketed by the company RTC, which supplies in the presence of an HF wave at FO frequency, a signal sinusoidal at the intermediate frequency FI, ie 70 KHz.

For a fixed station transmitting a signal with a power of 2 mW, the amplitude of the output signal of this circuit varies from 1 volt peak to peak at a distance of 1 meter, to a few millivolts peak to peak, to 10 meters.

The signal supplied by this type of component in the presence of an HF wave is represented in FIG. 4. As explained above, the output of this circuit which includes both the reception means 8, the mixer 12, the oscillator II and the intermediate frequency filter 13, delivers an intermediate frequency signal applied to the demodulator 14 and to the amplification means 15 described above.

These amplification means are in fact constituted by two low consumption operational amplifiers of the TLC 272 type. These operational amplifiers are mounted as non-inverting operational amplifiers.

These means are intended to take, under high impedance, the intermediate frequency signal from the reception circuit described above in order to bring it to an exploitable level.

In order to amplify the signal supplied by the reception circuit as much as possible, the positive input of the first operational amplifier is biased at Vcc / 2 via the resistor bridge R7 and R8. The output of this first operational amplifier is also at Vcc / 2, since the reaction branch formed by the resistors R15 and R16 is disconnected from ground by the capacitor C7. In dynamics, the impedance of this capacitor C7 is very low before the resistance R15 and the gain of this amplifier. operational is Gl = 1 + R16 / R15.

The DC component of the signal supplied by the reception circuit described above is filtered by the input capacitor C3. The filter cut-off frequency formed by this capacitor C3 and the resistor R8 in parallel on the resistor R7 must be lower) 70 KHz.

The second operational amplifier is po¬ larized to 0 at rest for two reasons: - on the one hand, the signal coming from the first operational amplifier is sufficient not to require prepolarization of the input;

- on the other hand, the output signal from it can directly attack the detection means which operate with logic levels.

The continuous level at Vcc / 2 of the first operational amplifier is eliminated by the high-pass filter constituted by the capacitor C8 and the resistor R17. The gain of the second operational amplifier is equal to G2 = 1 + R19 / R18.

On reception of a signal supplied by these amplification means, the detection means 10 described above, control the energization of the other functions, that is to say of the other organs of this device, by the intermediary of the interrupter 5a and maintain the power supply to the reception circuit independently of the control of the oscillator 6, by means of the switch 5b. The switch 5a is for example formed by a component of type B 5589 and the switch 5b by a component of type B 5592.

This state is maintained until a reset signal is sent for example by the microprocessor of the central unit of this device. tif towards the means of detection.

In fact, the detection means 10 are made up of six flip-flops D in CMOS logic as can be seen in FIG. 5 (component of type 14174).

The clock signal CLK is the signal supplied by the second operational amplifier of the amplification means 15. It is the sinusoidal signal supplied by the reception circuit, amplified, and whose negative half-wave has been eliminated.

These means remain permanently supplied so that the output of the last flip-flop which controls the MOS transistor forming the power switch 5a for the rest of the organs of this device, at its permanently defined level.

When the reception means and the amplification means are energized, the flip-flop reset signal remains at zero so as not to take account of the transient phenomena due to the establishment of the voltage.

Once the assembly in the stable state and the reset signal returned to "1", following the charging of the capacitor C6, each rising edge of the CLK signal advances by a rocker the "1" initially present at the entrance to the first seesaw of these means.

When the "1" arrives at the exit of the last rocker, it energizes using the MOS trans¬ istor, 5a, the rest of the organs of the device and maintains the supply of the receiving means, by l 'through the MOS transistor, 5b, independently of the oscillator, so that these can be used for data transfer.

Several scales were cascaded, because even in the absence of an HF wave, some parasites your can be amplified and reach the detection means.

Once the circuit output has changed to "1", only a reset signal coming for example from the microprocessor of the information processing unit of the portable device, can reset the flip-flops and cut the 'food.

It can therefore be seen that the lifetime of the electrical energy supply source 1 is determined by the following parameters:

- consumption of oscillator 6;

- scrutiny period;

- width of the detection or flow window; - capacity of battery 1; and consumption of detection electronics. Thus, for a supply voltage of the device of 6 V, the following parameters are fixed: - consumption of the oscillator low consumption: 1.5 μA consumption of the detection electronics: 7 mA

- width of the detection window: 0.2 ms.

For an oscillation period of 1 s and for a battery capacity of 150 mAH, we obtain an average consumption of;

- 1.5 μA of consumption of the low consumption oscillator;

- 7 x 10-3 _x 2 x 10 ^-4 , that is to say 1, 4 μA of average consumption of the electronic detection part, or a consumption of 2.9 μA. The autonomy of the whole is then equal to: 150 / 2.9 x 10-3 _x 24 x 365 = 5.9 years. It goes without saying of course that for an oscillation period of 2 seconds, the consumption of the detection electronics is divided by 2.

Powered at 3 volts, the device integrated in the portable object, sees the following parameters take the values:

0.5 μA for the consumption of the low consumption oscillator,

- 4 mA for consumption of detection electronics.

We then obtain for an oscillation period of 1 s, for a battery capacity of 150 mAH and for a listening window width of 0.2 ms, an average total consumption of 0.5 x 10 ^{- 4} + 4 x 10 ^-3 x 2 10 ^{~ 4} = 1.3 μA and a service life of 150 / 1.3 x 10 " ¹ x 24 x 365 = 13.1 years.

Claims

R E V E N D I C A T I O N S

1) Device for receiving and resigning information by radio, integrated in a portable object and suitable for exchanging information with an information processing station, said device comprising means of reception and means of transmission of information connected to a central information processing unit (2), and a source (1) of electrical energy supply, characterized in that it further comprises means (3) for periodically activating means (4) for detecting the emission of a radioelectric signal by the information processing station, the output of which is connected to means (5a) for controlling the supply of the remainder (2) organs of this device in response to the detection of said signal.

2) Device according to claim 1, ca¬ characterized in that the activation means (3) com¬ take an oscillator (6) whose output activates a switch (7) supplying the detection means (4 ), connected between the electrical energy supply source (1) and the detection means.

3) Device according to claim 1 or 2, characterized in that the detection means comprise means (8) for receiving the radioelectric signal, the output of which is connected to the input of determination means (9) and to detection means (10) of the intermediate frequency of said signal, to activate the control means (5a). 4) Device according to any one of the preceding re¬ vendications, characterized in that the control means comprise a switch (5a) for supplying the rest of the organs (2) of the device, connected between the power supply source electric (1) and these organs. 5) Device according to any one of the preceding re¬ vendications, characterized in that the means for receiving (8) and determining (9) the intermediate frequency of the signal are formed by the means for receiving information from the device.

6) Device according to any one of the preceding re¬ vendications, characterized in that it com¬ carries a switch (5b) for self-supply of the detection means (4), controlled by these means. 7) Device according to any one of the preceding re¬ vendications, characterized in that the detection means (4) receive a reini¬ tialization signal from the rest of the organs (2) of the device.

8) Device according to claims 2, 4 and 6, characterized in that said switches are formed by MOS transistors.