CA1258495A - Digital gain control for the reception of telemetry signals from implanted medical devices - Google Patents

Digital gain control for the reception of telemetry signals from implanted medical devices

Info

Publication number
CA1258495A
CA1258495A CA000491457A CA491457A CA1258495A CA 1258495 A CA1258495 A CA 1258495A CA 000491457 A CA000491457 A CA 000491457A CA 491457 A CA491457 A CA 491457A CA 1258495 A CA1258495 A CA 1258495A
Authority
CA
Canada
Prior art keywords
signals
gain
response
programming
noise
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000491457A
Other languages
French (fr)
Inventor
Katherine H. Anderson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Medtronic Inc
Original Assignee
Medtronic Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=24637230&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=CA1258495(A) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Medtronic Inc filed Critical Medtronic Inc
Application granted granted Critical
Publication of CA1258495A publication Critical patent/CA1258495A/en
Expired legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/37211Means for communicating with stimulators
    • A61N1/37252Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/37211Means for communicating with stimulators
    • A61N1/37252Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
    • A61N1/3727Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data characterised by the modulation technique
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S128/00Surgery
    • Y10S128/903Radio telemetry

Abstract

DIGITAL GAIN CONTROL FOR THE RECEPTION
OF TELEMETRY SIGNALS FROM IMPLANTED
MEDICAL DEVICES

Abstract of the Disclosure A gain control system for verifying the programming of an implanted medical device is provided for an external programming unit which receives transmitted signals from the implanted unit and verifies if these signals represent valid "1" and "0" data bits. If the signals of an encoded message unit are valid signals then proccessing continues. If some of the signals are invalid due to noise interference, the gain of the receiver of the programming unit is decremented in steps as long as the error rate exceeds a predetermined number of errors per unit time.

Description

This invention relates to a digital gain control for the reception of telemetry signals from implanted medical devices.
Background of the Invention -Implanted medical devices such as heart pacemakers are often programmed to use telemetric signals that are generated by a remote programming unit. Verification of the programming of implanted device is provided by the transmission of signals from the device to a receiving section of the programming unit. The programming signals are digital signals which are coded in some manner to signify logic 1 and 0 sig-nals. In the disclosed embodiment, the encoding employs pulse interval modulation, wherein the intervals between bursts of high frequency pulses are long or short depending on the logic level of the data bit being transmitted.
Signals from implanted devices in a hospital environ-ment are often subject to a relatively high level of noise, or interference. As long as the signal level is greater than the noise level, however, the gain of the receiver may be adjusted so that the noise level will be less than a threshold level.
The information content of the coded signal is then employed to adjust the gain of the receiver. When errors occur in the message being sent from the implanted device, the number of errors in the repeated signal are counted over a period of time. If more than a predetermined number of errors occur in that time, the gain will be adjusted by a predetermined amount, and the signal will be continually monitored to determine if the adjusted gain level has eliminated the errors. The adjust-ment continues until all of the bits of the encoded information are received without error, and then further processing of 4~.

~i849~

received data from the implanted device is allowed to proceed~
In accordance with the present invention there is provided a gain control system for verifying the programming of an implanted medical device wherein the programmed implanted device transmits telemetry confirmation signals to a programm-ing means with a variable-gain receiving means after the programming of said implanted device, wherein said signals are encoded binary signals that comprise a plurality of bits;
comprising: means for establishing the response of said receiving means so that said response may be altered to elimin-ate noise when the signal level exceeds the noise level; means for verifying that the encoded signals sent from said implanted device represent valid 1 and 0 data bits; means for processing further information from said implanted device only if all of the bits of said encoded signals are verified as valid 1 and 0 data bits; means for establishing a sampling period and for determining the number of error bits in said signals which are ca~sed by noise and which do not correspond to correct data bits of said encoded signals during said period oE time; and means for varying said response by a predetermined amount when the number of said error bits exceed a predetermined amount during one of said periods of time so that said response rela-tive to a threshold level is altered.

12S~3~9~

Description of the Drawings The present invention is described by reference to the drawings in which Fig. 1 is a diagramatic illustration of an incoming signal containing both telemetr~
5 inforrnation and noise at different gain settinqs relative to a threshold level;
Fig. 2 is a block didgram oF this system of the present invention; and Fig. 3 is a flow chart diaqram which illustrates the 10 operation ~f the gain control portion of the programming device of the present invention.

Technical Description of the Invention _ The digital gain control implementation of the present invention may be utilized in a remote programming 15 device for programming an implanted medical device such as a heart pacemaker in order to confirm that the program transmitted to the device has been implemented. In a hospital environment, the electrical noise level is often very high, and signals transmit-ted from the implanted 20 device must be received and detected despite high level of background noise.
Fig. 1 shows a series of information containing signals which are labeled "signal" which extend above the background noise levell which is labeled "noise".
25 However, the noise level does initially extend above the threshold level of the receiver, and therefore, the noise will cause errors in the received signal. The implanted device continually transmits an encoded predetermined message to the remote programminq device. The gain will 30 be decremented in 10 ms steps as long as the noise remains above the threshold level. When the noise drops below the threshold level so that only the signal is above the threshold the gain is no longer decremented.
Fig. 2 shows a portion of the receiving section of 35 the programming device which illustrates that the incoming siqnal 10, which may contain b~th siqnai and noise, is -3- lZS8495 received by the antenna 12 and coupled on the line 14 to an amplifier 16. A reference voltage is coupled on the terminal 34 to establish a threshold level. The output of the ampli-fier 16 is coupled to a demodulator 18 which forms the pulses 20 consisting of the envelopes of the burst of the high frequency incoming signals. The pulses 20 provide the digital encoded information that is received from the implanted device which can be distinguished from the noise when the gain has been adjusted so that the noise falls below the threshold level.
The spacing of the pulses 20 defines whether a 1 or a 0 bit has been transmitted. Information can be readily detected once the noise is below the threshold level. This signal is coupled onto line 22 to a microcomputer 24, where -the pulse interval modulated signal is decoded to determine if the implanted device has been transmitting the correct signals.
If the transmitted signals are correct, the programming device will indicate to the implanted device that processing of addi-tional information may take place, and the implanted device will send further digitally encoded signals to the amplifier 16 which will be coupled through the demodulator 18 and the input line 22 to be processed.
Gain control is achieved with the output lines 32 from the microcomputer 24 to the amplifier 16, which allows the amplifier to select various combinations of the input resistors in series with the lines which control the gain of the ampli-fier. Alternately, the threshold level of the amplifier could be varied by the microcomputer instead of the gain.
- The flow chart of Figure 3 illustrates an implementa-tion of the digital gain control system of the present inven-- 3a - ~258~S

tion. Initially the gain is set to a maximum and a sampling period is established, such as 10 ms, for example. The system is then activated to determine if any bursts of radio frequency (RF) pulses are present as indicated by step 42. If no RF
pulses are present and the 4_ ~58495 sampling, or initialization period of step 44 has expired, the gain will remain at a maximum, as indicated by step 40. However, if there are RF pulses present during the sampling period, the timing of the sampling period will be 5 reset as indicated at step 46 so that the sampling period will be continually started following the termination of the previous sampling period as long as RF pulses are present.
Once the RF pulses have been received and have been 10 transmitted by the demodulator 18 to the microcomputer 24, the microcomputer verifies whether all of the pulses are associated with valid 1 and O data bits, as indicated by step 48. The manner in which this is done is currently employed in pulse interval modulation systems by utili~ing 15 a high frequency clock which produces pulses that are much narrower than the width of the pulses of the waveform 20.
For example, the pulses in the waveform 20 may be lOOO
times wider than the width o~ the clock pulse. The number of pulses from this high frequency clock which occur while 20 the waveform 20 is at a high level are counted and this count indicates the width and the spacing between pulses of the waveform to a very precise degree. Spacing between the pulses of the waveform 20 may also be readily de-termined by the microprocessor utilizing either software 25 control or hardware implernentation by other methods well known to those skilled in the art.
In the event that all of the pulses that are initially sampled in step 4~ are valid "1's" and "O's", f the programming unit wi1l transmit a validation signal to 30 the implanted device. The implanted device upon receipt of the validation signal will then transmit further il signals to the programming device, and storage and 1!
processing of the transmitted data will continue as indicated by step 50. However, should there be errors in 35 the encoded message transmitted from the proqrammlng ;

if' ~25~ 95 device, further processing will not continue until all of the pulses of an encoded message are validated.
A second sampling period is employed during the reception of the encoded message at step 52, which is 5 utilized to count the number of the pulses 20 which have occurred which do not prove to be ei-ther a valid l or a 0 signal. This is done by laeasuring the interval between pulses, and if the pulse interval is less than that required for a valid "1", the pulse ls counted as an error I0 pulse~ If the number of invalid pulses exceed a predetermined number N over this period of time, the gain of the unit will be decremented one step as indicated by the steps 54 and 56. Further processing will then continue in the loop until the qain has been decremented 15 to its minimum value, and either no verification is possible, or until the gain has been decremented to the point where the noise signal falls below the established threshold level and valid signals are being received.
In the event that there are some invalid level 20 transitions detected at step 52, but the error rate is not sufficiently high to meet the condition of step 54, the gain will remain at the set level, but further processing will not continue. This condition will be generally a temporary one since the background noise will generally 25 either diminish or increase to change the signal to noise level and the response of the system.
The present invention has been described with reference to a gain control system in which th gain is decremented. It will be apparent to those skilled in the 30 art that increasing the gain would also come within the scope of the present invention. Furthermore, while the gain has been adjusted in the described embodiment, it will be apparent to those skilled in the art that the threshold level could alternately be varied in accordance 35 with the scope of the present invention.

~f A

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A gain control system for verifying the programming of an implanted medical device wherein the programmed implanted device transmits telemetry confirmation signals to a programming means with a variable-gain receiving means after the programming of said implanted device, wherein said signals are encoded binary signals that comprise a plurality of bits;
comprising:
means for establishing the response of said receiving means so that said response may be altered to eliminate noise when the signal level exceeds the noise level;
means for verifying that the encoded signals sent from said implanted device represent valid 1 and 0 data bits;
means for processing further information from said implanted device only if all of the bits of said encoded signals are verified as valid 1 and 0 data bits;
means for establishing a sampling period and for determining the number of error bits in said signals which are caused by noise and which do not correspond to correct data bits of said encoded signals during said period of time; and means for varying said response by a predetermined amount when the number of said error bits exceed a predetermined amount during one of said periods of time so that said response relative to a threshold level is altered.
2. A gain control system as claimed in claim 1 wherein said response of said receiving means is a gain response and the gain of said receiving means is decremented so that said noise level is eventually reduced below said threshold level.
CA000491457A 1984-10-04 1985-09-24 Digital gain control for the reception of telemetry signals from implanted medical devices Expired CA1258495A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/657,446 US4531523A (en) 1984-10-04 1984-10-04 Digital gain control for the reception of telemetry signals from implanted medical devices
US657,446 1984-10-04

Publications (1)

Publication Number Publication Date
CA1258495A true CA1258495A (en) 1989-08-15

Family

ID=24637230

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000491457A Expired CA1258495A (en) 1984-10-04 1985-09-24 Digital gain control for the reception of telemetry signals from implanted medical devices

Country Status (5)

Country Link
US (1) US4531523A (en)
EP (1) EP0177360B1 (en)
AU (1) AU570169B2 (en)
CA (1) CA1258495A (en)
DE (1) DE3586257T2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107875516A (en) * 2017-10-31 2018-04-06 乐普医学电子仪器股份有限公司 A kind of wireless communications method between implantable medical devices and vitro program controlled device

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US5218969A (en) * 1988-02-04 1993-06-15 Blood Line Technology, Inc. Intelligent stethoscope
US5010889A (en) * 1988-02-04 1991-04-30 Bloodline Technology Intelligent stethoscope
US5127404A (en) * 1990-01-22 1992-07-07 Medtronic, Inc. Telemetry format for implanted medical device
US5241961A (en) * 1990-07-13 1993-09-07 Cook Pacemaker Corporation Synchronous telemetry receiver and receiving method for an implantable medical device
US5107833A (en) * 1990-11-02 1992-04-28 Medtronic, Inc. Telemetry gain adjustment algorithm and signal strength indication in a noisy environment
US5335666A (en) * 1992-02-27 1994-08-09 Edentec Medical monitor with input regulation
US5411536A (en) * 1993-06-03 1995-05-02 Intermedics, Inc. Method and apparatus for communicating data between medical devices to improve detectability of errors
US5350411A (en) * 1993-06-28 1994-09-27 Medtronic, Inc. Pacemaker telemetry system
US5324315A (en) * 1993-08-12 1994-06-28 Medtronic, Inc. Closed-loop downlink telemetry and method for implantable medical device
DE4329898A1 (en) * 1993-09-04 1995-04-06 Marcus Dr Besson Wireless medical diagnostic and monitoring device
FR2714609B1 (en) * 1993-12-31 1996-03-29 Ela Medical Sa Method and device for collecting waves, for extracting a useful signal emitted by an implanted medical device and mixed with parasitic signals.
US5466246A (en) * 1994-07-29 1995-11-14 Pacesetter, Inc. Telemetry receiver for implantable device, incorporating digital signal processing
US6083248A (en) 1995-06-23 2000-07-04 Medtronic, Inc. World wide patient location and data telemetry system for implantable medical devices
US5683432A (en) * 1996-01-11 1997-11-04 Medtronic, Inc. Adaptive, performance-optimizing communication system for communicating with an implanted medical device
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US6947795B2 (en) 2001-10-01 2005-09-20 Transoma Medical, Inc. Frame length modulation and pulse position modulation for telemetry of analog and digital data
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Publication number Priority date Publication date Assignee Title
CN107875516A (en) * 2017-10-31 2018-04-06 乐普医学电子仪器股份有限公司 A kind of wireless communications method between implantable medical devices and vitro program controlled device

Also Published As

Publication number Publication date
DE3586257D1 (en) 1992-07-30
DE3586257T2 (en) 1992-12-10
AU570169B2 (en) 1988-03-03
EP0177360B1 (en) 1992-06-24
US4531523A (en) 1985-07-30
EP0177360A1 (en) 1986-04-09
AU4744485A (en) 1986-04-10

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