Efficient high data rate telemetry format for implanted medical device

• US 5,752,977 A
• Filed: 04/15/1997
• Issued: 05/19/1998
• Est. Priority Date: 04/15/1997
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Grevious, John J., Weijand, Koen J., Neumann, Robert A.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/842,581
• Time in Patent Office: 399 Days
• Field of Search: 607/32, 607/60, 128/903
• US Class Current: 607/32
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique

Abstract

A method and apparatus for transmitting information-encoded, telemetry signals percutaneously between an implanted medical device and an external device as telemetry RF pulses which are modulated in pulse position and/or in pulse width within a telemetry frame comprising at least a telemetry frame boundary RF pulse and a telemetry frame data RF pulse. Data to be transmitted in a given telemetry frame is encoded into a PPM code for positioning at least certain telemetry RF pulses at pulse positions of the telemetry frame and a PWM code for establishing the pulse widths of at least certain telemetry RF pulses of the telemetry frame. The telemetry frame is formatted from the PPM code, and the telemetry RF pulses are generated at the formatted pulse positions within the telemetry frame. The pulse widths of the telemetry RF pulses are controlled in accordance with the PWM code for the certain telemetry RF pulses. The PWM and PPM combinations of RF pulses of a telemetry frame can convey the data type, the telemetry frame frequency, number of pulse positions of the telemetry frame, data type and data content, including the identification of the implanted medical device. The selective PWM of certain or all RF pulses of the telemetry frame allows its data content to be increased or the telemetry frame size to be shortened or telemetry frame energy reduced by reducing the number of RF pulses of the telemetry frame or the range of possible pulse positions in the telemetry frame. The PWM may be reduced or disabled in noisy conditions.

Claims

1. A method for transmitting information-encoded, telemetry signals percutaneously between an implanted medical device and an external device as telemetry RF pulses within a telemetry frame comprising the steps of:

(a) encoding at least one of the telemetry RF pulses of the telemetry frame by;

(1) establishing a pulse width of the at least one telemetry RF pulse that partially identifies the information being transmitted in the telemetry frame; and

(2) establishing a pulse position of the at least one telemetry RF pulse within the telemetry frame that, together with the pulse width more fully identifies the information being transmitted in the telemetry frame;

(b) formatting the pulse positions of the telemetry frame within which at least one pulse width modulated telemetry RF pulse and at least one pulse position modulated RF pulse are to be transmitted, the telemetry frame extending over a predetermined time interval and having a predetermined number of discrete available pulse positions for the pulse position modulated telemetry RF pulse; and

(c) triggering telemetry transmission of the telemetry frame so that the pulse position modulated RF pulse is generated at the formatted pulse position and the pulse width modulated RF pulse is generated having the established pulse width.

2. The method of claim 1, wherein the pulse width identifies one of a data type and a data value and the pulse position identifies the other of the data type and the data value.

3. The method of claim 1, wherein the pulse width and pulse position of the telemetry RF pulse uniquely identifies a data type.

4. The method of claim 1, wherein the pulse width and pulse position of the telemetry RF pulse uniquely identifies a data value.

5. The method of claim 1, wherein the pulse position modulated RF pulse is also the pulse width modulated RF pulse.

6. Apparatus for transmitting information-encoded, telemetry signals percutaneously between an implanted medical device and an external device as telemetry RF pulses within a telemetry frame comprising:

(a) means for encoding the telemetry RF pulse within the telemetry frame by;

(1) establishing a pulse width of the at least one telemetry RF pulse that partially identifies the information being transmitted in the telemetry frame; and

(2) establishing a pulse position of the at least one telemetry RF pulse within the telemetry frame that, together with the pulse width more fully identifies the information being transmitted in the telemetry frame;

(b) means for formatting the pulse positions of the telemetry frame within which at least one pulse width modulated telemetry RF pulse and at least one pulse position modulated RF pulse are to be transmitted, the telemetry frame extending over a predetermined time interval and having a predetermined number of discrete available pulse positions for the pulse position modulated telemetry RF pulse; and

(c) means for triggering telemetry transmission of the telemetry frame so that the pulse position modulated RF pulse is generated at the formatted pulse position and the pulse width modulated RF pulse is generated having the established pulse width.

7. The apparatus of claim 6, wherein the pulse width identifies one of a data type and a data value and the pulse position identifies the other of the data type and the data value.

8. The apparatus of claim 6, wherein the pulse width and pulse position of the telemetry RF pulse uniquely identifies a data type.

9. The apparatus of claim 6, wherein the pulse width and pulse position of the telemetry RF pulse uniquely identifies a data value.

10. The apparatus of claim 6, wherein the pulse position modulated RF pulse is also the pulse width modulated RF pulse.

11. A method for transmitting data-encoded, telemetry signals percutaneously between an implanted medical device and an external device in a telemetry frame format within which at least one data RF pulse is to be transmitted, the telemetry frame extending over a predetermined time interval marked by a predetermined number of discrete pulse positions and further including at least one data RF pulse range comprising a sub-set of the discrete pulse positions for positioning the at least one data RF pulse with respect to the start of the telemetry frame, the method comprising the steps of:

providing a data source of data to be transmitted;

encoding the at least one data RF pulse within the telemetry frame to represent a data value selected from the data source by;

(1) establishing a pulse width of the data RF pulse that partially identifies a data value being transmitted; and

(2) establishing a pulse position of the data RF pulse at a predetermined data identifier pulse position within the sub-interval range that, together with the pulse width more fully identifies the data value being transmitted;

generating a telemetry frame boundary RF pulse to provide a time reference of the telemetry frame;

generating the at least one data RF pulse at the established pulse position within its respective sub-interval range following the telemetry frame boundary RF pulse; and

controlling the pulse width of the at least one data RF pulse, whereby the data RF pulse width and pulse position convey the encoded data value.

12. The method of claim 11, wherein the telemetry frame format includes a telemetry frame identification RF pulse within a telemetry frame identifier RF pulse range comprising a sub-set of the discrete pulse positions for positioning the telemetry frame identifier RF pulse with respect to the start of the telemetry frame and further comprising the steps of:

encoding the telemetry frame identifier RF pulse to represent a data type and a data value selected from the data source by;

(1) establishing a pulse width of the telemetry frame identifier RF pulse that identifies one of the telemetry frame type and a data value being transmitted; and

(2) establishing the pulse position of the telemetry frame identifier RF pulse at the predetermined data identifier pulse position within the identifier RF pulse range that identifies the other of the telemetry frame type and a data value being transmitted; and

controlling the pulse width of the telemetry frame identifier RF pulse, whereby the telemetry frame identifier RF pulse width and pulse position convey the data value and data type.

13. The method of claim 11, wherein the telemetry frame format includes a telemetry frame identification RF pulse within a telemetry frame identifier RF pulse range comprising a sub-set of the discrete pulse positions for positioning the telemetry frame identifier RF pulse with respect to the start of the telemetry frame and further comprising the steps of:

encoding the telemetry frame identifier RF pulse to represent a data type selected from the data source by;

(1) establishing a pulse width of the telemetry frame identifier RF pulse that partially identifies the telemetry frame type transmitted; and

(2) establishing the pulse position of the telemetry frame identifier RF pulse at the predetermined data identifier pulse position within the identifier RF pulse range that further identifies the telemetry frame type being transmitted; and

controlling the pulse width of the telemetry frame identifier RF pulse, whereby the telemetry frame identifier RF pulse width and pulse position convey the data type.

14. The method of claim 11, wherein the telemetry frame format includes a telemetry frame synchronization RF pulse at a predetermined pulse position within the telemetry frame and further comprising the steps of:

encoding the synchronization RF pulse to represent a telemetry frame type selected from the data source by establishing a pulse width of the telemetry frame identifier RF pulse; and

controlling the pulse width of the telemetry frame identifier RF pulse, whereby the telemetry frame identifier RF pulse width and pulse position convey the data value and data type.

15. The method of claim 11, further comprising the steps of:

encoding the telemetry frame boundary RF pulse to represent a telemetry frame size selected from the data source by establishing a pulse width of the telemetry frame boundary RF pulse; and

controlling the pulse width of the telemetry frame boundary RF pulse.

16. Apparatus for transmitting data-encoded, telemetry signals percutaneously between an implanted medical device and an external device in a telemetry frame format within which at least one data RF pulse is to be transmitted, the telemetry frame extending over a predetermined time interval marked by a predetermined number of discrete pulse positions and further including at least one data RF pulse range comprising a sub-set of the discrete pulse positions for positioning the at least one data RF pulse with respect to the start of the telemetry frame, the apparatus comprising:

a data source of data to be transmitted;

means for encoding the at least one data RF pulse to represent a data value selected from the data source by;

(1) establishing a pulse width of the data RF pulse that partially identifies a data value being transmitted; and

(2) establishing a pulse position of the data RF pulse at a predetermined data identifier pulse position within the sub-interval range that, together with the pulse width more fully identifies the data value being transmitted;

means for generating a telemetry frame boundary RF pulse to provide a time reference of the telemetry frame;

means for generating the telemetry frame identifier RF pulse and the at least one data RF pulse at the established pulse positions within the respective telemetry frame identifier RF pulse range and the data RF pulse range following the telemetry frame boundary RF pulse; and

means for controlling the pulse width of the at least one data RF pulse, whereby the data RF pulse width and pulse position convey the encoded data value.

17. The apparatus of claim 16, wherein the telemetry frame format includes a telemetry frame identification RF pulse within a telemetry frame identifier RF pulse range comprising a sub-set of the discrete pulse positions for positioning the telemetry frame identifier RF pulse with respect to the start of the telemetry frame and further comprising:

means for encoding the telemetry frame identifier RF pulse to represent a data type and a data value selected from the data source by;

(1) establishing a pulse width of the telemetry frame identifier RF pulse that identifies one of the telemetry frame type and a data value being transmitted; and

(2) establishing the pulse position of the telemetry frame identifier RF pulse at the predetermined data identifier pulse position within the identifier RF pulse range that identifies the other of the telemetry frame type and a data value being transmitted; and

said controlling means is operable to control the pulse width of the telemetry frame identifier RF pulse to the established pulse width, whereby the telemetry frame identifier RF pulse width and pulse position convey the data value and data type.

18. The apparatus of claim 16, wherein the telemetry frame format further includes a telemetry frame identifier RF pulse within a telemetry frame identifier RF pulse range comprising a sub-set of the discrete pulse positions for positioning the telemetry frame identifier RF pulse with respect to the start of the telemetry frame and further comprising:

means for encoding the telemetry frame identifier RF pulse to represent a data type selected from the data source by;

(1) establishing a pulse width of the telemetry frame identifier RF pulse that partially identifies the telemetry frame type transmitted; and

(2) establishing the pulse position of the telemetry frame identifier RF pulse at the predetermined data identifier pulse position within the identifier RF pulse range that further identifies the telemetry frame type being transmitted; and

said controller means is operable to control the pulse width of the telemetry frame identifier RF pulse to the established pulse width, whereby the telemetry frame identifier RF pulse width and pulse position convey the data type.

19. The apparatus of claim 16, further comprising:

means for encoding the telemetry frame boundary RF pulse to represent a telemetry frame size selected from the data source by establishing a pulse width of the telemetry frame boundary RF pulse; and

said controller means is operable to control the pulse width of the telemetry frame boundary RF pulse to the established pulse width, whereby the telemetry frame boundary RF pulse width conveys the telemetry frame size.

20. Apparatus for transmitting information-encoded, telemetry RF pulses percutaneously between an implanted medical device and an external device comprising:

a data bit source for telemetry frame identifier and data to be transmitted in a telemetry frame;

a data encoder for encoding the telemetry frame identifier and data of each telemetry frame into data-encoded RF pulse width defining code and RF pulse position defining code;

clock means for providing clock signals at preset clock intervals for use in defining pulse positions of the telemetry frame;

a telemetry frame formatter responsive to the clock means and the data-encoded RF pulse position defining code for generating RF pulse trigger signals at a synchronization RF pulse position, at an encoded telemetry frame identifier RF pulse position within a telemetry frame identifier range of possible telemetry frame identifier RF pulse positions and at an encoded data RF pulse position within a data range of possible data RF pulse positions;

an RF pulse generator responsive to the RF pulse trigger signals for generating an RF pulse at each of the synchronization RF pulse position, the telemetry frame identifier RF pulse position, and the data RF pulse position; and

an RF pulse width controller responsive to the data-encoded pulse width defining code from the data encoder for controlling the RF pulse width in at least certain ones of the RF pulses.

21. The apparatus of claim 20, wherein:

said telemetry frame formatter generates a telemetry frame boundary RF pulse trigger signal and said synchronization RF pulse trigger signal at a fixed pulse position in the telemetry frame in fixed time relation with respect to the telemetry frame boundary RF pulse trigger signal; and

said RF pulse generator is responsive to said telemetry frame boundary RF pulse trigger signal and said synchronization RF pulse trigger signal for generating respective telemetry frame boundary RF pulses and synchronizing RF pulses in fixed time relation with respect to one another from which the start of a new telemetry frame may be decoded.

22. The apparatus of claim 20, wherein the combination of pulse width and pulse position of the telemetry frame identifier RF pulse uniquely identifies a data type.

23. The apparatus of claim 20, wherein the combination of pulse width and pulse position of the data RF pulses uniquely identify a data value.

24. The apparatus of claim 20, wherein the combination of pulse width and pulse position of the telemetry frame synchronization RF pulse identifies one of the data type and the data value.

25. A method for transmitting information-encoded, telemetry signals percutaneously between an implanted medical device and an external device as telemetry RF pulses within a telemetry frame comprising a predetermined number of pulse positions, the method comprising the steps of:

providing a source of data to be transmitted;

encoding the data into a PPM code for positioning at least certain telemetry RF pulses at pulse positions of the telemetry frame and a PWM code for establishing the pulse widths of at least certain telemetry RF pulses of the telemetry frame;

formatting the telemetry frame from the PPM code;

generating the telemetry RF pulses at the formatted pulse positions within the telemetry frame; and

controlling the pulse widths of the telemetry RF pulses in accordance with the PWM code for the selected telemetry RF pulses.

26. The method of claim 25, wherein all of the telemetry RF pulses of the telemetry frame are encoded in pulse width with a PWM code.

27. The method of claim 25, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the data encoded and transmitted in the telemetry frame.

28. The method of claim 25, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the telemetry frame length.

29. The method of claim 25, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the number of data RF pulses in the telemetry frame.

30. Apparatus for transmitting information-encoded, telemetry signals percutaneously between an implanted medical device and an external device as telemetry RF pulses within a telemetry frame comprising a predetermined number of pulse positions, the apparatus comprising:

a data source for providing data to be transmitted;

encoder means for encoding the data into a PPM code for positioning at least certain telemetry RF pulses at pulse positions of the telemetry frame and a PWM code for establishing the pulse widths of at least certain telemetry RF pulses of the telemetry frame;

telemetry frame formatting means for formatting the telemetry frame from the PPM code;

generator means for generating the telemetry RF pulses at the formatted pulse positions within the telemetry frame; and

pulse width controller means for controlling the pulse widths of the telemetry RF pulses in accordance with the PWM code for the selected telemetry RF pulses.

31. The apparatus of claim 30, wherein all of the telemetry RF pulses of the telemetry frame are encoded in pulse width with a PWM code.

32. The apparatus of claim 30, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the data encoded and transmitted in the telemetry frame.

33. The apparatus of claim 30, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the telemetry frame length.

34. The apparatus of claim 30, wherein at least one telemetry RF pulse of the telemetry frame is encoded in pulse width with a PWM code identifying the number of data RF pulses in the telemetry frame.

35. A method for controlling the transmission of information-encoded, telemetry signals percutaneously in a telemetry uplink from a transmitter of an implanted medical device to the receiver of an external device as telemetry RF pulses within a telemetry frame in response to telemetry commands received from the external device in a telemetry downlink, the method comprising the steps of:

from the external device, effecting a telemetry downlink to the implanted medical device; and

transmitting a command to the implanted medical device to initiate a telemetry uplink to transmit encoded data telemetry frames to the external device; and

in the implanted medical device, responding to the downlink transmitted command by;

(1) encoding at least one of the telemetry RF pulses of each telemetry frame by;

from a predetermined range of available RF pulse widths, establishing a pulse width of the at least one telemetry RF pulse that partially identifies the information being transmitted in the telemetry frame; and

establishing a pulse position of the at least one telemetry RF pulse within a predetermined range of possible pulse positions of the telemetry frame that, together with the pulse width more fully identifies the information being transmitted in the telemetry frame;

(2) formatting the pulse positions of the telemetry frame within which at least one pulse width modulated telemetry RF pulse and at least one pulse position modulated RF pulse are to be transmitted, the telemetry frame extending over a predetermined time interval and having a predetermined number of discrete available pulse positions for the pulse position modulated telemetry RF pulse; and

(3) triggering telemetry transmission of the telemetry frame so that the pulse position modulated RF pulse is generated at the formatted pulse position and the pulse width modulated RF pulse is generated having the established pulse width.

36. The method of claim 35 further comprising the steps of:

in the external device,

receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

in conditions where the capability of accurately determining RF pulse width is compromised, transmitting a pulse width range limitation command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

in the implanted medical device, responding to the downlink transmitted, pulse width range limitation command by reducing the range of available RF pulse widths and repeating steps (1)-(3).

37. The method of claim 36 further comprising the steps of:

in the external device,

receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

in conditions where the capability of accurately determining RF pulse width continues to be compromised, transmitting a pulse width modulation elimination command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

in the implanted medical device, responding to the downlink transmitted, pulse width modulation elimination command by reducing the range of available RF pulse widths to a single pulse width and repeating steps (1)-(3).

38. The method of claim 35 further comprising the steps of:

in the external device,

receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

in conditions where the capability of accurately determining RF pulse width is compromised, transmitting a pulse width modulation elimination command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

in the implanted medical device, responding to the downlink transmitted, pulse width modulation elimination command by reducing the range of available RF pulse widths to a single pulse width and repeating steps (1)-(3).

39. Apparatus for controlling the transmission of information-encoded, telemetry signals percutaneously in a telemetry uplink from a transmitter of an implanted medical device to the receiver of an external device as telemetry RF pulses within a telemetry frame in response to telemetry commands received from the external device in a telemetry downlink, the apparatus comprising:

in the external device,

means for effecting a telemetry downlink to the implanted medical device; and

means for transmitting a command to the implanted medical device to initiate a telemetry uplink to transmit encoded data telemetry frames to the external device; and

in the implanted medical device, means responding to the downlink transmitted command including;

(1) means for encoding at least one of the telemetry RF pulses of each telemetry frame by;

from a predetermined range of available RF pulse widths, establishing a pulse width of the at least one telemetry RF pulse that partially identifies the information being transmitted in the telemetry frame; and

establishing a pulse position of the at least one telemetry RF pulse within a predetermined range of possible pulse positions of the telemetry frame that, together with the pulse width more fully identifies the information being transmitted in the telemetry frame;

(2) means for formatting the pulse positions of the telemetry frame within which at least one pulse width modulated telemetry RF pulse and at least one pulse position modulated RF pulse are to be transmitted, the telemetry frame extending over a predetermined time interval and having a predetermined number of discrete available pulse positions for the pulse position modulated telemetry RF pulse; and

(3) means for triggering telemetry transmission of the telemetry frame so that the pulse position modulated RF pulse is generated at the formatted pulse position and the pulse width modulated RF pulse is generated having the established pulse width.

40. The apparatus of claim 39, further comprising:

in the external device,

means for receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

means for monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

means operable in conditions where the capability of accurately determining RF pulse width is compromised for transmitting a pulse width range limitation command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

wherein;

said encoding means in said implanted medical device is responsive to the downlink transmitted, pulse width limitation command by reducing the range of available RF pulse widths and repeating the telemetry uplink transmission using the reduced range of available RF pulse widths.

41. The apparatus of claim 40, further comprising:

in the external device,

means for receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

means for monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

means operable in conditions where the capability of accurately determining RF pulse width continues to be compromised for transmitting a pulse width modulation elimination command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

in the implanted medical device, means responsive to the downlink transmitted, pulse width modulation elimination command for reducing the range of available RF pulse widths to a single pulse width and repeating the telemetry uplink transmission using the single RF pulse width.

42. The apparatus of claim 39, further comprising:

in the external device,

means for receiving and demodulating the at least one RF pulse of the telemetry frames of the telemetry uplink from the implanted medical device to derive both pulse position and pulse width of the at least one RF pulse of the telemetry frame;

means for monitoring the capability of determining the pulse width by application of the telemetry uplink RF pulse width demodulation; and

means operable in conditions where the capability of accurately determining RF pulse width is compromised for transmitting a pulse width modulation elimination command to the implanted medical device in a telemetry downlink to limit the range of RF pulse widths; and

in the implanted medical device, means responsive to the downlink transmitted, pulse width modulation elimination command for reducing the range of available RF pulse widths to a single pulse width and repeating the telemetry uplink transmission using the single RF pulse width.