System and method for a low rate, in-band broadcast communication for medical telemetry

• US 6,914,539 B2
• Filed: 10/07/2002
• Issued: 07/05/2005
• Est. Priority Date: 10/07/2002
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hershey, John Erik, Hoctor, Ralph Thomas
• Primary Examiner(s): WONG, ALBERT KANG
• Application Number:
  US10/265,497
• Publication Number:
  US 20040066312A1
• Time in Patent Office: 1,002 Days
• Field of Search: 340/870.07, 340/870.01, 340/870.12, 370/343, 370/344, 370/477, 455/41.2, 455/507, 455/63.1
• US Class Current: 340/870.12
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

A medical telemetry system includes a central station having a central station receiver and a central station transmitter that both operate on a frequency bandwidth having frequency multiplexed transmission channels and guard bands. A guard band separates each of the frequency-multiplexed transmission channels. The central station receiver wirelessly receives patient data from one of the frequency-multiplexed transmission channels. The central station transmitter wirelessly transmits control data information via each of the guard bands. At least one patient monitor is provided that includes a patient monitor receiver and a patient monitor transmitter that both operate on the frequency bandwidth. The patient monitor is wirelessly connected to the central station. The patient monitor receiver is configured for wirelessly receiving the control data information from the central station transmitter via the guard bands. The patient monitor transmitter is configured for wirelessly transmitting the patient data to the central station receiver via one of the frequency multiplexed transmission channels.

Claims

1. A medical telemetry system comprising:

a central station comprising a central station receiver and a central station transmitter, the central station receiver and the central station transmitter operating on a predetermined frequency bandwidth having a plurality of frequency-multiplexed transmission channels and a plurality of guard bands, each of the plurality of frequency-multiplexed transmission channels being separated in frequency by one of the plurality of guard bands, the central station transmitter being configured for wirelessly receiving patient data from at least one of the plurality of frequency-multiplexed transmission channels, the central station transmitter being configured for wirelessly transmitting control data information via the plurality of guard bands; and

a patient monitor comprising a patient monitor receiver and a patient monitor transmitter operating on the predetermined frequency bandwidth, the patient monitor wirelessly connected to the central station, the patient monitor receiver being configured for wirelessly receiving the control data information from the central station transmitter via at least one of the plurality of guard bands, the patient monitor transmitter being configured for wirelessly transmitting the patient data to the central station receiver via at least one of the plurality of frequency-multiplexed transmission channels.

2. The system of claim 1, wherein the central station transmitter of the central station transmits the control data information via the plurality of guard bands using multi-carrier modulation (MCM).

3. The system of claim 1, wherein a range of the predetermined frequency bandwidth is selected from the group consisting of 608 to 614 MHz, 1395 to 1400 MHz and 1427 to MHz.

4. The system of claim 1, wherein the predetermined frequency bandwidth comprises about 6 MHz.

5. The system of claim 1, wherein the plurality of frequency-multiplexed transmission channels and the plurality of guard bands comprises 240 channels.

6. The system of claim 1, wherein each of the plurality of frequency-multiplexed transmission channels is spaced about 25 kHz from each other.

7. The system of claim 1, wherein one of the plurality of guard bands comprises a frequency bandwidth of about 25 kHz.

8. The system of claim 1, wherein the central station receiver and central station transmitter are connected to an antenna node for wirelessly transmitting the control data information to the patient monitor receiver and wirelessly receiving patient data from the patient monitor transmitter.

9. The system of claim 1, wherein the central station is connected to a plurality of antenna nodes.

10. The system of claim 1, wherein the central station receiver is configured to use adaptive cancellation for canceling interference caused by the central station transmitter wherein the interference comprises control data being transmitted by the central station transmitter to the patient monitor receiver.

11. The system of claim 1, wherein the patient monitor comprises a plurality of patient monitors and wherein each of the plurality of patient monitors comprise a patient monitor receiver and a patient monitor transmitter.

12. The system of claim 1, wherein the patient monitor receiver is configured to use adaptive cancellation for canceling interference caused by the patient monitor transmitter wherein the interference comprises patient data being transmitted by the patient monitor transmitter to the patient monitor receiver.

13. The system of claim 12, wherein the patient monitor receiver further comprises a filter for filtering interference wherein the interference comprises patient data information being transmitted by others of the plurality of patient monitors.

14. The system of claim 10 wherein the central station receiver comprises:

an antenna selector connected to each of the plurality of antennas for selecting an antenna node for receiving the patient data;

a first IF mixer connected to the attenuator for processing the output from the antenna node and the synthesizer and generating an IF mixer output;

a synthesizer connected to the IF mixer;

a bandpass filter connected to the IF mixer;

a baseband mixer connected to the IF mixer to receive the IF mixer output;

an analog to digital converter (ADC) connected to the bandpass filter;

a digital signal processor (DSP) connected to the ADC;

a digitally controlled synthesizer coupled to the ADC and DSP;

a second IF mixer connected to the digitally controlled synthesizer for combining the output from the digitally controlled synthesizer and a baseband signal;

a variable phase shifter connected to the second IF mixer and the DSP; and

a summer connected between the bandpass filter, baseband mixer and the variable phase shifter.

15. The system of claim 14, wherein the central station receiver further comprises an attenuator connected to the antenna selector for attenuating a received signal to a desired level as an output.

16. The system of claim 1, wherein the patient monitor receiver comprises:

an antenna wirelessly connected to the patient monitor receiver for receiving the control data information via at least one of the plurality of guard bands from the central station transmitter;

an amplifier connected to the antenna for amplifying the received control data information;

an IF mixer connected to the amplifier to generate a IF signal;

a synthesizer connected to the IF mixer;

a bandpass filter connected to the IF mixer;

an interference reject filter connected to the bandpass filter for rejecting a known frequency of an interference signal; and

a baseband mixer connected to the interference reject filter for generating a complex baseband signal for processing by the patient monitor.

17. The system of claim 1 wherein the patient monitor receiver comprises a maximal ratio combining filter for estimating a channel frequency response for each of the guard bands and weighting conjugates of the estimated channel frequency responses such that the control data received via each of the guard bands can be combined into a signal control data signal by the patient monitor receiver.

18. The system of claim 17 wherein the estimation of the channel frequency response uses a Hadamard transform.

19. A medical telemetry system comprising:

a central station comprising a central station receiver and a central station transmitter, the central station receiver and the central station transmitter operating on a predetermined frequency bandwidth having a plurality of frequency-multiplexed transmission channels and a plurality of guard bands, each of the plurality of frequency-multiplexed transmission channels being separated in frequency by one of the plurality of guard bands, the central station receiver bring is configured for wirelessly receiving patient data from at least one of the plurality of frequency-multiplexed transmission channels and the central station transmitter being configured for wirelessly transmitting control data information via at least one of the plurality of guard bands, the central station receiver comprising;

an antenna selector connected to each of a plurality of antennas for selecting an antenna;

a first IF mixer connected to the antenna for an IF mixer output;

a synthesizer connected to the IF mixer;

a bandpass filter connected to the IF mixer;

a baseband mixer connected to the IF mixer;

an analog to digital converter (ADC) connected to the bandpass filter;

a digital signal processor (DSP) connected to the ADC for generating a DSP output;

a digitally controlled synthesizer coupled to the ADC and DSP;

a second IF mixer connected to the digitally controlled synthesizer for combining the output from the digitally controlled synthesizer and a baseband signal;

a variable phase shifter connected to the second IF mixer and the DSP; and

a summer connected between the bandpass filter, baseband mixer and the variable phase shifter; and

a patient monitor comprising a patient monitor receiver and a patient monitor transmitter, the patient monitor receiver and the patient monitor transmitter operating on at least one of the plurality of frequency-multiplexed transmission channels, the patient monitor wirelessly connected to central station, the patient monitor receiver being configured for wirelessly receiving the control data from the central station transmitter via at least one of the plurality of guard bands and the central station transmitter being configured for wirelessly transmitting the patient data to the central station receiver via at least one of the plurality of frequency-multiplexed transmission channels.

20. The system of claim 19, wherein the central station receiver further comprises an attenuator connected to the antenna selector for attenuating a received signal to a desired level as an output.

21. The system of claim 19, wherein the central station transmitter of the central station transmits the control data information via the plurality of guard bands using multi-carrier modulation (MCM).

22. The system of claim 19, wherein a range of the predetermined frequency bandwidth is selected from the group consisting of 608 to 614 MHz, 1395 to 1400 MHz and 1427 to MHz.

23. The system of claim 19, wherein the predetermined frequency bandwidth comprises about 6 MHz.

24. The system of claim 19, wherein the plurality of frequency-multiplexed transmission channels and the plurality of guard bands comprises 240 channels.

25. The system of claim 19, wherein each of the plurality of frequency-multiplexed transmission channels is spaced about 25 kHz from each other.

26. The system of claim 19, wherein one of the plurality of guard bands comprises a frequency bandwidth of about 25 kHz.

27. The system of claim 19 wherein the central station receiver is configured to use adaptive cancellation for canceling interference caused by the central station transmitter wherein the interference comprises control data being transmitted by the central station transmitter to the patient monitor receiver.

28. The system of claim 19, wherein the patient monitor comprises a plurality of patient monitors and wherein each of the plurality of patient monitors comprise a patient monitor receiver and a patient monitor transmitter.

29. The system of claim 19, wherein the patient monitor receiver is configured to use adaptive cancellation for canceling interference caused by the patient monitor transmitter wherein the interference comprises patient data being transmitted by the patient monitor transmitter to the patient monitor receiver.

30. The system of claim 19, wherein the patient monitor receiver further comprises a filter for filtering interference wherein the interference comprises patient data information being transmitted by others of the plurality of patient monitors.

31. The system of claim 19, wherein the patient monitor receiver comprises:

an antenna wirelessly connected to the patient monitor receiver for receiving the control data information via at least one of the plurality of guard bands from the central station transmitter;

an amplifier connected to the antenna for amplifying the received control data information;

an IF mixer connected to the amplifier to generate a IF signal;

a synthesizer connected to the IF mixer;

a bandpass filter connected to the IF mixer;

an interference reject filter connected to the bandpass filter for rejecting a known frequency of an interference signal; and

a baseband mixer connected to the interference reject filter for generating a complex baseband signal for processing by the patient monitor.

32. The system of claim 19 wherein the patient monitor receiver comprises a maximal ratio combining filter for estimating a channel frequency response for each of the guard bands and weighting conjugates of the estimated channel frequency responses such that the control data received via each of the guard bands can be combined into a signal control data signal by the patient monitor receiver.

33. The system of claim 32 wherein the estimation of the channel frequency response uses a Hadamard transform.

34. A method of two-way communication in a medical telemetry system comprising the steps of:

providing a central station transmitter in a central station for communicating to a plurality of individual patient monitors;

providing a patient monitor receiver in each of the plurality of individual patient monitors for communicating with the central station transmitter;

operating the central station transmitter and the patient monitor receiver on a predetermined frequency bandwidth having a plurality of frequency-multiplexed transmission channels and a plurality of guard bands, each of the plurality of frequency-multiplexed transmission channels being separated in frequency by one of the plurality of guard bands;

transmitting control data using the central station transmitter via the plurality of guard bands to each of the plurality of individual patient monitors; and

receiving the control data at the patient monitor receiver via the plurality of guard bands; and

processing the received control data at the patient monitor receiver.

39. The method of claim 34 further comprising the steps of:

providing a central station receiver;

providing a patient monitor transmitter in each of the plurality of patient monitors;

operating the central station receiver and the patient monitor transmitter on the predetermined frequency bandwidth using one of the plurality of frequency-multiplexed transmission channels;

transmitting patient data using the patient monitor transmitter via the one of the plurality of frequency-multiplexed transmission channels; and

receiving the transmitted patient data at the centrals station receiver.

40. The method of claim 39, further comprising the step of rejecting interference at the patient monitor receiver caused by the transmitted patient data from the patient monitor transmitter.

41. The method of claim 40, wherein the step of rejecting interference caused by the transmitted patient data comprises using adaptive cancellation to cancel the interference.

42. The method of claim 39, further comprising the step of rejecting interference at the patient monitor receiver caused by the transmitted patient data from others of the plurality of patient monitors.

43. The method of claim 42, wherein the step of rejecting interference at the patient monitor receiver comprises using a filter for filtering the interference from the received control data at the patient monitor receiver.

44. The method of claim 39, further comprising the step of rejecting interference at the central station receiver caused by the transmitted control data from the central station transmitter.

45. The method of claim 44, wherein the step of rejecting interference caused by the transmitted control data comprises using adaptive cancellation to cancel the interference.

46. The system of claim 34, wherein a range of the predetermined frequency bandwidth is selected from the group consisting of 608 to 614 MHz, 1395 to 1400 MHz and 1427 to MHz.

47. The system of claim 34, wherein the predetermined frequency bandwidth comprises about 6 MHz.

48. The system of claim 34, wherein the plurality of frequency-multiplexed transmission channels and the plurality of guard bands comprises 240 channels.

49. The system of claim 34, wherein one of the plurality of frequency-multiplexed transmission channels comprises a frequency bandwidth of about 25 kHz.

50. The system of claim 34, wherein each of the plurality of frequency-multiplexed transmission channels is spaced about 25 kHz from each other.

35. The method of 34, wherein the step of transmitting control data using the central station transmitter comprises using multi-carrier modulation (MCM).

36. The method of 34, wherein the step of transmitting control data using the central station transmitter comprises sending a sequence of successive data frames, each frame comprising a set of fields.

37. The method of 36, wherein the step of processing the received control data further comprises demodulating a specific field of each frame and identifying the control data for a particular one of the plurality of individual patient monitors.

38. The method of claim 37, wherein demodulating a specific field of each frame for identifying the control data information comprises demodulating other data frames and receiving a signal message when a field has been identified with the particular one of the plurality of individual patient monitors.