Embedded data link and protocol

• US 5,741,314 A
• Filed: 09/04/1996
• Issued: 04/21/1998
• Est. Priority Date: 10/19/1995
• Status: Expired due to Term

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Daly, Christopher Newton, McDermott, Hugh
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US08/708,348
• Time in Patent Office: 594 Days
• Field of Search: 607/55, 607/60, 128/903
• US Class Current: 607/60
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 69/26 Special purpose or proprietary protocols or architectures network applications for proprietary or special purpose networking environments H04L67/12
• CPC Class Codes: Y10S 128/903 Radio telemetry

Abstract

A data link and protocol for a subcutaneous, tissue stimulating device. While stimulation is taking place, under control of pulses whose durations in a data frame determine the stimulation pulse widths, data is actually transmitted and processed for determining the parameters of the next stimulation. Thus transmission of data occurs simultaneously with stimulation. Data is represented by sequences which have more 1s than 0s, with each 1 being represent by a number of successive RF cycles and a single 0 by the absence of a number of RF cycles. In this way a duty cycle of 75% can be achieved so that required power is transferred to the implant. Variations in link condition, e.g., degree of ringing, are accommodated by means of offset tuning the transcutaneous transmit and receive coils. This ensures that the oscillating signal in the receive circuit that persists during the transmission of a 0 becomes out-of-phase with the RF transmission that is received for the next 1. The signal induced in the receive coil with the transmission of a new 1 cancels the out-of-phase ringing in the receive coil due to the earlier transmission, thereby causing the oscillation'"'"'s amplitude to fall below a detection level to ensure the detection of an earlier transmitted 0 during the time that the next 1 is transmitted. A bit decoder is implemented that unambiguously recovers the number of 1s over a prescribed range of link transmission conditions.

Claims

1. A transmission system comprising an RF transmitter coil;

an RF receiver coil in close wireless proximity to said transmitter coil;

means for applying to said transmitter coil an RF transmission signal representing a first bit value by N successive cycles of an RF carrier frequency and representing a second bit value by the suppression of RF carrier transmission for M successive cycles;

the degree of inter-coil interaction determining the number of cycles of RF carrier frequency induced in said receiver coil in response to the transmission of successive bits of said first value, said inter-coil interaction being affected by inter-coil coupling, inter-coil distance and the Q values of said transmitter and receiver coils; and

means for operating on the RF signal induced in said receiver coil to unambiguously determine the number P of transmitted bits of said first value;

said operating means including means for counting modulo N, after an initial offset, the number of RF cycles induced in said receiver coil, and said inter-coil interaction being limited to a range that allows a unique number of induced cycles to be counted for each number P of transmitted bits of said first value.

2. A transmission system in accordance with claim 1 wherein at most one bit of said second value is transmitted between bits of said first value.

3. A transmission system in accordance with claim 1 wherein said operating means counts successive RF cycles based upon clock signals derived from the RF carrier transmission.

4. A transmission system in accordance with claim 1 wherein said operating means flags receipt of a bit of said second value when a cycle of the RF signal in said receiver coil falls below a detection threshold.

5. A transmission system in accordance with claim 1 wherein for P successive bits of said first value that follow transmission of a bit of said second value, where P>

1, at least (P-1)N+1 RF cycles are counted by said operating means.

6. A transmission system in accordance with claim 1 wherein M=N.

7. A transmission system in accordance with claim 1 wherein, depending upon said inter-coil coupling, said operating means counts a variable number of successive RF cycles for any given number of P successive bits of said first value, and said initial offset is an experimentally determined value.

8. A transmission system in accordance with claim 7 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, said receiver coil is tuned to a resonant frequency slightly offset from said RF carrier frequency such that during the transmission time for a bit of said second value the phase of the ringing signal in said receiver coil changes significantly from the phase of said RF carrier, and the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver coil to fall below said detection threshold.

9. A transmission system in accordance with claim 7 wherein said receiver coil exhibits an induced oscillation of fewer than N cycles above said detection threshold due to the transmission of N cycles of said RF carrier.

10. A transmission system in accordance with claim 1 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, said receiver coil is tuned to a resonant frequency slightly offset from said RF carrier frequency such that during the transmission time for a bit of said second value the phase of the ringing signal in said receiver coil changes significantly from the phase of said RF carrier, and the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver coil to fall below said detection threshold.

11. A transmission system in accordance with claim 1 wherein information is transmitted in the form of tokens each of which comprises X bits, each token representing Y data bits where Y<

X, and constraints are imposed on allowable sequences of bits in tokens.

12. A transmission system comprising an RF transmitter coil;

an RF receiver coil in close wireless proximity to said transmitter coil;

means for applying to said transmitter coil an RF transmission signal representing a first bit value by N successive cycles of an RF carrier frequency and representing a second bit value by the suppression of RF carrier transmission for M successive cycles;

the degree of inter-coil interaction determining the number of cycles of RF carrier frequency induced in said receiver coil in response to the transmission of successive bits of said first value, said inter-coil interaction being affected by inter-coil coupling, inter-coil distance and the Q values of said transmitter and receiver coils; and

means for operating on the RF signal induced in said receiver coil to unambiguously determine the number P of transmitted bits of said first value when the degree of inter-coil interaction is restricted to a predetermined range.

13. A transmission system in accordance with claim 12 wherein M=N.

14. A transmission system in accordance with claim 12 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, said receiver coil is tuned to a resonant frequency slightly offset from said RF carrier frequency such that during the transmission time for a bit of said second value the phase of the ringing signal in said receiver coil de-synchronizes significantly from said RF carrier, and the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver coil to fall below said threshold value.

15. A transmission system in accordance with claim 12 wherein said receiver coil exhibits an induced oscillation of fewer than N cycles above said threshold value due to the transmission of N cycles of RF carrier.

16. A transmission system in accordance with claim 12 wherein information is transmitted in the form of tokens each of which comprises X bits, each token representing Y data bits where Y<

X, and constraints are imposed on allowable sequences of bits in tokens.

17. A transmission system comprising an RF transmitter coil;

an RF receiver coil coupled to said RF transmitter coil;

means for applying to said RF transmitter coil an RF signal in which a 1 bit is represented by a predetermined number, greater than 2, of cycles of said RF signal and a 0 bit is represented by the absence of a predetermined number, greater than 2, of cycles of said RF signal;

the coupling between said coils being such that when the separation of said coils is within prescribed limits the transmission of a single 0 bit between two 1 bits gives rise to at least one RF cycle in said RF receiver coil having an amplitude below a defined percentage of the amplitude of the received RF signal; and

means for counting successive RF cycles in said RF receiver coil whose amplitudes exceed said percentage to decode received 0 and 1 bits.

18. A transmission system in accordance with claim 17 wherein said RF transmitter and receiver coils are offset tuned such that, during the transmission of a 0 bit, ringing current in said RF receiver coil changes phase so as to oppose the RF signal received during transmission of the next 1 bit.

19. A transmission system in accordance with claim 18 wherein successive data tokens are transmitted each in the form of X successive bits, with the allowed token values being a subset less than the 2^x possible token values and predominantly being those with the fewest 0 bits.

20. A transmission system in accordance with claim 18 wherein said counting means counts a variable number of successive RF cycles for any given number of successive 1 bits and incorporates a counting offset to determine unambiguously the number of successive 1 bits transmitted, said counting means selecting the counting offset according to the extent of the coupling between said coils.

21. A transmission system in accordance with claim 19 wherein the X bits of each data token represent Y data bits, where Y<

X, and the Y data bits represented by each data token constitute the information to be communicated by the transmission system.

22. A transmission system comprising an RF transmitter coil;

an RF receiver coil coupled to said RF transmitter coil;

means for applying to said RF transmitter coil an RF signal in which a 1 bit is represented by a predetermined number, greater than 2, of cycles of said RF signal and a 0 bit is represented by the absence of a predetermined number, greater than 2, of cycles of said RF signal;

said RF transmitter and receiver being tuned to slightly different frequencies such that, during the transmission of a 0 bit, any ringing current in said RF receiver coil changes phase so as to oppose the RF signal received during transmission of the next 1 bit giving rise to at least one RF cycle in said RF receiver coil having an amplitude below a defined percentage of the amplitude of the received RF signal; and

means for counting successive RF cycles in said RF receiver coil whose amplitudes exceed said percentage to decode received 0 and 1 bits.

23. A transmission system in accordance with claim 22 wherein successive data tokens are transmitted each in the form of X successive bits, with the allowed token values being a subset less than the 2^x possible token values and predominately being those with the fewest 0 bits.

24. A transmission system in accordance with claim 22 wherein said counting means counts a variable number of successive RF cycles for any given number of successive 1 bits utilizing a counting offset during the counting to determine unambiguously the number of successive 1 bits transmitted, said counting means selecting the counting offset to be discarded according to the extent of the coupling between said coils.

25. A transmission system in accordance with claim 23 wherein the X bits of each data token represent Y data bits, where Y<

X, and the Y data bits represented by each data token constitute the information to be communicated by the transmission system.

26. A method for effecting transmission between an RF transmitter coil and an RF receiver coil variably coupled to said transmitter coil, the inter-coil coupling between said receiver and transmitter coils varying between a predetermined maximum and a predetermined minimum dependent upon the specified range of separation between said coils, comprising the steps of applying to said transmitter coil an RF transmission signal, said RF transmission signal representing a first bit value by N successive cycles of an RF carrier signal and representing a second bit value by the suppression of RF carrier transmission for M successive cycles, and operating on the RF signal induced in said receiver coil by counting with a modulo N counting scheme successive cycles of the RF carrier that exceed a detection threshold and off-setting the count with respect to the start of the successive cycles that are to be counted, said offset being a function of said inter-coil coupling.

27. A method in accordance with claim 26 wherein at most one bit of said second value is transmitted between bits of said first value.

28. A method in accordance with claim 26 wherein in said operating step a bit of said second value is registered when a cycle of the RF signal in said receiver coil falls below a detection threshold.

29. A method in accordance with claim 26 wherein M=N.

30. A method in accordance with claim 26 wherein, depending upon said inter-coil coupling, in said operating step a variable number of successive RF cycles for any given number of successive bits of said first value are counted with a counting offset depending upon said inter-coil coupling to determine unambiguously the number of successive 1 bits transmitted.

31. A method in accordance with claim 26 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, and further including the step of tuning said receiver coil to a resonant frequency slightly offset from said RF carrier frequency such that during the transmission time for a bit of said second value the ringing signal in said receiver coil falls out of phase significantly from said RF carrier so that the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver coil to fall below said detection threshold.

32. A method in accordance with claim 26 wherein said receiver coil exhibits an induced oscillation of less than N cycles with amplitudes above said detection threshold due to the transmission of N cycles of said RF carrier.

33. A method in accordance with claim 26 wherein information is transmitted in the form of tokens each of which comprises X bits, each token representing Y data bits where Y<

X, and constraints are imposed on allowable sequences of bits in tokens.

34. A method in accordance with claim 33 wherein in any token at most one bit of said second value may be transmitted between bits of said first value.

35. A method for effecting transmission between an RF transmitter coil and an RF receiver coil variably coupled to said transmitter coil, damping in said receiver coil varying between a predetermined maximum and a predetermined minimum dependent upon the specified range of separation between said coils, comprising the steps of applying to said transmitter coil an RF carrier signal, said RF carrier signal representing a first bit value by N successive cycles and representing a second bit value by the suppression of RF carrier transmission for M successive cycles;

and operating on the RF signal induced in said receiver coil by counting modulo N, with a counting offset depending on the degree of inter-coil coupling, successive cycles of the RF carrier signal in the coil that exceed a threshold value.

36. A method in accordance with claim 35 wherein N and M have values related to the characteristics of said coils and the coupling between said coils is limited to a range such that while a variable number of successive RF cycles may be counted for any given number of successive bits of said first value, the number of successive received bits of said first value may be determined unambiguously.

37. A method in accordance with claim 35 wherein for P successive bits of said first value that follow transmission of a bit of said second value, where P>

1, at least (P-1)N+1 RF cycles are counted.

38. A method in accordance with claim 35 wherein M=N.

39. A method for effecting transmission between an RF transmitter coil and an RF receiver coil coupled to said RF transmitter coil comprising the steps of applying to said RF transmitter coil an RF signal in which a 1 bit is represented by a predetermined number, greater than 2, of cycles of said RF signal and a 0 bit is represented by the absence of a predetermined number, greater than 2, of cycles of said RF signal;

establishing the coupling between said coils such that when the separation of said coils is within prescribed limits the transmission of a single 0 bit between two 1 bits gives rise to at least one RF cycle in said RF receiver coil having an amplitude below a defined percentage of the amplitude of the received RF signal; and

counting successive RF cycles in said RF receiver coil whose amplitudes exceed said percentage to decode received 0 and 1 bits.

40. A method in accordance with claim 39 wherein said RF transmitter and receiver coils are tuned at slightly different frequencies such that, during the transmission of a 0 bit, ringing current in said RF receiver coil changes phase so as to oppose the RF signal received for the next 1 bit.

41. A method in accordance with claim 40 wherein a variable number of successive RF cycles are counted for any given number of successive 1 bits, said counting commencing with a counting offset that is dependent upon said intercoil coupling, to determine unambiguously the number of successive 1 bits transmitted.

42. A method in accordance with claim 40 wherein successive data tokens are transmitted each in the form of X successive bits, with the allowed token values being a subset less than the 2^x possible token values and predominately being those with the fewest 0 bits.

43. A method in accordance with claim 42 wherein the X bits of each data token represent Y data bits, where Y<

X, and the Y data bits represented by each data token constitute the information to be communicated by the transmission system.

44. A method for effecting transmission between an RF transmitter coil and an RF receiver coil coupled to said RF transmitter coil comprising the steps of applying to said RF transmitter coil an RF signal in which a 1 bit is represented by a predetermined number, greater than 2, of cycles of said RF signal, and a 0 bit is represented by the absence of a predetermined number, greater than 2, of cycles of said RF signal;

slightly offsetting the tuning of said RF transmitter and receiver coils such that, during the transmission of a 0 bit, ringing current in said RF receiver coil changes phase so as to oppose the RF signal received for the next 1 bit giving rise to at least one RF cycle in said RF receiver coil having an amplitude below a defined percentage of the amplitude of the received RF signal; and

counting successive RF cycles in said RF receiver coil whose amplitudes exceed said percentage to decode received 0 and 1 bits.

45. A method in accordance with claim 44 wherein successive data tokens are transmitted each in the form of X successive bits, with the allowed token values being a subset less than the 2^x possible token values and predominately being those with the fewest 0 bits.

46. A method in accordance with claim 44 wherein a variable number of successive RF cycles are counted for any given number of P successive 1 bits, said counting commencing with a counting offset that is dependent upon said inter-coil coupling, to determine unambiguously the number P.

47. A method in accordance with claim 45 wherein the X bits of each data token represent Y data bits, where Y<

X, and the Y data bits represented by each data token constitute the information to be communicated by the transmission system.

48. A transmission system comprising an RF transmitter coil;

an RF receiver coil in close wireless proximity to said transmitter coil;

means for applying to said transmitter coil an RF transmission signal representing a first bit value by N successive cycles of an RF carrier frequency and representing a second bit value by the suppression of RF carrier transmission for M successive cycles;

the degree of inter-coil interaction determining the number of cycles of RF carrier frequency induced in said receiver coil in response to the transmission of successive bits of said first value, said inter-coil interaction being affected by inter-coil coupling, inter-coil distance and the Q values of said transmitter and receiver coils; and

means for operating on the RF signal induced in said receiver coil to unambiguously determine the number P of bits of said first value transmitted when the degree of inter-coil interaction is restricted to a predetermined range R'"'"',R*-1!, where R*=R'"'"'+N and R'"'"' is the lowest value of R calculated by R=K-N(P-1)determined by experimentation for preset N and P with variable inter-coil interaction, and K is a count of the number of RF carrier frequency cycles induced in the receiver coil exceeding a detection threshold so that P is determined to be a unique integer satisfying (K+1-R'"'"')/N≦

P≦

(K-R'"'"')/N+1.

49. A transmission system in accordance with claim 48 wherein for P successive bits of said first value that follow transmission of a bit of said second value, where P>

1, K is a unique integer satisfying N(P-1)+R'"'"'≦

K≦

NP+R'"'"'-1.

50. A transmission system in accordance with claim 48 wherein, depending upon said inter-coil coupling, said operating means counts a variable number of successive RF cycles for any given number of successive bits of said first value and ignores a variable number of counted cycles depending upon said inter-coil coupling to determine unambiguously the number of successive transmitted bits of said first value.

51. A transmission system comprising an RF transmitter coil;

an RF receiver coil in close wireless proximity to said transmitter coil;

means for applying to said transmitter coil an RF transmission signal representing a first bit value by N successive cycles of an RF carrier frequency and representing a second bit value by the suppression of RF carrier transmission for M successive cycles;

the degree of inter-coil interaction determining the number of cycles of RF carrier frequency induced in said receiver coil in response to the transmission of successive bits of said first value, said inter-coil interaction being affected by inter-coil coupling, inter-coil distance and the Q values of said transmitter and receiver coils; and

means for operating on the RF signal induced in said receiver coil to unambiguously determine the number P of bits of said first value when the degree of inter-coil interaction is restricted to a predetermined range R'"'"',R*-1!, where R*=R'"'"'+N and R'"'"' is the minimum of a plurality of values of R calculated by R=K-N(P-1) determined by experimentation for preset N and P over a range of several inter-coil interactions, said operating means performing each calculation by (i) discarding the first R'"'"'-1 cycles of the K successive RF cycles induced in said receiver coil, (ii) counting modulo N all remaining cycles of the successive RF cycles, and (iii) determining the number P by generating a flagging event on every modulo N count of 1.

73. A transmission system in accordance with claim 51 wherein for P successive bits of said first value that follow transmission of a bit of said secured value where P>

1, K is a unique integer satisfying N(P-1)30 R'"'"'≦

K≦

NP+R'"'"'-1.

52. A cochlear implant system comprising:

a wearable speech processor for receiving ambient sounds and generating in response a plurality of sequential stimulation signals, each said stimulation signal having a duration, said processor including a transmitter for transmitting said sequential stimulation signals; and

an implantable cochlear stimulator, said stimulator including a receiver for receiving said stimulation signals and a plurality of electrodes for applying said stimulation signals to a patient'"'"'s aural nerve, each stimulation signal being applied for the corresponding duration for said stimulation signal;

wherein said transmitter transmits said sequential stimulation signals as a stream of digital data partitioned into frames, each frame corresponding to one of said stimulation signals, each said frame including data defining characteristics of a following stimulation signal except for the duration of said following stimulation signal, each frame having a frame duration which defines the duration of the current stimulation signal.

53. A cochlear implant system comprising:

an internal stimulator having a receiver, and a plurality of electrodes for applying stimulation to the patient'"'"'s aural nerve; and

an external speech processor for receiving ambient sounds and for generating in response a plurality of processed signals, each processed signal including data defining a duration and at least one other characteristic of a corresponding stimulation signal, said processor including a transmitter for transmitting a sequence of data frames corresponding to each said processed signal, each frame including frame data defining said other characteristic and a frame duration defining the duration of the current stimulation signal.

54. The system of claim 53 wherein said plurality of electrodes are arranged in electrode pairs, and wherein said one characteristic includes a designation of one of said electrode pairs.

55. The system of claim 53 wherein each stimulation signal is defined by an amplitude, a starting electrode and a stimulation mode.

56. The system of claim 53 wherein each frame includes data defining at least one characteristic of the immediately following stimulation signal.

57. The system of claim 53 wherein

said sequence of data frames includes consecutive first and second frames corresponding to consecutive first and second signals wherein said second frame includes data defining at least said one characteristic of said first signal and has a second frame duration which defines the duration of said first signal.

58. A system comprising an RF transmitter and an RF receiver, said transmitter and said receiver both operating on frames having a predetermined format and representing both digital data and time-interval information;

said RF transmitter including means for selectively generating and suppressing RF carrier cycles to represent digital data and to do so within a frame for an overall variable period representative of time-interval information, the RF carrier cycles representative of said digital data being embedded within the overall RF transmission representative of said time-interval information; and

said RF receiver including means for detecting individual carrier cycles in the received RF transmission, means for decoding individually detected carrier cycles to derive digital data, and means for deriving time-interval information from the period required to detect all carrier cycles in the current frame.

59. A system in accordance with claim 58 further including means responsive to digital data and time-interval information derived by said RF receiver for generating an output that is a function of both, each generated output being a function of the time interval information represented in the current frame and the digital data represented in the preceding frame.

60. A system in accordance with claim 59 wherein said output generating means is a cochlear implant, and said RF transmitter and RF receiver are spaced apart by a distance characteristic of a cochlear implant system.

61. A system in accordance with claim 60 wherein said RF transmitter includes a coil and said RF receiver includes a coil variably coupled to said transmitter coil, the extent of nulling of any ringing signal in said receiver coil due to presently transmitted RF cycles varying between a predetermined maximum and a predetermined minimum dependent upon the specified range of separation between said coils;

said generating and suppressing means applies to said transmitter coil an RF transmission signal representing a first bit value by N successive cycles of an RF carrier frequency and representing a second bit value by the suppression of RF carrier transmission for M successive cycles; and

said RF receiver detecting means operates on the RF signal induced in said receiver coil to unambiguously determine the number P of bits of said first value when the degree of inter-coil interaction is restricted to a predetermined range.

62. A system in accordance with claim 61 wherein at most one bit of said second value is transmitted between bits of said first value.

63. A system in accordance with claim 61 wherein said detecting means counts successive RF cycles based upon clock signals derived from the RF carrier transmission.

64. A system in accordance with claim 61 wherein said detecting means flags receipt of a bit of said second value when a cycle of the RF signal in said receiver coil falls below a detection threshold.

65. A system in accordance with claim 61 wherein, depending on the separation between said coils, said detecting means counts a variable number of successive RF cycles as being indicative of any given number of successive bits of said first value.

66. A system in accordance with claim 65 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, said receiver coil is tuned to a resonant frequency slightly offset from said RF carrier frequency such that during the transmission time for a bit of said second value the ringing signal in said receiver coil falls out of phase significantly from said RF carrier, and the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver coil to fall below said detection threshold.

67. A system in accordance with claim 61 wherein said receiver coil may exhibit ringing for a number of cycles exceeding N, said receiver coil is tuned to a resonant frequency such that during the transmission time for a bit of said second value the ringing signal in said receiver coil changes in phase significantly from said RF carrier, and the subsequent receipt of RF cycles representing a bit of said first value causes at least one cycle of the RF signal in said receiver could to fall below said detection threshold.

68. A system in accordance with claim 61 wherein said digital data is transmitted in the form of tokens each of which comprises X bits, each token representing Y data bits where Y<

X, and constraints are imposed on allowable sequences of bits in tokens.

69. A system in accordance with claim 68 wherein in any token at most one bit of said second value may be transmitted between bits of said first value.

70. A transmitter for transmitting variable-duration frames having a predetermined format and representing both digital data and time-interval information comprising means for selectively generating and suppressing RF carrier cycles to represent digital data, and means for transmitting the generated RF carrier cycles within a frame for a period representative of time-interval information, the RF carrier cycles representative of said digital data being embedded within the overall RF transmission representative of said time-interval information.

71. A method of transmitting successive frames, each frame having both analog and digital command information for selected utilization circuits, comprising the steps of transmitting in each frame the analog command information for a first respective utilization circuit and transmitting in each frame the digital command information for a second respective utilization circuit, wherein said second utilization circuit operates on the digital command information conveyed in the previous frame.

72. A method for effecting transmission between an RF transmitter and an RF receiver, said transmitter and said receiver both operating on frames having a predetermined format and representing both digital data and time-interval information, comprising the steps of controlling said RF transmitter to selectively generate and suppress RF carrier cycles to represent digital data and to do so within a frame for an overall variable duration representative of time-interval information, the RF carrier cycles representative of said digital data being embedded within the overall RF transmission representative of said time-interval information;

and detecting in said RF receiver individual carrier cycles in the received RF transmission, decoding individually detected carrier cycles to derive digital data, and deriving time-interval information from the period required to detect all carrier cycles in the current frame.