Transbody communication systems employing communication channels

1. A communication system characterized by an uncertainty in a first frequency of a signal from an ingestible transmitter, the system comprising:

the ingestible transmitter comprising:

a silicon chip comprising:

an integrated circuit;

a first surface coated with a first digestible material; and

a second surface coated with a second digestible material, wherein the first and second digestible materials power the integrated circuit while being digested; and

an oscillator comprising a conductor, a resistor, a capacitor, and a transistor, the oscillator configured to produce the first frequency that varies within a range of plus or minus 1% from a target frequency when the oscillator is ingested;

wherein the ingestible transmitter is configured to transmit the signal, the signal comprising, according to a communication protocol, a beacon channel at the first frequency and a message channel at a second frequency that is related to the first frequency by a first fixed ratio; and a receiver comprising:

one or more electrodes configured to detect the signal, and

a processor configured to:

determine the first frequency associated with the signal;

determine the second frequency associated with the signal; and

compute a first computed ratio between the first detected frequency and the second detected frequency.

2. The system of claim 1 , wherein the oscillator is a silicon oscillator.

3. The system of claim 1 , wherein the signal is a conductive signal that is transmitted by the ingestible transmitter to the receiver via body fluids.

4. The system of claim 1 wherein the ingestible transmitter is further configured to transmit the signal that further comprises, according to the communication protocol:

a first arrival time of the first frequency;

a second arrival time of the second frequency; and

a second fixed ratio comparing the first arrival time to the second arrival time.

5. The system of claim 4 , wherein the processor is further configured to:

determine the first arrival time of the first frequency;

determine the second arrival time of the second frequency; and

compute a second computed ratio of the first arrival time to the second arrival time.

6. The system of claim 5 , wherein the processor is further configured to:

compare the computed first ratio to the first fixed ratio;

compare the computed second ratio to the fixed second ratio; and

compute an estimate of the first and second frequencies using the comparisons of the computed and fixed ratios.

7. A method of a communication system characterized by a large uncertainty in a carrier frequency from an ingestible transmitter, the system comprising the ingestible transmitter and a receiver, the method comprising:

transmitting a conductive signal through a living body, by the ingestible transmitter after it has been ingested, the signal comprising, according to a communication protocol:

a beacon channel at a first frequency that varies within a range of plus or minus 1% from a target frequency during transmission of the signal, wherein the variance is uncertain to the receiver; and

a message channel at a second frequency that is related to the first frequency by a first fixed ratio;

determining, by the receiver, the first frequency;

determining, by the receiver, the second frequency; and

computing, by the receiver, a first computed ratio between the first determined frequency and the second determined frequency.

8. The method of claim 7 , wherein the ingestible transmitter transmits the signal using a silicon oscillator.

9. The method of claim 8 , wherein the silicon oscillator comprises a conductor, a resistor, a capacitor, and a transistor.

10. The method of claim 7 , wherein the conductive signal is transmitted by the ingestible transmitter to the receiver via body fluids.

11. The method of claim 7 , wherein transmitting the signal, by the ingestible transmitter, further comprises transmitting, according to the communication protocol:

a first arrival time of the first frequency;

a second arrival time of the second frequency; and

a second fixed ratio comparing the first arrival time to the second arrival time.

12. The method of claim 11 , further comprising:

determining, by the receiver, a first arrival time of the first frequency;

determining, by the receiver, a second arrival time of the second frequency; and

computing, by the receiver, a second computed ratio of the first the arrival time to the second arrival time.

13. The method of claim 12 , further comprising:

comparing, by the receiver, the computed first ratio to the first fixed ratio;

comparing, by the receiver, the computed second ratio to the fixed second ratio; and

computing, by the receiver, an estimate of the first and second frequencies using the comparisons of the computed and fixed ratios.

14. A method of a receiver of a communication system characterized by a large uncertainty in a carrier frequency from an ingestible transmitter, the method comprising:

receiving a conductive signal through a living body, the signal comprising, according to a communication protocol:

a beacon channel at a first frequency that varies within a range of plus or minus 1% from a target frequency during transmission of the signal, wherein the variance is uncertain to the receiver; and

a message channel at a second frequency that is related to the first frequency by a first fixed ratio;

determining the first frequency;

determining the second frequency; and

computing a first computed ratio between the first determined frequency and the second determined frequency.

15. The method of claim 14 , wherein the signal is transmitted using a silicon oscillator.

16. The method of claim 15 , wherein the silicon oscillator comprises a conductor, a resistor, a capacitor, and a transistor.

17. The method of claim 14 , wherein the conductive signal is transmitted by the ingestible transmitter to the receiver via body fluids.

18. The method of claim 14 , wherein receiving the signal further comprises receiving, according to the communication protocol:

a first arrival time of the first frequency;

a second arrival time of the second frequency; and

a second fixed ratio comparing the first arrival time to the second arrival time.

19. The method of claim 18 , further comprising:

determining the first arrival time of the first frequency;

determining the second arrival time of the second frequency; and

computing a second computed ratio of the first the arrival time to the second arrival time.

20. The method of claim 19 , further comprising:

comparing the computed first ratio to the first fixed ratio;

comparing the computed second ratio to the fixed second ratio; and

computing an estimate of the first and second frequencies using the comparisons of the computed and fixed ratios.