Electromagnetic induction field communication
Consistent with an example embodiment there is an electromagnetic induction field communication system, illustratively, for communicating on or around the body. Two transceivers (or receiver and transmitter) contain coils and capacitors suitable for generating an electromagnetic induction field surrounding the body and are capable of communicating therebetween.
1. A communication system comprising:
a transmitter located at a first position on a living body, the transmitter having:
a first coil,
a first capacitor having first and second plates, said first capacitor connected in parallel with said first coil, said first plate being coupled to the living body at the first position and said second plate being configured to be exposed to an environment, and
a signal generator configured to produce a communication signal used to provide current to said first coil to generate a magnetic near field and to provide voltage to said first capacitor to generate an electric near field, wherein said electric near field is coupled to and available around the living body; and
a receiver located at a second position on the living body distant from the first position, the receiver having:
a second coil configured to receive said magnetic near field, wherein said magnetic near field passes through the living body, and
a second capacitor, configured to receive said electric near field available around the living body, said second capacitor having third and fourth plates, said second capacitor connected in parallel with said second coil, said third plate being coupled to the living body at the second position and said fourth plate being exposed to the environment, there being no galvanic connection between said transmitter and ground or between said receiver and ground.
2. The communication system of claim 1 , further comprising: a tuning capacitor in said transmitter configured to tune the first coil and the first capacitor to resonate at a desired operational frequency.
3. The communication system of claim 1 , further comprising: a tuning capacitor in said receiver configured to tune the second coil and the second capacitor to resonate at a desired operational frequency.
4. The communication system of claim 1 , wherein said transmitter is a first transceiver.
5. The communication system of claim 4 , wherein the receiver is a second transceiver.
6. The communication system of claim 5 , wherein the first transceiver and the second transceiver are configured for bidirectional communication.
7. The communication system of claim 1 , wherein said transmitter is included in a hearing aid.
8. The communication system of claim 7 , wherein the receiver is included in the hearing aid.
9. The communication system of claim 1 , in which said transmitter and receiver are tuned in accordance with said living body's capacitance to effect communication.
10. The communication system of claim 1 , further comprising:
a wireless control unit configured to be held by the hand, wherein the wireless-control unit is configured to communicate with either said receiver or said transmitter via a combination of said magnetic near field and said electric near field.
11. The communication system of claim 10 , wherein said wireless control unit has a third capacitor with two plates, a first plate of said two plates is configured for contact with said living body, and a second plate of said two plates is exposed to the environment.
12. The communication system of claim 10 , wherein said wireless control unit has a display.
13. The communication system of claim 1 , wherein the receiver is configured to sense the communication signal via both the magnetic near field and the electric near field respectively received on the second coil and the second capacitor.
14. The communication system of claim 1 , wherein the signal generator comprises a first source coupled to a first terminal of the first coil and a second source coupled to a second terminal of the first coil.
15. The communication system of claim 14 , wherein the first and second sources are configured to generate a balanced voltage across the first coil.
16. A communication system transceiver comprising:
a transmitter located at a first position on a living body, the transmitter comprising:
a first coil;
a first capacitor having a first plate and a second plate, the first capacitor connected in parallel with the first coil, the first plate placed in closer proximity to the living body than the second plate; and
a signal generator configured to produce a generated communication signal used to provide current to the first coil to produce a generated magnetic near field and to provide voltage to the first capacitor to produce a generated electric near field; and
a receiver configured to communicate with another transceiver located at a second position on the living body distant from the first position, the receiver comprising:
a second coil configured to sense a received magnetic near field; and
a second capacitor having a first plate and a second plate, the second capacitor connected in parallel with the second coil, the first plate of the second capacitor placed in closer proximity to the living body than the second plate of the second capacitor, the second capacitor configured to sense a received electric near field,
wherein the transmitter further comprises a third capacitor, the third capacitor having a value selected to tune a desired operational frequency of the first coil and first capacitor based on a capacitance value of the first capacitor; and
wherein the receiver further comprises a fourth capacitor, the fourth capacitor having a value selected to tune a desired operational frequency of the second coil and second capacitor based on a capacitance value of the second capacitor.
17. The communication system transceiver of claim 16 , wherein a dielectric portion of the first capacitor includes the living body.
18. The communication system transceiver of claim 17 , wherein a dielectric portion of the second capacitor includes the living body.
19. The communication system transceiver of claim 16 , wherein the receiver is configured to detect a received communication signal via both the received magnetic near field and the received electric near field respectively sensed by the second coil and the second capacitor.