RECEIVER AND METHOD FOR RETRIEVING AN INFORMATION SIGNAL FROM A MAGNETIC INDUCTION SIGNAL

• US 20120281843A1
• Filed: 05/04/2012
• Published: 11/08/2012
• Est. Priority Date: 05/06/2011
• Status: Active Grant

• Current Assignee: Oticon A/S (William Demant Fonden)
• Original Assignee: Oticon A/S (William Demant Fonden)
• Inventors: CHRISTENSEN, Kåre Tais, JENSEN, Rasmus Glarborg
• Granted Patent: US 9,300,367 B2
• Time in Patent Office: Days
• US Class Current: 381/23.1
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04R 2225/51 Aspects of antennas or their circuitry in or for hearing aids
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils
• CPC Class Codes: H04R 25/558 Remote control, e.g. of amplification, frequency
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A receiving antenna circuit is arranged in a reactive near-field of a modulated magnetic induction signal and forms a narrow band-pass filter. The output of the antenna circuit is not subjected to any frequency translation prior to digitising, and the signal may nevertheless be digitised with low resolution, which radically reduces the power consumption of the receiving circuits. The reduction in power consumption is of several orders of magnitude, which allows implementation of such receiving circuits in battery-driven devices such as hearing devices without substantially affecting the battery life.

Claims

1. A receiver for retrieving an information signal from a magnetic induction signal comprising a carrier signal modulated in dependence on the information signal, the receiver having a signal path comprising:

an antenna circuit adapted to receive the magnetic induction signal and to provide a corresponding electric antenna signal;

an amplifier adapted to amplify the electric antenna signal;

a digitiser adapted to digitise the amplified signal; and

a digital demodulator adapted to retrieve the information signal by demodulating the digitised signal,

characterised in that the antenna circuit forms a narrow band-pass filter and that the receiver is adapted to retrieve the information signal without any frequency translation in the signal path between the antenna circuit and the digitiser.

2. A receiver according to claim 1, wherein the receiver is adapted to retrieve the information signal without any substantial frequency filtering in the signal path between the antenna circuit and the digitiser.

3. A receiver according to claim 1 or 2, wherein the relative 3-dB bandwidth of the antenna circuit is less than 10%, less than 5%, less than 3% or less than 2%.

4. A receiver according to claim 1, wherein the centre frequency of the antenna circuit is below 100 MHz, below 30 MHz or below 10 MHz and/or above 300 kHz, above 1 MHz or above 3 MHz.

5. A receiver according to claim 1, wherein the largest physical extension of the antenna circuit is less than 5 cm, less than 2 cm or less than 1 cm.

6. A receiver according to claim 1, wherein the antenna circuit comprises an antenna coil and one or more tank capacitors and/or one or more resistors.

7. A receiver according to claim 6, further comprising one or more switching means operable to switch different sets of tank capacitors and/or different sets of resistors to the antenna coil, thereby allowing electronically controlled changing of the centre frequency and/or the bandwidth of the antenna circuit.

8. A receiver according to claim 1, wherein the digitiser is adapted to provide a digitised signal with a resolution of 4 bits, 3 bits, 2 bits or one bit.

9. A receiver according to claim 1, wherein the power consumption of the receiver is less than 10 mW, less than 3 mW or less than 1 mW.

10. A receiver according to claim 1, wherein the carrier signal is modulated by phase modulation, frequency modulation, phase-shift keying and/or frequency-shift keying.

11. A hearing device adapted to be arranged at or in an ear of an individual and comprising a receiver according to claim 1.

12. A binaural hearing system comprising a first hearing device according to claim 11 and a second hearing device adapted to be arranged at or in the respective other ear of the individual, the second hearing device comprising a transmitter for transmitting the magnetic induction signal such that the antenna circuit of the first hearing device is within the reactive near-field of the magnetic induction signal when both hearing devices are arranged at or in the respective ears.

13. A hearing system comprising a hearing device according to claim 11 and an auxiliary device adapted to be worn on the body of the individual, the auxiliary device comprising a transmitter for transmitting the magnetic induction signal such that the antenna circuit of the hearing device is within the reactive near-field of the magnetic induction signal when the hearing device is arranged at or in the ear and the auxiliary device is worn on the body.

14. Use of a receiver according to claim 1 for retrieving an information signal from a magnetic induction signal comprising a carrier signal modulated in dependence on the information signal wherein the antenna circuit is arranged within the reactive near-field of the magnetic induction signal.

15. A method for retrieving an information signal from a magnetic induction signal comprising a carrier signal modulated in dependence on the information signal, the method comprising:

receiving the magnetic induction signal in an antenna circuit arranged in the reactive near-field of the magnetic induction signal and providing a corresponding electric antenna signal;

amplifying the electric antenna signal;

digitising the amplified signal; and

retrieving the information signal by digital demodulation of the digitised signal,

characterised in that the antenna circuit functions as a narrow band-pass filter and that the electric antenna signal is not subjected to any frequency translation prior to digitising.