METHOD OF IMPROVING SENSITIVITY AND INTERFERENCE REJECTION IN WIRELESS RECEIVERS

• US 20110028113A1
• Filed: 07/23/2010
• Published: 02/03/2011
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: Microsemi Semiconductor AB (Microchip Technology Incorporated)
• Original Assignee: Zarlink Semiconductor Inc. (Microchip Technology Incorporated)
• Inventors: Karlsson, Magnus, Bradley, Peter
• Granted Patent: US 8,711,979 B2
• Time in Patent Office: Days
• US Class Current: 455/296
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04B 17/373 Predicting channel quality or other radio frequency [RF] parameters

Abstract

A wireless receiver for receiving a signal with a characteristic pattern includes a predictor for predicting the presence of a non-zero value of the characteristic pattern. A tracker tracks a noise component in the received signal between predicted non-zero values. The resulting noise component is subtracted from the received signal to output a processed signal, which is then decoded by a pattern discriminator and demodulator. The wireless receiver is less sensitive to noise and interference.

Claims

1. A wireless receiver for receiving an RF signal with an asynchronous characteristic pattern, comprising:

a pattern discriminator for detecting the characteristic pattern in the received signal in an asynchronous mode;

a predictor for predicting the presence of a non-zero value of a subsequently received portion of the signal in pseudo synchronous mode;

a tracker for tracking a noise component in the received signal between predicted non-zero values;

a subtractor for subtracting the noise component from the received signal to output a processed signal; and

a demodulator for demodulating the processed signal.

2. A wireless receiver as claimed in claim 1, wherein the received signal is pulse encoded, and the predictor predicts the times between the pulses of the pulse encoded signal.

3. A wireless receiver as claimed in claim 2, wherein the pulse encoded signal is position pulse encoded.

4. A wireless receiver as claimed in claim 3, wherein the predictor is a time-based predictor that predicts when a pulse is to be expected based on said signal pattern.

5. A wireless receiver as claimed in claim 1, wherein the tracker comprises a filter controlled by the predictor to track the noise between pulses.

6. A wireless receiver as claimed in claim 5, further comprising an adaptive sensitivity controller for dynamically adjusting the sensitivity of the receiver in accordance with the reception conditions.

7. A wireless receiver as claimed in claim 6, wherein the sensitivity controller is configured to activate the receiver periodically for a defined time, and if no valid signal is received during this defined time, to stepwise increase the sensitivity if a predetermined maximum threshold sensitivity has not been reached.

8. A wireless receiver as claimed in claim 7, wherein the sensitivity controller is configured to stepwise decrease the sensitivity when a valid signal pattern is detected.

9. A wireless receiver as claimed in claim 1, which is an ultra low power duty cycled receiver.

10. A method of enhancing sensitivity and interference rejection in an ultra low power duty cycled receiver responsive to an RF signal with an asynchronous characteristic signal pattern, comprising:

detecting the presence of the asynchronous characteristic pattern in an asynchronous mode;

predicting the presence of a non-zero value in a subsequently received portion of the signal in a pseudo-synchronous mode;

tracking a noise component in the received signal between predicted non-zero values;

subtracting the noise component from the received signal to output a processed signal; and

demodulating the processed signal.

11. A method as claimed in claim 10, wherein the received signal is pulse encoded, and the noise component is predicted between the pulses of the pulse encoded signal.

12. A method as claimed in claim 11, wherein the pulse encoded signal is position pulse encoded.

13. A method as claimed in claim 10, further comprising dynamically adjusting the sensitivity of the receiver in accordance with the reception conditions.

14. A method as claimed in claim 10, wherein the receiver is periodically activated for a defined time, and if no valid signal is received during this defined time, the sensitivity is stepwise increased if a predetermined maximum threshold sensitivity has not been reached.

15. A method as claimed in claim 14, wherein the sensitivity stepwise decreased when a valid signal pattern is detected.

16. A method as claimed in claim 10, wherein the receiver is an ultra low power duty cycled receiver.

17. A method as claimed in claims 10, which is applied in a medial application.

18. A method as claimed in claim 10, which is applied to an implanted or body worn medical device.