Method and apparatus for multipath signal detection, identification, and monitoring for wideband code division multiple access systems

• US 20020127987A1
• Filed: 03/12/2002
• Published: 09/12/2002
• Est. Priority Date: 03/12/2001
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Kent, Mark
• Granted Patent: US 7,110,725 B2
• Time in Patent Office: Days
• US Class Current: 455/255
• CPC Class Codes: H04W 52/029 reducing the clock frequency of the controller
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods to generate a mobile time reference are provided. A representative method includes providing a high frequency clock, providing a low frequency clock, generating a mobile time reference using the high frequency clock, maintaining the mobile time reference using the low frequency clock when the high frequency clock is turned off, and continuing to generate the mobile time reference using the high frequency clock when the high frequency clock has been turned back on. Systems and other methods are also provided.

Claims

1. A method of providing a mobile time reference in a portable transceiver system, comprising:

providing a high frequency clock;

providing a low frequency clock;

generating a mobile time reference using the high frequency clock;

maintaining the mobile time reference using the low frequency clock when the high frequency clock is not available; and

continuing to generate the mobile time reference using the high frequency clock when the high frequency clock is available.

2. The method of claim 1, wherein the mobile time reference includes at least one of a clock-phase, a chip-counter, a slot-counter, and a frame-counter.

3. The method of claim 1, wherein the high frequency clock is generated by a temperature controlled crystal oscillator.

4. The method of claim 1, wherein the high frequency clock provides a signal of at least 30 MHz.

5. The method of claim 1, wherein the mobile time reference has an accuracy of at least 32 nanoseconds.

6. The method of claim 1, wherein the low frequency clock is generated by a crystal oscillator.

7. The method of claim 1, wherein the low frequency clock provides a 32 KHz signal.

8. The method of claim 1, further comprising estimating the drift of the low frequency clock.

9. The method of claim 8, wherein maintaining the mobile time reference includes counting the cycles of the low frequency clock and adding in the drift estimate.

10. A portable transceiver system comprising:

an antenna;

a radio frequency subsystem coupled to the antenna and including a high frequency oscillator and a low frequency oscillator; and

a baseband subsystem coupled to the radio frequency system and including a free running counter coupled to the high frequency oscillator and the low frequency oscillator;

the free running counter providing a mobile time reference to the system and having an active mode and an idle mode, during the active mode the free running counter uses the high frequency oscillator to generate the mobile time reference, and during the idle mode the free running counter uses the low frequency oscillator to maintain the mobile time reference.

11. The system of claim 10, wherein the high frequency oscillator is a temperature controlled crystal oscillator.

12. The system of claim 11, wherein the temperature controlled crystal oscillator provides a 30.72 MHz clock signal.

13. The system of claim 10, wherein the low frequency oscillator is a crystal oscillator.

14. The system of claim 13, wherein the crystal oscillator provides a 32 KHz clock.

15. The system of claim 10, wherein the baseband subsystem includes a multipath monitor and the mobile time reference is provided to the multipath monitor.

16. The system of claim 10, wherein the baseband subsystem includes a multipath signal recovery circuit and the mobile time reference is provided to the multipath signal recovery circuit.

17. The system of claim 10, wherein the mobile time reference is constantly available.

18. The system of claim 10, wherein the mobile time reference has an accuracy of at least 32 nanoseconds.

19. The system of claim 10, wherein the free running counter includes a phase locked loop coupling the low frequency oscillator to the high frequency oscillator.

20. The system of claim 10, wherein the free running counter includes a drift estimator for the low frequency oscillator.