Precision reference generation system and method

• US 6,377,585 B1
• Filed: 06/05/1998
• Issued: 04/23/2002
• Est. Priority Date: 06/05/1998
• Status: Expired due to Term

• Current Assignee: Microsemi Frequency And Time Corporation
• Original Assignee: Datum Incorporated (Microchip Technology Incorporated)
• Inventors: Funderburk, Richard E., Ott, Christopher C.
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): SHAND, ROBERTA A
• Application Number:
  US09/092,452
• Time in Patent Office: 1,418 Days
• Field of Search: 370/343, 370/335, 370/441, 370/479, 370/516, 375/142, 375/205, 375/373, 375/376, 375/371, 375/355, 375/364
• US Class Current: 370/441
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception

Abstract

An apparatus for generating a precision frequency includes a receiver that tracks a CDMA pilot signal and extracts frequency and phase information. This information is then used by a processor to control a precision oscillator. The precision oscillator generates a precise frequency based on the CDMA pilot signal. Time of day information is also extracted by the receiver and processor.

Claims

1. An apparatus for precision frequency reference generation, comprising:

means for receiving CDMA pilot signals and providing a phase and a frequency of the pilot signal;

means for differencing connected to the means for receiving for computing a difference between the phase and a phase of a corrected frequency signal to produce a difference signal;

means for processing connected to the means for differencing for processing the frequency to produce a control signal and a timing signal;

means for oscillating connected to the means for processing for generating the corrected frequency signal based upon the control signal.

2. The apparatus of claim 1, wherein the means for processing comprises:

a low-pass filter for filtering the difference signal and the frequency to produce a filter signal; and

a lead-lag filter connected to the low-pass filter for filtering the filter signal to generate the control signal.

3. The apparatus of claim 1, wherein the means for oscillating generates the corrected frequency signal by direct manipulation of a high stability oscillator through an electrical tuning input.

4. The apparatus of claim 1, wherein the means for oscillating generates the corrected frequency signal by direct digital frequency synthesis.

5. The apparatus of claim 1, wherein the means for oscillating generates the corrected frequency signal by full analog frequency synthesis.

6. A method for generating a precision frequency reference, comprising the steps of:

receiving CDMA pilot signals and providing a phase and a frequency of the pilot signal;

calculating a difference between the phase and a phase of a corrected frequency signal to produce a difference signal;

processing the frequency to produce a control signal and a timing signal; and

generating the corrected frequency signal based upon the control signal.

7. The method of claim 6, further comprising the steps of:

processing the phase and the frequency of the CDMA pilot signals with the corrected frequency signal to produce the control signal and the timing signal; and

generating the corrected frequency signal by comparing the timing signal to a signal generated by an oscillator.

8. The method of claim 7, wherein the oscillator generates the corrected frequency signal by direct manipulation of a high stability oscillator through an electrical tuning input.

9. The method of claim 7, wherein the oscillator generates the corrected frequency signal by direct digital frequency synthesis.

10. The method of claim 7, wherein the oscillator generates the corrected frequency signal by full analog frequency synthesis.