Rate locked loop radar timing system

• US 7,551,703 B2
• Filed: 01/30/2006
• Issued: 06/23/2009
• Est. Priority Date: 01/30/2006
• Status: Expired due to Fees

• Current Assignee: Mcewan Technologies LLC
• Original Assignee: Mcewan Technologies LLC
• Inventors: McEwan, Thomas Edward
• Primary Examiner(s): Torres; Juan A
• Application Number:
  US11/343,049
• Publication Number:
  US 20070177704A1
• Time in Patent Office: 1,240 Days
• Field of Search: 375/376
• US Class Current: 375/376
• CPC Class Codes: G01S 7/28 Details of pulse systems
• CPC Class Codes: G04F 10/06 by measuring phase G04F10/005 takes precedence
• CPC Class Codes: H03L 7/0812 and where no voltage or current controlled oscillator is used
• CPC Class Codes: H03L 7/085 concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal H03L7/10 takes precedence; circuits for comparing the phase or frequency of two mutually-independent oscillations H03D13/00
• CPC Class Codes: H03L 7/093 using special filtering or amplification characteristics in the loop H03L7/087 - H03L7/091 take precedence

Abstract

A rate locked loop (RLL) regulates phase slip between two clock signals to provide precision timing for radar, TDR and laser ranging systems. Two clocks having a small mutual frequency offset exhibit a slowing changing relative phase, or phase slip, that produces a stroboscopic time expansion effect in a ranging system. A phase detector converts clock phase to voltage and the voltage is differentiated to provide a rate-of-change signal to a loop controller that precisely regulates the rate-of-phase change. The RLL controls a VCO to produce a constant, linear phase slip having phase errors below the time equivalent of 1-picosecond.

Claims

1. A rate locked loop, comprising:

a frequency source for providing a first and second clock signal and further comprising a phase control, wherein the phase control adjusts the phase between the clock signals,

a phase detector responsive to the phase between the first and second clock signals for producing a phase detector output proportional to phase,

a differentiator having an output proportional to the derivative of the phase detector output to produce a derivative signal; and

a controller responsive to the derivative signal for producing a feedback signal to the phase control, wherein the first and second clock signals provide timing for a pulse-echo rangefinder.

2. The circuit of claim 1 wherein the frequency source comprises a reference oscillator to provide the first clock signal and a voltage controlled oscillator (VCO) having a frequency/phase control to provide the second clock signal.

3. The circuit of claim 1 wherein the frequency source comprises a reference oscillator to provide the first clock signal and a phase adjuster coupled to the reference oscillator to provide the second clock signal, wherein the phase adjuster further comprises a phase control.

4. The circuit of any of claims 1-3 further comprising producing a feedback signal to the phase control to produce a constant phase slip between the first and second clock signals.

5. The circuit of any of claims 1-3 wherein the second clock signal is harmonically related to the first clock signal.

6. A method for generating clock signals having a relative phase slip, comprising:

generating a first clock frequency,

generating a second clock frequency,

detecting the phase between the first and second clock frequencies to produce a phase signal,

differentiating the phase signal to produce a derivative signal; and

controlling the second clock phase using the derivative signal to produce a controlled phase slip.

7. The method of claim 6 wherein producing a controlled phase slip further comprises producing a controlled clock phase having a substantially constant rate of change in phase.

8. The method of claims 6 or 7 further comprising generating a second clock frequency at a harmonic of the first clock frequency.

9. A radar, laser or TDR ranging system comprising:

a transmitter triggered by a first clock signal,

a receiver gated by a second clock signal,

a phase detector responsive to phase between the first and second clock signals for producing a phase signal,

a differentiator for producing a derivative signal from the phase signal,

a phase control for adjusting the phase of the second clock signal; and

a controller responsive to the derivative signal for producing a feedback control signal to the phase control.

10. The system of claim 9 wherein the second clock signal is provided by a VCO having a frequency/phase control port.

11. The system of claim 9 wherein the second clock signal is provided by a phase adjuster coupled to the first clock signal, the phase adjuster further comprising a phase control.

12. The system of any of claims 9-11 wherein producing a feedback control signal to the phase control further comprises producing a feedback control signal to the phase control to produce a constant phase slip between the first and second clock signals.

13. The system of claims 9 or 10 further comprising a second clock signal that is harmonically related to the first clock signal.