Digital phase-locked loop

Details Digital phase-locked loop Digital phase-locked loop

1987-07-17

1989-07-04

Tarcza, Thomas H.

Communications, electrical: acoustic wave systems and devices

Echo systems

Returned signal used for control

342195, 329122, G01S 968

Patent

active

048456853

ABSTRACT:
A digital phase-locked loop provides substantially real-time measurements of frequency differences between an applied input signal and a reference signal. The system is especially adapted for the measurement of Doppler frequency shift in a Doppler sonar detection system. A two phase clock receives a reference signal and generates complementary clock signals. A phase-frequency detector receives an applied input signal containing a frequency shift and a further reference signal derived and applied in closed loop fashion. Frequency and phase discrepancies between the applied input signal and a second reference signal are gated to a counter to increment the frequency count or blank the frequency count for a predetermined period, thereby to synchronize the second reference signal with the applied input signal in frequency and phase. The frequency difference is detected by counting pulses gated into a divide by N counter thereby to advance or retard the phase of the second reference signal to match the incoming signal under observation. Since no filtering or integration is required, the circuit obtains loop lock within one cycle of the input frequency. An embodiment adapted for pulsed Doppler sonar detection systems employs a secondary counter which is incremented or decremented in accordance with the phase error signal to provide a high resolution low jitter real-time measure of frequency shift.

REFERENCES:
patent: 4077016 (1978-02-01), Sanders et al.
patent: 4145914 (1979-03-01), Newman
patent: 4339731 (1982-07-01), Adams
patent: 4400667 (1983-08-01), Belkin
patent: 4409562 (1983-10-01), Kurihara
patent: 4504799 (1985-03-01), Elmis et al.
patent: 4535459 (1985-08-01), Hogge, Jr.
patent: 4539524 (1985-09-01), Goode
patent: 4594563 (1986-06-01), Williams

Affiliated with

Also associated with

Rating

Digital phase-locked loop does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Digital phase-locked loop, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Digital phase-locked loop will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-857922