Title: Navigation receiver system for synchronizing to noisy, asymmetrical signals

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Claims: What is claimed is:

1. In a navigation receiver, a system for consistently phase synchronizing to a predetermined position of received navigation signals comprising:

means for receiving navigation signals to provide a first signal having a plurality of cycles;

means for generating a second signal having a plurality of cycles which are adjustable in phase in response to a control;

means for detecting relative timing between a predetermined point on said second signal and a predetermined point on said first signal on a first slope thereof to provide a first early/late signal indicative of relative timing and for detecting relative timing between a further predetermined point on said second signal and a further predetermined point on said first signal on a second slope thereof opposite to said first slope to provide a second early/late signal indicative of relative timing; and

means for developing said control in response to said first and second early/late signals to produce an adjustment of the phase of said second signal representative of each said early/late signal in which said first and second signals are synchronized with the predetermined and further predetermined points on said second signal having a set relationship to said predetermined and further predetermined points on said first and second slopes of said first signal.

2. The synchronizing system of claim 1 wherein said first signal is a noisy, asymmetrical, limited signal.

3. The synchronizing system of claim 1 wherein said second signal has a substantially longer period than said first signal to limit the detection of effects from a single disturbance in said first signal.

4. The synchronizing system of claim 3 wherein said first and second signals are generally related by an odd harmonic relationship.

5. The synchronizing system of claim 1 wherein said predetermined points of first and second slopes are rising and falling edges of said first signal.

6. In an Omega navigation receiver, a system for synchronizing an internally generated signal to received Omega broadcasts including:

means for receivingg Omega braodcasts to provide a generally asymmetrical, hard limited signal for each received station with noise variations in the rising and falling edges thereof having a distribution which exceeds the variations in said edges due to asymmetry;

A plurality of tracking loops each asociated with an Omega station broadcast and one of said internally generated signals with a substantially longer period than said hard limited signal, the period of said hard limited signal being an odd harmonic of said internally generated signal period;

means for comparing a plurality of falling edges of said hard limited signal for each uninterrupted Omega station broadcast with a predetermining point of the internally generated signal from a corresponding tracking loop to develop a plurality of first control signals indicating the relative timing of each falling edge with respect to the predetermined point, and for comparing a plurality of rising edges of said hard limited signal in alternating sequence with the compared falling edges for each uninterrupted Omega station broadcast with a further predetermined point of that internally generated signal to develop a plurality of second control signals indicating the relative timing of each rising edge with respect to the further predetermined point; and means for controlling each tracking loop to adjusting the phasing of each corresponding internally generated signal in response to each corresponding first and second control signal whereby the corresponding hard limits signals and internally generated signals become synchronized with the predetermined and further predetermined points of the internally generated signal separated from respective falling and rising edges of said hard limited signal by substantially equal time intervals.

Other info:

Inventors: Zitzow, Harold P. (Reading, MA, US)
Marshall, Alan C. (Framingham, MA, US)

Application Number: 366023
Filing Date: 1973-06-01
Publication_date: 1976-04-13
Assignee: EPSCO, Incorporated (Westwood, MA)
Primary Class(es): 342/396 324/76.79
Other Classes:
US Patent Ref:

2814725	Nov, 1957	Jacobs et al.	324/83.
3573828	Apr, 1971	Hawley	343/105.
3689925	Sep, 1972	Hulland	343/105.

Other Refs:
Primary Examiner: Wilbur, Maynard R.
Assistant Examiner: Montone, Gregory E.
Attorney: Weingarten, Maxham & Schurgin