US4855689A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase lock loop with switchable filter for acquisition and tracking modes
Assignee: Raytheon Co
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Filing: 1987-02-13
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Granted: 1989-08-08
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Expires: 2007-02-13
Abstract
Abstract A phase lock loop for use in carrier acquisition employing a predetection filter and a loop filter switchable between a constant phase margin and second order characteristic. In the acquisition mode, the constant phase margin characteristic is employed to acquire the carrier and the second order characteristic is thereafter employed to track the carrier. The second order characteristic retains only the pole at the origin and the lowest frequency zero of the constant phase margin characteristic. The filter parameters are selected to minimize the mean square deviation of a phase margin expression which includes contributions from the predetection filter pole and from positive poles generated by the loop's voltage controlled oscillator. The loop filter is further provided with gain coefficients selected to maximize the probability of carrier acquistion at a plurality of frequencies and carrier to noise density ratios.
Inventors
- 👤 John F. Kinkel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:32
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/10; H03L7/12; H03L7/085; H03L7/093; Y; Y10; Y10S; Y10S331/00; Y10S331/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
53 words
In a phase lock loop including a phase detector and voltage controlled oscillator (VCO), the improvement comprising: a loop filter means connected between said phase detector and voltage controlled oscillator for switching between a constant phase margin filter in a carrier acquisition mode and a second order filter in a carrier tracking mode.
Claim 2
Dependent Claim
53 words
In a phase lock loop including a phase detector and voltage controlled oscillator (VCO), the improvement comprising: a loop filter means connected between said phase detector and voltage controlled oscillator for switching between a constant phase margin filter in a carrier acquisition mode and a second order filter in a carrier tracking mode.
Claim 3
Dependent Claim
24 words
The phase lock loop of claim 1, wherein said second order filter and said constant phase margin filter share a common pole and zero.
Claim 4
Dependent Claim
57 words
The phase lock loop of claim 2 wherein the constant phase margin filter includes at least one pole and zero in addition to said common pole and zero and wherein said one pole and zero are selected to minimize the mean square deviation of a phase margin expression from a desired value over a selected frequency range.
Claim 5
Dependent Claim
38 words
The phase lock loop of claim 3 further including a predetection filter having a pole and connected between said loop filter means and said VCO wherein said phase margin expression contains a contribution from the predetection filter pole.
Claim 6
Dependent Claim
22 words
The phase lock loop of claim 4 wherein said phase margin expression further includes a contribution from at least one parasitic pole.
Claim 7
Dependent Claim
50 words
The phase lock loop of claim 5 wherein said loop is used in carrier frequency acquisition, wherein said loop filter means has a gain coefficient and wherein said gain coefficient is selected to maximize the probability of carrier acquisition at a plurality of frequencies and carrier to noise density ratios.
Claim 8
Dependent Claim
23 words
The phase lock loop of claim 6 wherein said gain coefficient is selected to yield a steady state tracking error of π/8 radians.
Claim 9
Dependent Claim
20 words
The phase lock loop of claim 6 wherein said phase margin expression includes contributions from first and second parasitic poles.
Claim 10
Dependent Claim
31 words
The phase lock loop of claim 6 wherein the selected frequency range extends from twice the frequency of said common zero to one half the frequency of the predection filter pole.
Claim 11
Dependent Claim
19 words
The phase lock loop of claim 8 wherein said first and second parasitic poles are generated by said VCO.
Claim 12
Dependent Claim
56 words
A loop filter for a phase lock loop comprising: first filter means exhibiting a constant phase characteristic for acquiring a carrier; second filter means exhibiting a second order filter characteristic for tracking the carrier; and means for switching from said first filter means to said second filter means upon detection of phase locking to said carrier.
Claim 13
Dependent Claim
56 words
A loop filter for a phase lock loop comprising: first filter means exhibiting a constant phase characteristic for acquiring a carrier; second filter means exhibiting a second order filter characteristic for tracking the carrier; and means for switching from said first filter means to said second filter means upon detection of phase locking to said carrier.
Claim 14
Dependent Claim
53 words
The loop filter of claim 11 wherein said first filter means comprises: an operational amplifier means having an inverting input and an output; a first resistance connected to said inverting input; and a constant phase network connected in the feedback path from the output to the inverting input of said operational amplifier means.
Claim 15
Dependent Claim
77 words
The loop filter of claim 12 wherein said constant phase network comprises: first, second and third capacitors each having a first terminal connected to said output and a second terminal; and first, second and third resistors each having a first terminal connected to a second terminal of a respective one of said first, second and third capacitors and a second terminal, the second terminals of said first, second and third resistors being connected to said inverting input.
Claim 16
Dependent Claim
49 words
The loop filter of claim 13 further including a second resistance and wherein said switch means comprises means for switching said inverting input to substitute said second resistance for said first resistance and to remove said second and third capacitors and second and third resistors from said loop filter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-07 | 1993-02-06 | 1993-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-07 | 1997-02-06 | 1997-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-07 | 2001-02-06 | 2001-08-08 | $7700.00 | Window Closed / Lapsed |