US3916320A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Loran receiver signal canceller
Assignee: Johns Hopkins University
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Filing: 1974-06-07
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Granted: 1975-10-28
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Expires: 1994-06-07
Abstract
Abstract A signal canceller for use in the RF section of a Loran receiver, for example. Three basic feedback loops, each utilizing a phase comparator, operate with a differential amplifier to effectively cancel an undesired signal. An existing Loran navigation control computer is used with sample and hold devices in each loop to allow accurate and continuous cancelling of an undesired signal in the presence of a desired signal with no degradation of the desired signal and no attendant effect on the cancelling loop signal by the desired signal.
Inventors
- 👤 Ronald G Roll
- 👤 Jr Henry H Elliott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:38
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02; G01S1/08; G01S1/20; G01S1/24; G01S1/245
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
268 words
A signal canceller for removing an undesired signal from a received composite signal containing said undesired signals and pulses of a known rate of occurrence, said signal canceller being responsive to apparatus which demarcates when a pulse is and is not occurring within said composite signal and comprising: first circuit means responsive to said composite signal and said pulse demarcating apparatus and rendered effective when a pulse is not occurring in said composite signal for producing a signal whose phase and frequency correspond continuously to the phase and frequency of said undesired signal within said composite signal, said first circuit means including holding means capable when rendered effective for holding constant the phase and frequency of said produced signal, comparator means responsive to said composite signal and said signal produced by said first circuit means for producing a difference signal representing the difference in amplitudes of said composite signal and said signal produced by said first circuit means, and second circuit means responsive to said difference signal and said pulse demarcating apparatus and rendered effective when a pulse is not occurring in said composite signal for adjusting the amplitude of said signal produced by said first circuit means to equal the amplitude of the composite signal, said second circuit means including holding means capable when rendered effective for holding constant the amplitude of said produced signal, said holding means of said first and second circuit means being rendered effective each time a pulse occurs within said composite signal for holding constant during each pulse the amplitude, phase and frequency of said signal produced by said first circuit means.
Claim 2
Dependent Claim
268 words
A signal canceller for removing an undesired signal from a received composite signal containing said undesired signals and pulses of a known rate of occurrence, said signal canceller being responsive to apparatus which demarcates when a pulse is and is not occurring within said composite signal and comprising: first circuit means responsive to said composite signal and said pulse demarcating apparatus and rendered effective when a pulse is not occurring in said composite signal for producing a signal whose phase and frequency correspond continuously to the phase and frequency of said undesired signal within said composite signal, said first circuit means including holding means capable when rendered effective for holding constant the phase and frequency of said produced signal, comparator means responsive to said composite signal and said signal produced by said first circuit means for producing a difference signal representing the difference in amplitudes of said composite signal and said signal produced by said first circuit means, and second circuit means responsive to said difference signal and said pulse demarcating apparatus and rendered effective when a pulse is not occurring in said composite signal for adjusting the amplitude of said signal produced by said first circuit means to equal the amplitude of the composite signal, said second circuit means including holding means capable when rendered effective for holding constant the amplitude of said produced signal, said holding means of said first and second circuit means being rendered effective each time a pulse occurs within said composite signal for holding constant during each pulse the amplitude, phase and frequency of said signal produced by said first circuit means.
Claim 3
Dependent Claim
75 words
The apparatus of claim 1 further comprising: third circuit means responsive to said signal produced by said first circuit means for producing a signal to hold said signal produced by said first circuit at a constant level, and means operably connected to said third circuit means and rendered effective each time a pulse occurs within said composite signal for holding constant during each pulse the amplitude of said signal produced by said third circuit means.
Claim 4
Dependent Claim
16 words
The apparatus of claim 1 wherein said first circuit means comprises a phase lock loop circuit.
Claim 5
Dependent Claim
102 words
The apparatus of claim 3 wherein said phase lock loop comprises: phase comparator means having a first input connected to receive said composite signal and a second input connected to receive a feedback signal for producing a phase difference signal representing the difference in phase between said composite signal and said feedback signal, integrator means connected to receive said phase difference signal from said phase comparator means for producing an integrated output signal therefrom, and voltage controlled oscillator means connected to receive said integrated signal for producing said feedback signal having a frequency proportional to the amplitude of said integrated output signal.
Claim 6
Dependent Claim
13 words
The apparatus of claim 1 wherein said comparator means comprises a differential amplifier.
Claim 7
Dependent Claim
32 words
The apparatus of claim 2 wherein said means operably connected to said first and second circuit means and said means operably connected to said third circuit means comprise sample and hold devices.
Claim 8
Dependent Claim
130 words
The apparatus of claim 6 wherein said second circuit means comprises an ampliTude control loop including second phase comparator means having a first input connected to receive said difference signal and a second input connected to receive said signal from said first circuit means for producing a signal representing the difference in phase of said difference signal and said signal from said first circuit means, integrator means connected to receive said phase difference signal from said phase comparator means for producing an integrated output signal therefrom, and variable gain attenuator means having a first input connected to receive said signal produced by said first circuit means and a second input connected to receive said integrated output signal for adjusting the amplitude of said signal produced by said first circuit means.
Claim 9
Dependent Claim
155 words
The apparatus of claim 7 wherein said third circuit means comprises an automatic gain control loop including: second variable attenuator means having a first input connected to receive said composite signal and a second input connected to receive a feedback signal for producing an output signal representing said composite signal having an amplitude controlled by said feedback signal, third phase comparator means having a first input connected to receive said output signal from said second variable attenuator means and a second input connected to receive said signal from said first circuit means for producing an output signal representing the difference in phase of said output signal from said second variable attenuator and said signal from said first circuit means, and integrator connected to receive said output signal from said third phase comparator for integrating said output signal from said third phase comparator and producing said feedback signal signal connected to said second variable attenuator means.
Claim 10
Independent Claim
193 words
A method of cancelling an undesired signal from a received composite signal containing said undesired signal and pulses of a known rate of occurrence, said method being responsive to apparatus which demarcates when a pulse is and is not occurring within said composite signal and comprising the steps of: producing a first signal which can lock-onto and follow the phase and frequency of the undesired signal, taking the difference between the composite signal and the produced first signal to produce a second signal free of the undesired signal, producing a third signal having an amplitude dependent upon the phase of the second signal, combining the third signal and the first signal in a variable gain amplifier to increase or decrease the level of the first signal, and controlling by said pulse demarcating apparatus the production of said first and third signals to permit said first and third signals to be adaptive to changes in the composite signal in the time between the pulses of known rate and prohibiting the first and third signals from being adaptive to changes in the composite signal during the time of occurrence of the pulses of known rate.
Claim 11
Independent Claim
193 words
A method of cancelling an undesired signal from a received composite signal containing said undesired signal and pulses of a known rate of occurrence, said method being responsive to apparatus which demarcates when a pulse is and is not occurring within said composite signal and comprising the steps of: producing a first signal which can lock-onto and follow the phase and frequency of the undesired signal, taking the difference between the composite signal and the produced first signal to produce a second signal free of the undesired signal, producing a third signal having an amplitude dependent upon the phase of the second signal, combining the third signal and the first signal in a variable gain amplifier to increase or decrease the level of the first signal, and controlling by said pulse demarcating apparatus the production of said first and third signals to permit said first and third signals to be adaptive to changes in the composite signal in the time between the pulses of known rate and prohibiting the first and third signals from being adaptive to changes in the composite signal during the time of occurrence of the pulses of known rate.
Claim 12
Dependent Claim
19 words
The method of claim 9 comprising the further step of: maintaining at a constant amplitude the first signal produced.
Claim 13
Dependent Claim
63 words
The method of claim 10 wherein the step of producing a first signal comprises the steps of: comparing the phase of the composite signal to the phase of feedback signal and producing a phase difference output signal, integrating the phase difference output signal and producing an integrated output signal, and producing the feedback signal having a frequency proportional to the integrated output signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |