US4019148A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lock-in noise rejection circuit
Assignee: Sperry Sun Inc
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Filing: 1975-12-29
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Granted: 1977-04-19
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Expires: 1995-12-29
Abstract
Abstract A lock-in filter that may be used to detect an AC data signal in the presence of high level noise signals that may occur in such systems as those used for acoustical telemetry in boreholes includes a pair of parallel capacitors receptive of the data and noise signals and circuitry operating in response to signals in the capacitors for alternately switching the capacitors to receive the noise and data signals in phase with the data signal.
Inventors
- 👤 Elbert N. Shawhan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:07
CPC Classifications
E; E21; E21B; E21B47/00; E21B47/12; E21B47/14; E21B47/16; H; H04; H04B; H04B11/00
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
91 words
Circuit for locking in on an alternating current signal comprising: means receptive of the alternative current signal; a pair of storage capacitors; resistor isolation means between the receptive means and the capacitors; and feedback means connected between the isolation means and said capacitors responsive to signals from the capacitors for connecting one of the capacitors to the alternating current signal during positive half cycles of said alternating current signal and connecting the other of said capacitors to said alternating current signal during the negative half of the cycles of said signal.
Claim 2
Dependent Claim
91 words
Circuit for locking in on an alternating current signal comprising: means receptive of the alternative current signal; a pair of storage capacitors; resistor isolation means between the receptive means and the capacitors; and feedback means connected between the isolation means and said capacitors responsive to signals from the capacitors for connecting one of the capacitors to the alternating current signal during positive half cycles of said alternating current signal and connecting the other of said capacitors to said alternating current signal during the negative half of the cycles of said signal.
Claim 3
Dependent Claim
19 words
The circuit of claim 1 wherein the connecting means comprises: switch means; and means for operating the switch means.
Claim 4
Dependent Claim
32 words
The circuit of claim 2 wherein the switch operating means comprises: oscillator means; and means for synchronizing the frequency of the oscillator means with the frequency of the signal from the capacitors.
Claim 5
Dependent Claim
12 words
The circuit of claim 3 wherein the synchronizing means comprises a phase-locked-loop.
Claim 6
Dependent Claim
15 words
The circuit of claim 4 wherein the switch operating means further includes phase shift means.
Claim 7
Dependent Claim
14 words
The circuit of claim 5 wherein the switch operating means further includes filter means.
Claim 8
Dependent Claim
82 words
Circuit for locking in on an AC signal, comprising: means receptive of the AC signal; a pair of parallel storage capacitors; resistor isolation means connected between the receptive means and the capacitors; and feedback means connected between the isolation means and said capacitors responsive to signals in the capacitors for communicating the AC signal to one of the capacitors during positive half cycles of said AC signal and to the other of said capacitors during negative half cycles of said AC signals.
Claim 9
Dependent Claim
82 words
Circuit for locking in on an AC signal, comprising: means receptive of the AC signal; a pair of parallel storage capacitors; resistor isolation means connected between the receptive means and the capacitors; and feedback means connected between the isolation means and said capacitors responsive to signals in the capacitors for communicating the AC signal to one of the capacitors during positive half cycles of said AC signal and to the other of said capacitors during negative half cycles of said AC signals.
Claim 10
Dependent Claim
19 words
The circuit of claim 7 wherein the communicating means comprises: switch means; and means for operating the switch means.
Claim 11
Dependent Claim
32 words
The circuit of claim 8 wherein the switch operating means comprises oscillator means; and means for synchronizing the frequency of the oscillator means with the frequency of the signal from the capacitor.
Claim 12
Dependent Claim
12 words
The circuit of claim 9 wherein the synchronizing means comprises a phase-locked-loop.
Claim 13
Dependent Claim
15 words
The circuit of claim 10 wherein the switch operating means further includes phase shift means.
Claim 14
Dependent Claim
14 words
The circuit of claim 11 wherein the switch operating means further includes filter means.
Claim 15
Dependent Claim
61 words
A lock-in circuit for detecting an AC signal voltage, comprising: a pair of capacitors chargeable by the AC voltage and having a common terminal; switch means for connecting an AC voltage to either of the capacitors; and feedback means responsive to an AC voltage at the common terminal for operating the switch means in synchronism with said voltage at said terminal.
Claim 16
Dependent Claim
61 words
A lock-in circuit for detecting an AC signal voltage, comprising: a pair of capacitors chargeable by the AC voltage and having a common terminal; switch means for connecting an AC voltage to either of the capacitors; and feedback means responsive to an AC voltage at the common terminal for operating the switch means in synchronism with said voltage at said terminal.
Claim 17
Dependent Claim
78 words
A circuit for filtering an AC signal from a noise-infested signal appearing across a pair of terminals, comprising: switch filter means connected between the terminal pair, said switch filter means including a pair of capacitors receptive of the noise-infested signal at a first of the terminal pair; switch means for connecting either of the capacitors to the second of the terminal pair; and feedback means responsive to signals in the pair of capacitors for controlling the switch means.
Claim 18
Dependent Claim
78 words
A circuit for filtering an AC signal from a noise-infested signal appearing across a pair of terminals, comprising: switch filter means connected between the terminal pair, said switch filter means including a pair of capacitors receptive of the noise-infested signal at a first of the terminal pair; switch means for connecting either of the capacitors to the second of the terminal pair; and feedback means responsive to signals in the pair of capacitors for controlling the switch means.
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) | 1980-04-18 | 1980-10-18 | 1981-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-18 | 1984-10-18 | 1985-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-18 | 1988-10-18 | 1989-04-19 | $7700.00 | Window Closed / Lapsed |