US3721913A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dc to sub-microsecond frequency change detector
Assignee: United States Department of the Navy
•
Filing: 1971-09-02
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Granted: 1973-03-20
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Expires: 1991-09-02
Abstract
Abstract An input network phase shifts received signals by substantially 180* and also attenuates received signals as a function of the frequency. A summing circuit receives the phase shifted signal as well as the unaltered received signal, to develop signals as a function of the instantaneous difference in amplitude between them. The summing circuit includes a constant current sink connecting it to ground and a constant voltage device connecting the low potential side of the summing circuit to the low potential side of the unaltered received signals as a reference. In its preferred embodiment the frequency change detector is capable of detecting such frequency changes within one cycle of the received signals for frequencies ranging from dc to the multi-MHz range.
Inventors
- 👤 D Theobald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:38
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/14
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
135 words
A dc to sub-microsecond frequency change detector comprising: an input network having input and output terminals; means connected between said terminals for developing output signals having variations in amplitude as a function of the variations in frequency of received input signals and substantially 180* phase shifted relative to said received signals; a summing circuit for developing resultant signals as a function of the instantaneous difference in amplitude between first and second signals; means connecting said received input signals to said summing circuit as said first signals; means connecting said output signals to said summing circuit as said second signals; an adjustable constant-current sink connected to said summing circuit; and an adjustable constant-voltage device connecting the low potential side of said summing circuit to the low potential side of said received input signals as a reference.
Claim 2
Dependent Claim
135 words
A dc to sub-microsecond frequency change detector comprising: an input network having input and output terminals; means connected between said terminals for developing output signals having variations in amplitude as a function of the variations in frequency of received input signals and substantially 180* phase shifted relative to said received signals; a summing circuit for developing resultant signals as a function of the instantaneous difference in amplitude between first and second signals; means connecting said received input signals to said summing circuit as said first signals; means connecting said output signals to said summing circuit as said second signals; an adjustable constant-current sink connected to said summing circuit; and an adjustable constant-voltage device connecting the low potential side of said summing circuit to the low potential side of said received input signals as a reference.
Claim 3
Dependent Claim
32 words
A dc to sub-microsecond frequency change detector as claimed in claim 1 wherein the means connected between the input and output terminals of the input network comprises a lowpass, constant K filter.
Claim 4
Dependent Claim
35 words
A dc to sub-microsecond frequency change detector as claimed in claim 1 wherein the means connected between the input and output terminals comprises an amplifier having a resonant tank circUit for developing said output signals.
Claim 5
Dependent Claim
31 words
A dc to sub-microsecond frequency change detector as claimed in claim 1 wherein the means connected between the input and output terminals comprises a crystal filter tuned to a predetermined frequency.
Claim 6
Dependent Claim
25 words
A dc to sub-microsecond frequency change detector as claimed in claim 1 wherein said summing circuit comprises two transistors having common emitter and collector connections.
Claim 7
Dependent Claim
65 words
A dc to sub-microsecond frequency change detector as claimed in claim 3 wherein said constant-current device comprises a third transistor having its emitter connected to said common emitter connection of its collector connected in circuit with said common collector connection, and its base connected to a reference potential for developing a differential output across the collector of said third transistor and said common collector connection.
Claim 8
Dependent Claim
41 words
A dc to sub-microsecond frequency change detector as claimed in claim 4 wherein said third transistor has a variable tap resistance connected in circuit with its base connection for selectively establishing the detection threshold relative to the amplitude of the inputs.
Claim 9
Dependent Claim
45 words
A dc to sub-microsecond frequency change detector as claimed in claim 5 wherein said adjustable constant-current sink is connected in circuit with said common emitter connection for selectively establishing the optimum quiescent operating point of said common collectors relative to the amplitude of the inputs.
Claim 10
Dependent Claim
30 words
A dc to sub-microsecond frequency change detector as claimed in claim 6 wherein said adjustable constant-current sink comprises a transistor circuit connected to ground potential through a variable resistive element.
Claim 11
Dependent Claim
51 words
A dc to sub-microsecond frequency change detector as claimed in claim 1 wherein said adjustable constant voltage device comprises a source of dc potential, a variable tap resistance connected across said potential and a diode having a non-linear transfer characteristic connected in series between said variable tap and said summing circuit.
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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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |