Patent US3755814A successfully refreshed from Google Patents.
US3755814A
Expired / Lapsed
US
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Precision transponder system
Assignee: United States Department of the Navy
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Filing: 1971-02-08
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Granted: 1973-08-28
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Expires: 1991-02-08
Abstract
Abstract A gas discharge tube is placed in the transmission line of a radar to briefly interrupt the transmitted signal to form a notched pulse that is transmitted to a transponder. The notching is reproduced in the responding signal from the transponder by using the incoming RF signal itself to build up the responding signal. By this means, the uncertainty of the delay associated with the transponder is limited to a few cycles of radar frequency rather than a much larger time interval. At the radar receiver the distance to the transponder and back is then determined with high accuracy by measuring the time interval between the notch on the transmitted signal and that on the responding signal.
Inventors
- 👤 F Alpers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:10
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/74; G01S13/82
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
177 words
In a precision transponder system the combination comprising: a. an RF frequency transmitter for transmitting an RF frequency pulses of a predetermined time duration, said pulses having a brief interruption of the transmitted energy at a point approximately intermediate the duration time of said pulse, b. a transmitting antenna, c. a circulator for directing the RF energy to said transmitting antenna, d. switching means connected in circuit with said circulator and said antenna and normally allowing RF energy to flow from said transmitter to said antenna, e. control circuit means coupled to said switching means for briefly interrupting the flow of RF energy in said switching means, f. a transponder circuit means for receiving said transmitted pulses and being responsive to said received signals for generating responding signals so that the brief interruptions in said responding signals correspond approximately with the brief interruptions in the received signals, g. receiving circuit means for receiving said responding signals and being responsive thereto for generating a clock pulse coincident with the occurrence of the brief interruptions in said responding signals.
Claim 2
Dependent Claim
177 words
In a precision transponder system the combination comprising: a. an RF frequency transmitter for transmitting an RF frequency pulses of a predetermined time duration, said pulses having a brief interruption of the transmitted energy at a point approximately intermediate the duration time of said pulse, b. a transmitting antenna, c. a circulator for directing the RF energy to said transmitting antenna, d. switching means connected in circuit with said circulator and said antenna and normally allowing RF energy to flow from said transmitter to said antenna, e. control circuit means coupled to said switching means for briefly interrupting the flow of RF energy in said switching means, f. a transponder circuit means for receiving said transmitted pulses and being responsive to said received signals for generating responding signals so that the brief interruptions in said responding signals correspond approximately with the brief interruptions in the received signals, g. receiving circuit means for receiving said responding signals and being responsive thereto for generating a clock pulse coincident with the occurrence of the brief interruptions in said responding signals.
Claim 3
Dependent Claim
163 words
The transponder system of claim 1 wherein said transponder circuit means includes: a. an antenna for receiving the signal pulses transmitted from said transmitting circuit, b. an RF amplifier coupled to said receiving antenna for amplifying the incomming RF signal, c. a mixer circuit having a first input coupled to said RF amplifier and a second input coupled to a heterodyning frequency oscillator for generating sum and difference frequency signals, d. an RF filter circuit coupled to said mixer circuit for passing only one of said sum and difference frequency signals, e. video detector circuit means coupled to said RF amplifier, f. modulator circuit means coupled to said video detector circuit means for generating an output modulating signal of approximately the same time duration of said received signal, g. an RF power amplifier coupled to said RF filler and to said modulator for generating an output responding signal having a brief interruption in time coincidence with the brief interruption of said received signal.
Claim 4
Dependent Claim
96 words
The transponder system of claim 1 wherein said clock pulse generating means includes: a. a crystal detector for detecting the responding signal, b. a differentiation network coupled to said crystal detector, c. a bistable multivibrator coupled to said differentiation network and being responsive to the differentiated signal to generate an output pulse that stops with the beginning of the brief interruption of said responding signal, and d. a short pulse generator coupled to said bistable multivibrator for generating an output pulse in response to the start of decay of the outpuT pulse of said bistable multivibrator.
Claim 5
Dependent Claim
14 words
The system of claim 1 wherein said switching means is a gaseous switching tube.
Claim 6
Dependent Claim
21 words
The system of claim 1 wherein said control circuit means includes the transmitter trigger circuit in circuit with a delay line.
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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |