Patent US4686534A successfully refreshed from Google Patents.
US4686534A
Expired / Lapsed
US
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Retro directive radar and target simulator beacon apparatus and method
Assignee: United States Department of the Air Force
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Filing: 1984-02-02
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Granted: 1987-08-11
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Expires: 2004-02-02
Abstract
Abstract A radar target simulator apparatus and method especially useful with a pulse compression radar located in a remote, unattended, and unpowered, terrain. Provision for generating signals which will pass through moving target indication (MTI) and minimum velocity threshold circuits are included. Transmission of the detected simulated target data through narrow-band communications lines, such as telephone lines, is contemplated. The capability for minimum discernible signal and radar power output evaluations are also provided.
Inventors
- 👤 Frederick N. Eddy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:31
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/40; G01S7/4052; G01S7/4082
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
245 words
Radar apparatus comprising the combination of: pulse compression radar transmitter and receiver means including low velocity target suppression threshold apparatus for emitting and receiving radio frequency radar signals having predetermined variations of carrier phase and frequency; beacon antenna means remotely fixed in position from said transmitter and receiver means for receiving pulse compression radio frequency signals therefrom, said antenna means including a radio frequency electrical signal conveying port; retroradiating means fixed in position from said transmitter for transmitting to said radar transmitter and receiver means a return radio frequency signal related to said antenna means radio frequency electrical signal; radio frequency signal generator means connected with said retroradiating means for generating said related radio frequency electrical signal including time varying amplitude modulation and time varying frequency and phase modulation components supplemental to said pulse compression modulation from said antenna means radio frequency electrical signal and from modulation input signals; modulation signal generator means connected with said radio frequency signal generator means and generating beacon modulation signals for varying the amplitude of said return radio frequency signal above and below a minimum discernible signal level in said radar receiver means and for varying the frequency and phase of said return radio frequency signal to velocity representations above and below said target suppression threshold; whereby the modulated signal received by said receiver means from said retroradiating means enables transmitter power output, receiver sensitivity, and target velocity threshold verifications of said pulse compression radar transmitter and receiver means.
Claim 2
Dependent Claim
245 words
Radar apparatus comprising the combination of: pulse compression radar transmitter and receiver means including low velocity target suppression threshold apparatus for emitting and receiving radio frequency radar signals having predetermined variations of carrier phase and frequency; beacon antenna means remotely fixed in position from said transmitter and receiver means for receiving pulse compression radio frequency signals therefrom, said antenna means including a radio frequency electrical signal conveying port; retroradiating means fixed in position from said transmitter for transmitting to said radar transmitter and receiver means a return radio frequency signal related to said antenna means radio frequency electrical signal; radio frequency signal generator means connected with said retroradiating means for generating said related radio frequency electrical signal including time varying amplitude modulation and time varying frequency and phase modulation components supplemental to said pulse compression modulation from said antenna means radio frequency electrical signal and from modulation input signals; modulation signal generator means connected with said radio frequency signal generator means and generating beacon modulation signals for varying the amplitude of said return radio frequency signal above and below a minimum discernible signal level in said radar receiver means and for varying the frequency and phase of said return radio frequency signal to velocity representations above and below said target suppression threshold; whereby the modulated signal received by said receiver means from said retroradiating means enables transmitter power output, receiver sensitivity, and target velocity threshold verifications of said pulse compression radar transmitter and receiver means.
Claim 3
Dependent Claim
26 words
The radar apparatus of claim 1 wherein said retroradiating means includes said beacon antenna means, a single antenna means being used for both receiving and retroradiating.
Claim 4
Dependent Claim
39 words
The radar apparatus of claim 2 wherein said radio frequency signal generator means includes a semiconductor crystal diode, the operating point of said diode being moved along a characteristic curve in response to said time-varying modulation signal generator components.
Claim 5
Dependent Claim
17 words
The radar apparatus of claim 3 wherein said pulse compression radar means includes linear frequency modulation means.
Claim 6
Dependent Claim
34 words
The radar apparatus of claim 4 further including a second semiconductor crystal diode in said radio frequency signal generator means, said two crystal diodes being driven in phase quadrature by time-varying periodic modulator signals.
Claim 7
Dependent Claim
15 words
The apparatus of claim 4 wherein said modulation signal generator signal includes a sawtooth waveform.
Claim 8
Dependent Claim
22 words
The radar apparatus of claim 1 wherein said pulse compression radar means includes modulation means operating in accordance with a Barker code.
Claim 9
Dependent Claim
30 words
The radar apparatus of claim 1 further including fusion center means for combining target indications received from a plurality of radar transmitters and receivers into a composite single target indication.
Claim 10
Dependent Claim
227 words
Passive retrodirective calibration and target simulation apparatus for a radar transmitter and receiver set comprising: parabolic dish antenna means remotely located from said transmitter and receiver set and including first and second quarter wave spaced dipole elements for bidirectionally communicating microwave radio frequency signals with said transmitter and receiver, said first dipole element being a short-circuited reflector element and said second dipole element being an active element having signal conveying terminals; semiconductor diode means connected to said second element signal conveying terminals for varying the impedance connecting said terminals incrementally between short circuit and open circuit conditions in response to diode controlling modulation, radio frequency current flow in said diode and said second dipole antenna also generating a radiated retrodirected radio frequency signal receivable by said radar receiver; modulation signal generating means coupled to said diode for changing the voltage and current operating point and the radio frequency impedance thereof, the strength and carrier phasing of said radiated retrodirected signal being responsive to said diode radio frequency impedance, said modulation signal generating means including means for changing said diode controlling signal in accordance with a time related algorithm; whereby said retrodirected radio frequency signal provides a simulated target of apparent varying radar cross section and target velocity in a known location with respect to said radar for calibration and function verification of said radar transmitter and receiver.
Claim 11
Dependent Claim
227 words
Passive retrodirective calibration and target simulation apparatus for a radar transmitter and receiver set comprising: parabolic dish antenna means remotely located from said transmitter and receiver set and including first and second quarter wave spaced dipole elements for bidirectionally communicating microwave radio frequency signals with said transmitter and receiver, said first dipole element being a short-circuited reflector element and said second dipole element being an active element having signal conveying terminals; semiconductor diode means connected to said second element signal conveying terminals for varying the impedance connecting said terminals incrementally between short circuit and open circuit conditions in response to diode controlling modulation, radio frequency current flow in said diode and said second dipole antenna also generating a radiated retrodirected radio frequency signal receivable by said radar receiver; modulation signal generating means coupled to said diode for changing the voltage and current operating point and the radio frequency impedance thereof, the strength and carrier phasing of said radiated retrodirected signal being responsive to said diode radio frequency impedance, said modulation signal generating means including means for changing said diode controlling signal in accordance with a time related algorithm; whereby said retrodirected radio frequency signal provides a simulated target of apparent varying radar cross section and target velocity in a known location with respect to said radar for calibration and function verification of said radar transmitter and receiver.
Claim 12
Dependent Claim
22 words
The retrodirective calibration and target simulation apparatus of claim 9 wherein said radar transmitter and receiver set include pulse compression modulation means.
Claim 13
Dependent Claim
15 words
The apparatus of claim 9 wherein said time related algorithm includes a sawtooth waveform signal.
Claim 14
Independent Claim
124 words
A method for verifying and calibrating a pulse compression radar set having low velocity target suppression comprising the steps of: receiving a pulse compression radio frequency signal from said radar set, the received signal including pulse compression determined first components of carrier phase and frequency modulation; modulating said received signal with a second, time varying, component of carrier phase and frequency modulation, first and second time portions of said time varying component representing target velocities above the threshold of said target suppression; radiating back to said radar set a signal representing said second component modulated signal; verifying the presence and absence of target indications corresponding with said first and second time portions of said second modulation component in the output of said radar set.
Claim 15
Independent Claim
124 words
A method for verifying and calibrating a pulse compression radar set having low velocity target suppression comprising the steps of: receiving a pulse compression radio frequency signal from said radar set, the received signal including pulse compression determined first components of carrier phase and frequency modulation; modulating said received signal with a second, time varying, component of carrier phase and frequency modulation, first and second time portions of said time varying component representing target velocities above the threshold of said target suppression; radiating back to said radar set a signal representing said second component modulated signal; verifying the presence and absence of target indications corresponding with said first and second time portions of said second modulation component in the output of said radar set.
Claim 16
Dependent Claim
53 words
The method of claim 12 further including the step of amplitude modulating said second component modulated signal with a third time varying modulation component, first and second time portions of said third time varying amplitude modulation component being interpretable as signals above and below the minimum discernible signal threshold at said radar set.
Claim 17
Dependent Claim
19 words
The method of claim 13 further including applying a sawtooth-shaped waveform to generate said second and third modulation components.
Claim 18
Dependent Claim
34 words
The method of claim 14 including the step of employing said sawtooth-shaped waveform for varying the operating point of a radio frequency crystal diode for generating said amplitude and phase and frequency modulation components.
Claim 19
Dependent Claim
132 words
Verifying and calibrating apparatus for a pulse compression radar set having a predetermined target velocity suppression threshold comprising: means remotely located from said radar set for receiving a pulse compression radio frequency signal therefrom, the received signal including pulse compression related first components of carrier phase and frequency modulation; means for modulating said received signal with a second time varying component of carrier phase and frequency modulation, first and second time portions of said time varying component representing target velocities above said target velocity suppression threshold; means for radiating back to said radar set a signal representing said second modulated signal; means for indicating the presence and absence of target indications corresponding with said first and second time portions of said second modulation component in the target output of said radar set.
Claim 20
Dependent Claim
132 words
Verifying and calibrating apparatus for a pulse compression radar set having a predetermined target velocity suppression threshold comprising: means remotely located from said radar set for receiving a pulse compression radio frequency signal therefrom, the received signal including pulse compression related first components of carrier phase and frequency modulation; means for modulating said received signal with a second time varying component of carrier phase and frequency modulation, first and second time portions of said time varying component representing target velocities above said target velocity suppression threshold; means for radiating back to said radar set a signal representing said second modulated signal; means for indicating the presence and absence of target indications corresponding with said first and second time portions of said second modulation component in the target output of said radar set.
Claim 21
Dependent Claim
21 words
The apparatus of claim 16 further including means for amplitude modulating said received signal with a third time varying modulation component.
Claim 22
Dependent Claim
40 words
The apparatus of claim 17 wherein the period of said third time varying modulation component is selected to permit distinguishing return signal portions having amplitudes below and above the minimum discernible signal level in the output of said radar set.
Claim 23
Dependent Claim
23 words
The apparatus of claim 16 wherein said second time varying component and said third time varying component of modulation include sawtooth-shaped time waveforms.
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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) | 1990-08-10 | 1991-02-09 | 1991-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-10 | 1995-02-09 | 1995-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-10 | 1999-02-09 | 1999-08-11 | $7700.00 | Window Closed / Lapsed |