US3754266A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direction finder automatic calibration updating control system
Assignee: International Standard Electric Corp
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Filing: 1971-12-22
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Granted: 1973-08-21
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Expires: 1991-12-22
Abstract
Abstract An updating control system for two channel direction finders which includes dual loop antennas and a sense antenna; and circuits for setting the direction finder to a ''''Frequency'''' condition during which the direction finder may be tuned to a new frequency and to a ''''Bearing'''' condition in which bearings corresponding to the new frequency are taken. Individual amplifying means are provided to connect each of the two loop antennas to a plate pair of a cathode ray tube. Circuits are also shown for updating (adjusting) the phase and gain of the two signals, and for interconnecting the inputs of the two amplifiers during the updating process and for instrumenting correction of quadrantal errors.
Inventors
- 👤 D Poppe
- 👤 O Mathiesen
- 👤 G Odegaard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 22:06
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/143
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
229 words
In a direction finder system which includes two directionsensitive antennas and a paIr of corresponding receiver channels and means for selecting ''''Frequency'''' and ''''Bearing'''' modes of operation alternatively for tuning to selected signals and for making bearing determinations respectively, the combination comprising: an amplifier gain controllable in response to a gain control signal, in a least one of said receiver channels; a mixer circuit substantially at the input of each of said receiver channels for producing and applying IF signals in said channels, said gain controllable amplifier receiving IE signals from a corresponding one of said mixer circuits; gain calibration updating means compqring the gains of said receiver channels and for applying a first control signal to said amplifier to produce gain equality in each of said channels; phase calibration updating means including means responsive to the outputs of said receiver channels to detect phase errors introduced therein and for developing and applying a phase control signal to said mixer in the channel corresponding to said gain controllable amplifier; and sequence control means for enabling said both gain and phase calibration means continuously during said Frequency mode of operation and intermittently during said Bearing mode of operation, said sequence control being arranged to parallel the inputs of said two receiving channels whereby the same input signal is applied to both of said channels during said Frequency mode of operation.
Claim 2
Dependent Claim
229 words
In a direction finder system which includes two directionsensitive antennas and a paIr of corresponding receiver channels and means for selecting ''''Frequency'''' and ''''Bearing'''' modes of operation alternatively for tuning to selected signals and for making bearing determinations respectively, the combination comprising: an amplifier gain controllable in response to a gain control signal, in a least one of said receiver channels; a mixer circuit substantially at the input of each of said receiver channels for producing and applying IF signals in said channels, said gain controllable amplifier receiving IE signals from a corresponding one of said mixer circuits; gain calibration updating means compqring the gains of said receiver channels and for applying a first control signal to said amplifier to produce gain equality in each of said channels; phase calibration updating means including means responsive to the outputs of said receiver channels to detect phase errors introduced therein and for developing and applying a phase control signal to said mixer in the channel corresponding to said gain controllable amplifier; and sequence control means for enabling said both gain and phase calibration means continuously during said Frequency mode of operation and intermittently during said Bearing mode of operation, said sequence control being arranged to parallel the inputs of said two receiving channels whereby the same input signal is applied to both of said channels during said Frequency mode of operation.
Claim 3
Dependent Claim
45 words
Apparatus according to claim 1 in which means for applying quadrantal error corrections are provided, said means comprising additional means for applying a second control signal for further modifying the gain of said gain controllable amplifier as a function of a predetermined quadrantal correction signal.
Claim 4
Dependent Claim
56 words
Apparatus according to claim 2 in which said means for applying quadrantal error corrections comprises an attenuator in series with the output of said receiver channel having said gain cOntrollable amplifier in the feedback path for controlling said gain controllable amplifier, thereby to provide an offset between said channel outputs representative of said quadrantal error correction.
Claim 5
Dependent Claim
57 words
Apparatus according to claim 1 in which said sequence control unit is adapted to interrupt bearing determination during said ''''Bearing'''' mode of operation for a period on the order of 20 milliseconds every other second, whereby said channel inputs are paralleled for determination and application of said gain and phase corrections during said ''''Bearing'''' mode of operation.
Claim 6
Dependent Claim
81 words
Apparatus according to claim 4 and additional means comprising a cathode ray display having first and second orthogonal beam deflection element pairs, means connecting the output of said receiver channel which includes said gain controllable amplifier to said first beam deflection element pair and the other receiver channel output to said second deflection element pair, means controlling said display to present an indication constituting a visual check on said gain and phase updating substantially only during said ''''Frequency'''' mode of operation.
Claim 7
Dependent Claim
43 words
Apparatus according to claim 5 in which said display presents a full diameter line at a 45* angle modified by an angle corresponding to the quadrantal error supplied and corresponding to the particular frequency to which said system is tuned at any time.
Claim 8
Dependent Claim
42 words
Apparatus according to claim 5 in which the bearing readings determined during said ''''Bearing'''' mode of operation are presented on said cathode ray display as a radius line and said display includes a bearing scale about the face circumference of said display.
Claim 9
Dependent Claim
76 words
Apparatus according to claim 1 in which said direction sensitive antennas are defined as disposed with their null receiving angular positions mutually 90* apart in the plane of bearing determination, bearing evaluation means are included for generating a signal representative of the bearing angle of received radiant energy from the relative amplitudes of signals in said receiver channels, and means are included for converting said bearing determination to digital form for presentation on a digital display.
References Cited (Backward Citations)
US2473491A
Cited
US2977588A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-20 | 1977-02-19 | 1977-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-20 | 1981-02-19 | 1981-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-20 | 1985-02-19 | 1985-08-21 | $7700.00 | Window Closed / Lapsed |