US3863055A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Doppler scanning guidance system receiver with fourier transform computer
Assignee: International Standard Electric Corp
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Filing: 1973-04-27
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Granted: 1975-01-28
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Expires: 1993-04-27
Abstract
Abstract A Doppler type guidance system in which the frequency shift fd of the signal received at any airborne receiving station with respect to the emitted signal is determined by computing digitally the Fourier transforms X1 and X2 for the two frequencies which are multiples of the scanning frequency, on both sides of fd and then by interpolation from these two values X1 and X2 for determining the center frequency of the received signal spectrum. The frequency thus determined is an accurate analog of the angle of the airborne station with respect to the array normal.
Inventors
- 👤 Jean-Marie Henri Colin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:16
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02; G01S1/08; G01S1/38; G01S1/40
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
230 words
A receiving system for use at a remote station in a Doppler scanning guidance system which includes a ground beacon having a transmitter, a linear array of antenna elements, and commutator means for successively energizing said antenna elements from said transmitter at a frequency f + fo, said array also being arranged to transmit a reference signal at a frequency f, and wherein said receiver system operates to determine a spatial angle of said remote station with respect to a predetermined reference line extending from said array, the combination comprising: means within said receiver system for receiving and deriving a beat signal between said f and (f + fo) signals, said receiving system inherently receiving said signals by direct and reflected paths; counting means responsive to said transmitted signal for determining the frequencies of the two multiples of the repetition frequency of said ground beacon commutation, said two multiples being the ones bracketing the value of the Doppler frequency resulting from said ground beacon array commutation, received on the said direct path signal; a Fourier transform computer responsive to said beat signal for deriving a pair of Fourier transforms thereof corresponding to said two multiples as determined by said counting means; and angle computing means responsive to said transforms for determining an intermediate value representative of said spatial angle of said remote station with respect to said predetermined reference line.
Claim 2
Dependent Claim
230 words
A receiving system for use at a remote station in a Doppler scanning guidance system which includes a ground beacon having a transmitter, a linear array of antenna elements, and commutator means for successively energizing said antenna elements from said transmitter at a frequency f + fo, said array also being arranged to transmit a reference signal at a frequency f, and wherein said receiver system operates to determine a spatial angle of said remote station with respect to a predetermined reference line extending from said array, the combination comprising: means within said receiver system for receiving and deriving a beat signal between said f and (f + fo) signals, said receiving system inherently receiving said signals by direct and reflected paths; counting means responsive to said transmitted signal for determining the frequencies of the two multiples of the repetition frequency of said ground beacon commutation, said two multiples being the ones bracketing the value of the Doppler frequency resulting from said ground beacon array commutation, received on the said direct path signal; a Fourier transform computer responsive to said beat signal for deriving a pair of Fourier transforms thereof corresponding to said two multiples as determined by said counting means; and angle computing means responsive to said transforms for determining an intermediate value representative of said spatial angle of said remote station with respect to said predetermined reference line.
Claim 3
Dependent Claim
21 words
A system in accordance with claim 1, further defined in that said predetermined reference line is the normal to said array.
Claim 4
Dependent Claim
62 words
Apparatus according to claim 2 in which said angle computing means include summing and dividing circuits for computing the quantity (X1 - X2)/(X1 + X2), where X1 and X2 are said transform pair, to provide a value substantially proportional to the angular deviation between the angle of said remote station and the angle corresponding to a frequency shift median between said multiples.
Claim 5
Dependent Claim
69 words
Apparatus according to claim 2 in which said angle computing means includes summing and dividing circuits for supplying the values X1/(X1 + X2) and X2/(X1 + X2), a read-only memory addressed by said values for supplying a signal representative of the angular deviation between the angle of said remote station and the angle corresponding to a frequency shift median equal to one of said multiples or between said multiples.
Claim 6
Dependent Claim
13 words
Apparatus according to claim 3 in which said angle is the bearing angle.
Claim 7
Dependent Claim
13 words
Apparatus according to claim 4 in which said angle is the bearing angle.
Claim 8
Dependent Claim
53 words
Apparatus according to claim 3 in which said Fourier transform computer comprises meanS for demodulating said beat signal to produce an audio frequency beat signal, sampling and coding circuits for encoding said beat signal into digital form and in which said angle computing means includes circuits for performing summing and dividing operations digitally.
Claim 9
Dependent Claim
53 words
Apparatus according to claim 4 in which said Fourier transform computer comprises means for demodulating said beat signal to produce an audio frequency beat signal, sampling and coding circuits for encoding said beat signal into digital form and in which said angle computing means includes circuits for performing summing and dividing operations digitally.
Claim 10
Dependent Claim
66 words
Apparatus according to claim 7 wherein said Fourier transform computer includes a coefficient computing circuit which comprises a read-only memory addressed by the rank supplied by said counting device and supplying a corresponding phase increment, a looped addition circuit responsive thereto for supplying, successively, the phase values corresponding to said coefficients and a second read-only memory receiving said phase values and supplying in response said coefficients.
Claim 11
Dependent Claim
66 words
Apparatus according to claim 8 wherein said Fourier transform computer includes a coefficient computing circuit which comprises a read-only memory addressed by the rank supplied by said counting device and supplying a corresponding phase increment, a looped addition circuit responsive thereto for supplying, successively, the phase values corresponding to said coefficients and a second read-only memory receiving said phase values and supplying in response said coefficients.
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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) | 1978-01-27 | 1978-07-29 | 1979-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-27 | 1982-07-29 | 1983-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-27 | 1986-07-29 | 1987-01-28 | $7700.00 | Window Closed / Lapsed |