US3611380A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for frequency correction in a radar equipment
Assignee: US Philips Corp
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Filing: 1969-06-02
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Granted: 1971-10-05
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Expires: 1989-06-02
Abstract
Abstract A device for frequency correction in radar equipment having a tunable transmitting tube with means for continually varying the tuning frequency and triggering the transmitting tube to generate and transmit radar pulses of varying frequency. A local oscillator of a receiver is locked in frequency at the triggering moment to a value which is related in a predetermined manner to the frequency of the transmitted pulse. This value is maintained during an interval after triggering to produce a predetermined, constant intermediate frequency when combined with received echo pulses. Further corrections are produced in an automatic frequency regulation circuit to correct for the combination of slow regulation and rapid final correction, and in a correction circuit to compensate for deviations in the difference frequency dependent upon where triggering occurs on the tuning curve.
Inventors
- 👤 Nils Rune Carlsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:51
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/08; G01S13/10; G01S13/24; G01S7/00; G01S7/02; G01S7/28; G01S7/282
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
300 words
A device for frequency correction in a radar equipment comprising a tunable transmitter tube (2) with means for continuous variation of the tuning frequency of the transmitter tube and means (5) for instantaneous excitation, triggering, of the transmitter tube for generation and transmission of radar pulses of varying frequency, and a receiver comprising a local oscillator (3) which by means of memory means (9) is locked in frequency at triggering to a value which is related in a certain manner to the frequency of the transmitted pulse, upon which value it is then maintained a predetermined time after triggering for producing a predetermined constant intermediate frequency in combination with received echo pulses, a frequency discriminator (16) being arranged for the purpose of frequency correction of the local oscillator after the transmission, to which discriminator is applied the difference frequency between the transmitted pulse and the locked oscillator frequency in the transmission moment and which discriminator delivers a voltage pulse representing the deviation of the said difference frequency from the predetermined intermediate frequency, and memory means (17) for storing the value of the voltage pulse during the echo time interval, which pulse is applied to the frequency determining means of the local oscillator (3) for correcting the oscillator frequency at the transmission, characterized by a further correction circuit (22) comprising means (23) which are sensitive for the tuning variation of the transmitter tube with time, i.e. the derivative of the tuning curve, and memory means (27) for storing the derivative value existing in the triggering moment during the echo time interval, which memory means are adapted to influence the frequency determining means of the local oscillator in the triggering moment for producing a correction of the oscillator frequency appearing in time before the transmission moment and corresponding to the derivative value.
Claim 2
Independent Claim
300 words
A device for frequency correction in a radar equipment comprising a tunable transmitter tube (2) with means for continuous variation of the tuning frequency of the transmitter tube and means (5) for instantaneous excitation, triggering, of the transmitter tube for generation and transmission of radar pulses of varying frequency, and a receiver comprising a local oscillator (3) which by means of memory means (9) is locked in frequency at triggering to a value which is related in a certain manner to the frequency of the transmitted pulse, upon which value it is then maintained a predetermined time after triggering for producing a predetermined constant intermediate frequency in combination with received echo pulses, a frequency discriminator (16) being arranged for the purpose of frequency correction of the local oscillator after the transmission, to which discriminator is applied the difference frequency between the transmitted pulse and the locked oscillator frequency in the transmission moment and which discriminator delivers a voltage pulse representing the deviation of the said difference frequency from the predetermined intermediate frequency, and memory means (17) for storing the value of the voltage pulse during the echo time interval, which pulse is applied to the frequency determining means of the local oscillator (3) for correcting the oscillator frequency at the transmission, characterized by a further correction circuit (22) comprising means (23) which are sensitive for the tuning variation of the transmitter tube with time, i.e. the derivative of the tuning curve, and memory means (27) for storing the derivative value existing in the triggering moment during the echo time interval, which memory means are adapted to influence the frequency determining means of the local oscillator in the triggering moment for producing a correction of the oscillator frequency appearing in time before the transmission moment and corresponding to the derivative value.
Claim 3
Dependent Claim
102 words
A device as claimed in claim 1, characterized in that the correction pulses from the said memory means (27) adapted to store the derivative value in the triggering moment during the echo interval are superimposed upon correction pulses obtained from a device (19) having a large time constant, which device is fed with the pulses from the discriminator (16), the pulses produced by the said device having large time constant being also adapted to produce a precorrection of the local oscillator, which is such that the mean value of a large number of foregoing discriminator pulses will be substantially equal to zero.
Claim 4
Dependent Claim
29 words
A device as claimed in claim 1 wherein the correction produced by said further derivative sensitive correction circuit is substantially proportional to the measured derivative in the triggering moment.
Claim 5
Dependent Claim
43 words
A device as claimed in claim 1 whereas said local oscillator is locked in frequency at triggering so that the frequency thereof in an interval before triggering in each triggering moment equals the tuning frequency of the transmitted tube in an unexcited condition.
Claim 6
Dependent Claim
87 words
A device as claimed in claim 1 wherein said further corrections circuit comprises a differentiating circuit for receiving a control voltage produced by continuous measurement of the tuning frequency of the tunable transmitter tube to produce a voltage proportional to the derivative of said control voltage, memory means for storing the derivative voltage from said differentiating circuit, and gating means connected to said memory means for applying the derivative voltage to the frequency determining means of said oscillator in an interval before triggering in each triggering moment.
Claim 7
Dependent Claim
14 words
A device as claimed in claim 1 wherein said memory means comprises a capacitor.
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) | 1974-10-04 | 1975-04-05 | 1975-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-04 | 1979-04-05 | 1979-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-04 | 1983-04-05 | 1983-10-05 | $7700.00 | Window Closed / Lapsed |