US3680089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aircraft electronic landing responser system using airborne chirp interrogation
Assignee: TDK Micronas GmbH
•
Filing: 1970-03-30
•
Granted: 1972-07-25
•
Expires: 1990-03-30
Abstract
Abstract An instrument landing system particularly adapted for VTOL aircraft, including an airborne chirp pulsed interrogator. A ground station antenna has the characteristic of directively transmitting and receiving at a beam angle which is a function of frequency. The ground station also includes a power amplifier and RF hybriding apparatus, so that the ground station can perform as a selective amplifying reflector or phase coherent repeater. Reradiated energy from the ground station is then at the same angle as reception. The reradiated frequency is compared with the airborne chirp frequency (as it correlates with ground station antenna beam angle) to obtain an air-derived approach angle. Range is determined in the air by correlating reradiated frequency with chirp frequency as it relates to time delay (round trip transmission time). The ground antenna beam is relatively broad in the plane orthogonal to the plane of angle measurement.
Inventors
- 👤 Lon L Sanders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:11
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/88; G01S13/91; G01S13/913; G01S13/74; G01S13/76; G01S13/762
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
190 words
An air navigation system particularly adapted for instrument landing of VTOL aircraft, comprising the combination of: first airborne means including means for generating and transmitting a series of frequency modulated transmitter pulses of duration short compared to the repetition period of said pulses but long compared to the two-way transmission time to an intended landing point, toward said landing point; a ground responser station located adjacent said landing point, said ground station including a directive antenna for receiving and transmitting a beam of electromagnetic energy at an angle in a plane which is a function of frequency, and means cooperating with said antenna to cause amplified reradiation of received energy at the angle of reception substantially during the time of said reception; second airborne means for receiving said reradiation during at least a portion of the time of said transmitter pulses, including first discriminator means for comparing the frequency of the energy of said reradiation with the instantaneous frequency of said frequency modulated transmitter pulses at the time of reception of said reradiation at said airborne means to determine the elevation angle of said aircraft measured from said ground station.
Claim 2
Dependent Claim
190 words
An air navigation system particularly adapted for instrument landing of VTOL aircraft, comprising the combination of: first airborne means including means for generating and transmitting a series of frequency modulated transmitter pulses of duration short compared to the repetition period of said pulses but long compared to the two-way transmission time to an intended landing point, toward said landing point; a ground responser station located adjacent said landing point, said ground station including a directive antenna for receiving and transmitting a beam of electromagnetic energy at an angle in a plane which is a function of frequency, and means cooperating with said antenna to cause amplified reradiation of received energy at the angle of reception substantially during the time of said reception; second airborne means for receiving said reradiation during at least a portion of the time of said transmitter pulses, including first discriminator means for comparing the frequency of the energy of said reradiation with the instantaneous frequency of said frequency modulated transmitter pulses at the time of reception of said reradiation at said airborne means to determine the elevation angle of said aircraft measured from said ground station.
Claim 3
Dependent Claim
32 words
The invention set forth in claim 1 in which said discriminator means is defined as being calibrated in terms of angle of radiation and reception by said ground station antenna versus frequency.
Claim 4
Dependent Claim
108 words
The invention defined in claim 2 in which said transmitter pulse frequency modulation and the angle of said ground antenna radiation as a function of frequency vary in a continuous smooth manner having no change of slope sense during measurement operation, and second discriminator means responsive to said reradiation received at said aircraft are included for producing a signal which is the analog of range from said aircraft to said ground station, said second discriminator means being calibrated in terms of time versus frequency, thereby to provide first and second analog signals representative of elevation angle and range respectively, of said aircraft with respect to said ground station.
Claim 5
Dependent Claim
45 words
The invention set forth in claim 3 in which said frequency modulation is defined as varying linearly as a function of time over the duration of said transmitter pulses, and said second discriminator means produces said second analog signal as a linear function of frequency.
Claim 6
Dependent Claim
68 words
The invention set forth in claim 1, further defined in that range computing means responsive to said reradiated energy are included for producing a signal which is the analog of range from said aircraft to said ground station, said range computing means being calibrated to produce an output proportional to the time from the start of each of said transmitter pulses as a function of said frequency modulation.
Claim 7
Dependent Claim
117 words
Apparatus according to claim 1, in which said ground station antenna contains at least one dispersive multi-element linear array oriented to form a narrow beam in at least the angular coordinate to be measured, said beam being formed at an angle in the same coordinate which is a function of frequency, and including a radio frequency power amplifier connected to receive said frequency modulated transmitter pulses through said antenna, and first hybrid means connected between the input and output of said power amplifier and to said antenna for directing energy received by said ground station antenna to the input of said power amplifier and simultaneously from the output of said power amplifier to said antenna for reradiation.
Claim 8
Dependent Claim
15 words
Apparatus according to claim 6 in which said power amplifier is a travelling wave tube.
Claim 9
Dependent Claim
138 words
Apparatus according to claim 6 in which said first and second airborne means comprise: an airborne antenna; a receiver capable of passing all frequencies reradiated from said ground station corresponding to measurement angles of interest; a second hybrid connected between said means for generating transmitter pulses and said receiver and to said airborne antenna, for passing said reradiated energy received by said airborne antenna to said receiver while simultaneously passing energy from said means for generating transmitter pulses to said airborne antenna; and angle detecting means responsive to said transmitter pulses and the output of said receiver for producing an angle representing signal having a frequency which is a function of said receiver output; and means for applying said angle representing signal to said first discriminator means to produce a signal which is the analog of elevation angle.
Claim 10
Dependent Claim
76 words
Apparatus according to claim 8 in which said second airborne means includes a phase detector circuit responsive to the output of said receiver and said transmitter to produce a range representing signal having a frequency which is a function of the difference between said transmitter and receiver output frequencies; and including a second discriminator, calibratable in terms of range, responsive to said range representing signal for producing an output signal which is the analog of range.
Claim 11
Dependent Claim
150 words
Apparatus according to claim 6 in which said first and second airborne means comprise: a frequency modulated pulse transmitter, a receiver, an airborne antenna and a duplexer interconnected for contemporaneously transmitting said frequency modulated pulses and receiving said reradiated energy from said ground station; a phase detector responsive to the output of said receiver and said transmitter to provide an output Delta f including the beat frequency of said transmitter and receiver outputs; a mixer responsive to the frequency modulation signal ft component present in said transmitter without the RF carrier of said transmitter and to said Delta f signal for providing the mixer output ft - Delta t; means comprising said first discriminator circuit responsive to said ft - Delta t signal to produce an output angle analog signal; and means comprising a second discriminator circuit responsive to said Delta f signal to produce an output range analog signal.
References Cited (Backward Citations)
US3266038A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |