Communications: directive radio wave systems and devices (e.g. – Determining direction – Scanning
Patent
1991-04-16
1992-07-07
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Determining direction
Scanning
342372, G01S 1300
Patent
active
051286831
ABSTRACT:
A multipurpose system provides radar surveillance for air traffic control purposes. The system includes four separate active phased-array antennas, each with .+-.45.degree. coverage in azimuth, from 0.degree. to 60.degree. in elevation. Each antenna element of each phased-array antenna is coupled by a low-loss path to the solid-state amplifier associated with a transmit-receive (TR) module. Each antenna produces a sequence of pencil beams, which requires less transmitted power from the TR modules than a fan beam, but requires more time because the pencil beam must be sequenced to cover the same volume as the fan beam. In order to scan the volume in a short time, the PRF is responsive to the elevation angle of the beam, so higher elevation angles use a higher PRF. Low elevation angle beams receive long transmitter pulses for high power, and pulse compression is used to restored range resolution, but the long pulse results in a large minimum range within which targets cannot be detected. A second can is provided at low elevation angles with a short transmitter pulse to fill in the short-range coverage. Beams at higher elevation angles transmit pulse widths which are shorter than beams at low elevation angles, so that the minimum range requirement is met without a second scan, which also reduces the time required for volumetric scan. The number of pulses which are integrated to produce a return increases off-axis, to restore system margin lost due to off-axis power gain reduction. The volumetric scan rate is increased by a dynamic scan regimen by which subsets of beams are pulsed with a high transmitter PRF but with a low effective beam PRF to reduce range ambiguity and preserve Doppler resolution without the usual increase of scan time. For best range resolution, Doppler processing is used, with range sidelobe pulse suppression applied separately to each Doppler frequency bin.
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patent: 3833904 (1974-09-01), Gebhardt et al.
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patent: 4901032 (1990-02-01), Komiak
patent: 4951059 (1990-08-01), Taylor, Jr.
patent: 4954830 (1990-09-01), Krikorian et al.
patent: 4983982 (1991-01-01), Roberge
Paper entitled "Advanced Air Traffic Control Radar", by Jerome E. Freedman, presented and distributed at International Symposium on Flight Safety held in Rome, Italy in Nov., 1990.
"Air Traffic Control" appeared at pp. S1-S11 of the Dec. 3, 1990 issue of Aviation Week & Space Technology.
"Sweden Develops New Radar, computer for Gupen and Airborne/Early Warning" by Nordwall et al., appeared at pp. 49-51 of the Jul. 2, 1990 issue of Aviation Week & Space Technology.
Freedman Jerome E.
Gallagher John J.
Perry Michael S.
Blum Theodore M.
General Electric Company
Meise William H.
Nieves Carlos A.
Young Stephen A.
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