Communications: directive radio wave systems and devices (e.g. – Determining distance – With frequency modulation
Patent
1992-02-28
1994-11-01
Hellner, Mark
Communications: directive radio wave systems and devices (e.g.,
Determining distance
With frequency modulation
342175, 342196, 343793, G01S 1308, H01Q 916
Patent
active
053610725
ABSTRACT:
A lower-frequency compact radar system for wide-angle surveillance. Direction-finding receive antennas consisting of colocated orthogonal electric and magnetic dipoles provide target angles from the radar. The size of this antenna unit is reduced to the point where internal noise is comparable to external to achieve maximum compactness. High sensitivity is achieved with an efficient class of pulsed/gated, linearly swept-frequency waveforms that are generated and processed digitally. For backscatter radars, close to 50% duty factors are realized. The rules for waveform design and processing overcome problems of range/Doppler aliasing and/or blind zones. After mixing in the receiver, processing bandwidths are much less than RF signal bandwidths, so that simple, inexpensive personal computers are used for real-time signal processing. Digital FFT algorithms determine target range and Doppler, and DF algorithms determine its angles. Frequency hopping can be incorporated in the waveform design by synchronizing all timing and sampling functions, allowing spread-spectrum advantages while still achieving the high sensitivity afforded by coherent processing.
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Barrick Donald E.
Isaacson Jimmy
Lilleboe Peter M.
Lipa Belinda J.
Codar Ocean Sensors, Ltd.
Hellner Mark
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