초록 ▼

An FM-CW radar system with improved range discrimination and improved immunity to clutter, chaff, jamming and multiple target environments. The FM-CW apparatus involves a repetitive cycle including a first, constant-transmitted-frequency (monochromatic) transmission, a linear frequency upsweep as a

An FM-CW radar system with improved range discrimination and improved immunity to clutter, chaff, jamming and multiple target environments. The FM-CW apparatus involves a repetitive cycle including a first, constant-transmitted-frequency (monochromatic) transmission, a linear frequency upsweep as a second period and a linear frequency downsweep as a third period within each transmission frame. Pseudorandom coding is superimposed on the FM-CW waveform, a code word duration being selected to place the first Doppler ambiguity beyond the highest expected equivalent target velocity. The resulting range ambiguities are resolved by means of the unambiguous range-determining capability of the FM-CW feature.

대표청구항 ▼

A CW radar system comprising: transmitting and receiving antennas having patterns covering substantially the same spatial sector; first means for generating a radio frequency signal according to a timed program to produce a repetitive pattern of transmission signal frames, each including a first per

A CW radar system comprising: transmitting and receiving antennas having patterns covering substantially the same spatial sector; first means for generating a radio frequency signal according to a timed program to produce a repetitive pattern of transmission signal frames, each including a first period during which a monochromatic radio frequency transmission signal is generated, a second period during which the frequency of said transmission signal is varied substantially linearly in a first sense, and a third period during which the frequency of said transmission signal is varied substantially linearly in a second sense, thereby producing frequency modulation during said second and third periods; second means responsive to the output of said first means for biphase coding the output of said first means according to a repetitive pseudo-random coded sequence having a predetermined word duration and for applying said coded first means output to said transmitting antenna; third means responsive to said receiving antenna for correlating received echo signals resulting from illumination of targets within said spatial sector by said transmitting antenna against a replica of said biphase coding applied in said second means to produce an output including a range-representing signal during the time of each of said sequence word durations, said range-representing signal retaining the modulation applied during said second and third periods; and fourth means responsive to said third means output for demodulating received signals containing said frequency modulation to select a range-representing pulse from the output of said third means, said selected pulse unambiguously representing the range of a corresponding target.