Pulse type radar system

Claim 2

A radar system having a high range resolution comprising: means for transmitting a series of pulses whose carrier frequencies are distributed within a band B and whose time positions are associated with the frequencies in accordance with a linear relationship, said series of pulses being repeated with a given recurrence periodicity, means for receiving the echo signals from objects in space and for effecting demodulation using the corresponding waves which gave rise to them, filtering means having a band width substantially equal to the spectral width of the pulses, and a plurality of filters coupled to said filtering means for producing at different outputs different signals which correspond to separate objects in space.

Claim 3

A radar system having a high range resolution comprising: generating means for producing n waves of different frEquencies, said frequencies being regularly distributed within a frequency band B, switching means having n positions for successively and cyclically select one of said waves with a given recurrence periodicity, chopping means for chopping a pulse of given duration from each wave, said duration corresponding to a pulse spectral width which is at least equal to B/n, transmitting means for transmitting said pulses in the space, receiving means for receiving the echo signals from objects in space, demodulating means coupled to said receiving means and said switching means for producing demodulated echo signals, filtering means connected to said demodulating means and having a band width which is substantially equal to the spectral width of the emitted pulses, and a bank of filters coupled to said filtering means for producing at different outputs different signals which correspond to separate objects in space.

Claim 4

A radar system having a high range resolution comprising: generating means for producing n waves of different frEquencies, said frequencies being regularly distributed within a frequency band B, switching means having n positions for successively and cyclically select one of said waves with a given recurrence periodicity, chopping means for chopping a pulse of given duration from each wave, said duration corresponding to a pulse spectral width which is at least equal to B/n, transmitting means for transmitting said pulses in the space, receiving means for receiving the echo signals from objects in space, demodulating means coupled to said receiving means and said switching means for producing demodulated echo signals, filtering means connected to said demodulating means and having a band width which is substantially equal to the spectral width of the emitted pulses, and a bank of filters coupled to said filtering means for producing at different outputs different signals which correspond to separate objects in space.

Claim 5

A radar system having a high range resolution comprising: generating means for producing n waves of different frequencies, said frequencies being regularly distributed within a frequency band B, first switching means having n positions for successively and cyclically select one of said waves with a given recurrence periodicity, chopping means for chopping a pulse of given duration from each wave, said duration corresponding to a pulse spectral width which is at least equal to B/n, means for transmitting said pulses in the space, receiving means for receiving the echo signals from objects in space, second switching means having n positions, connected to said generating means, for successively and cyclically select one of said waves in synchronism with said first switch means but with a position offset which depends on the range of objects to be observed, demodulating means coupled to said receiving means and said second switch means for producing demodulated echo signals, filtering means connected to said demodulating means and having a band width which is substantially equal to the spectral width of the emitted pulses and, a bank of filters coupled to said filtering means for producing at different outputs different signals which correspond to separate objects in space.

Claim 6

A radar system having a high range resolution comprising: generating means for producing n waves of different frequencies, said frequencies being regularly distributed within a frequency band B, first switching means having n positions for successively and cyclically select one of said waves with a given recurrence periodicity, chopping means for chopping a pulse of given duration from each wave, said duration corresponding to a pulse spectral width which is at least equal to B/n, means for transmitting said pulses in the space, receiving means for receiving the echo signals from objects in space, second switching means having n positions, connected to said generating means, for successively and cyclically select one of said waves in synchronism with said first switch means but with a position offset which depends on the range of objects to be observed, demodulating means coupled to said receiving means and said second switch means for producing demodulated echo signals, filtering means connected to said demodulating means and having a band width which is substantially equal to the spectral width of the emitted pulses and, a bank of filters coupled to said filtering means for producing at different outputs different signals which correspond to separate objects in space.

Claim 7

A radar system as claimed in claim 3, further comprising a computer for determining the position offset of the second switch means with respect to the first one, on the basis of a signal which is a function of the range of the objects to be observed, and control means for controlling the first and second switch means with said position offset.

Claim 8

A radar system as claimed in claim 4 further comprising a range gate inserted between the filtering means and the bank of filters and a gate control circuit for controlling the operation of said range gate in response to a range signal which is a function of the range of the objects to be observed.

Claim 9

A radar system as claimed in claim 3, wherein said bank of filters is constituted by an n-channel digital device for computing the Fourrier transform of n successive demodulated echo signals, said device being associated with an input storage circuit for storing said echo signals and for delivering them together to said digital device and means for picking off the n output signals of said device and for producing a series of n digital signals which are representative of the appearance of a block of space.

Claim 10

A radar system as claimed in claim 3 further comprising compensating means for compensating the variation in propagation time of waves through the transmitting means in response to the variation in carrier frequency, said compensating means comprising coupling means between the transmitting and the receiving means for transmitting a series of pulses directly from the transmitting means to the receiving means during a zero range echo simulation, means for measuring the phase-shift between each emitted pulse and the corresponding reCeived pulse, means for storing the series of phase-shift values which are measured during said simulation, and a phase-shaft operating circuit inserted between the filtering means and the bank of filters for substracting said stored phase-shift values to the phases of the demodulated echo signals respectively during the normal operation of the radar system.

Claim 11

A radar system as claimed in claim 7 further comprising a radial speed correction device coupled to the phase-shift operating circuit for correcting furthermore the phase-shifts operated by said circuit in response to a radial speed signal.