US 4,538,148 AGranted

Coherent radar

AssigneeLMT Radio Professionnelle

InventorsChristian Petitjean, Maurice Marchand

Life of this patent

Estimating the term…

Loading patent…

Abstract

A coherent radar including separate transmitting and receiving chains. The transmitting chain includes a master oscillator providing a signal at frequency F0. A multiplier multiplies F0 by a predetermined amount to produce a signal at a frequency F1. A second multiplier multiplies the signal at frequency F1 to produce a signal at frequency F2, F1 and F2 being coherent with F0. A first mixer mixes F1 with F0 and a second mixer mixes F2 with the product of the first mixer to produce a transmission signal. In the receiving chain, a received signal is amplified and filtered and then mixed in a third mixer with the second signal at frequency F2 from the transmitting chain. The mixing product of the third mixer is amplified and filtered and mixed in a fourth mixer with the first signal. The fourth mixer product is then coupled to a processor for producing a radar display.

Claims5

Dependent claims

A coherent radar comprising:

a single master oscillator generating a master signal at a fixed frequency F0;
means, coupled to said master oscillator, for generating a first signal at a fixed frequency F1 and a second signal at a variable frequency F2, said first and second signals each being coherent with said master signal;
a first bandpass filter for filtering the first signal;
a second bandpass filter for filtering the second signal;
first means for mixing the first signal as filtered with said master signal to provide a first mixer signal coherent with said master signal;
second means for mixing the second signal as filtered with said first mixer signal to produce a transmission signal coherent with said master signal;
a transmission antenna for radiating the transmission signal;
a receiving antenna for receiving a reception signal having a frequency component FR;
a third bandpass filter for filtering the reception signal;
third means for mixing the reception signal filtered by the third filter with the second signal and providing a third mixer signal having a frequency component FR-F2;
an amplifier for amplifying the third mixer signal;
a fourth bandpass filter for filtering the third mixer signal amplified by the first preamplifier;
a fifth bandpass filter for filtering the first signal;
fourth means for mixing the third mixer signal filtered by the fourth filter with the first signal filtered by the fifth filter and for delivering a fourth mixer signal having a frequency component FR-F1-F2;
a sixth filter for filtering the fourth mixer signal;
and
processing and display means for utilizing the fourth mixer signal to provide a radar indication.

14 more elements

Dependencies are inferred from the claim text.