Low noise generator for frequency swept signals

Abstract

A signal generation system suitable for use in a radar system comprises a local oscillator (LO) and an intermediate frequency IF oscillator, wherein the IF oscillator is a Direct Digital Synthesiser, and the LO is a free runn ing oscillator not itself locked to another oscillator but which acts as a c lock reference for the DDS and is the highest frequency oscillator in the sy stem. The LO may also act as a reference for a receive chain digitiser. The invention exploits phase noise advantages of a free running oscillator at so me distance from the carrier whilst maintaining coherency with other system components. The system typically finds application in FMCW radars.

Description

Technical field

[0001] The present invention relates to signal generation systems, such as those commonly used in radar systems. In particular, the present invention relates to radar systems, especially FMCW (Frequency Modulated Continuous Wave) radar systems, in which it is advantageous to keep the phase noise generated in key system components as low as possible in practice and economically to obtain improved operating performance . Background technique

[0002] The FMCW radar system is characterized by having simultaneous transmitting and receiving functions. This may lead to problems that are not encountered in more traditional pulse radars. In more traditional pulse radars, the signal may often "leak" from the transmitter to the receiver via the corresponding antenna. The energy comes directly from the transmitter. It is difficult to detect the signal received from the target. This problem is improved by designing the transmitting and receiving antennas and related subsystem...

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