Stepped-frequency signal generation method based on combination of DDS (Direct Digital Synthesis) and ping-pong type phase-locked loop

Abstract

The invention discloses a stepped-frequency signal generation method based on combination of DDS (Direct Digital Synthesis) and a ping-pong type phase-locked loop. In the invention, the good narrow-band applicability of the DDS is utilized so as to realize tiny frequency stepping, the phase-locked loop is easy for realization of broadband application and particularly has a complementary advantage of good comprehensive performance during broadband large stepping application, two identical phase-locked loops and one microwave single-pole double-throw switch are combined to constitute the ping-pong type phase-locked loop, the DDS and the ping-pong type phase-locked loop are combined for performing frequency synthesis, the DDS is used for synthesizing narrow-band small stepping signals, the ping-pong type phase-locked loop is used for synthesizing broadband large stepping signals, and the broadband large stepping signals and the narrow-band small stepping signals are combined together in a frequency shifting manner, so that broadband radar stepping frequency signals with low phase noise, low stray, small stepping and frequency agility are generated. Therefore, the tactic index of a radar frequency synthesizer is greatly increased, and the technical index of the radar stepped-frequency signals is subjected to a qualitative leap.

Description

technical field [0001] The invention belongs to the technical field of radar, in particular to a method for generating a step frequency signal based on the combination of direct digital frequency synthesis (DDS) and a ping-pong phase-locked loop. Applied in the design of the step frequency radar frequency synthesizer, the performance of the step frequency radar frequency synthesizer can be greatly improved. Design provides good reference. Background technique [0002] With the development of modern radar technology, it has become an important research and development direction of modern radar to use high-resolution radar signals for high-resolution imaging of targets, so as to realize the detection and recognition of targets. The step frequency signal is a common high-range high-resolution radar signal. It is a pulse train containing N transmission frequencies. The transmission frequency of each pulse is different, and the frequency step is a fixed value. From the perspect...

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Problems solved by technology

[0007] The problem to be solved by the present invention is aimed at the mutual influence and interaction between the frequency hopping time, minimum step, phase noise, spurious level, bandwidth, volume and cost and other indicators existing in the above-mentioned several current main step frequency signal generation methods. Restricted defects, provide a new step frequency signal generation method, so that the above indicators can be taken into account and further optimized, so as to design a high-performance step frequency signal

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