Method for generating stepped frequency signals based on combination of direct digital synthesis (DDS) and ping-pong phase locked loop

Abstract

The invention discloses a method for generating stepped frequency signals based on the combination of direct digital synthesis (DDS) and a ping-pong phase locked loop. DDS has the advantages of high narrowband application performance and capability of easily realizing extremely small frequency step, and the phase locked loop has the advantages of easily realizing broadband application and ensuring high comprehensive performance particularly in broadband great-step application. In the method, advantage complementarity between the DDS and the phase locked loop is utilized, a ping-pong phase locked loop is formed by combining two identical phase locked loops and a microwave single-pole double-throw switch, frequency synthesis is performed by combining the DDS and the ping-pong phase locked loop, the DDS is used for synthesizing narrowband small-step signals, the ping-pong phase locked loop is used for synthesizing broadband great-step signals, and the broadband great-step signal and the narrowband small-step signals are combined together in a frequency shifting way, thereby generating broadband radar stepped frequency signals with low phase noise, low stray, small step and frequency agility. Therefore, tactical and technical indexes of a radar frequency synthesizer are greatly increased, and qualitative leaps in technical indexes of the radar stepped frequency signals are achieved.

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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