Self-adaptive metrewave radar automatic frequency control (AFC) system based on direct digital synthesizer (DDS) technology

Abstract

The invention provides a self-adaptive metrewave radar automatic frequency control (AFC) system based on a direct digital synthesizer (DDS) technology, belonging to the field of communication engineering and relating to a metrewave radar AFC system. The system of the invention comprises a metrewave radar, a decimetre wave radar and a centimeter wave radar; and a receiver of the system is in a superheterodyne mode generally. The decimetre wave radar and the centimeter wave radar are respectively provided with an AFC system in general due to higher working frequency, wherein the AFC system is used for controlling changes of automatic follow transmitting frequency of local frequency or the transmitting frequency to automatically stabilize on a frequency point corresponding to the local frequency, thus ensuring the stable intermediate frequency of the radar receiver.

Description

Technical field: [0001] The invention belongs to the field of communication engineering, and relates to an automatic frequency control system of an adaptive meter-wave radar based on DDS technology. Background technique: [0002] Due to the limitation of the analog circuit itself, the traditional analog single-loop or double-loop AFC system makes the tracking speed of the AFC slow, the tracking frequency range is narrow, the accuracy is low, and there may even be wrong tracking; in addition, the control of the local oscillator Since the self-frequency control radar is equipped with a frequency adjustment device on the local oscillator, the frequency stability of the local oscillator is affected, which is unacceptable to the target radar. Meter wave radar basically has no automatic frequency control system due to its low operating frequency. The range of variation is from tens of kilohertz to hundreds of kilohertz, usually between 500 and 600kHz. Although the absolute value...

AI Technical Summary

Problems solved by technology

Although the absolute value of the resulting IF frequency change will not exceed the passband range of the IF amplifier (the passband of the IF amplifier is usually ≤1MHz), the change of hundreds of kilohertz prevents the echo signal from being amplified most effectively , resulting in a reduction in the technical and tactical performance of the radar receiver. Even if DSU equipment is installed at this time, the performance of the DSU cannot be brought into full play due to the influence of the frequency drift of the intermediate frequency.

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