Realization method for four-channel T/R assembly by using DDS as local oscillator to realize digital phase shift

Abstract

The invention belongs to the field of radar microwave transceiver assemblies, and particularly relates to a realization method for a four-channel T / R assembly by using DDS as a local oscillator to realize a digital phase shift. DDS output is used as a third local oscillator of a transmission path of the four-channel T / R assembly, and a second local oscillator generated by a radar frequency synthesizer is used as a clock signal of the DDS; a centralized waveform generator is adopted by a radar system, and power is divided and input to each T / R channel and then mixed with three local oscillators. The digital phase shift of the whole transmission path can be achieved through phase control of the DDS, and purpose of forming phased array radar beams is achieved. According to the realization method, differential serial signals are adopted in wave control code, signals can be transmitted over long distances without interference, and phase codes of the four T / R channels are sent serially through a protocol, so that the number of control lines is not increased, and expansion is easy.

Description

technical field [0001] The invention belongs to the field of radar microwave transceiver components, in particular to a four-channel T / R component realization method for realizing digital phase shift by using DDS as a local oscillator. Background technique [0002] With the application of phased array radar, the integration requirements of T / R components are getting higher and higher, and the phase control of the transmission path and the reception path has become more important. The number of control bits and precision is the key to measure the phase shift performance technology. The phase control of the receiving channel is mostly realized by DBF (Digital Beam Forming) technology without adding hardware circuits in the channel, but the phase control of the transmitting channel is usually realized by a digital phase shifter or generated by a DDS (Direct Digital Synthesizer). Waveform simultaneously and phase-shifted way to achieve. [0003] Traditional digital phase shift...

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Problems solved by technology

[0003] Traditional digital phase shifters are mostly realized by PIN tubes, with limited number of bits and high price. At present, 6-bit or 8-bit phase shifters are commonly used, and at least one phase shifter is required for each transmission channel. Generally speaking, the quality is heavy ,Big size

[0004] Although the method of generating the transmitted waveform and shifting the phase through DDS can solve the problem of the limited number of phase shifts of the traditional digital phase shifter, the output signal has limitations in performance and mode.

Generally speaking, radars require many types of transmit waveforms and complex modulation methods, and have high requirements for the signal quality of transmit waveforms. It is relatively simple for DDS to output linear frequency modulation signals, but for non-linear frequency modulation and phase-coded signals, It is more complicated to implement, and the phase noise and spurious suppression indicators of the DDS output signal are relatively low. In order to meet the signal quality, it is often necessary to improve the requirements for the DDS chip. In order to realize the generation of complex waveforms, it is necessary to improve the control chip FPGA (Field Programmable GateArray) performance requirements directly lead to an increase in design cost

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