4 results about "Phase noise" patented technology

The invention discloses a broadband microwave frequency source circuit with low phase noise. The reference frequency is input into a digital phase detector and a low phase noise amplifier respectively. The output end of the digital phase detector is connected with the input end of a passive loop filter, and the output end of the passive loop filter is connected with the first end of a plurality ofactive loop filters respectively. The output of the low phase noise amplifier is connected to the input of the sampling phase detector. The output of the sampling phase detector is connected to the input of the first set of multiplexers, the output terminals of the first group of multiplexers are respectively connected with the second terminals of a plurality of active loop filters, the third terminals of the plurality of active loop filters are respectively connected with the input terminals of the second group of multiplexers, the output terminals of the second group of multiplexers are respectively connected with a plurality of VCOs, and a plurality of VCOs select one output. The selected VCO output signal is fed back to the sampling phase detector as the system output and fed back tothe digital phase detector through the N divider. The invention realizes the effects of wide frequency band and low phase noise.

The invention discloses a rapid scanning microwave detector and a detection method, and the microwave detector employs the same microwave source to transmit signals and carries out the down-conversion of the transmitted signals twice, greatly reduces the phase noise, is simple in structure, does not need a lengthy delay line, does not need the length matching of the delay line and a radio frequency line, and improves the detection efficiency, and rapid detection of different physical quantities such as distance, speed, density and the like can be realized in a specific measurement environment.

Compared with a traditional FDD system measurement and control station, an uplink and downlink common-frequency aerospace ground measurement and control station disclosed by the invention has higher measurement and control spectrum efficiency and higher measurement precision. A first-stage interference suppression module is formed by four channels, and a second-stage interference suppression module formed by a sum channel, an azimuth difference channel and a pitch difference channel is arranged between a down-conversion module and a measurement and control baseband module; a time delay estimation module based on a spreading code is added in a second-stage interference suppression module so as to improve the synchronization precision between an interference reconstruction signal and a receiving signal; the antenna feed source adopts a transmitting and receiving feed source split antenna in which a transmitting feed source and a receiving feed source are separated, so that the isolation degree between transmitting and receiving signals is increased; a receiving and transmitting common-local-oscillator scheme is adopted, a unified local oscillator signal is distributed to the up-conversion module and the down-conversion module, it is guaranteed that reference signals and received self-interference have the same phase noise distribution, the self-interference cancellation efficiency is improved, and the technical difficulty of uplink and downlink common-frequency self-interference suppression is reduced.