5 results about "Down conversion" patented technology

The invention provides a control method of a flyback converter. The control method is a control method in a mixed control mode; in other words, the flyback converter works in a non-complementation state under light loads, the clamp switch pipe on time is shortened through down conversion, and light load losses are effectively reduced through down conversion; flyback converter works in a fixed-frequency drive complementation state under heavy loads, and the clamp switch pipe on time is prolonged. Compared with the prior art, the control method has the advantages that the voltage stress of a main switch pipe and a clamp capacitor can be effectively reduced, the main switch pipe off losses can be reduced, the clamp circuit current change slope is decreased, the EMI interference is reduced, the secondary current change slope is decreased, and the longer detection reaction time is provided for synchronous rectification. Meanwhile, the working area of a magnetic core in the third quadrant is enlarged, the maximum flux density is reduced, and the size of the magnetic core is reduced.

The invention particularly relates to an inter-channel phase difference and amplitude difference high-precision measurement method comprising the following steps that (A) supposing that multichannel input signals are r(k); (B) digital down-conversion processing is performed on each channel and the IQ data r<ddc>(k) after down-conversion are obtained by the decimation filter; (C) any one channel r(m) is selected to act as the reference channel and conjugating of r<ddc>(m) is performed so as to obtain r<*><ddc>(m); (D) the down-conversion data of other channels and the down-conversion conjugatedata of the reference channel are multiplied so as to obtain the processed complex signal r<mul>(k)=r<ddc>(k).r<*><ddc>(m); and (F) the phase difference phi<delta>(k) and the amplitude difference A<deltah>(k) between the kth channel and the mth channel are calculated according to the obtained complex signal: mean filtering is performed on the DC component after conjugate multiplying and there is no spectrum leakage so that the calculation precision is higher than that of conventional FFT; and mean filtering is realized by using the first-order CIC filter so that the calculation amount is muchlower in comparison with that of the conventional FFT method and the advantage is more obvious especially in case of high number of channels.

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.

The invention provides a test terminal platform of a transformer substation safety automatic device. The test terminal platform comprises a switch chip, a self-adaptive power supply module and a function realization module, wherein the self-adaptive power supply module and the function realization module are connected with the switch chip. The self-adaptive power supply module connected with a PCcomprises two network ports, two first switches, an external power supply interface, at least one step-down conversion module and a second switch. The function realization module is also connected with a transformer substation safety automatic device. After one network port is connected with the PC or a network device and the other network port is in cascade connection with a network port of an adjacent test terminal platform and adjacent power supply is not received, corresponding switch control is carried out, so that power is provided for the adjacent test terminal platform by utilizing thenetwork port cascaded connection after local independent power taking and data are transmitted with the adjacent test terminal platform, the substation safety automatic device, the PC and the like ina self-networking manner. Therefore, the dependence on a switch can be eliminated; independent configuration of power supply concentrators with power supplies or various power supplies can be avoided; and the access cost and difficulty of the test terminal platform and other network equipment can be reduced.

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.