38 results about "Square law detector" patented technology

The invention discloses a real-time monitoring microwave dicke radiometer based on a reference load temperature and belongs to the field of microwave passive remote sensing. The radiometer comprises a dicke input switch, wherein a first end of the dicke input switch is sequentially connected with a radio frequency and intermediate frequency amplifying circuit, a square law detector, a low frequency amplifier, a synchronous detector, a low pass filter and a data collecting and processing module, a second end of the dicke input switch is switched between a reference load and an antenna under the driving of a switch signal generator, and a temperature measuring circuit is arranged on the reference load and connected with the data collecting and processing module. The reference load of the microwave dicke radiometer is not required to be kept in a constant temperature state, only the temperature measuring circuit is used for monitoring the temperature changes of the reference load in real time, the monitored variable quantity of the temperature of the reference load is plugged into a radiometer scaling equation for modification, and an antenna temperature of the measured scene is obtained. According to the real-time monitoring microwave dicke radiometer based on the reference load temperature, the measuring accuracy is improved and the structure of the existing microwave dicke radiometers is simplified.

A transmitter 1 transmits from a transmission antenna 7 a mixture signal containing a radio-frequency (RF)-band modulated signal, and a portion of power of a local oscillation signal used for frequency conversion. Meanwhile, a receiver 8 detects the transmitted signal by means of a reception antenna-detection section 9. In the reception antenna-detection section 9, a plurality of base unit reception circuits 11 are disposed. Each base unit reception circuit 11 includes a planar printed antenna 12 such as a patch antenna, an amplifier circuit 13 formed on a very small planar circuit by means of an MMIC technique, and a mixer circuit 14 serving as a square-law detector. Respective outputs of the base unit reception circuits 11 are power-mixed and fed to the IF signal demodulation section. The IF signal demodulation section 10 demodulate reception data. This configuration enables realization of a reception antenna which occupies a very small space, has a detection function and a high gain, and has a wide beam characteristic comparable to that of a single-element antenna.

An apparatus and method for differential optical dispersion using a first sample and a second sample are disclosed. The apparatus includes a single frequency chirped laser source configured to generate a single frequency chirped laser beam. A first beam splitter is configured to split the single frequency chirped laser beam into first and second optical branches, the first sample being located in the first optical branch, the second sample being located in the second optical branch. A frequency shifter is located in the second optical branch, downstream of the second sample. A second beam splitter is configured to combine the first and second optical branches and generate a chirp-modulated mixed light beam. A square law detector is configured to detect the chirp-modulated mixed light beam and generate a heterodyne beatnote signal. A demodulator is configured for detection of the heterodyne beatnote signal to generate a transmission / differential optical dispersion spectrum.

The invention relates to an adaptive constant false alarm rate target detection method, comprising the following steps: 1): inputting data received by a radar into a matched filter; 2): inputting a signal output by a matched filter into a square law processing in the detector; 3): Finally, the signal output from the square law detector is passed to the CFAR detector for processing, and the estimated value Z of the clutter power level generated by the reference unit sampling according to the corresponding CFAR algorithm is obtained; 4): according to 3) Obtained reference unit sampling According to the estimated value Z of the clutter power level generated by the corresponding CFAR algorithm, the CFAR detector outputs the final decision, that is, whether there is a target in the detection unit. According to the statistical mean value x and variance of the sampling values ​​in the reference sliding window, the method deletes the sampling values ​​whose variance is greater than a certain value, replaces the sampling value with the mean value of the remaining effective sampling values, and recalculates the mean value of the sampling values.

The invention relates to a nonlinear vector network analyzer calibration method, in particular relating to a phase response calibration method of a nonlinear vector network analyzer based on fine frequency grid calibration. The method provided by the invention can be used for the problem that the existing phase response calibration method of a nonlinear network analyzer has low phase calibration frequency resolution. The method comprises: constructing an amplitude modulation signal xAM(t); constructing a fine frequency grid on both sides of a carrier frequency fc; calibrating the phase of a square law detector by use of the fine frequency grid to obtain the phase transmission standard of the fine frequency grid; and carrying out fine frequency phase calibration of the nonlinear vector network analyzer by use of the phase transmission standard of the fine frequency grid. The method is applicable to the phase calibration of the nonlinear vector network analyzer.