6 results about "Phase detector" 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.

An FDM-CPM multi-user detector (30) jointly detects the received symbols for all users by determining from the received multi-user signal an a-posteriori probability mass function (pmf) of a time-sequence of states and transmitted symbols of all users, by iterative message passing corresponding to a specific factorisation of the pmf. The factorisation involves a combined variable representing possible transmitted symbols and CPM states of each user for each symbol time interval, so as to make the iterative process convergent. Non exponential complexity is enabled by disregarding multiple access interference (MAI) from at least some of the other users. Applications can include hubs for satellite communication ground stations.

The invention provides a direction finding method based on a radio frequency analog receiving system. The method comprises steps of obtaining the phase difference between each path of antenna and an adjacent antenna through a phase discriminator for an N-element uniform circular array antenna, and recording the phase difference as the phase difference of the phase discriminator; recording the phase difference of each phase discriminator as an initial phase difference when an incoming wave enters the circular array antenna at an elevation angle of 0 degree; constructing a plurality of phase discriminators corresponding to each phase discriminator; according to an elevation angle and an azimuth angle, k is the number of iterations, and calculating the theoretical phase difference of each phase discriminator; introducing a vector X and a direction vector G, and calculating an elevation angle and an azimuth angle of a two-dimensional incident angle of iteration times k+1 in combination with the constructed complex number, calculating the difference between the two-dimensional incident angle with the iteration frequency of k+1 and the iteration frequency of k, comparing the two-dimensional incident angle with a threshold value, and entering an output elevation angle and an azimuth angle when the two-dimensional incident angle is smaller than the threshold value, otherwise, adding 1to the value of k, and calculating the theoretical phase difference. The method is advantaged in that problems of logic judgment and other operations, phase ambiguity and unbalanced amplitude of an input signal of the phase discriminator are avoided, and direction finding precision is improved.