Correlator


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correlator

[′kär·ə‚lād·ər]
(electronics)
A device that detects weak signals in noise by performing an electronic operation approximating the computation of a correlation function. Also known as correlation-type receiver.

Correlator

 

(correlation-type receiver), an instrument used to measure the correlation functions of random processes. A knowledge of the correlation coefficient permits an analysis to be made of physical phenomena having probabilistic characteristics, such as the noise in radio receiving apparatus, cosmic particle showers, and biopotentials (see). When two random signals in the form of AC electrical voltages U1(t) and U2(t) are supplied to the inputs of a correlator, its output voltage is proportional to the cross-correlation function of these signals. If a signal Uc(t) is supplied to both inputs, the correlator measures the autocorrelation coefficient.

Electronic correlators are the most widely used. The indicator is usually a pointer-type instrument calibrated in terms of the correlation coefficient, or a cathode-ray tube. Provision is usually made for the connection to a digital or a chart recording system. Correlators are employed in radio-communication devices (to measure the transient attenuations in multi-channel systems); in radar, sonar, and radio astronomical equipment (for correlation direction finding and to improve the resolution of transmission); and in medical diagnostic equipment. The signals studied in a cross-correlation have frequencies ranging from 1 Hz to 50 MHz. Special signal-processing methods are used to raise the signal frequency factor to 500 MHz. The measuring gauge for the correlation coefficient ranges from 0.01 to 1, and the error of the correlator is between 5 and 10 percent.

REFERENCES

Lange, F. Korreliatsionnaia elektronika. Leningrad, 1963. (Translated from German.)
Mirskii, G. la. Radioelektronnye izmereniia, 2nd ed. Moscow, 1969.
Valitov, R. A., and V. N. Sretenskii. Radiotekhnicheskie izmereniia. Moscow, 1970.

E. G. BILYK

References in periodicals archive ?
[16] Li, C., Yin, S., Yu F., "Non zero-order joint transform correlator," Opt.
Caption: Figure 9: The binary codes whose correlation coefficient is less than the threshold T for the output of the filter and the polarity correlator.
which is the gauge boson correlator in an arbitrary gauge; the freedom to choose [xi] follows from the symmetry of (81) under interchange of the Lorentz indices (3).
Under the assumption that transmitter and receiver are synchronized in time, the received signal [r.sub.i] is multiplied by the received signal delayed by M, [r.sub.i-M], and correlator output is averaged over the last half of bit duration.
The signal tracking uses electronic circuits called correlators that calculate the correlation between a received signal and a replica signal for a single frequency shift and two or several delays.
In the proposed MRC, the outputs of the N correlators are multiplied by the conjugate of the channel gain [[alpha].sub.k], which is estimated in the receiver.
where i = 1, ..., N; it represents the current integration interval and goes from 1 to N and N is the number of received data bits; [y.sub.k] is the correlator samples.
After receiving the 1-bit data, the correlator unit computes the cross correlation coefficients with the 1-bit data.
10, with two mmW front-ends, I/Q demodulators, sampling and correlators shown.
In this scheme, multiple active correlators for demodulation are replaced with a matched filter-based cross-correlator.
It has been carried out by constructing a complex quaternion correlator and a max-product fuzzy neural network classifier.