SU809603A1 - Device for measuring signal-to-noise ratio - Google Patents

Description

(54) DEVICE FOR MEASURING RELATIONSHIP SIGNAL / NOISE

one

The invention relates to radio engineering and can be used in receivers of discontinuous, signals of simplex radio stations in two-way communication.

A device for measuring the signal-to-noise ratio, comprising a series-connected adjustable amplifier and a detector, an automatic gain control unit, a signal strength level unit 1, and a synchronization unit 1, is known.

However, such a device has a small range of measurable relations.

SIGNOSH / NOISE.

The purpose of the invention is to expand the measurement range.

This goal is achieved by the fact that a noise memory block, first and second averaging filters are inserted into a signal-to-noise ratio measurement device containing a series-connected adjustable amplifier and detector, an automatic gain control unit, a signal level memory block, and a synchronization block. a differential amplifier, a nonlinear converter and an indicator; the detector output is connected through a series-connected noise level memory block, the first averaging filter, a differential amplifier to the indicator input, the detector output is connected to the input of the automatic gain control blocks, the output of which is connected via a non-linear converter to the control input of the adjustable amplifier, the detector output is connected to the first input of the signal level memory, the second input of which is connected the input of the memory block of the noise level, and the output is connected through

5, the second averaging filter to the other input of the differential amplifier.

The drawing shows the structural electrical circuit of the proposed device.

The device contains an adjustable amplifier 1, a detector 2, an automatic gain control unit 3 (AGC), a signal level memory block 4,

5 synchronization unit 5, noise memory unit 6, averaging filters 7 and 8, differential amplifier 9, nonlinear converter 10 and indicator 11.

The proposed device works

0 as follows.

Upon reception and absence of a signal (for example, continuous monochromatic), the voltage at the output of detector 2 is proportional to the magnitude of the signal and the noise level, respectively, and is in logarithmic dependence on the values of that and the other. The nonlinear converter 10, connected in series to the AGC circuit, significantly increases the signal variation range by 40-50 dB, with the coderr, the logarithmic dependence of the output voltage of detector 2 with a high degree of accuracy (not lower than 1 dB) over the entire range of signal variation is maintained 110 dB input. The output voltage of the detector 2 is alternately connected to the input of block 4 during reception of the signal and to the input of block 6 during the absence of reception of the signal. This connection is made by synchronization unit 5. The output voltages of blocks 4 and b are averaged by filters 8 and 7, whose output circuits are connected to differential amplifier 9. The output voltage of differential amplifier 9, proportional to the signal-to-noise ratio, is fixed by indicator 11, which has a linear scale calibrated in decibels.

Use in the device of nonlinear converter, made, for example, in the form of a diode array. the shunt elements of which (diodes) turn on the control voltage in a sequence that corrects the deviation of the output voltage of the detector from the logarithmic law, the use of a noise memory block, two averaging filters of averaging signal levels and noise, and the use of a differential amplifier is beneficial distinguishes the proposed device for measuring the signal-to-noise ratio from the known one, since the range of measured signal ratios significantly increases

noise, improved measurement accuracy and increased operational use of measurement results for various tasks of receiving devices and special purpose stations. As a result, the area of application of the device is expanded and the need for applications of multi-channel signal-to-noise ratio devices is eliminated.

Claims (1)

1. US patent 3831093, CL.325-56, 1974. About