SU429544A1 - DEVICE FOR MEASURING RELATIONSHIP SIGNAL / INTERFERENCE AT FREQUENCY MANIPULATION - Google Patents

Description

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The invention relates to a radio metering technique and can be used to monitor the quality of the telegraph channels of single-channel and multichannel communication systems with frequency shift during operation and to predict the quality of channels on a group of frequencies allocated for communication.

Signal-to-noise ratio measurement devices for frequency manipulation are known, containing an FM signal receiver consisting of a radio receiver connected in series, a limiter and a frequency detector, and an FM signal receiver output connected to the regenerator input, a parcel filter whose input is connected to the input pause filter, as well as noise level and signal level meters, the outputs of which are connected to the inputs of the signal-to-noise ratio indicator.

The aim of the invention is to improve the accuracy of measuring signal levels and interference.

For this, the output of the radio signal receiver is connected via a delay line to the inputs of the parcel and pause filters, the outputs of which are connected respectively to the inputs of the noise level and signal level meters through an electronic switch, to the input of which the output of the regenerator and the input of the pulse generator are connected, the output of which is connected simultaneously to the same inputs electronic keys, to the other inputs of which are connected respectively the outputs of the filter parcels and pauses. The drawing shows a block diagram of the proposed device.

The device has an FM signal receiver 1, a telegraph signal regenerator 2, information output 3 to a message receiver, a radio signal receiver 4, a delay line 5,

parcel separation filter 6, pause separation filter 7, electronic switch 8, noise level meter 9, signal level meter 10, signal-to-noise ratio indicator 11, electronic keys 12 and

13, pulse generator 14.

The output at the intermediate frequency of the radio signal receiver 4 is connected to the input of the delay line 5. The output of the delay line 5 is connected to the inputs of the separation filters 6 and

7, the outputs of which are connected to the inputs of the electronic switch 8. The electronic switch has two inputs, two outputs and control circuits. One output of the switch is connected to the input of the noise level meter 9, and the other to the input of the level meter 10. The switch control circuits are connected to the output 3 of the regenerator 2 telegraph signals. The outputs of the meters 9 and 10 are connected to the inputs of the indicator 11. Conclusions

filter containers 6 are connected to the terminals

the electronic key 12, and the filter terminals to the terminals of the electronic key 13. The control circuits of the electronic keys 12 and 13 are connected to the output of the pulse generator 14, the synchronization circuit of which is connected to the output 3 of the regenerator 2.

The distorted pulse signal from the output of the receiver of the FM signals 1 after detection comes pa regenerator 2 and then from output 3 to the recipient of the message. At the same time, the signal with interference at the intermediate frequency from the output of the radio signal receiver 4 arrives at the delay line 5. The delay time of the line corresponds to the delay time of the borders of the parcels at the output 3 of the regenerator 2, so that the borders of the parcels at the output of the delay line and at the output 3 of the regenerator 2 match. The signal with interference from the output of the delay line 5 is fed to separate filters b and 7. Depending on the sign of the transmitted parcel, the signal plus signal is always present at the output of one of the filters, and the signal at the output of the other. When the sign of the sending is changed, the situation changes: in the first filter there is interference, and in the second, the signal plus interference. Since it is of practical interest to measure the signal / interference from 10 to 40 dB, the voltage signal plus interference can be considered as a signal voltage without noticeable error.

The signal (or noise) from the output of the filter b is fed to one input of the electronic switch 8, and from the output of filter 7 to the other. On the control circuit of the switch 8, the switching signal is supplied from the output 3 of the regenerator 2 (corrected parcels of standard duration). Depending on the sign of the parcel at the output 3 of the regenerator 2, the input of each filter is connected to one or the other output of the switch 8, so that there is always a voltage on one of its outputs

interference, and on the other - the signal voltage. The interference voltage from the first output of the switch 8 goes to the noise level meter 9, and the signal voltage from the other output goes to the signal level meter 10. Since the gain from the receiver input to the output of the level meters is pre-calibrated and known, then by the measured levels the meters 9 and 10 determine

absolute signal levels and interference at the receiver input. The ratio indicator 11 is used to determine the signal-to-noise ratio at the receiver input.

Subject invention

A signal-to-noise ratio measurement device for frequency manipulation containing an FM signal receiver consisting of a series-connected radio signal receiver, a limiter and a frequency detector, and an FM signal receiver output connected to the regenerator input, a parcel filter whose input is connected to the filter input

pauses, as well as noise level and signal level meters, the outputs of which are connected to the signal-to-noise ratio indicator inputs, characterized in that, in order to improve the accuracy of signal and noise level measurement, the output of the radio signals through the delay line is connected to the parcel filter inputs and pauses, the outputs of which are connected respectively to the inputs of the noise level meters and the signal level through the electronic switch, to the input of which the output of the regenerator and the input of the pulse generator, the output of which is connected at the same time to one input of electronic keys, which other inputs

connected respectively the outputs of the filter parcel and pause.

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