RU2055444C1 - Multichannel device for receiving sampled frequency signals - Google Patents

Abstract

FIELD: reception of sampled frequency signals. SUBSTANCE: device has N band filters 1, N controlled signal-integrating units 2, N threshold units 3, N amplitude detectors 4, N+1 controlled-gain amplifiers 5,6, and 9, reference-voltage units 10 and 11, search, tracking, and demodulating unit 12, N frequency channels 7. EFFECT: improved power signal-to-noise ratio. 1 dwg

Description

 The invention relates to radio engineering and can be used to receive discrete frequency signals under the influence of narrow-band interference.

 The purpose of the invention is to increase the noise immunity of a multichannel device for receiving discrete frequency channels due to increased accuracy of the weighting of signals in the channels of the device.

 A functional diagram of the proposed device is shown in the drawing, where a bandpass filter 1, a controlled signal integration unit 2, a threshold unit 3, an amplitude detector 4, the first 5 and second 6 amplifiers with an adjustable transmission coefficient, a frequency channel 7, an extreme signal selection block 8, an amplifier are indicated 9 with an adjustable transmission coefficient, the first 10 and second 11 blocks of the reference voltage and block 12 search, tracking and demodulation.

 The device operates as follows.

 The input signal passes through an adjustable amplifier 9 to the combined inputs of the channels 7. The band-pass filters 1 in the channels divide the frequency band of the input signal into N equal, adjacent bands, thereby forming N parallel frequency channels on the receiving side, tuned to the elements of the discrete frequency signal .

 Adjustable amplifier 5 is covered by an AGC ring. Due to the inclusion of a controlled integration unit 2 in the AGC circuit, the level of narrow-band interference at the output of amplifier 5 will not change when their input level changes. In addition, the level of interference at the output of amplifier 5 will change slightly when the level of the discrete frequency signal at the input of the device changes.

уровень выходного сигнала усилителя 5, при котором напряжение на выходе детектора 4 огибающей равно порогу срабатывания порогового блока 3. Предположим, что уровень помех на входе усилителя 5 увеличился. Следовательно, напряжение на выходе детектора 4 станет больше порога срабатывания порогового блока 3.Assume first that there is no useful signal at the input, i.e. P _in5 P _n5 . Denote by

the output signal level of amplifier 5, at which the voltage at the output of the envelope detector 4 is equal to the threshold of threshold unit 3. Suppose that the noise level at the input of amplifier 5 has increased. Therefore, the voltage at the output of the detector 4 will become greater than the threshold of the threshold unit 3.

 Suppose that the gain of the adjustable amplifiers 5.6 and 9 decreases with increasing input control signals. Then, in accordance with the foregoing, the signal at the output of the controlled signal integration unit 2 will begin to decrease. This will lead to a decrease in the gain of the adjustable amplifier 5 until the signal at the output of the amplitude detector 4 is less than the threshold of the threshold unit 3. This will increase the signal at the output of the controlled unit 2 and the gain of the amplifier 5 until the signal at the output of the detector 4 does not exceed the threshold of the threshold unit 3.

Предположим, что полезный сигнал на входе присутствует.Suppose that the gain of the adjustable amplifiers 5.6 and 9 decreases with increasing input control signals. Then, in accordance with the foregoing, the signal at the output of the controlled signal integration unit 2 will begin to decrease. This will lead to a decrease in the gain of the adjustable amplifier 5 until the signal at the output of the amplitude detector 4 is less than the threshold of the threshold unit 3. This will increase the signal at the output of the controlled unit 2 and the gain of the amplifier 5 until the signal at the output of the detector 4 does not exceed the threshold of the threshold unit 3. Thus, the slightest deviation of the signal at the output of the detector 4 from the threshold will lead to a change in the gain of amplifier 5 in such a way In order for the signal at the output of detector 4 to become equal to the threshold value in the threshold block 3. Therefore, when the input signal level is P _n5 , the transfer coefficient of the adjustable amplifier 5 is automatically set equal to
K ₅ =

Suppose that a useful input signal is present.

 When the output signal of the detector 4 exceeds the value in the threshold block 3 under the action of the useful signal, the controlled integration unit 2 is charged from the first block 10 of the reference signal. Moreover, the magnitude of the output signal of the first block 10 is chosen such that during the duration of the pulse of the useful signal, block 2 does not have time to charge so that there is a noticeable decrease in the transfer coefficient of adjustable amplifiers 5 and 6.

 After the disappearance of the pulse of the useful signal, the block 2 quickly discharges to the initial level due to the fact that the output signal of the second block 11 is selected much larger than the output signal of the first block 10.

 Thus, the presence of a discrete-frequency useful signal practically does not lead to a change in the gain of the adjustable amplifier 5.

т.е. автоматически устанавливается обратно пропорционально мощности помех в канале, что является оптимальным.Adjustable amplifiers 5 and 6 are the same. Then, with the transmission coefficient of the band-pass filter 1 equal to unity (which is not important), the transmission coefficient of channel 7 will be equal to
KK ₅ • K ₆ = K $\genfrac{}{}{0ex}{}{\text{2}}{\text{5}}$ =

those. automatically set inversely with the interference power in the channel, which is optimal.

 The control signals from the outputs of the integration unit 2 are fed to the inputs of the extreme signal selection unit 8. From the output of block 8, the signal is supplied to the control input of amplifier 9 with an adjustable transmission coefficient. Due to this, the level of interference at the input of the adjustable amplifier 5 in the channel with a minimum level of interference is kept constant and the device is able to operate in a wide range of changes in the levels of input signals.

 The output signals of channels 7 go to block 12, which performs a search for a useful signal, tracking the detected signal, as well as its demodulation.

 The proposed device can improve the accuracy of weighing signals in the channels of the device and, as a result, increase the noise immunity of the reception of discrete frequency signals when exposed to narrow-band interference.

Claims (1)

 MULTI-CHANNEL DEVICE FOR RECEIVING DISCRETE FREQUENCY SIGNALS, comprising a first reference voltage block, an extremal signal selection block in series, and an amplifier with an adjustable transmission coefficient, the signal input of which is the device input, N frequency channels, the inputs of which are combined, each of N frequency channels containing serially connected band-pass filter, the input of which is the input of the frequency channel, the first amplifier with an adjustable transmission coefficient and amplitude the first detector, as well as the second amplifier with an adjustable transmission coefficient, the output of which is the output of the frequency channel, characterized in that the second block of the reference voltage, the search, tracking and demodulation unit are introduced into it, in addition, series-connected in each of the N frequency channels a threshold unit and a controlled unit for integrating signals, the output of the first amplifier with an adjustable transmission coefficient connected to the input of the second amplifier with an adjustable transmission coefficient, the first inputs are controlled of the second signal integration blocks of all N frequency channels are combined and connected to the output of the reference voltage block, the second inputs of the controlled signal integration blocks are combined and connected to the output of the second reference voltage block, the control input of the controlled integration block of each of the N frequency channels is connected to the output of the threshold block, input which is connected to the output of the amplitude detector, the output of each controlled signal integration unit is connected to the control inputs of the first and second amplifiers with an adjustable transmission coefficient and the corresponding input of the extreme signal selection block, the outputs of N frequency channels are connected to the corresponding inputs of the search, tracking, and demodulation block.