SU542348A1 - Wireless telephone receiver with controlled companding - Google Patents

Description

one

The invention relates to radio communications, can be used in radio telephone communication systems with controlled companding.

One of the known devices includes receiving and transmitting parts; the latter includes delay lines, a compressor, a low-pass filter, a summing device, an envelope selection unit and a frequency-multiplexed oscillator, and the receiving part contains a filter for selecting the speech spectrum, a fader controller, a delay line, an expander, a band-pass filter, a limiter and a frequency detector, moreover, an amplitude discriminator of relay type 1 is connected between the envelope selection unit and the frequency detector.

However, the known device is not sufficiently high noise immunity.

Closest to the proposed receiving device is a radiotelephone communication with controlled companding, containing connected circuits on the input, one of which is made in the form of serially connected bandpass filter, compressor

and a delay unit, and another one from a series-connected band-pass filter, a frequency detector and a controlled expander 2.

However, the known device distorts the received speech signal.

The purpose of the invention is to reduce the distortion of the speech signal.

To this end, a radiotelephone communication receiver with controlled companding, containing pedestrians combined at the input, one of which is made in the form of serially connected bandpass filter, compressor and delay unit, and the other one of serially connected bandpass filter, frequency detector and controlled expander, introduced a series-connected narrow-band tunable filter, a phase shifter, a modulator and an adder, as well as a threshold block and a sheet of serially-connected multipliers, keys integrator with the input of a narrowband tunable filter combined with one input of the first multiplier and a second input of the adder connected to the output of the delay unit, another input of the first multiplier connected to the output of a narrowband tunable filter to the second input of which the output of the first integrator is connected, and the output the adder is connected to the input of the controlled expander and to one of the inputs of the second multiplier, the other input of which is connected to the input of the modulator connected to the output of the second integrator, By means of which the control inputs of the keys through the threshold block are connected to the output of the frequency detector. The drawing shows a structural eleitric diagram of a radiotelephone receiving device with controlled companding. The device contains circuits connected at the input, one of which is designed as a series-connected band-pass filter 1, a compressor 2 and a delay block 3, and the other one of a series-connected band-pass filter 4, a frequency detector 5 and a controlled expander 6, a narrow-band tunable filter 7, phase shifter 8, modulator 9 and adder 10, as well as threshold block 11 and chains of serially connected multipliers 12, 13 keys 14, 15 and integrators 16, 17. At the same time, the input of a narrowband tunable filter 7, combined one input of the multiplier 12 and with the second input of the adder Yu, is connected to the output of the delay unit 3j, the other input of the multiplier 12 is connected to the output of the narrowband tunable filter 7, to the second input of which the output is connected (integrator 16, and the output of the adder 10 is connected to the input of the controlled expander 6 and to one of the inputs of the multiplier 13, the other input of which is connected to the input of the modulator 9 connected to the output of the integrator 17, and the control inputs of the keys 14, 15 through the threshold unit 11 are connected to the output of the frequency detector 5. Device y to earn follows. The speech signal and the frequency-modulated (FM) control signal arrive at the bandpass filters 1 and 4. Filter 1 selects the components of the speech signal, and filter 4 controls the signal that arrives at the frequency detector 5, the output voltage of the detector 5, proportional to the level of the transmitted speech signal. the signal is fed to the controlled expander 6 and the threshold unit 11. The output signal of the filter 1 is normalized in amplitude by the compressor 2 and through the delay unit 3 is fed to the narrow-band tunable filter 7; After clearing the narrowband interference, the speech signal is fed to the expander 6. A speech signal with a restored dynamic range is formed on the output stitch. In the absence of a speech signal, the voltage at the output of the detector 5 is close to zero and is below the threshold of the threshold unit 11. In this case, the keys 14 and 15 are closed and the narrowband interference is monitored. When a speech signal appears at the output of the detector 5, a voltage appears proportional to the level of the transmitted speech signal, the threshold unit 11 triggers, and a voltage appears at its output disconnecting the keys 14 and 15. The voltage at the outputs of the integrators 16 and 17 is constant . Tuning to narrowband interference occurs in the pauses between syllables, words and sentences. With the keys 14 and 15 closed, two self-tuning circuits are formed. The first circuit includes a narrowband tunable filter 7, a multiplier 12, a key 14 and an integrator 16, the second - a modulator 9, an adder 10, a multiplier 13, a key 15, an integrator 17. If the resonant frequency of the filter 7 coincides with the frequency of the narrow-band input voltage disturbance at its output, it shifts in phase with respect to the frequency of the input signal by 90 °, and the voltage at the output of the integrator 16 does not change. If the interference frequency does not coincide with the resonant frequency of the filter 7, the phase shift between the input and output voltages is different from 9 ° and the average component of the output voltage of the multiplier 12 is different from zero. With a positive average component voltage at the output of the multiplier 12, with the key 14 closed, the voltage at the output of the integrator 16 rises, which leads to a reorganization of the filter 7 in the direction of increasing the resonant frequency. With a negative average component, the resonant frequency of the filter decreases. Thus, when the key is closed 14, the filter monitors the narrowband interference. When the filter 7 is tuned to the frequency of narrow band interference, the input voltage phase is rotated by 90. This phase shift is compensated by the phase shifter 8. With zero phase shift in the circuit containing the NARROWBAND tunable filter 7, the phase shifter 8, the modulator 9, and with a single transfer ratio This narrowband interference is completely rejected, since the same voltage is applied to both inputs of the adder 10.

Claims (2)

1. USSR author's certificate No. 403082, CL H 04 B 3/22, 1971. 2. Buhviner V.E. et al., Managed companding of voice signals in radiotelephony, Elektrosvy s, M., 1974, No. 1, p. 57 (prototype). /five ,