SU1517119A1 - Speech detector - Google Patents

Abstract

The invention relates to radio engineering and communication and can be used to identify channels of active subscribers in communication systems with analog form of information representation. The purpose of the invention is to improve the detection accuracy. The goal is achieved by introducing into the speech detector circuit a key 3, two comparators 5 and 6, a switch 7 and a source 8 of reference voltages. In order to rationally determine the response time of the speech detector and the release time, it is necessary that the response threshold be greater than the release threshold. 2 Il.

Description

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The invention relates to radio engineering and communications, and can be developed: it is used to detect the channels of active subsystems in communication systems with an analogue form of representation.

The aim of the invention is to improve the detection accuracy.

On the fit. a structured electronic1; ctricheskl scheme of speech detector; on () ig.2 - voltage diagrams that show the operation of a speech detector,

The speech detector contains a phi amplifier: 1 2 low frequency, key 3, envelope detector 4, first 5 and second comparators 6, switch 7, reference voltage source 8 and driver 9 V1,

Speech detector works as follows.

The input analog signal is amplified to the required value by amplifier 1, but is limited by filter 2 and d; more, it goes to information 1d, key input 3, At the moment the subscriber begins to be active, control input key 3 is logically opened, key. Further, the signal knocks on detector 4.

At the moment when the voltage at the detector k reaches 1 level L (Fig. 2) corresponding to its lower limit of the dynamic range of input sigp levels and, accordingly, the threshold of abone} 1t, a signal appears at the output of the first comparator 5 logical 1 (Fig. 2, E) as a result of which the shaper 9 generates a signal that indicates the presence of a useful component in the path. At the same time, a single logical potential is supplied to the control input of the switch 7, as a result of which the voltage of the speech detector is actually connected to the second input of the first comparator 5, instead of the voltage A, it is connected to the voltage B. For a rationalization of the setting of the response time of the EEC detector and the time from starting 1P1I it is necessary that the trigger threshold} P1 be greater than the release threshold.

Then, at the moment of the burden, when the voltage on the detector 4 reaches the level C specified by source 8 (FIG. 2), at the output of the second comparator 6 a logic level O appears (FIG. 2) and the switch 3 goes to

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the locked state, while removing the input voltage from detector 4. The voltage on detector 4 will begin to decrease (FIG. 2) and, having reached level C, will return the second comparator 6 to the previous state and reopen key 3.

Thus, the voltage on detector 4 will fluctuate around level C in a relatively small f, the range determined by the hysteresis of the second comparator 6, which allows you to limit the path holding time from above, as it has a stabilizing effect on this parameter at the moment of high subscriber activity. For normal functioning of the speech detector, it is advisable to choose a threshold of limitation slightly higher than the value of A (Fig. 2). On the other hand, changing the switching threshold of the first comparator 5 at the time the speech detector is triggered limits the hold time from below, since the hold time in this case is the interval during which the signal at the detector output and the envelope changes from A to B,

Claims (1)

Invention Formula A speech detector containing a series-connected amplifier and low-pass filter, as well as an envelope detector and an output shaper, characterized in that, in order to improve the accuracy of the detector, a key, first and second comparators, a switch and a source of reference voltages are introduced the first and second outputs of which are connected respectively to the first and second inputs of the switch, the output of which is connected to the first input of the first comparator, the second input of which is combined with the first input of the second comparator and connected The output of the envelope detector, between the input of which and the output of the low-pass filter, is a key whose control input is connected to the output of the second comparator, the second input of which is connected to the third output of the voltage source, and the output of the first comparator is connected to the output of the output signal generator and the control switch input. Phie.g  t