SU898612A1 - Switching device for acoustic signals for sound recording apparatus - Google Patents

Description

(S) SOUND SIGNAL SWITCH FOR SOUND RECORDING EQUIPMENT

The invention relates to a pulse technique and can be used in Discrete attenuators, digital-to-analog converters, recording equipment, and other devices that require the switching noise to be suppressed by control signals.

An analog signal switch is known comprising a modulator with two diode keys connected to a control input, a transformer, an AC amplifier and a demodulator 1.

The disadvantage of such a device lies in the appearance of switching interference at the output, since they are not phased with modulation voltages; these interferences cannot be filtered out and lie in the frequency band of the switched signal.

Closest to the proposed invention in its technical essence and the achieved result is an analog signal switch containing two key elements made on field effect transistors 2.

Such a device achieves a reduction in switching noise

account of mutual compensation of recharge currents and interelectrode capacitances of transistors. However, since it is impossible to achieve complete identity of the parameters of the transistors and control signals in real conditions, the switching interference cannot be less than a certain value.

ten

The purpose of the invention is to reduce switching noise.

The goal is achieved by the fact that the audio switchboard for recording equipment, containing the first and

15 second key elements, contains a pulse generator, a synchronizer made, for example, in the form of a D-flip-flop, and a low-pass filter, with the output of the pulse generator connected to the clock input of the synchronizer and the control input of the second key element, the synchronizer information input is connected to the control switch input, and you

25, the synchronizer stroke is connected to the control input of the first key element, the output of which is connected to the input of the second key element, the output of the latter is connected to the input

30 low pass filter.

Figure 1 shows the functional block diagram of the audio signal co-generator # 4 for recording equipment; figure 2 - timing diagrams of signals at certain points of the schek.

The device contains - successively connected key element 1, key element 2 and low pass filter 3, a pulse generator 4 connected to the control input of key element 2 and to the clock input of synchronizer 5, the output of which is connected to the control input of key element 1, and information the input is connected to the control input of the terminal,

The device works as follows.

The input of the key element 1 is fed to lg / tiruem1 1st analog signal (Fig, 2,). The information input of the synchronizer 5 receives a switch control signal (Ugv4, -r, p). The clock input of the synchronizer 5, as well as the control input of the key element 2, receives a signal from the output of the generator 4 (Upy; /). Element 2 interrupts the commutated signal with a frequency of the generator of 4 pulses,; 1 so that the information contained in the utilized signal is a pesedana without distortion, the pulse frequency of the generator 4 is chosen by the HC less than twice as high as the surface the spectrum of the switched with:; D; ala according to the Oh Kot9l theorem; ICG) :; a

G. ,, - gastota SLS Pov puli; F - -high frequency spectrum comt ;; r:)., Ldiruemogo signal By -: - compliance with this condition, the key element 2 does not distort j s and the spectrum of the switched signal. Syncro} jammer 5, for example, 0-trig herr synchronizes the key element 1 control signal (Ugaiys with key element 2 control (Ufc.;. A). From the output of key element 1, the switched signal fr, 1 TToc- vnaGT to key entry

L; aL- | Vj / .- J - element 2,. This signal represents the sum of the switched signal itself and the signaling of the transfer gap. Switching of the key element 1 occurs at the moments of signal interruption by the key element 2,

Under the condition of the end of the transient process caused by the switching of the key element 1, by the moment of the end of the break, the interference of the switch on the switch 6 of the commator anapogov:;. no signals in range .-; frequencies of the mutated signal.

Switching disturbances introduced by the class element 2 are eliminated with noMoijiT-T 1 and -.ltra 3 low frequencies, the cut-off frequency of which is chosen than the upper frequency of the switched signal spectrum, but lower than the switching frequency of key element 2. The input of filter 3 receives a quantized the signal from the output of the key element 2 (). At the output of filter 3, which is the output of the device, there is a signal and. || ,,,

Quantizing the signal, synchronizing the switch switching with the moment the signal is interrupted, and subsequent filtering of the quantization noise effectively reduces the level of switching noise in this device. Switching interference level is independent of parameter identity.

neither key elements nor control signals. In addition, the level of interference does not depend on the difference in the levels of the coaxial signal before and after the KOMJ-iyTaTopa f, since the combining is performed at the moment when there is no output signal. This expands the application possibilities of the proposed switch with the on-line switching of high-quality analog signals, expands the dynamic range.

switching signals, makes it possible to create a high-quality attenuator sound signals of discrete action.

KoMiv, yTaTOp of sound signals for sound recording equipment, containing the first and second key elements, which means that it contains a pulse generator, a synchronizer, made to for example, in the form of a D-flip-flop, and a low-pass filter, where the output of the pulse generator is connected to the clock input of the synchronizer and to the level input of the second key element, the information input of the synchronizer is connected to the control-control input, and the output of the synchronizer is connected to . control of the input of the first key element, the output of which is connected to the input of the second

5 key element, the output of the latter is connected to the input of the low-pass filter.

Sources of information, Q taken into account in the examination

1.Drhovsky V.F. Switching circuits - and analog signals. M., Energie, 1970, p. 108-109, fig. 5-6.

2, US Patent No. 3457435, 5 cl. 340-251, 1969,

b out

Claims (1)

Claim Audio signal switch For recording equipment containing the first and second key elements, it is important that, in order to reduce switching interference, it contains a pulse generator, a synchronizer made, for example, in the form of a D-trigger, and a low-pass filter, the output of the pulse generator being connected to the clock input of the synchronizer and to the control input of the second key element, the information input of the synchronizer is connected to the switching control input, and the synchronizer output is connected to. the control input of the first key element, the output of which is connected to the input of the second key element, the output of the latter is connected to the input of the low-pass filter.