SU1160522A1 - Infra-low frequency signal generator - Google Patents

Abstract

refffipAtw W HOW LOW MACTOt, containing consecutively connected tunable pulse generator and reversible counter, as well as serially connected fixed memory unit, digital-analogue converter, the reference input of which is connected to the output of the source of the reference voltage, polarity switch, control (a reference switch, polarity switch, control switch, polarity switch, control switch connected to the code of the taPmero bit of the reversible counter, and the low-pass filter, distinguished by the fact that, in order to reduce non-linear distortions, it was entered in series clock generator and shift register data inputs kotbrogo podkgoocheny porazr dnym to respective outputs of the reversible counter and the output -k corresponding inputs of block permanent memory. t / jt.

Description

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The invention relates to measurement technology and can be used in digital measuring equipment for various purposes.

The aim of the invention is to eliminate non-linear distortion.

FIG. Figure 1 shows a structural electrical circuit of the generator of infra-low frequency signals; And FIG. 2 and 3 - timing charts of the generator of signals of low frequency in the formation of the signal

frequency and frequency.

The infra-low frequency signal generator contains a voltage source 1, a diffraction-analog converter 2, a polarity switch 3, a low frequency band 4, a fixed memory block 5, a clock generator 6, a register 7, a tunable pulse generator 8, a reversible counter 9.

The generator of signals of infra-low frequencies works as follows.

pulses from the output of a tunable generator of 8 pulses {FIG. 20) is fed to the input of the reversible counter 9, the code of which changes according to the linear-increasing law (4shg. 2a). When overflow occurs, the reversing switch 9 is turned on and the code falls linearly. With a code equal to zero, the direct counting is turned on, the unit is entered into the high-order bit of the reversible counter 9, and the progression is repeated. The one in the higher-resolution de-reversing counter 9 is fed to the control input of the switch 3 polarity. At its output, a half wave of the signal is negative.

The pulses of the generator 6 (Fig. 2d) gate write the code of the reversible counter 9 to the shift register 7 (2c). So the inputs

The fixed memory unit 5 receives the code of the reversible counter 9 with the frequency of the clock pulses of the generator 6. The code of the reversible counter 9 is the address code for the block 5 of the permanent memory. With the arrival of the address code on the high level of the block 5 of the permanent memory, the code of the generated signal appears. This code arrives at the information inputs of the diffro-analog converter 2. At the output of the digital-analog converter 2, a one-part step approximation of the signal is formed (Fig. 2e). A bipolar step approximation from the output of the polarity switch 3 is fed to a low-pass filter (Fig. 2e).

In this infra-low frequency signal generator, the duration of the approximation steps is constant, and their number depends on the period of the generated signal (Fig. 3a). Such a construction of the infrared frequency signal generator provides a constant filtration depth when changing the period of the generated signal, which in turn does not require a large number of approximation stages for the period of the generated signal and, therefore, the high-speed analog-to-analog converters.

It was found from the calculations that the nonlinear distortion factor in the proposed device decreases with decreasing frequency by increasing the number of approximation stages, which allows generating signals in a wide frequency range with high accuracy without using more high-speed digital-analog converters and tunable low-pass filters.

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Claims (1)

INFRANIZED FREQUENCY SIGNAL GENERATOR, comprising a tunable pulse generator and a reversible counter connected in series, as well as a constant memory unit connected in series, a digital-to-analog converter, the reference input of which is connected to the output of the reference voltage source, a polarity switch, the control input of which is connected to the high-order output of the reversible counter, and a low-pass filter, characterized in that, in order to reduce non-linear distortion, sequentially introduced into it a separate clock generator and a shift register, the information inputs of which are connected to the corresponding bit outputs of the reversible counter, and the outputs to the corresponding inputs of the read-only memory block.