SU114782A1 - A device for generating pulses using a delay line - Google Patents

Description

In a number of branches of technology, as well as in research and pedagogical work, there is a need for a device that could generate periodic pulses with a curve shape that is widely adjustable.

The basis of the proposed device, providing the possibility of obtaining pulses of the required production form, is based on the use of a delay line.

A feature of this device is the use of a delay line fed by frequency-modulated oscillations and connected by its taps through amplifiers with an adjustable gain factor to an adder, the output of which includes a detector.

FIG. 1 shows a diagram of the proposed device; in fig. 2 and 3 show voltage plots at various points in this circuit.

The device consists of the following basic elements: a generator of frequency-modulated oscillations 1, a delay line 2, an amplifier 3 with an adjustable gain factor, an adder 4 and a detector 5.

The frequency-modulated oscillations from the generator / are fed to the delay line 2, along which there are taps. An amplifier 5 is connected to each tap, allowing you to change (adjust) the well and polarity of the signal being forked.

The signals thus obtained are fed to the adder 4, where they are added. The common signal is detected by detector 5, with the result that pulses are obtained with a repetition frequency equal to the oscillating frequency of the generator /, and with the shape determined by the magnitudes and polarities of the signals branched from the delay line.

The principle of pulse formation is as follows.

As is known, the transfer function of the block A consisting of a delay line connected to its taps of adjustable amplifiers and sum 14782

matora, can be represented in the frequency range from O to a, “in the form of a Fudier array:

F (t) - a „-f- Z {a, + b.} Cos + JZ (sin ЛЛ

From this expression it is clear that, depending on the number and values of the coefficients ao, a. L get different values of the transfer function. In this case, the block A has various frequency characteristics.

If the values of the coefficients a, a.and b ,, are set in accordance with the required mode of oscillation, then the frequency response of block A will reflect this form of oscillation.

When a frequency-modulated signal changing according to a linear law is applied to the input of block A, a frequency-modulated signal will be removed from the output of this block whose envelope will correspond to the shape of the frequency response of the block. If this signal is controlled by the sawtooth voltage (Fig. 2), then, by detecting the voltage taken from the output of block A, we will receive periodic pulses with the required oscillation shape.

FIG. 2a shows the law of frequency variation in the oscillator. The voltage AND, "at the output of the generator / in this case remains constant (Fig. 26). The voltage I. at the output of the block L is shown in FIG. 2c. After detection, periodic pulses are obtained, the voltage form of which corresponds to the frequency response of block A (Fig. 2d).

The frequency of the resulting pulses of arbitrary shape is determined by the frequency of the sweep generator /. If the sweep frequency is adjusted, then the pulse frequency of the output pulses will change accordingly.

The law of change of the oscillator frequency / can be taken as shown in fig. 3c.

In this case, the shape of the output pulses will be as shown in FIG. 3g.

The law of frequency variation of a frequency-modulated oscillator oscillator, produces pulses of arbitrary shape at the device output. This makes it possible to obtain an even greater number of pulse shapes with given values of the coefficients a. and d.

The delay line is selected in accordance with the need to obtain chia.1a branched signals and the fidelity of a given waveform. The delay time between adjacent taps should be of the order, where and, is the higher frequency of oscillations generated by the generator. The delay line must be precisely matched at the ends and must pass, without distortion, the entire oscillation spectrum of the generator to the frequency ,,,.

Subject invention

A device for generating pulses using a delay line, characterized in that, in order to obtain pulses of a desired arbitrary shape, an excited frequency-modulated oscillation of the delay line is applied, to the taps of which, through an amplifier with adjustable gain, an adder is connected.