SU687575A1 - Pulse stretcher - Google Patents

Description

The invention relates to a pulse technique and can be used in radio devices and automation systems. Pulse expanders are known that utilize the effect of accumulation of charge in pn junctions, which contain a saturated forming stage with a transistor switch as a regulating leakage resistor and a matching emitter follower IJ. The emitter follower output is connected via a differentiating chain to the base of the key transistor. Such a device allows each incoming pulse to be expanded by an order of magnitude 1-4 of the ISS. However, it does not allow each input pulse to produce a constant expansion increment regardless of the frequency and duration due to the use of the saturation effect in the p-junction of the transistor ... .1 a pulse shaper is known that contains a transistor cascade controlled by the input signal, charge and discharge resistors, concentration electrochemical diode, output forming transistor cascade and power supply 2. The anode of the concentration electrochemical diode is connected to the common connection point of the base output transistor, charge and discharge resistors, and the cathode to the common power supply bus. At the output of the device, a rectangular impulse is formed, the duration of which is equal to the sum of the durations of the input impulse and the time of the resorption process of minority carriers in the diode. This time is proportional to the electric charge flowing through the pump during the action of the input pulse. Thus, the duration of the output pulse is proportional to the input pulse and is not proportional to the frequency of the input pulses. It should be noted that such a device has all the disadvantages of the previous device, since the principle of their operation is based on the property of the material to expand the incoming pulses in a saturated p-junction. The device does not allow to expand each incoming pulse from units per second to several hundred microseconds, and also to give a constant expansion increment to each incoming pulse regardless of the frequency and duration of the input pulses.

A pulse expander is also known, which contains a matched delay line with taps, capacitors, diode-capacitor expanders with emitter followers and separation resistors. The emitter inputs of the repeaters are connected to the taps of the delay line, and the capacitors are connected in parallel with each other and the load through separation resistors. In this device, the transfer coefficient of the mass expander depends on the duration of the input pulse. However, this Pulse expander has the above-mentioned disadvantages of devices using the effect of saturation of the pn junction and obtaining expansion due to the slow absorption of minority carriers in the material of the diode.

In addition to TorOf, the use of a diode-capacitor expander, in which the capacitance charge depends on the frequency and duration of the input pulses, leads to the dependence of the length of the extended output pulses also on the frequency and duration of the input pulses, i.e. such a circuit does not provide a constant the expansion increments to the duration of the input signal regardless of the frequency and duration of the latter. Since in this scheme the main magnitude of the pulse width expansion is due to the fact that the time constant of the charge circuit of the capacitance diode-capacitor expander is many times smaller than the constant time of the discharge circuit, therefore, the magnitude of the extension increment to the input signal will be depend on the frequency of following them.

 There are a large number of pulse extenders that generate pulses of constant duration, regardless of the duration of the input pulses with a short recovery time or allow the floor: There is a high linearity of the expansion coefficient in a wide range of durations of the output pulses 4 However, with these devices it is impossible to get expansion of the kilogram of each incoming pulse without skipping, when an irregular pulse sequence arrives at the input of the device, since as an expanding element and mainly relaxation generators are used, which have a very short but finite recovery time.

Therefore, pulse spreaders, the principle of which is based on

Using relaxation generators, it is not possible to obtain a constant expansion increment to the duration of each input signal, regardless of the frequency and duration of the latter.

The closest to the present invention is a pulse expander, containing matched n-connected delay lines sequentially, amplifiers 5. The positive qualities of this device should be attributed to the fact that it expands every incoming pulse without skipping, the amount of expansion being determined by the length of the delay line.

However, this device does not allow each input pulse to produce a constant expansion increment regardless of the frequency and duration. The dependence of the magnitude of the expansion on the duration of the input signal is determined by the fact that pulses of various durations can arrive at the input of the delay line, while the passband of the delay line is constant.

The shorter the pulse is applied to the input of the delay line, the wider the bandwidth must be for undistorted transmission. Therefore, the amount of distortion introduced by the delay line, when a pulse signal is applied to its input, depends on its duration. Therefore, the shorter the pulse signal is applied to the input of the device, the higher the expansion increment relative to the input signal will be. In addition, the magnitude of the expansion of the input pulses in this device also depends on their frequency.

The aim of the invention is to obtain a constant expansion increment for each incoming pulse regardless of the frequency and duration of the input pulses.

To this end, a device containing a consistently connected n delay lines, amplifiers, a differentiating circuit, an OR diode element, resistors, a diode, and the input of the device are connected via a differentiating circuit connected to the power source, and through series-connected diode and a resistor with the base of the transistor of the second amplifier, and the collector of the transistor of the first amplifier is connected through a resistor to the common bus and to the input of the n series-connected These delay lines, whose taps through the diode element OR and the resistor are connected to the base of the transistor of the second amplifier, connected through a resistor to the common bus, and the collector of the transistor of the second amplifier are connected via a resistor to the power supply bus, are connected to the power supply bus, and second to a common bus.

FIG. 1 is a schematic diagram of the device; FIG. 2 shows timing diagrams explaining its principle of operation.

The device contains matched in series n delay lines 1-1 - 1-p, amplifiers 2 and 3 differentiating circuit consisting of a capacitor 4 and a resistor 5, a diode element OR b, resistors 7-12 and a diode 13.

The device works as follows.

In the initial state, when the supply voltage is turned on and there are no probe pulses at the device input, the amplifiers on transistors 2 and 3 practically do not consume current from the power source, since the bases of the transistors have zero potential relative to emitters. Therefore, the device consumes current from the power source only for the duration of the pulse signal.

The first incoming probe pulse to the device input (see Fig. 2a) is fed to a differentiating circuit 4, 5c of the output of which the removed differentiated opposite-polarity pulses (see Fig. 26) act on the base of transistor 2. Transistor 2 of the input amplifier in the initial state closed and has pnp conductivity. Therefore, for the first time a negative pulse, formed from the leading edge of the probing signal, the amplifier does not react and closes even more. With the arrival of a second bipolar pulse of positive polarity, received from the trailing edge of the probing signal, the amplifier opens, amplifies the input pulse, and reverses its polarity (see Fig. 2c). It should be noted that from the output of the amplifier 2 pulses of normalized duration are removed, the duration of which does not depend on the duration of the input pulses. With the BfJXO amplifier 2, negative polarity pulses are fed to the input of n series-connected delay lines, delayed pulses are removed from the taps of the links, which are summed in time on the total load 11 of the OR element (see Fig. 2d). To produce high-quality summation without failure in the duration of the output pulse, you must connect the diodes of the element OR to such taps of the delay line so that the duration of the minimum input signal a

there was more than a delay between adjacent taps of the delay line.

In addition, the probe pulses directly arrive at the summation of the load on the 11 5 element OR through the diode 13 and the second limiting resistor 10. The limiting resistors 9 and 10 are needed to equalize the amplitudes arriving at the base of the transistor 3 of the terminal amplifier. Since the input signal goes directly to the base of transistor 3, while the extended pulse arrives with attenuation in amplitude, obtained after

When it passes through the deceleration lines, it is necessary to equalize their amplitudes in order to amplify both signals qualitatively. An expanded output pulse is obtained from the collector of transistor 3, the expansion value being determined by the length of the delay line. Output extended pulses are dependent on

25

X

  Ia9 abh,

7

where - the duration of the input pulse; iuQ delay value one

delay lines;

n - the number of series-connected delay lines;

LnH value of the duration of the extended pulse from the output device.

Since the length of the delay line is constant, the above formula can be written differently.

 g

u.5wx f-upac

as n-t. iras

   g

where D is arkg-constant value of the increment to the pulse duration.

In the proposed pulse extender, the magnitude of the expansion depends on the length of the delay line and can range from a few to several hundred microseconds.

Claims (5)

1. USSR author's certificate No. 265185, cl. H 03 K 5/04, 03/04/68. 2. USSR author's certificate  337918, cl. H 03 K 3/40, 16.11.70. 3. USSR author's certificate No. 509989, cl. H 03 K 5/04, 07.24.74. 4. The author's certificate of the USSR And 341152, cl. N. OZ K 5/04, 12. 10.70. 5. The patent of England 1095386, cl. H 3 V, 20.12.67 (prototype).