SU1292163A1 - Pulse=code modulator for m-type microwave generator - Google Patents

Abstract

The invention can be used in pulsed radio transmitting devices. The purpose of the invention is to increase the stability of the excitation of the main type of oscillations of the M-type microwave generator. The modulator contains a power supply 1, a charging element 2, a capacitive energy storage 3, a switch 4, a pulse transformer 5, a resistor 6, a load 8 (microwave generator M-type), a trigger pulse generator 9 and a submodulator 11. Introduction elements 12 and 14, submodulators 13 and 16, made with adjustment of the amplitude of the output pulses, and elements 10 and 15 of the delay with adjustment of the delay of the pulses to form new functional connections contribute to the achievement of the goal. 1 3.p. f-ly, 3 ill. from tsd WITH to 05 with

Description

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The invention relates to a pulse technique and can be used in pulsed radio transmitters.

The purpose of the invention is to increase the stability of the main mode of oscillation of the M-type microwave generator.

FIG. 1 shows a functional diagram of a pulse-code modulator; in fig. 2 - its equivalent circuit; in fig. 3 voltage plots at the main points of the device circuit.

Pulse-code modulator contains power supply 1, charge element 2, capacitive energy storage 3, switch 4, pulse transformer 5, resistor 6, additional switch 7, load 8 (microwave generator M-type), trigger pulse generator 9, the first delay element 10, the first submodule 11, the first element 12, the second submodule 13, the second element 14, the second delay element 15 and the third submodule 16.

The sources of the power supply 1 are connected to the series-connected charging element 2 and the storage device 3, in parallel with which the primary winding of the pulse transformer 5 and the switch 4 are connected. The secondary winding of the transformer 5 is connected to the serially connected load 8 and the resistor 6, in parallel with which an additional switch 7 is connected in the conductive direction. The output of the generator 9 is connected to the control input of the switch 4 through a delay element 10, a submodule 11 and an isolation element 12, as well as through a submodule 13 and an isolation element 14. The output of the generator 9 is connected to the control input of the switch 7 through the delay element 15 and the submodule 16.

The equivalent circuit of a pulse-code modulator (Fig. 2) presents: switch 4 modulators — two parallel-connected circuits containing serially connected switch 17 (18) and internal resistance R- (R,) of open switch 4 of modulator, with It is assumed that the closure of the key 7 corresponds to the supply of a pulse from the output of the first submodule I1 to the control electrode, and the closure of the key 18 to the control of the second submodule 13; pulse transformer -5 - in

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the scattering inductance Q and the magnetizing inductance of the additional switch 7 are sequentially connected by a switch 19 and the resistance Rj, j of the open switch; load 8 (microwave generator) - resistance R equal to the dynamic resistance of the microwave generator during its operation, which is switched on by key 20 when the threshold voltage on the generator is reached, resistance H "equal to the resistance of the microwave generator and the capacitance With, which takes into account the capacity of the microwave generator, installation capacity and parasitic capacitance of the windings of the pulse transformer 5,

The pulse code modulator operates as follows.

In the initial state, the accumulator 3 is charged to approximately the voltage level of the power source 1, at all other points: the points of the pulse-voltage modulator circuit and the currents are zero.

At the instant-time t from the output of the generator 9 of the triggering pulses, a pulse and (Fig. 3, a) are applied simultaneously to delay elements 10 and 15 and a second submodule 13, at the output of which a pulse is formed and (Fig. 3, c). Through element 14, which, like element 12, is designed to eliminate the mutual influence of submoduli 11 and 13, this impulse Uj,. (Fig. 3, d) is fed to the control input of the switch 4 of the modulator and opens it slightly - the key 18 closes (Fig. 2). At the same time, the current starts to flow through the circuit (Fig. 2) the positive output of the accumulator 3 - internal resistance R-, the modulator switch 4 - inductance-dissipation Lg of the pulse transformer 5 - resistor 6 - load capacitance C 8 minus output drive 3. When a given current flows, charge of capacitor C occurs.

During the formation of the pulse front, the current flowing through the magnetizing inductance b can be neglected. and through the resistance N. of the microwave generator, due to the small magnitude of these currents as compared with the charging current of capacitance C ,, and also to simplify the description of the processes in the modulator. In addition, drive 3 can

be considered a power source with an infinitely small internal resistance, since the value of the capacity of storage device 3 is much larger than the value of capacity C. Under accepted assumptions, the charge of capacitance C (formation of the pulse front) occurs in the circuit R and is determined by the parameters of this circuit, the variable in which is resistance equal to the sum of the resistances RJ- and resistance of the resistor 6, Since the resistance value of the resistor 6 is chosen from the condition of providing the minimum time of discharge of capacitance C through the magnetizing inductance L when forming the back edge of the pulse and the post-pulse transient, then the change in the duration of the leading edge of the pulse ca achieved changing resistance value E, the internal resistance of the switch 4 of the modulator, which in turn can be obtained by changing values of the pulse amplitude at the output 13 of the second submodule torus.

A change in the amplitude of the pulse can be obtained by varying the supply voltage on the submodulator 13.

With increasing pulse amplitude

and "(dotted line, fig. 3, c) and, and (dotted line, fig, 3, d) at the control input of the switch 4 of the modulator - reduction of the internal resistance Ri, of the switch 4 of the modulator - the voltage U ,, ( dotted line, Fig. 3, e) on the secondary winding of the pulse transformer 5 and an increase in the voltage rise rate U, (dotted line, | Fig. 3, h) on the load.

When reaching at time t.j (fig. 3, h) the voltage level C, equal to the threshold voltage U,

 The microwave generator, in parallel with the capacitance, is connected the resistance R (the switch 20 is closed) and the voltage rise on the capacitor C stops. At this moment in time, the input of the third submodule of the torus 16 is received by i

 pulse delayed by the second time delay element 15 ().

The output impulse u "(fig. 3, e) of the third submodulator 16 opens an additional one, switch 7 turns on key 19, the resistance of resistor 6 is shunted by small internal resistance R of open switch 7, as a result of which

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The voltage increases at load 8, during which excitation of the main mode oscillations occurs in the microwave generator. The rate of voltage rise at load 8 at this time point is determined by the magnitude of the internal resistance R; open switch 7 and can be changed by adjusting the amplitude and pulse at the output of the third submodule.

When forming a pulse with a high voltage buildup and on a load (dotted line, fig. 3, h) at the beginning of the pulse, the last one at the output of the third submodule 16 must be delayed for a shorter time (t,) and with a smaller amplitude of the pulse (dash line Fig. 3, d), the rate of increase of the voltage on the load during the formation of the ledge will be less.

By the time tj, when the microwave generator operates stably on the main mode, from the output of the first submodulator 11 to the control input of the switch 4 of the modulator, an impulse 12 is applied to the control input (Fig. 3, b) whose amplitude is greater than the pulse amplitude the output of the second submodule 13 and which is delayed by time () by the first delay element 10 (when forming a pulse with a steeper leading edge, it is equal to,). As a result, the pulse shape yyy on the control input of the switch 4 of the modulator has a stepped shape (Fig. 3, d). At the same time, the switch 4 of the modulator is fully opened and the top of the pulse at the load is formed. In the equivalent circuit (Fig. 2), the process of forming the pulse tip corresponds to the closure of the key 17 and the disconnection of the key 18.

The cut of the pulse and "" (Fig. 3, h) on the load begins to form at the moment of time t, - the end of the pulse and (Fig. 3.6) at the output of the first submodule I1 (impulse U of the output of the second submodulator 13 by this time must be finished). The moment of the beginning of the formation of the cutoff of the output pulse of the modulator on the equivalent circuit corresponds to the switching off of the switch 17. This starts the discharge of the capacitance C through the resistance R, the resistance of the resistor 6, the magnetizing inductance L ..

pulse transformer 5 and the resistance R until the moment of time until the voltage on the capacitance C „reaches the threshold voltage U ,,, (FIG. 3, g) of the microwave generator — turn off the switch 20. From this point in time the discharge rate of capacitance C The voltage decreases and is mainly determined by the current flowing through the magnetizing inductance L and the resistance of the resistor 6, the value of which is selected from the condition of the maximum possible discharge rate of capacitance C, namely, the aperiodic discharge in the critical mode.

This is where the pulse shaping process in the modulator circuit ends.

The process of pulse formation in the modulator is considered under the condition that there is no voltage drop across the capacitance of accumulator 3, no current flows through the magnetizing inductance L of the pulse transformer 5, as well as the idealization of the pulse transformer when creating the equivalent circuit. All of the above factors cause a change in the voltage on the secondary winding of a pulse transformer at the peak of a pulse, namely, a drop in the peak and an oscillation process on the peak after the formation of the front caused by the energy stored in the scattering inductance Lg and parasitic between the turns capacitance windings (dotted line, Fig. 3, e).

Since in the pulse-code modulator the load 8 is connected in series with the additional switch 7, the internal resistance E. which determines mainly the current in the load, when using a current stabilizer, for example, a modulator lamp with a pentode current-voltage, as an additional switch characteristic of a different

sort of voltage change U .., on

the secondary winding of the pulse transformer during the formation of the peak of the pulse, in toM number and the decrease in amplitude

, a pulse of pulses during the passage of a burst of pulses, can be compensated by changing the voltage U on the internal resistance of the additional switch (dotted line, Fig. 3, g).

Claims (2)

1. An impulse code modulator for an M-type microwave generator, containing a power source with serially connected charges connected to the outputs of which; an element and a capacitive energy storage unit, in parallel with which a primary winding of a pulse transformer is connected in series, the secondary winding of which is connected to a serially connected M-type microwave generator, a resistor, a switch, a trigger generator and the first submodule, characterized in that the goal of sustainability excitation of the main type of oscillations of an M-type microwave generator, the second and third submodulators, the first and second delay elements, the first and second isolators, the additional switch, the additional switch off parallel to the resistor in the conductive direction, the generator starting the pulses are connected to the control input of the switch through the first delay element connected in series, the first submodulator and the first isolating element, and also through the second connected in series the second the modulator and the second decoupling element, and with the control input of the additional switch — through the second delay element and the third submodule connected in series. 2. The modulator according to claim 1, about tl and - due to the fact that, in order to regulate and the steepness of the pulse front at the beginning and end, The second and third submodulators are made with an amplitude adjustment of the output pulses, and the first and second delay elements are with an adjustable pulse delay. G7-II