SU896747A1 - Phase modulator - Google Patents

Description

(S) PHASE MODULATOR

. I

The invention relates to radio engineering and can be used to generate phase-modulated signals, for example, in radio transmitting devices.

The phase modulator is known, containing the first, second and third oscillatory circuits with controllable reactivities connected in series through the appropriate coupling elements, while the output of the first decoupling element, the input of which is input to the first oscillation circuit with controllable reactivity, is connected. the modulated signal, and all controlled reactivity through the corresponding isolating elements are connected to the output of the source of the modulating signal and to the constant displacement source {1.

However, the well-known phase modulator does not provide a sufficiently 4nevenness of modulation characteristic, because, when used in

For three coupled circuits, its phase-frequency characteristic (phase response) at a certain frequency of the input signal has a jump in the JT rad, after which it varies monotomically. Because of this jump, the phase response has a stepped fracture approximately in the middle of the linear section, and therefore, with three connected circuits, the linear section is equal to

10 is not ZG pleased, but iJT / Z, as in the case of two coupled circuits.

The purpose of the invention is to increase the linearity of the modulation characteristic.

15

Claims (1)

The goal is achieved by the fact that the phase modulator containing the first, second and third oscillatory circuits with controlled reactivity, are sequentially connected through the appropriate communication elements, and the output of the first decoupling element is connected to the first oscillatory circuit with controlled reactivity The input of which is the input of the modulated signal, and all controllable reactivities are connected to the output of the source of the modulating signal and to the source through the appropriate extension elements. m constant displacement, to the third oscillatory circuit with controlled reactivity, an additional communication element is connected to an input serially connected phase splitter and a switch, the control input of which is connected to the output of the modulating signal through the input threshold element, while the output of the switch is phase output modulator of the torus. FIG. 1 shows the proposed device, the structure of an electrical circuit, in FIG. 2 - PHC proposed (a) and known (b) devices; in fig. 3 - the third circuit, implementation is possible. In addition, in FIG. 2, the abscis axis does not represent the frequency, but the generalized detuning, which is proportional to the level of the modulating signal. The negative phase response is symmetric about the origin. The phase modulator contains the first decoupling element 1, the first second and third oscillating circuits 2 - k with controlled reactivity, respectively 5-7, elements 8 and 9 of the connection, additional element 10 of the connection, the decoupling elements 11-15, the source 16 is a modulating signal, a constant bias source 17, a phase splitter 18, a switch 19, a threshold element 20. The phase modulator operates as follows. Contours 2 - k, together with their controllable reactivities 5–7, are tuned to resonance at the frequency of the modulated signal at the input of the phase modulator. With a zero modulating signal at another input of the modulator, the phase shift of the frequency of the modulated signal at its output is zero relative to the signal at the input (Fig. 2). With an increase in the level of the modulating signal, the circuits 2–4 are tuned in frequency, and the output signal is shifted in phase relative to the input modulated signal by an angle H according to curve a (Fig. 2). Starting from the level of the modulating signal, corresponding to a generalized detuning about 1, 5 of the frequency response, is abruptly replaced by J rad and then goes onotonically according to the curve. B (Fig. 2), if there is no correction device consisting of blocks 20 - 19. If there is the correction device, when the modulating signal reaches the level corresponding to oL 1.5, the threshold element 20, the switch 19 from it, passes the output signal from the splitter 18 ase with the opposite phase. In this way, the phase response is corrected with an increase in the modulating signal level modulo. If, however, the level of the modulating signal decreases and reaches again the track corresponding to A 1.5, then the threshold element is turned off, which causes the switch to pass through the output signal with the initial (zero) (|) signal. As a result of this correction, the phase response varies along curve a (Fig. 2). In this case, the linear portion of the phase response (modulation characteristic) with the parameter of the connection between the circuits / i. 2 really lies in the range of ± + 1rad. The correction device can be connected not only to the third circuit 4, but also to the first 2 or second 3. In this case, the output of the switch 19 is connected to the subsequent circuit via the communication element. The implementation of one of the circuits, for example, the third one, is implemented in the form of a circuit with a varicap controlled reactivity (Fig. 3 a, b) from a constant capacitance connected to the circuit through a diode connected in parallel and counter to each other and operating in a key mode one-way scheme. 8 as isolation elements 12 - .15 may be (FIG. 3) or resistors, as a decoupling element 11 - a capacitor that does not allow a constant bias to the source of the modulating signal and not affect the modulating signal. The elements 8 and 9 of the connection can be capacitors - external capacitance (Fig. In) or transformers - transformer connection. As a communication element 10, for example, a phig transformer is used. Behind). In the simplest case, an electromechanical or electronic relay is used as the switch 19. The threshold element 20 can be performed on the amplifier operating in key mode. Thus, in the proposed phase modulator, the linearity of the modulation characteristic is improved, and in the case of using a phase modulator in the transmitting device, its reliability is increased, its size and weight are reduced. Claims of the Invention A phase modulator comprising first, second and third oscillatory circuits with controlled reactivity are serially connected via corresponding communication elements, while the first oscillator is connected to the first oscillating circuit with controlled reactivity, the input of which is the input of the modulated signal, and all controlled reactivity through the corresponding isolating elements are connected to the output of the source of the modulating signal and to the source of a constant bias , about. In order to increase the linearity of the modulation characteristic, the sequentially connected phase splitter and switch, the control input of which is connected through the input threshold element to the output of the modulating source, are connected to the third oscillatory circuit with controlled reactivity. signal, with the switch output being the output of the phase modulator. Sources of information taken into account in the examination 1. Swiss patent number, cl. 21, t964 (prototype). 3 hell 5 je-2 If 5 Z / ABOUT  2 X / -one D. II "5 Figure 2 / V Phage.Z