SU1501249A1 - Phase-modulated to frequency-modulated signals - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to reduce the distortion of the law of modulation of frequency-modulated signals. The converter contains a reference r-1, a phase modulator 2, a source of 3 low-frequency signals, controlled attenuators (UA) 4 and 5, mixers 6 and 7, a wide-band amplifier 8 and an amplitude detector 9. With an increase in the amplitude of the output signal of the amplifier 8 at the output A detector appears in detector 9, which simultaneously reduces the gains of A / V 4 and 5 until the amplitude of the signal at the output of amplifier 8 is equal to a certain value. Thus, the limitation of the amplitude of the output signal is due to the action of the automatic adjustment of the amplitude carried out by means of UA 4 and 5. At the same time, regardless of the amplitude of the input signals, a constant amplitude is maintained at the output of amplifier 8. The goal is achieved by ensuring in the frequency-modulated signal that there is no conversion of the parasitic amplitude modulation that occurs when the signal passes through modulator 2. 1 Il.

Description

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The invention relates to the paniu-technique and can be used (QLS) to create phase-modulated signal in the frequency modulator in various radio devices.

The purpose of the invention is to reduce the distortion of the law of modulation of frequency-modulated signals.

The drawing shows the structural electrical circuit of the proposed phase-modulated signal converter into frequency-modulated signals.

A converter of phase-modulated signals into frequency-modulated signals contains a reference oscillator 1, a phase modulator 2, a source 3 of low-frequency signals, the first 4 and second 5 controllable attenuators, the first 6 and second 7 mixers, the broadband amplifier 8, the amplitude detector 9.

The converter of phase-modulated signals into frequency-modulated signals operates as follows.

Oscillations with a frequency f from the output of the reference generator 1 at a zero level of the signal coming from the source 3 of low-frequency signals are fed to the input of the attenuator 4 and to the input of the phase modulator 2. The signal from the output of the phase modulator 2 is fed to the input of the attenuator 5. V The first time point is the attenuator transfer factors A and 5 are maximum and equal to one. In this case, the signal from the first inputs of attenuators 4 and 5 is passed to the inputs of mixers 6 and 7, respectively. At the same time, the output of the wideband amplifier 8 produces signal fluctuations arriving at the second input of the mixer 6. After being converted to the mixers 6 and 7, these fluctuations arrive at the input of the wideband amplifier 8. Thus, the wideband amplifier 8 is covered by the feedback circuit whose input is the second input of the mixer 6, and the output is the output of the mixer 7. This feedback circuit is a two-pole feedback network (QCS). When the conditions of the bianna of the phases and amplitudes are fulfilled, in the NR of the closest battalion sysgm, the formed 1 - () is a single ring;

1 | 1IrP1 -. (AND IFM mustache ILITTCHPSM I POS,

Kochrbapi r occur at a frequency fj, depending on the difference in the phase of oscillations, 11th unit) at the inputs of mixers 6 and 7. At the output of mixer 6, a signal with frequency

2

where f, is the frequency of the output signal

"Attenuators 4 and 5, GJ - the frequency of the output signals

broadband amplifier 8, and at the output of the mixer 7 - a signal with frequency

f, f. - fp.

0

5 - 5 50 55

Moreover, mixers 6 and 7 are single-lane.

As the amplitude of the signal at the output of the wideband amplifier 8 on the code of the amplitude detector 9 increases, a signal appears that is proportional to the amplitude of the oscillation frequency fj, which simultaneously reduces the attenuation coefficients of the attenuator 4 and 5 until this signal amplitude at the output of the wideband amplifier 8 will be equal to a certain value.

At the same time, there are no synchronization effects, since the operation modes of mixers 6 and 7, as well as the wideband amplifier 8, can be chosen so that they will be linear devices for the CHK signals passing through them, while limiting the amplitude of the output The signal is caused by the automatic amplitude control performed by attenuators 4 and 5, and regardless of the amplitude 1. The input signals at the output of the amplifier 8 are maintained at a constant amplitude.

Claims (1)

Thus, a phase modulated signal converter into a frequency-modulated signal is isochronous, and the parasitic amplitude modulation transformation that occurs when the signal passes through the phase modulator; Street 2, in the FM signal is missing. Invention Formula Phase-modulated signal to frequency modulated converter 15P12 | 9 signals containing the phase modulus-in-phase modulator and the second the torus, the input 1 of the modulating signal, the co-input of the second mixer, is inserted in two, the controlled attenuator is connected to the source output, and between low-frequency signals, and the output of the second mixer and the modulated-signal control — with the output input of the first controlled at-stop generator, as well as the after-tenuator are introduced in series formatively connected first and wto-connected broadband amplifier A mix of amplifiers, an amplitude detector, and the fact that, in order to reduce the output of the wideband amplification modulation law amplifier, is frequency-coupled to the second input of the first mixed-modulated signals, the course of the reference generator and the first-controlled attenuator is connected to the input of the first mixer is entered by a per-output of the amplitude detector, a controlled attenuator, between 15 and 15