SU905873A1 - Method of analysis spectrum of phase modulation and phase fluctuations - Google Patents

Description

The invention relates to radio engineering and can be used in radio navigation and radio communications.

A known method for analyzing the spectrum of phase fluctuations is based on the separation of the phase mismatch of the unwatched and delayed signal under study and the spectral analysis of the second mismatch {1.

The disadvantage of this method lies in the low sensitivity and resolution of the analysis of the phase modulation spectrum for frequencies located near the carrier.

The closest to the technical essence of the invention is a method of analyzing the spectrum of phase modulation and phase fluctuations, based on the phase error of the input signal and the generator signal, the frequency and phase of the generator filtered by the low frequency phase mismatch and spectral analysis of this error. In this device, in the tracking mode, the constant component of the phase error signal is filtered in the control ring at a low frequency and controls the frequency and f Zoe controlled oscillator

so that the latter monitors the carrier phase of the input signal. The selected phase mismatch, in this case, has non-suppressed spectral components determined by the spec- trum of phase modulation and phase fluctuations of the input signal carrier, located outside the control bandwidth of the control ring. This spectrum

10 and analyzed by a low frequency analyzer 2.

However, this method has insufficient sensitivity.

The purpose of the invention is to increase the sensitivity.

This goal is achieved by the fact that in the method of analyzing the spectrum of phase modulation and phase fluctuations, based on separating the phase spread of the generator input signal, controlling the frequency and phase of the generator, low-frequency-filtered phase mismatch and spectral analysis of this mismatch, create a mode of weakly damped natural oscillations , amplify and select the spectral composition under study, with the gain and the time constant of the low frequency filter T and T

Claims (2)

30 in the control ring is selected from the condition of small damping of the control ring i ± KT 1. In FIG. 1 shows a block diagram of a device implementing this method; in fig. 2 shows the frequency response of a control ring consisting of a controlled oscillator, a phase detector and a low-frequency filter. A device for implementing the present method contains a source 1 of the input signal of the spectrum under study connected to the input of the phase detector 2, another input of which is connected to the output of the controlled oscillator 3, the input of which is connected via a low-frequency filter 4 to the output of the phase detector 2, to which Spectrum analyzer 5 is connected. When analyzing in tracking mode, a control generator 3 monitors the phase carrier of source 1 of the input signal with a small constant phase error. In this case, the control ring operates in a linear mode. Any component of the spectrum near the carrier that coincides with the frequency i) about the natural oscillations of the control ring will be significantly increased and selected with a small damping of the ring. Frequency u) about the resonance of the ring, larger than the resonance peak Q and its width (bandwidth) 2 nd correspondingly associated with ring parameters. This is illustrated by the example of a ring having a gain factor K with a low-pass filter having a transfer function, where T and T are the time constants of the low-pass filter. The components of the Sfgx spectrum (see Fig. 1) with the frequency cDJ to be analyzed are transformed in accordance with the frequency response of the control rings into the components of the DI TJ .-, 1 -t-jaiT. The module of this characteristic is shown in FIG. 2. When the frequency component of the spectrum (o: relative to the carrier) coincides with the presentness of the natural oscillations of the ring, i. when) o -f (1) and low ring damping, i.e. at 1, the value of the resonant 2N / Q peak, which provides an increase in the sensitivity of the analysis due to the enhancement of the spectral component under study. At the same time, the width of the resonant peak (bandwidth). ., ... and rm ° (3) This allows an increase in the resolution of the device due to the additional selection of the spectral component under study. Thus, when analyzing spectral components of different frequencies (ranging from fractions of Hz to several hundred Hz), the frequency UJ is determined by changing K or T according to relation (1), and the value of Q (ten times) or 2 uCU with analysis is changed by changing} K, T, or T according to relations (2) and (3). The present method allows analyzing the spectrum of phase modulation and phase fluctuations for frequencies slightly different from the carrier (from fractions of Hz to several hundred Hz and more), with the possible separate separation of spectral components differing from each other by tenths Hz and an increase in these components are ten times, which is of great importance in the development and operational control of radio sources with improved short-term frequency stability and high spectral frequency. I Claims The method of analyzing the spectrum of phase modulation and phase fluctuations based on separating the phase error of the input signal and the generator signal, controlling the frequency and phase of the generator, phase-mismatching filtered by low frequency, and spectral analysis of this error that differs in that create a mode of weakly damped natural oscillations, amplify and select the spectral component under study, with the gain K and constant nnye low frequency filter time T, and T in the control ring selected from the conditions of small ring of damping control tg T ChIstochniki information received note in the examination 1.Avtorskoe USSR Certificate 463920, Cl. G 01 R 23/16, 1975. 2. US patent 3649909, cl. 324-77, 14.03.72. 77} glsh - - g th; ,, KG (KTt-H Sh