SU1287049A1 - Method of measuring level of side components of quasi-harmonic oscillations - Google Patents

Abstract

The invention relates to the field of electrical measurements. The purpose of the invention is to improve the accuracy of measuring the level of the side spectral components of quasi-harmonic oscillations. The device that implements the method contains a mixer 2, the local oscillator 3, a bandpass amplifier 4 and a recording device 5. A predetermined dP band, at which the noise voltage is measured, is chosen as two separate bands, the value of ДР / 4 each, with a gap value of DP / 4 between them, when the detuning frequency of the local oscillator by the value. AF / 8 to both sides of the center of the selected band. Moreover, after each detuning, the voltage of the selected side spectral components is measured. The description provides a formula for determining the sum of their voltages. 2 Il. (L

Description

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The invention relates to electrodynamic measurements and can be applied to measure the level of side spectral components (PSS) and the signal / noise ratio of sources of quasi harmonic oscillations.

The purpose of the invention is to improve the accuracy of measuring the level of the side spectral components of quasi-harmonic oscillations, achieved by adding the power of the noise measured in two adjacent frequency bands.

Figure 1 shows a possible embodiment of the proposed method of measurement; Fig. 2 shows a spectral diagram of the processes occurring in the meter.

The investigated oscillation of the nominal frequency c (Fig. 1), the input 20 of the device 1 is fed to the input of the mixer 2, to the other input of which the oscillation of the local oscillator 3 with the frequency ff is applied. .. The output of the mixer 2 is connected to the input of the band amplifier 4, the output of which is connected to the input of the recording device 5.

Figure 2 shows the spectral diagrams of the processes in the nodes of the meter that implements the proposed method for measuring the PSS level.

Let it be necessary to measure the level of the MSS of a quasi-harmonic wheel: a bath with a nominal frequency q in a given frequency band of DR with retracting at d with respect to f.

With the help of a local oscillator 3 and a mixture -. The body 2 oscillation of the nominal frequency f is converted into the oscillation of the converted frequency „.

The passband of the DGpu DR / 4 bandpass amplifier, its lower limiting frequency F DR / 8.

First, the spectrum of the studied oscillation is transposed; the local oscillator frequency is set to fg. C + if - DR / 8.

The band amplifier selects the FSS conversion products of the studied oscillation, which lie in two bands; As the value of ДР / 4 with a discontinuity of ДР / 4 between them, located on the frequency axis is symmetrical with respect to the frequency of the local oscillator f. (Fig.26). The recording device measures the voltage of the conversion products of these PSSs — UnoBt. Then, the local oscillator frequency is set to ff. p + uf + lp / 8 and similarly measure the voltage of the PSS conversion products of the studied oscillation lying in two bands of AF / 4 each with a discontinuity DP / 4 between them, located on the frequency axis symmetrically relative to ff - Unos ).

Then, using the formula, calculate 1 April of the sum of the PSS of the studied oscillation lying in the entire AF band, measure the voltage of the entire transposed oscillation U, and determine the level of the PSS as expressed in decibels ratio / U.

Using the proposed method of measuring the PSS level, compared with the known methods, an increase in the measurement accuracy by eliminating measurement errors due to the mirror channel and flicker noise of the amplifier path. Moreover, when using the mirror channel for measurements, the proposed method eliminates the need for or compensation.

Claims (1)

Invention Formula A method of measuring the side spectral components of quasi-harmonic oscillations, which consists in measuring the noise voltage U in a given frequency band uF, the center of which is separated from the carrier quasi-harmonic oscillation at a given frequency, and determining the level of the side spectral components as expressed in dB tension Unog noise to the voltage U of the entire signal when transposing the signal spectrum and dividing the AF analysis band into separate bands located on the frequency axis symmetrically with respect to the local oscillator frequency, which in order to improve the measurement accuracy, the measurement band is chosen as two separate bands of AF / 4 each with a discontinuity of uF / 4 between them when the heterodyne frequency detuning by uF / 8 to both sides of the center of the selected band, the voltages of the selected side spectra being measured after each detuning eral constituting ISnosi- and Ugop and determined voltage side we selected spectral constituents by the formula and,.  eat L 2 jft PHB1 10B;