SU1397847A1 - Device for measuring variation of frequency from rated value - Google Patents

Abstract

The invention relates to a pulse tehnike and serves to increase the reliability of the device. The device contains reference oscillators 1 and 2, adder 3, limiting amplifiers 4, 5 and 6, mixer 7, filter 8 lower parts and JK trigger 10. The introduction of limiting amplifier 9 and JK trigger 11 allows using only one bias channel frequencies. 3 il.

Description

(L

with

with

oo

NU

.one

The invention relates to a pulse technique and can be used to measure over a wide range of frequency deviations from the nominal value.

The aim of the invention is to increase reliability by using only one channel of frequency mixing.

FIG. 1 is a functional diagram of an apparatus for measuring frequency deviation from nominal; in fig. 2, 3 - timing charts of the device.

In the device (Fig. I), the outputs of the first and second reference oscillators 1 and 2 are connected to the inputs of the adder 3 and the inputs of the first and second limit suppressors 4, 5, respectively, the output of the adder 3 is connected to the input of the third limiting amplifier 6 and to the heterodyne input of the mixer 7, the output of which is connected via a low-pass filter 8 to a fourth limiting amplifier 9. The outputs of the first, second, and TpeTbei o limiting amplifiers 4, 5, 6 are connected respectively to the first, second, and clock inputs of the first JK-trigger 10. The outputs JK-trigger 10 podkl cheny ustanovochn1 1m to inputs of the second JK-flip-flop II, to the clock input of which is connected ighod chetvertogch) limiting amplifier 9.

The device works as follows.

(The signals of the first and second reference generators 1 and 2 are fed to the inputs of the adder 3 and to the inputs of the first 4 and second 5, 1y-limiters. From the output of the adder 3, the signal (Fig. 2a) is fed to the input of the third amplifier 6 and the heterodyne the input of the mixer 7, to the signal input of which through the input bus 12 enters the signal under study. The voltages applied to the inputs of the adder 3, represented by-. 1NOTE in the form of expressions: and I I cos (I HUM + -) t + and I cos (Mn m - 2) t; Ll., L - ,, cos (bK, M + AF) t,

where fnoM is the nominal frequency of the analyzed voltage; mixing the frequency of the analyzed signal;

detuning but the frequency of heterodyne oscillations by referring to the value of the nominal frequency.

As a result of nonlinear conversion in the adder 3 and after low-pass filtering, the output of the filter 8 will have oscillations with difference frequencies:

(Lsh "+) - (L °" -) 2L

(night + U) - (and “+ d F) (2-L F;

(| Noi - О) - („„ „-f Д F) - О-Д F.

If), then the output oscillations of the filter 8 are characterized mainly by the frequency. Li The information about the frequency offset is lost. In contrast, in the case of Ui-cUiJ, the output voltage of the filter 8 is determined by both the frequencies U and DR: iff 4U | U9SociJtcosAFt,

LR

0

five

0

five

0

five

and is represented by oscillations with a frequency C modulated in phase and amplitude by a lower frequency (). In this case, the voltage ifnch is similar to the voltage at the output of the adder 3 and is represented by the time dependence shown in FIG. la. After amplification and limitation by amplifier limiter 9, the output is dependent on the output shown in FIG. 36 is similar in nature to the diagram in FIG. 26. A common feature of the diagrams in FIG. 26 and 36 is the presence of phase jumps, the difference is in the absolute values of the frequencies, which are respectively equal to AND and LR. The main feature of the signal at the output of the amplifier-O1 of the delimiter 9 (Fig. 36) is that the frequency of these phase jumps determines the frequency shift from the nominal value of the Gno.

The dotted line (Figs. 2 and 3) depicts the sections of the diagrams in the case when the amplitude of the beats does not fall to zero (in the case of the inequality of the amplitudes of the components of the oscillations (J + Af and YD).

The measurement accuracy is ensured by the frequency stability of the reference oscillators 1, 2 and the use of a minimum number of transformations (by heterodyning). Frequency deviation information is retrieved from a parameter that is not sensitive to amplitude. Conversion error. The accuracy of the measurements is affected only by the error of the accuracy of the installation and frequency drift of the reference oscillators 1, 2. The measurement accuracy and the lower limit of the measurement range of the frequency from the nominal frequency are an order of magnitude larger than the indicated errors and are 10-10 using the reference oscillators 1, 2 with a stability of 10 -10.

Claims (1)

Invention Formula A device for measuring the frequency deviation from nominal 0, containing an adder, two reference oscillators, a mixer, to the output of which a low-pass filter is connected, and an input input is connected to the signal input, the first and second limiting amplifiers, the outputs of which are connected respectively to the installation J, K-inputs of the first JK-flip-flop, the third amplifier-limiter, characterized in that, in order to improve reliability, the fourth amplifier-limiter, the second synchronous JK-flip-flop, the installation J, of the K-inputs of which with the outputs of the first JK-flip-flop, the input of the fourth limiting amplifier is connected to the output of the low-pass filter, and the output of the fourth amplifier-limiting is connected to the second input of the second JK-flip-flop, while the outputs of the reference oscillators are connected to the inputs of the adder and to the inputs first and second limiting amplifiers, output the adder is connected to the heterodyne input of the mixer and through the third power amplifier /, 5 П П n | l p IN 1. J / i   2 g ,, rpi / hero /  Bb, TpUiifpa 10 and pppppppnnpppppppppp chk-UZM t - / „„ 5 n .. n n P rl n P g. N P n run n p g. P p p p. T go / rca jpaacpa H Ll reader with clock input iiepBOi o JK-r) Hi re pa. Swxorf cyHMomopjJ Output UO6 rLTl n P np p n YahoZ trigger 0   2 g ,, rpi / hero /  Bb, TpUiifpa 10 ppppp i / AJ FIG. 3