SU651273A1 - Method of measuring carrier frequency of amplitude-modulated signal - Google Patents

Description

the constant voltage corresponding to the peak tension envelope, after which the difference between the two butt- ery post-negligible ratios is determined that is proportional to the alternating voltage of the fundamental frequency, and this difference is measured

FIG. 1 shows a chart am. a nite-modulated (AM) signal with a stony tensioned carrier frequency; in fig. 2 is a diagram of the signal of this signal in FIG. 3 depicts a structural electrical circuit diagram of the device, peamisjTomero method.

The essence of the invention is that an amplitude modulated signal (flg. 1) is detected twice independently of each other and in one case receive a constant voltage equal to the maximum instantaneous voltage (peak voltage) of the amplitude modulated signal (.) .and where

Max. . (x.nes. -. / loksiv

maximum amplitude; stress

None, vn LA, aps. the modulation factor at the maximum carrier voltage, and in the second case, an alternating low-frequency voltage corresponding to the envelope of the amplitude modulated signal (Fig. 2) is obtained. Then, the low-frequency voltage is de-tested and a nocTosniHoe voltage is obtained equal to the maximum amplitude and the envelope

Mox-BcBax, this is not what determines the difference between two constant constants and the resulting differential sub-path Uj, measured.

U, .. .., .... J-U.

LLAX. SHADSHKS-MeS.

and%; l

-t

m

llax P.

m.oks.iees.Alix-nvs.

Thus, your pointer instrument is determined by the constant T in the flow period: the magnitude and does not depend on either the modulation coefficient or the intermediate values of the carrier voltage.

This method can be implemented, for example, with the help of devices (Fig. 3), containing a peak detector of significant amplitude-modulated signal, detector 2 for selecting

the envelope of the amplitude-modulated signal, the detector of 3 peak values of the io-and-frequency voltage, the readout device 4 and the measuring device 5. The output signal of the detector 1 and the input of the detector 2 are connected to the input terminal of the device, the output of the detector 2 is connected to the detector 3, the outputs of the detectors 1 and 3 are connected to the inputs of the reading device 4, the output of which is under) is shyuchen to the measuring device 5.

The present method provides a measurement of the voltage of the carrier frequency,

, which changes according to the level of the broadcast signal, and can be used in measuring devices of the four-program wire broadcasting system.

Claims (2)

1.Valitov R.A. and Sretensky V.N. Radiotechnical Measurements, Soviet Radio, Moscow, 1970 / p. 51O, fig. 1O-39. 2. USSR author's certificate № 1145OO, cl. Q 01 K 19 / 1O, 1953. Rokhod FIG.