SU1370797A1 - Device for measuring residual detuning of heterodyne frequency - Google Patents

Abstract

The invention relates to radio measurements and allows to improve the accuracy of measurements of the residual detuning of the local oscillator. The device contains a switch 1, a generator 2, a TV set 4-, including a local oscillator 5 and an intermediate image frequency amplifier 6, a frequency meter 10 and a key 11. The introduction of amplifiers 3 and 9, a controlled oscillator 7, a mixer 8 and a frequency meter 13 ensures equal control Voltage voltages and, accordingly, the equality of the local oscillator is determined using a frequency meter 13, which provides the required measurement accuracy, which is especially important, in the range of decimeter waves. 1 il.

Description

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The invention relates to radio measurements and is intended to determine the parameters of the oscillator frequency of the television.

The purpose of the invention is to improve the accuracy of measurements of the residual detuning of the local oscillator.

The drawing shows a block diagram of the device.

The device contains a switch 1, a generator 2, an amplifier 3, a TV 4, a local oscillator 5, an intermediate image frequency amplifier (UPCHI) 6, a controlled oscillator 7, a mixer 8, an amplifier 9, a frequency meter 10, a key 11, a coupling capacitor 12, a frequency meter 13.

The generator 2 is connected via switch 1 to the antenna input of the television 4, and a signal is given to the second input of the switch. The varicap 5 of the local oscillator is connected through a series-connected controlled oscillator 7, the mixer 8 and the amplifier 9 is connected to the input of the frequency meter 10, and the output of the UPcha 6 is connected through the serially connected switch 11 and the coupling capacitor 12 to the input of the frequency meter 13. The output of the generator 2 is connected via an amplifier 3 The second entrance of the mixer is 8.

The device works as follows.

The antenna input of the TV 4 from generator 2 through the switch 1 receives the image carrier voltage when the local oscillator frequency auto tuning system (ALFG) is turned off. The TV 4 by varying the voltage on the varicap 5 of the local oscillator is adjusted so that the frequency of the local oscillator differs from the nominal one by a given value, which is ensured by measuring the frequency of the signal from the output of the HPA 6 with a frequency meter 13 when the switch is closed 11. Then the switch 11 is opened the circuits of the frequency meter 13 on UPCHI 6 of TV 4, switch the switch 1, applying to the antenna input of the TV 4 from the second input of switch 1 a television signal with the same carrier frequency as the signal of the generator 2, then turn on the system APCG of the TV 4. Under the action of the APCG system, the initial control voltage applied to the local oscillator 3 varies, approximating

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LO frequency to nominal value. At the same time, the control voltage is supplied to the input of the controlled generator 7, the generation frequency of which, under the influence of the control voltage, is close to the local oscillator frequency of the TV. The signal from the output of the controlled generator 7

0 is fed to the first input of the mixer, 8, to the second input of which a signal comes from the generator 2, from the output of the amplifier 3. From the output of the mixer 8, the signal of the difference frequency close to

The 15 nominal intermediate frequency of the television 4 is fed to the amplifier 9 and then to the frequency meter 10, the readings of which are fixed. Next, re-install switch 1 and key 11 in

20 an initial state in which a signal from generator 2 is supplied to the input of TV 4, and a frequency meter 13 is connected to the output of UPCA 6 via the coupling capacitor 12 and the system is turned off

25 APCGs of TV 4, by varying the control voltage applied to the local oscillator 5 and the controlled oscillator 7, match the readings of the frequency meter 10 with the previously recorded frequency value.

Thereafter, an intermediate frequency is measured at a frequency meter 13 and the residual detuning is determined by the formula

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f - f f

n J-ocT .np. -NO.pr.

where f, is the measured intermediate frequency of the image signal;

nomr nominal intermediate frequency signal

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Compared with the known device, in which the equality of the control voltages is determined by the indications of a digital voltmeter that does not provide the required accuracy, in the proposed device, the equality of the control voltages and, accordingly, the equality of the local oscillator, ensuring the required accuracy of measurements, which is especially important in the range of decimeter waves.

Claims (1)

Apparatus of the Invention A device for measuring the residual detuning of a local oscillator, comprising a generator connected to the input of a switch, to a second input 3 1370797 which is supplied with a television signal that, in order to increase accuracy, fuel is added, and the output is connected to the antenna, it is entered sequentially on the TV input, which includes a controlled oscillator, a mix, a varicap heterodyne and an amplifier, an amplifier and a second a frequency meter, an intermediate frequency tel of the image, as well as a second amplifier, the output of which is, the output of the amplifier is interconnected to the second input of the sweep image frequency through a transmitter, and the input is combined with the output of the serially connected key and, wherein the input capacitor controllably communication connected to the input of the generator connected to the frequency varicap heteroaryl, wherein homeland.