SU460515A2 - Measuring the average frequency of the passband electoral devices - Google Patents

Description

one

This invention relates to the field of radio metering technology.

A known meter of the average frequency of the passband of electoral devices according to the author. St. No. 375588, consisting of a panoramic frequency response meter, including a linear voltage generator, an electronic counting frequency meter, time selectors, a trigger circuit and a level setting device.

A disadvantage of the known device is the considerable duration of the measurement process, due to the fact that the useful time interval during which the variable frequency of the oscillating frequency generator (HKCH) is within the passband of the selective device is often substantially less than the period of linearly varying voltage.

In order to increase the speed in the proposed meter, the generator of linearly varying voltage is made in the form of a generator with a controlled slope of voltage change, and its input is connected to the output of the trigger circuit.

By maintaining the necessary slope of changing the sawtooth voltage at time intervals when the frequency of the GCh frequency lies in the passband of the electoral device under investigation, and by dramatically increasing the slope of the voltage change at the remaining moments of time, it is possible to achieve a significant (more than an order of magnitude) reduction in the measurement time of the average frequency Bands skip 5 ekani election devices.

The drawing shows a structural diagram of the described meter comprising a selective device 1, oscillating frequency generator 2, detector 3, amplifier 4, electron beam tube 5, linearly varying voltage generator 6, pulse shaper 7, time selectors 8, 9, pulse counter 10, the release circuit 11, the device setting level 12, the time selector 13,

5 generator of 14 pulses, time counter 15 and trigger 16.

The meter works as follows. A linear voltage generator generates a signal that linearly

0 changes the frequency of the oscillating frequency generator and, in phase with this, horizontally scans the screen of the cathode ray tube 5. The variable frequency signal with a high rate of change from the output of the generator 2 enters the input of the electoral device under investigation, causing the appearance of a frequency-modulated radio pulse at its output, which, after detection and amplification, enters the vertically deflecting plates of the cathode ray tube 5,

the rice on its screen shows the frequency response of the device under investigation. At the same time, the video impulse from the output of the amplifier 4 is fed to the input of the trigger circuit 11, when triggered, the saw-tooth generator operates in a mode of relatively slow linear variation of its output voltage.

At the same time, the rate of increase of the sawtooth voltage at the output of the generator 6, therefore, the rate of change of the frequency of the signal entering the input of the selective device 1 from generator 2, are small. The trigger level of the trigger circuit 11 is determined by the voltage coming from the level setting device. The impulse at the output of the trigger circuit exists only when the voltage at the output of the amplifier 4 exceeds the set level determined by the device 12. When the trigger circuit 11 reverses, the generator b does not receive a signal from the trigger circuit, which causes a significant increase in the rate of change of sawtooth voltage , consequently, the rate of change of the frequency of the generator 2. Since at these times the measurement of the average frequency is practically not performed, then any requirements for the linearity of the change of pi Oring voltage are not pred.

A rectangular pulse of the trigger circuit 11 of duration t opens the time selector 8, and the signal from the output of the selective device 1, previously converted into an in-phase pulse sequence in the driver 7, through open selectors 8 and 9 goes to the pulse counter 10. Since the number of pulses L in time Since ti is usually small, in order to increase accuracy, the measurement is carried out over a time interval of 1 second. For this, a rectangular pulse from the output of the trigger circuit 11 simultaneously with the temporary selector 8 opens the temporary selector 13, through which the pulses of the reference (known) frequency from the generator 14 arrive at the time counter 15, made so that after the arrival of the number of pulses from the generator 14, which corresponds to 1 sec, the time counter overflows, and at its output a pulse appears, which, acting on trigger 16, flips it. In this case, the time selector 9 closes, the pulse counter 10 stops receiving pulses from the imaging unit 7, and the digital display of the counter shows the number of pulses in the time interval corresponding to nti l sec (n is the number of sawtooth periods with variable slew rate), t. e. the mean value of the setting frequency of the selective device.

Subject invention

Measuring instrument of average frequency of a band of passing of selective devices according to the author. St. No. 375588, characterized in that, in order to improve the speed, the sawtooth generator is designed as a generator with a controlled steepness change in voltage, and its input is connected to the output of the release circuit.

CSpoc