SU1652925A1 - Device to measure alternating infralow frequency voltages - Google Patents

Abstract

The invention relates to radio measurements, in particular to the measurement of voltage signals of infra-frequency frequencies. The purpose of the invention is the expansion of the frequency range in the region of infrared frequencies. The device contains a phase shifter 1, a signal generator 4, a multiplier 3 and an adder 2. Along with a voltage source 8, a key, a measuring transducer 6 and a DC voltmeter 7, these elements compensate for the variable component of the infra-low frequency at the output of the converter 6. 1 Il.

Description

The invention relates to radio engineering measurements, namely to measuring the voltage signals of infra-low frequencies.

The purpose of the invention is the expansion of the frequency range in the area of infralow frequencies (INCH).

The drawing shows a block diagram of a device for measuring alternating voltage LF.

SUBSTANCE: device for measuring alternating voltage of the LF contains a phase shifter 1, an adder 2, a multiplier 3, a signal generator 4, a key 5, a measuring transducer 6, a DC voltmeter 7 and a voltage source 8 with an adjustable DC voltage, and the input terminal of the device is connected to the input of the phase shifter 1 and to the second input of the adder 2. The output of the phase shifter 1 is connected to the first input of the multiplier 3, the second input of which is connected to the output of the signal generator 4. The output of the multiplier is connected to the second input of the adder 2, The output of the adder 2 is connected to the first input of the key 5, the output of which is connected through the measuring transducer 6 to the input of the DC voltmeter 7. The second input of the key 5 is connected to the output of the source 8 with an adjustable DC voltage.

The operation of the device consists in following the output of the adder 2 signal (2) through the key 5 is fed to the measuring transducer 6.

A measuring transducer, if it is a thermoelectric transducer, can be represented as a series-connected quadrator and a low-pass filter. Then arriving at the transducer 6 signal (2), first 10 squared) = Κι ζκυ slnQt · Ui slnwt + UcosQtf = = Ki K ² U ² Tsya | 'n January ² sin ² Ω (· sin ² ω t + 2 Ki K ⁵ U ² Uf slnQt sinv) t COS Y1 + + Ki U ² cos ² Ω: = 0 _ _cos 2 Ωt) (1 - cos 2 «t) + + j _ cosωt + cos wt + cos (2 Ω - ω ) t - cos (2Ω + ω) ι] |. (3) «- ^ (i + ossoo, where Κι is the proportionality coefficient of transducer 6, and then the harmonic components with a frequency different from ω are filtered in the low-pass filter. At the output of transducer 6, a signal appears in the form

(4)

If K is the transfer coefficient of a smart 3Q resident, choose such that the equalizer is observed.

The key 5 is set to position 1. The studied LF signal of a sinusoidal shape is fed to the phase shifter 1 and to the first input of the adder 2. From the output of the phase shifter 1, the signal with the phase shifted relative to the studied by ^ is fed to the first input of the multiplier 3. At the second input of the multiplier 3 s the output of the generator 4 signals 4 receives a sinusoidal signal with a known amplitude. The output of the multiplier 3 multiplied input signals in the form.

U (t) ~ K U sin Ωί · Ui sin 0) ΐ, (1) where U is the amplitude of the signal under study:

Ui is the amplitude of the signal of the generator 4;

Ω is the frequency of the investigated signal;

a> is the frequency of the signal of the generator 4; 5 t - current time;

K is the transmission coefficient of the multiplier 3, and a ^ Y. arrives at the second input of the adder 2. In the adder 2, the signal under study is summed with the signal (1) 5

U ₂ (t) = K U sin Ωΐ Ui sin ωτ + U cos Ωτ, (2)

Κι Κ U ^{2 2} 1st = Κι U ² (5j the variable components of the signal (4) are mutually compensated, and the constant component is doubled compared with KiU ^2/2, i.e. becomes ² O KiU. Measured by voltmeter 7 voltage of a constant component, its indications are noted.

Next, the key 5 is installed in the second position. The output of the constant voltage 5 voltage source 8 is connected to the input of the measuring transducer 6. By changing the magnitude of the output voltage, Un of the voltage source 8, the readings of the direct current voltmeter 7 are set equal to its previously noted readings, i.e. KU ² · = KiUrA This establishes the equality of the measured value of the alternating current voltage U and the equivalent value of the direct current voltage Un, which is installed at the output of the constant voltage source with high accuracy, by the thermal effect on the thermoconverter

U = and _n .

(6)

A positive effect is to expand the frequency range of the measured signals in the LFM region. This effect is achieved by compensating for the variable component of the LFM at the output of the measuring transducer 6, the presence of which limits its frequency range.

Claims (1)

SUMMARY OF THE INVENTION A device for measuring alternating voltages of infra-low frequencies, comprising an input terminal, a key, the first input of which is connected to a source of adjustable DC voltage, the output of the key is connected to the input of measuring transducer 15, the output of which is connected to the input of a DC voltmeter, which is that, in order to expand the measurement frequency range to the region of infralow frequencies, a phase shifter, a multiplier, a signal generator and an adder are introduced into the device, and the input is phase shifted A first input of the adder is connected to the input klem10 my output of the phase shifter - the first input of the multiplier, a second input coupled to an output of the signal generator, the multiplier output - to a second input of the adder whose output is connected to the second input key.