SU1672385A2 - Panoramic device for measuring standing wave ratios and attenuations - Google Patents

Abstract

This invention relates to a radio metering technique and can be used to automatically measure frequency SWR. The purpose of the invention is to improve the measurement accuracy of large attenuations and small CWS. Panoramic meter of CWS and attenuation contains oscillator 1 oscillating frequency, directional couplers 2 and 3, respectively, incident and reflected waves, the first 4, second 5 and third 6 detectors, ratio meter 7, panoramic indicator 8, amplifier 9, switch 10, first 11, second 12 and the third 13 are additional switches for the quadrupole under study 17. The introduction of the quadratic root extraction unit 14, the subtraction unit 15, the reference voltage source 16 makes it possible to measure small attenuation and large VSWR with high accuracy. 1 il.

Description

This invention relates to a radio metering technique and can be used to automatically measure frequency SWR.

The purpose of the invention is to improve the measurement accuracy of large attenuations and small CWS.

The drawing shows a structural electrical circuit of a panoramic meter of the CWS and attenuation.

Panoramic meter of CWS and attenuation contains oscillator 1 oscillating frequency, directional couplers 2 and 3, respectively, incident and reflected waves, the first 4, second 5 and third 6 detectors, ratio meter 7, panoramic indicator 8, amplifier 9, switch 10,

the first 11, the second 12 and the third 13 additional switches, the square root extraction unit 14, the subtraction unit 15, the reference voltage source 16 and the quadripole 17 under study.

The meter works as follows.

The first stage of calibration. The main channel output of the directional tap 3 is connected to the third detector 6. The switches 10-13 are set to the first position. The output signal of the third detector 6 Ue is fed through a switch 10 to the second input of the meter 7 and to the input of the amplifier 9. The output signal of the first detector 4 1L} is fed to the first input

From xi

ka

CJ 00

ate

Yu

meter 7, with voltage at its output

U7 K6K7U6 / U4,

where Kb is the coefficient having the dimension of voltage;

K - channel gain factor of the divisible meter 7.

The voltage U through the switches 11 and 13 is fed to the input of the panoramic indicator 8. Controller K, achieve a single voltage level U, while

Ke U4 / U6. (1)

The second stage of calibration. The switches 10-13 are set to the second position. The signal Ue from the output of the third detector through the switch 10 is fed to the second input of the meter 7, and the signal 1M to its first input. The output signal of the meter 7 through the switches 11 and 12 is fed to the first input of the block 15, the second input of which receives the output voltage Die of the source 16. At the same time, the block 15 produces a signal

(U16-U7),

where KIS is the scale factor of the block 15. through the second input and output of the third additional switch 13 is fed to the panoramic indicator 8.

By adjusting the level of the reference voltage U16, a zero signal level (zero mark) is obtained on the scale of the panoramic indicator 8 at the output of block 15. The life span resulting from this adjustment remains unchanged for the measurement mode of small attenuations.

U GB Uy. (2)

The CWS measurement mode is preceded by a two-stage calibration mode.

At the first calibration stage, a short circuiter is connected to the output of the main channel of the directional response 3. The switches 10-13 are set to the third position. The signal Us from the output of the detector 5 through the first input and output of the switch 10 is fed to the second input of the meter 7, the signal U4 is fed to its first input. Voltage

U K at Ks U5 / U4.

where Ks is the gain of the channel of the divisible meter 7,

is fed through switch 11 to block 14, the output of which is Ui4, where Ki4 is the scale factor of block 14.

The signal Ui4 through the switch 9 enters the indicator 8, calibrated in the values of the SWR. The operator, by adjustment, achieves on the scale of the panoramic display indicator 8 a unit of

voltage level (signal corresponding to the module of the reflection coefficient equal to one or VSWR °) at the output of block 14. At the same time, KsUs W and, therefore, dU14 K14VK7,

Coefficient value

Ks U4 / U5 (3) remains unchanged for the measurement period.

CWS

In the second calibration step, the switches 10-13 are set to the fourth position. The signal Us from the output of the detector 5 through the first input and output of the switch

10 is supplied to the second input of the meter 7, to the first input of which a signal is applied. The output signal from meter 7 U K7 is fed through switch 11 to unit 14, the output of which is.

The signal Ui4 through the switch 12 is fed to the first input of block 15, to the second input of which a signal UIG is applied. Block 15 generates a signal

U15 MU16-U),

which is fed through the switch 13 to the panoramic indicator 8. By adjusting the level of the reference voltage, the Uieone-controller achieves a zero signal (zero mark on the scale of the panoramic indicator 8) at the output of the block 15. The voltage

Ui6 Ui4, (4)

the value resulting from this adjustment remains unchanged for the measurement mode of large SWR. This completes the calibration.

In the mode of measuring large and medium attenuation between the output of the main

the channel of the directional coupler 3 and the input of the third detector 6 turn on the quadrupole under study 17. The switches 10-13 are set to the first position.

When attenuating the investigated quadrupole 17, equal to the maximum measurable attenuation, there is no signal at the output of amplifier 9. The signal level of generator 1 is set so that

The first detector 4 operated at the upper boundary of the quadratic region. The third detector 6 at the same time operates at the lower boundary of the quadratic part of the characteristic, since the quadripole under study

17 made a big weakening. As the attenuation decreases, as the third detector 6 reaches the upper boundary of the quadratic portion, a voltage appears at the output of amplifier 9 proportional to the output signal of the third detector

6, which is fed to the control input of generator 1, reduces the signal level until the operating point of the third detector 6 returns to the lower boundary of the quadratic segment. Accordingly, it is set to the lower boundary of the quadratic portion and the operating point of the first detector 4. A further decrease in attenuation of the quadrupole 17 under study causes the operating point of the third detector b to move to the upper boundary of the quadratic portion (to the region of small attenuations).

Thus, the attenuation characteristics of the quadrupole 17 under study are measured in a dynamic range equal to twice the quadratic range of the characteristic of the third detector 6.

Taking into account the condition (1) of the first calibration stage, the signal at the input of the panoramic indicator 8 will be

,

where Kx KeUe / U is the modulus of the transmission coefficient of the studied quadrupole 17.

The Kx value is measured on a scale of the panoramic indicator 8.

In the small attenuation measurement mode, the switches 10-13 are set to the second position. In this case, the operating point of the third detector 6 is located on the upper boundary of the quadratic part of the characteristic. The signal from the output of the third detector 6 is fed through the switch 10 to the input of the meter 7. The voltage U Uy Kx from its output is fed through the switches 11 and 12 to the block 15. The output signal of the unit 15, taking into account the calibration condition (2), will look like

Ui5 Ki5Uie (1-Kx). (5)

The Kx value is measured on a scale of the panoramic indicator 8.

In the mode of measuring small and medium VSWR, the switches 10-13 are set to the third position. At the same time, the panoramic CWS and attenuation meter operates in a mode similar to that described for large and medium attenuation, respectively. Taking into account the condition (3) of the first calibration stage, the signal at the input of the panoramic indicator 8 will be

 Gh,

where Гх / K5U5 / U4 is the modulus of the reflection coefficient of the studied quadrupole 17.

The value of the CWS is measured on a scale of the panoramic indicator 8.

In the measurement mode of large SWRs, switches 10-13 are set to the fourth position. In this case, the operating point of the second detector 5 is located on the upper boundary of the quadratic part of the characteristic. Taking into account the conditions (3) of the first calibration stage, the signal at the output of block 14 will be #

Ui4 Uu Gh.

The voltage from its output is fed through switch 12 to block 15, the output signal of which, taking into account calibration (4), will be

-U15 K15U16 (1 - Gh). (6)

The value of the CWS is measured on the scale of the panoramic indicator 8. From expression (5) it is not difficult to obtain a formula for 5 kx, the relative measurement error Kx. For this, from equation (5),

Kx 1-Ul5 / (Ki5Ul6).

The formula for 5k is determined from the following expression:

-T5 & I + T & “+

+ ls

From where receive

(5i15-5i, b-ak15). (7)

where (5ui5.5ui6 Ki5 is the relative error of setting the voltage Ui5, Uie and the scale factor Ktz.

The graphs of the dependence of 5 kx on Kx, calculated for various values of the "Juie-u-MsAis. Are given in

FIG. 2

Analysis of formula (7) and graph shows that the measurement error Kx is less dependent on (5ui6, Ui5.Ki5. The smaller the attenuation of the quadrupole 17 under study, i.e., closer to unity, and is 0.03% for Kx 0 , 01d5. At the same time, the measurement error calculated by the formula

Bq + (0.05KH + 0.35) dB. will be 8.4%.

It follows from formulas (5) and (6) that they are identical, therefore, what has been said above regarding the measurement of small attenuations is fully applicable to measurements of large CWS.

Thus, the insertion of the blocks 14, 15 and the source 16 makes it possible to measure small attenuations and large CWS with high accuracy.

Claims (1)

Invention Formula Panoramic gauge of CWS and attenuation according to ed. St. N 1306086, which is also distinguished by the fact that, in order to improve the measurement accuracy of small attenuation and large VSWR, the output of the relationship meter is connected to the input of the panoramic indicator through the first additional switch, the square root extractor, the second additional switch, the subtractor and the third additional switch, the second output The first additional switch is connected to the second inputs of the second and third additional switches, the first input of the second additional switch is connected to the first input of the third additional switch, and the second input of the subtractor is connected to the output of the input reference voltage source.