SU920572A1 - Receiving device noise temperature meter - Google Patents

Description

I

The invention relates to radio engineering and can be used to measure the noise temperature during adjustment and testing of the radio system. those containing low noise receivers.

Known noise temperature meters of receiving devices are used in their adjustment and testing tl.

The disadvantage of these devices is low measurement accuracy.

The closest in technical essence to the present invention is a device comprising a clock signal generator connected in series, a modulated noise generator consisting of a noise generator modulator and its own noise generator, a test device consisting of a low-noise amplifier, a frequency converter and an intermediate frequency preamplifier , amplifier with adjustable gain.

power splitter, electronically controlled attenuator, first quadratic detector, video amplifier, first synchronous detector and indicator. A second quadratic detector connected in series, a second video amplifier and a second synchronous detector, the output of which is connected to the control input of an amplifier with an adjustable gain, are connected to the second output of the coupler. The control inputs of the synchronous detectors are connected directly to the output of the clock signal generator, and the control input of the electronically controlled attenuator is connected via the operation mode switch 2.

The measurement of noise temperature is carried out in two stages - calibration and measurement itself. At both stages, the operator must control the instrument and read the readings from it. In this connection, an overestimate of the time spent on measurement is observed. The operator’s participation in the measurement process leads to subjective errors associated with the need for readings from the indicator, manual adjustment of the low-frequency path gain in the calibration mode, inaccuracy of the attenuation setting of the electronically controlled attenuator (dissipation of its attenuation due to variation of the parameters of its elements), and The signal on the quadratic detector enters the non-quadratic regions of its characteristics when using AGC by the magnitude of the excess noise temperature.

The aim of the invention is to improve the accuracy and speed of measurement.

The goal is achieved by the fact that a noise-temperature meter of receivers containing a serially connected clock generator, a modulated noise generator, a receiver and an amplifier with adjustable gain, a first quadratic detector, a video amplifier and the first synchronous detector, as well as a second quadratic and synchronous detector, are connected sequentially analog storage unit, integrator and the first threshold element, the first binary counter, the first signal switch, reversible two a paired counter and a digital memory indicator, as well as a second signal switch, second and third threshold elements, a gain control unit, an OR element, a binary decimal counter, a code comparator, a noise temperature input unit, a second binary counter and a block control, while the inputs of quadratic detectors through the second signal switch are connected to the output of an amplifier with adjustable gain, the control input of which is connected to the output of the gain control unit, the output of the second quadratic detector is connected with the subtracting input of the video amplifier, to the output of which the input of the second synchronous detector is connected, the output of the second synchronous detector is connected to the inputs of the second and third threshold elements, the outputs of which are connected to the control inputs of the gain control unit and the second

| and the third inputs of the control unit, the outputs of the binary-decimal meter and the noise temperature input unit are connected to the inputs of the code comparator, the output of which is connected to the fourth input of the control unit, the output of the first synchronous detector is connected to the input of the analog storage unit, the first output of the sync signal generator connected to the seventh input of the control unit, the second to the control input of the second signal switch and the synchronous input of the second synchronous detector, the third 5 to the synchronous input of the gain control unit and the recording of the analog storage unit, the fourth to the zero input of the second synchronous detector, fifth, sixth and seventh zero respectively to the synchronous input, the zero installation and start inputs of the first synchronous detector, the eighth to the input of the zero installation of the integrator and the first input of the OR element, the output of which is connected to the input of the installation of a zero binary-decimal counter, the ninth one - to the counting inputs of the binary-decimal and first binary counters and the synchronous input of the control unit, as well as to the second

the input of the first switchboard of signals, the outputs of the first threshold element and the second binary counter are connected respectively to the first and 5th inlets of the control unit, the first output of which is connected to the integrator start input, the second to the second input of the OR element and the installation inputs of the first and second 0 binary and reverse binary-decimal counters, the third to the input of the zero setting of the first and the counting input of the second binary counters, the fourth to the control inputs 45 of the noise temperature input unit and the first switch signal signals and to the sign input of the reversible binary-decimal counter; fifth to the recording input of the digital indicator with memory.

FIG. 1 depicts a structural

50 diagram of the noise temperature meter receiving-amplifying devices; in fig. 2 - voltage plots showing the work of the meter.

55 The device contains a sync generator 1, modulated noise generator 2, a test device 3, an amplifier with adjustable amplification, a second switch 5 signal, a first and second quadratic detectors 6 and 7f video amplifier 8, first and second synchronous detectors 9 and 10, an integrator 11, analog storage unit 12, first second and third threshold units 13-15, gain control unit 16, element OR 17, binary decimal counter 18, code comparator 19, noise temperature input unit 20, first binary counter 21, first switch 22 si catch, reversing the binary coded decimal digital indicator 23 ELAPSED 2k memory with the second binary counter 25 and the control unit 26. The device works as follows. Generator 2 noise (GSH), control

signal S; j from generator 1 sync. signals is alternately in

cold and

hot condition.

The temperature of the noise at its output is equal to T and TIV, respectively. The noise power at the output of the device 3 being tested is equal to

(Tx-Sinr-Sin) -GAf.

where K is the Botsman constant T, G, {s.f is the noise temperature, power transfer ratio and noise band of the device under study 3, respectively,

S, S - Signals receiving 5 O, S | 1 with cold GSh2, S 1, Sj O with hotter than GSh2. From the output of the tested device 3, the signal through the amplifier 4 is fed to the switch 5 to the control input of which the signal S is fed. like signal S, is a meander. The frequencies of the signals St and Sa. are chosen from the equality fj, 2V f,, where f, fg are the frequencies of the signals S-i and Sa, respectively, n is a positive integer, n 1. The signals from the output of switch 5 are detected by quadratic detectors 6 and 7, from the outputs of which video signals are taken:

A (S, .U + SvUr) .Si,. A2 (Si-Ux + SvUr) -S2,

drift.in the detector and following the path; in addition, from single detectors and secondary modulation in the IF path, the duration of the measured noise signal being processed is doubled 5, which at a fixed measurement time makes it possible to reduce the fluctuation error by a factor of / Y and decrease 1/2 time measurement time.

Next, the signal AZ is fed to two channels: adjusting the signal level J in the IF path and measuring.

Claims (1)

1. USSR author's certificate No. 4664b9, cl. G 01 R 27/28, 19752. Martyshevsky K.N. On the direct measurement of the noise temperature of low-noise amplifiers and high - Works of sensitive receivers. NIIR, 1973, If 3.; u. .TI,, u f; I ...,, ... .1U nnn n n n n n Ln gjj n P n n nnn g6l P n I Inn fln n n nnn nnn nnn PG nnC3n. m n nnn rnn n g ppp ppp ppp pg n n n n n n n n n n n tfflfl: tPftft-. "- II fL ...