SU1493963A1 - Two-channel switched radiometer - Google Patents

Abstract

The invention relates to a technique for measuring on microwave and can be used in radio astronomy. The purpose of the invention is to increase the fluctuation sensitivity. The radiometer contains antenna 1, reference radiation source 2, modulator 3, microwave receivers 4 and 5, quadratic detectors 6 and 7, subtractive device 8, synchronous detector 9, low-pass filter / LPF / 11, r-12 modulation frequency . Two adders 13.16 amplifier 14 of direct current, two operational amplifiers 15.10, low-pass filter 17 are added to the radiometer. Since Since the bandwidth of the low-pass filter 17 is much smaller than the pass-band of the low-pass filter 11, the voltage fluctuations at the inputs of the amplifier 10 will be weakly correlated. This condition allows the setting of a coefficient. transmit amplifier 15 to increase the fluctuation sensitivity of the radiometer. 1 il.

Description

one

(21) 4280875 / 24-09

(22) 07/09/87

(46) 07.15.89. Bul K- 26

(71) Special Design Bureau of the Institute of Radio Engineering and Electronics, USSR Academy of Sciences

(72) V.S. Abl Call

(53) 621.317.341.1 (088.8) (56) Measurement of radiothermal and plasma radiation / Ed. Basharinova AE, Moscow: Soviet Radio, 1968, p. 355.

Esepkina I.A. and others. Radio telescopes and radiometers. M .: Spider, 1973, p. 258.

(54) TWO-CHANNEL MODULATING

RADIOMETER

(57) Invention relates to machinery.

measurements on the microwave and m. used

in radio astronomy. The purpose of the invention is to increase the fluctuation sensitivity. The radiometer contains antenna 1, reference radiation source 2, modulator 3, microwave receivers 4 and 5, quadratic detectors 6 and 7, subtraction device 8, synchronous detector 9, low-pass filter (LPF) 11, r-12 frequency modulation. In addition, two adders 13, 16 are added to the radiometer, DC amplifier 14, two operadion amplifiers 15, 10, low-pass filter 17. Because Since the bandwidth of the low-pass filter 17 is much smaller than the pass-band of the low-pass filter 11, the voltage fluctuations at the inputs of the amplifier 10 will be weakly correlated. This condition allows the setting of a coefficient. transfer amplifier 15 to increase the fluctuation sensitivity of the radiometer. 1 il.

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The invention relates to a microwave technique on microwave and can be used in radio astronomy.

The purpose of the invention is to increase the fluctuon sensitivity.

The drawing shows an electrical structural diagram of a two-channel modulation radiometer.

The radiometer contains antenna 1, reference radiation source 2, modulator 3, first and second microwave receivers 4 and 5, first and second quadratic detectors 6 and 7, subtractive device 8, synchronous detector 9 second operational amplifier 10, first low-pass filter 11, frequency modulator 12 generator 12., the first adder 13, the amplifier 14 dc, the operational amplifier 15, the second adder 16, the second low-pass filter 17.

A two-channel modulation radiometer operates as follows.

Measured signal with noise temperature T ;. received by antenna 1 and the signal T from the source 2 of the reference radiation, antiphased to the modulator in modulator 3, are alternately fed to the inputs of microwave receivers 4 and 5, in which they are amplified in two parallel channels and detected by kradratichnye detectors 6 and 7. After This difference voltage, taken from the output of the subtracting device 8, is amplified and detected again in the synchronous detector 9, amplified by the second operational amplifier 10 and, the passage of the first low-pass filter 11 creates a voltage V at the radiometer output, Independent user whose value is proportional DT TO - T ,. The control voltage of the form square wave for the operation of the modulator 3 and the synchronous detector 9 is removed from the outputs of the generator 12 of the modulation frequency.

At the same time, the signals from the outputs of the quadratic detectors 6 and 7 are fed to the inputs of the first adder 13, amplified by the direct current amplifier 14, the first operational amplifier 15, the second operational amplifier 10, and, passing the first low-pass filter 11, a positive voltage is generated at the radiometer output Vn, the mean of which is also proportional to τ. The exception in this case is the permanent component

50

5 0 5 0

five

0

five

the voltage caused by the detection of the own pumrv microwave receivers 4 and 5 is achieved by summing the second adder 16 constant voltages from the outputs of the synchronous detector 9 and the direct current amplifier 14, filtering them with a narrow band second filter 17 17 (the bandwidth of the filter 1 7 is much less filter band II) and subtracting when the second total voltage is applied in the first operational amplifier 15. At the same time, the transfer ratio of the direct current amplifier 14 and the phase of the control voltage on the modulator 3 is set poured in such that the voltage at the output of the second adder 16 does not depend on T, since the bandwidth of the second low-pass filter 17 is much smaller than the bandwidth of the perforated filter 11, the voltage fluctuations at the inputs of the second operational amplifier 10 will be weakly correlated. This condition allows setting the transmission coefficient of the first operational amplifier 15 to increase the fluctuation sensitivity of the radiometer to a value of 5 T

2C (/ g

where C and C are the signal-to-noise power ratios at the inputs of the second operational amplifier 10, and 8 TQ is the fluctuation sensitivity of the ideal compensation radiometer.

Claims (1)

Invention Formula A two-channel modulation radiometer containing a serially connected antenna, a modulator, a first microwave receiver, a first quadratic detector, a subtractive device and a synchronous detector, a source of reference radiation, the output of which is connected to the second modulator input, are connected in series to a second microwave receiver, whose input connected to the second output of the modulator, and the second quadratic detector, the output of which is connected to the second input of the detractor, a modulation frequency generator, the first output of which is connected with the control input of the modulator, and the second output with the second input of the synchronous detector, the first low-pass filter, the output PT 1 f. - ° s, + C. o14yj963 which is the output of a two-channel amplifier, whose vmhots is from a single modulation radiometer, with the input of the first low filter, characterized by the fact that, and the inverter-to-top input is high, in order to increase the fluctuation path of the synchronous detector, after-sensitivity, the first adder, the first input of which is connected to the first input of which is connected to the output of the synchronous detector, and the course of the first quadratic detector-second input to the output of the amplifier Pa, and the second with the output of the second dc current, and the second filter of the quadratic detector, amplification frequencies, the output of which is a direct current, the first operation with the inverting input of the first amplifier and the second op-amp operation amplifier.