SU1553924A1 - Radiometer for measuring moisture content in the upper atmosphere - Google Patents

Abstract

The invention relates to a technique for the remote sensing of meteorological parameters of the atmosphere, can be used to measure the water vapor content in the atmosphere, and makes it possible to increase the accuracy of measuring humidity in the upper layers of the atmosphere. The radiometer contains a serially connected antenna, switch, mixer, intermediate frequency amplifier, amplitude detector, low frequency amplifier, first and second synchronous detectors, as well as the first and second reference frequency generators, noise generator, through an attenuator connected to the second input of the switch, and the third synchronous detector, through an integrator connected to the attenuator control input. 2 Il.

Description

The invention relates to a remote sensing technique for the meteorological parameters of the atmosphere and can be used to measure the water vapor content in the stratosphere.

The purpose of the invention is to improve the accuracy of measuring humidity in the upper layers of the atmosphere.

Figure 1 is a functional block diagram of a radiometer for measuring humidity in the upper atmosphere; Fig. 2 shows the dependence of the solar radiation transmittance on frequency.

The readometer contains serially connected antenna 1, switch 2, mixer 3, intermediate-frequency amplifier 4 (UPCH), amplitude detector 5 (BP), low-frequency amplifier 6 (ULF), first synchronous detector 7, second synchronous detector 8, and also serial a circuit from the third synchronous detector -9 connected to the ULF 6, the integrator 10, and the attenuator 11, the output of which is connected to the second input of the switch 2.

In addition, the radiometer includes the first reference frequency generator 12, the output of which is connected to the synchronous detector 7 and to the input of the local oscillator 13, the output of which is connected to the second input of the mixer 3, and the second reference frequency oscillator 14, the outputs of which are connected to the second input of the synchronous detector & and with the second input of the synchronous detector 9, as well as the noise generator 15, the output of which is SD

cl

with so to

4i

pogo connected to the signal input attenuator 11.

The device works as follows.

The reference frequency generator 14 generates a low frequency periodic signal controlled by switch 2. At the same time, the input of mixer 3 is periodically connected either to the output of antenna 1 or to the output of attenuator 11. The duration of the time during which the signal from the output of antenna goes to input of mixer 3 1, is equal to the duration of the time interval during which the signal comes from the output of attenuator 11. Solar radiation, evenly distributed over a wide frequency range, passage through the atmosphere, partially absorbed are water vapor in the vicinity of the frequency fo 22,235 GSU forming absorption line.

Dependency ratio

25

thirty

Neither Ta from the frequency f near the absorption line is shown in FIG.

In the time interval during which antenna 1 is connected to mixer 3, narrowband IF amplifier 4 extracts a signal in the frequency band uf from the input signal (FIG. 2) using the oscillator 12 of the reference frequency and the frequency of the local oscillator 13 periodically changes with frequency F fw. By varying the frequency of the local oscillator 13, the frequency of the received thermal radiation 35 also changes. At the output of the amplitude detector 5, a signal is formed, the constant component of which is proportional to the input radiation power of solar radiation, and the variable co-voltage is a harmonic function with frequency F, the amplitude of which is determined by the difference in transmittance at the center of the absorption line and wing. This signal is amplified in the ULF 6 and fed to the input of the synchronous detector 7, the second input of which receives a signal from the output of the generator 12. As a result, the output of the synchronous detector of the torus 7 generates a signal characterizing the difference in the transmittances of the atmosphere in the center of the absorption line on her wing:

l (55

/ f ""

45

 d

about 1

U,

Signals generated by receiving solar radiation and connecting a noise source to the mixer input from the ULF 6 output go to a synchronous detector 9, the second input of which receives a signal from generator 14. A signal proportional to the level difference is generated at the output of synchronous detector 9 constants: solar radiation power and noise components. The difference signal is integrated by the integrator 10 and is fed to the control input of the attenuator 11. At the same time, the attenuation coefficient of the attenuator 11 is changed until the solar radiation power and the noise power become equal. The variable component formed at the output of the ULF 6 in the time interval when the input of the mixer 3 is connected to the output of the attenuator 11, because it is possible to receive the signal Uh at the output of the synchronous detector 7. Thus, when switch 2 is connected to the output of antenna 1, a sig- + Uh is generated at the output of synchronous detector 7, and when the switch

cash U0 U.,

L- | “-“ w оv h ix w, u, a. vwrruTij i a. i w ± y

i t TgCCJdl J Te (f) dfjj, 2 switched to attenuator 11 - formate at f.-T

t 0 M

The 11 g II n signal is measured. These signals

0

0

five

0

35 40 50

55

45

where) is the spectral power density of the input signal.

However, in a real device, the magnitude of the signal generated by the detector 7 is influenced by frequencies — the dependence of the transmittance of any element of the waveguide path and the mixer (see Fig. 2), which leads to the appearance of an erroneous signal U j Ut + Uh. To eliminate this error, the switch 2 to the input of the mixer 3 periodically with the frequency F connects the output of the attenuator 11, the input of which is connected to the output of the noise generator 15, which generates a signal whose frequency spectrum is uniform in the frequency range f0 f f0 + fM

In the time interval in which the attenuator 11 is connected to the input of the mixer 3 by the switch 2, a signal is generated at the output of the amplitude detector 5, the constant component of which is proportional to the noise power, and the variable component depends on the frequency non-uniformity of the waveguide path. This signal is also fed to the ULF 6 input.

The signals generated by receiving solar radiation and connecting the noise source to the mixer input from the ULF 6 output go to a synchronous detector 9, the second input of which receives a signal from the generator 14. Thus, a signal proportional to the constant level difference is generated at the output of the synchronous detector 9 : solar radiation power and noise components. The difference signal is integrated by the integrator 10 and is fed to the control input of the attenuator 11. In this case, the change in the attenuation coefficient of the signal in the attenuator 11 occurs until the solar radiation power and the noise power become equal to each other. The variable component formed at the output of the ULF 6 in the time interval when the input of the mixer 3 is connected to the output of the attenuator 11, because it is possible to receive the signal Uh at the output of the synchronous detector 7. Thus, when switch 2 is connected to the output of antenna 1, a sig- + Uh is generated at the output of synchronous detector 7, and when the switch

cash U0 U.,

 w оv h ix w, u, a. vwrruTij i a. i w ± y

2 is switched to attenuator 11 — an 11 g II n signal is generated. These signals

five

arrive at the input of the synchronous detector 8, at the output of which a signal Uj (U, + Un) - and U ,, is formed, which does not depend on the frequency irregularity of the waveguide path.

Claims (1)

Invention Formula Radiometer for measuring humidity in the upper layers of the atmosphere, containing a serially connected antenna, switch, mixer, intermediate frequency amplifier, amplitude detector, low frequency amplifier, first and second synchronous detectors, first reference frequency generator, output that is connected to the second input the first synchronous detector, the second reference frequency generator, the output of which is connected to the second input of the second synchronous and the local oscillator, the output of which is to the second input of the mixer, and that u u and so that, with the detector is connected o tl and h To improve the accuracy of measuring humidity in the upper atmosphere, a third synchronous detector, an integrator, a noise generator and an attenuator are introduced, the attenuator being connected between the output of the noise generator and the second input of the switch, the control input of which is connected to the output of the second reference frequency generator, the third synchronous detector and the integrator is connected in series between the output of the low-frequency amplifier and the control input of the attenuator, the output of the first reference oscillator is connected to the control input of the heterodyne on, and the output of the second reference frequency generator is connected to the second input of the third synchronous detector. 1 TV (/) / FIG. 2