CN110210078A - A kind of total power type micro-wave radiometer system emulation mode - Google Patents
A kind of total power type micro-wave radiometer system emulation mode Download PDFInfo
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Abstract
The present invention relates to microwave remote sensing instruments and signal processing skill technical field, more particularly to a kind of total power type micro-wave radiometer system emulation mode, comprising: which simulation generates calibration cold source input signal and calibration heat source input signal respectively according to the heat radiated noise model pre-established；Above-mentioned input signal is separately input into total power type micro-wave radiometer system, accordingly output calibration heat source output voltage and calibration cold source output voltage, calculate the simulation performance index of total power type micro-wave radiometer system；The parameter of total power type micro-wave radiometer system is adjusted until simulation performance index is met the requirements.
Description
Technical field
The invention belongs to microwave remote sensing instrument and signal processing technology fields, and in particular to a kind of total power declines wave radiation
Meter systems emulation mode.
Background technique
With the development of space technology, electronic technology and information technology, microwave remote sensing technique especially satellite-borne microwave remote sensing
Technology is all rapidly developed, it has also become the important means of earth observation and space exploration.Microwave radiometer is main micro-
One of wave remote sensing instrument, occupies an important position in microwave remote sensing.It is different from infrared remote sensor, not by or seldom by cloud, rain,
The limitation of the weather such as mist, does not need illumination condition, has round-the-clock and round-the-clock ability to work, or even can also penetrate certain depth
Earth's surface and vegetation, it is hereby achieved that under the information and earth's surface of vegetative coverage earth's surface certain depth target information etc.；In addition,
Microwave radiometer can also multifrequency, multipolarization, obtain to multi-angle of view multi-faceted target information.
The structure of total power type micro-wave radiometer is simple, radiosusceptibility is relatively high, in atmosphere and oceanographic observation by
To being widely applied.At this stage, the signal simulation method flow of total power type micro-wave radiometer is simple, and clear principle is understandable,
Analyze, realize according to the signals transmission simplified, still, signal simulation result and expectation only with well known theoretical formula
There are biggish errors；Existing signal simulation method has done a large amount of simplification in derivation process, is not able to satisfy high-precision want
It asks.It is analyzed in terms of fine degree, current signal simulation method and step is excessively simple, does not carry out to microwave radiometer accurate
Modeling, the index so as to cause each component part of radiometer is not perfect, examines without foundation.
Summary of the invention
It is an object of the present invention to solve existing signal simulation method, there are drawbacks described above, and the invention proposes one kind
Total power type micro-wave radiometer system emulation mode, this method establish each device of radiometer from the angle of signal processing
The simulation frame of parameterized model and total power type micro-wave radiometer, assesses simulation result, when performance indicator satisfaction is set
When meter expectation, the parameter of each device is required design value；If performance indicator is unsatisfactory for design expectation, each device is adjusted
Parameter is completed, is terminated until meeting design desired value.
To achieve the goals above, the invention proposes a kind of total power type micro-wave radiometer system emulation mode, the party
Method specifically includes:
According to the heat radiated noise model pre-established, simulation generates calibration cold source input signal respectively and calibration heat source is defeated
Enter signal；
Above-mentioned input signal is separately input into total power type micro-wave radiometer system, accordingly output calibration heat source is defeated
Voltage and calibration cold source output voltage out, calculate the simulation performance index of total power type micro-wave radiometer system；
The parameter of total power type micro-wave radiometer system is adjusted until simulation performance index is met the requirements.
One of as an improvement of the above technical solution, the heat radiated noise model that the basis pre-establishes is simulated respectively
Generate calibration cold source input signal and calibration heat source input signal；It specifically includes:
When the radiation spectrum of observed object is constant, for example, high and low temperature source when calibration, heat radiated noise is with limit
White Gaussian noise.Wherein, white Gaussian noise is generated by pseudo random number, and mean value and standard deviation are determined by formula (1):
μ=0
σ=kT (1)
Wherein, k is Boltzmann constant；T is the bright temperature of heat radiated noise；μ is the mean value of white Gaussian noise；σ is Gauss
The standard deviation of white noise；Wherein, the bright temperature T of heat radiated noise is the bright temperature for calibrating heat source or the bright temperature for calibrating heat source；
For white Gaussian noise, time domain and frequency-region signal all Normal Distributions:
S (t)~N (0, σ)
S (f)~N (0, π σ) (2)
Wherein, s (t) is the time domain of white Gaussian noise；S (f) is the frequency domain of white Gaussian noise；
If rectangular window function is C (f), then the white Gaussian noise S with limitb(f) are as follows:
Sb(f)=C (f) S (f) (3)
Assuming that observed object radiation spectrum is A (f), then the frequency spectrum S of heat radiated noiseA(f) are as follows:
SA(f)=A (f) Sb(f) (4)
Wherein, according to Gaussian Profile, SA(f) distribution function are as follows:
SA(f)~N (0, A (f) π σ) (5)
Therefore, the frequency spectrum S of heat radiated noiseA(f) be heat radiated noise model, each frequency point obey mean value be zero,
Variance is the Gaussian Profile of A (f) π σ, carrys out the Realization of Simulation using in the pseudo random number of Gaussian Profile；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating heat sourceHWhen；According to the heat radiated noise model of foundation, simulation
Generate calibration heat source input signal, the spectrum of heat source S as heat radiated noiseA(f)；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating cold sourceCWhen；According to the heat radiated noise model of foundation, simulation
Generate calibration cold source input signal, the cold source frequency spectrum S as heat radiated noiseA(f)。
One of as an improvement of the above technical solution, the total power type micro-wave radiometer system includes five cascade low
Make an uproar put, frequency mixer, radio frequency amplifier, filter, wave detector；Each device in total power type micro-wave radiometer system is joined
Numberization modeling obtains the parameterized model of low noise, the parameterized model of frequency mixer, the parameterized model of radio frequency amplifier, filter
The parameterized model of wave device and the parameterized model of wave detector, and it is arranged in correspondence with each device in total power type micro-wave radiometer system
The design parameter of part.
Wherein, the parametrization for obtaining the parameterized model of low noise, the parameterized model of frequency mixer, radio frequency amplifier
The parameterized model of model, the parameterized model of filter and wave detector；It specifically includes:
The parameterized model S of the low noisel(f) are as follows:
Sl(f)=Hl(f)SA(f)+Nl(f) (6)
Wherein, NlIt (f) is the noise signal of low noise；Hl(f) it is the transmission function of low noise, indicates the gain of low noise,
For receiving input signal, and input signal is transferred to the parameterized model of frequency mixer；
Consider that frequency mixer self-noise contributes Nm(f), and it is uncorrelated to input signal, the parameterized model S of frequency mixerm(f)
Are as follows:
Sm(f)=Sl(f)Hm(f)-Nm(f) (7)
Wherein, HmIt (f) is the transmission function of frequency mixer；NmIt (f) is frequency mixer self-noise；
Wherein, the transfer function H of frequency mixerm(f) are as follows:
Hm(f)=Am(f)δ(f-f0-Δf) (8)
Wherein, Δ f indicates the offset of local frequency；δ () is unit impulse response；AmIt (f) is conversion loss；F is frequency
Rate；f0For local frequency；
The transfer function H of frequency mixerm(f), for receive by low noise transmission function transmitting input signal, and by its
It is transferred to the transmission function of radio frequency amplifier；
The major parameter of radio frequency amplifier has gain and flatness, noise coefficient and linear zone.Since microwave radiometer connects
What is received is heat radiation faint in nature, and power is very small, and in the linear zone in amplifier, therefore radio frequency amplifier is not
Nonlinearity erron can be generated.
The parameterized model S of radio frequency amplifiera(f) are as follows:
Sa(f)=Ha(f)Sm(f)+Na(f) (9)
Wherein, Ha(f) it is the transmission function of radio frequency amplifier, indicates the gain of radio frequency amplifier；Na(f) amplify for radio frequency
The noise signal of device；
The transfer function H of radio frequency amplifieraIt (f), will for receiving by the input signal of the transmission function transmitting of frequency mixer
Its transmission function for being transferred to filter；
For practical bandpass filter, it is difficult to realize the frequency response of rectangular window.If the frequency response of bandpass filter is
Hf(f), the self-noise of filter is Nf(f), then the parameterized model S of filterf(f) are as follows:
Sf(f)=Hf(f)Sa(f)+Nf(f) (10)
Wherein, Hf(f) it is the transmission function of bandpass filter, indicates the frequency response of bandpass filter；
NfIt (f) is the self-noise of filter；
The transfer function H of bandpass filterf(f), for receiving by the input letter of the transmission function transmitting of radio frequency amplifier
Number, it is passed to the parameterized model of wave detector；
In realistic model, the non-linear effects of transistor, the parameterized model of wave detector are considered are as follows:
Vd(t)=c0{IFFT(Sf(f))}2e(p) (11)
Wherein, c0For detection coefficient；IFFT is inverse Fourier transform；E (p) is linear factor, the function as input signal
Rate function；When input signal power reaches the inelastic region of wave detector, e (p) is less than 1；When input power continues to increase, it is more than
When the inelastic region of wave detector, e (p) is equal to zero, and wave detector reaches saturation region；VdIt (t) is the output voltage of wave detector.
Total power type micro-wave radiometer uses quadratic detection, indicates signal power value with detecting circuit value.By detection
Signal is essentially direct current signal after integral, and the time-domain description of the mathematical model of wave detector is relatively simple, thus the model by when
Domain representation.Acceleration geophone parameter model receives the noise signal by filter parameter Model Transfer, by inverse Fourier transform,
The voltage for exporting the noise signal, using the voltage value can computer sim- ulation radiometer sensitivity, the linearity and dynamic range
Performance indicator.Specifically, the input signal is believed input by above-mentioned each parameterized model and its corresponding transfer function
It number is finally transmitted to acceleration geophone parameter model, and by the acceleration geophone parameter model, utilizes Vd(t), input signal is turned
It is changed to corresponding calibration heat source output voltage VHWith calibration cold source output voltage VC。
One of as an improvement of the above technical solution, described above-mentioned input signal is separately input into total power to decline amplitude
It penetrates in meter systems, accordingly output calibration heat source output voltage and calibration cold source output voltage；It specifically includes:
The input signal is finally transmitted to the parameterized model of wave detector, and will by the parameterized model of the wave detector
Input signal is converted to corresponding output voltage；Specifically, by inverse Fourier transform, calibration cold source input signal is converted to
Calibrate cold source output voltage VC；Calibration heat source input signal is converted into calibration heat source output voltage VH。
One of as an improvement of the above technical solution, the simulation performance index packet of the total power type micro-wave radiometer system
It includes: radiometer sensitivity Δ T, the linearity R and dynamic range Δ V of emulation.
One of as an improvement of the above technical solution, the radiation of the emulation for calculating total power type micro-wave radiometer system
Count sensitivity Δ T；It specifically includes:
The variation for comprehensively considering calibration heat source and cold source, by the bright temperature value and wave detector output voltage of heat source and cold source and
Its standard deviation carrys out the radiometer sensitivity Δ T of computer sim- ulation:
Wherein, THFor the bright temperature for calibrating heat source；TCFor the bright temperature for calibrating cold source；VHTo calibrate heat source output voltage, that is, calibrate
The corresponding wave detector output voltage of heat source；VCTo calibrate cold source output voltage, that is, calibrate the corresponding wave detector average voltage of cold source；
Standard difference operation is sought in STD () expression；Wherein, STD (VH)2For the flat of the corresponding wave detector output voltage standard deviation of calibration heat source
Side；STD(VC)2For square of the corresponding wave detector output voltage standard deviation of calibration cold source.
One of as an improvement of the above technical solution, the emulation for calculating total power type micro-wave radiometer system is linear
Spend R；The linearity of radiometer is defined as the linearly related degree between the output voltage of wave detector and input noise temperature, uses line
Property coefficient R, specifically:
Wherein, N is measurement points；For the wave detector output voltage of i-th measurement；Represent wave detector output voltage
Mean value；TiFor the input noise temperature of i-th measurement；Represent the mean value of input noise temperature.
One of as an improvement of the above technical solution, the dynamic of the emulation for calculating total power type micro-wave radiometer system
Range delta V；The dynamic range of radiometer is defined as when the antenna of microwave radiometer is directed toward to be become calibrating cold source from calibration heat source,
The dynamic range amount of radiometer output voltage；Specifically:
Wherein, mean () expression is averaged；For the wave detector output voltage of the calibration heat source of i-th measurement；It is
The wave detector output voltage of the calibration cold source of i measurement.
One of as an improvement of the above technical solution, adjust the design parameter of each device of total power type micro-wave radiometer until
System performance index is met the requirements；It specifically includes:
It is corresponding to judge whether radiosusceptibility Δ T, the linearity R of emulation and dynamic range Δ V performance indicator all meet
Pre-set desired value；
If emulation radiosusceptibility Δ T be less than pre-set desired value, and emulate linearity R be greater than set in advance
The desired value set, and the dynamic range Δ V of emulation are greater than pre-set desired value, then radiosusceptibility Δ T, the line emulated
Property degree R and dynamic range Δ V performance indicator all meet corresponding pre-set desired value, then complete signal processing, and terminate；
If the radiosusceptibility Δ T of emulation is greater than pre-set desired value, or the linearity R of emulation is less than in advance
The desired value of setting, emulation dynamic range Δ V be less than pre-set desired value, then it is the radiosusceptibility Δ T emulated, linear
Degree R and dynamic range Δ V performance indicator are unsatisfactory for corresponding pre-set desired value, then repeat above-mentioned signal processing method,
Input signal is iterated, until emulation radiosusceptibility, the linearity and dynamic range performance index meet it is corresponding pre-
The desired value being first arranged is completed signal processing, and is terminated.
The beneficial effect of the present invention compared with the prior art is:
It is made an uproar by building heat radiated noise source model and each parameterized model, the radiation described accurately under actual scene
Sound source and total power type micro-wave radiometer, the evaluation for each performance indicator provide model supports；In simulations, radiation spirit is introduced
The performance indicator of sensitivity, the linearity and dynamic range improves the levels of precision to evaluation of simulation result, while can be linear
Degree and the true value of dynamic range and the control errors of theoretical value are within 1%, the true value of sensitivity and the mistake of theoretical value
Difference control within 10%, make it have higher simulation accuracy, ensure that method proposed by the present invention correctness and effectively
Property.
Detailed description of the invention
Fig. 1 is a kind of flow chart of total power type micro-wave radiometer system emulation mode of the invention；
Fig. 2 (a) is in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention to target
The schematic diagram of the simulation result of time domain waveform after heat radiated noise modeling；
Fig. 2 (b) is in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention to target
The schematic diagram of the simulation result of frequency-domain waveform after heat radiated noise modeling；
Fig. 3 (a) is radiometer in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention
The schematic diagram of the time domain waveform simulation result of front end；
Fig. 3 (b) is radiometer in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention
The schematic diagram of the frequency-domain waveform simulation result of front end；
Fig. 4 (a) is radiometer in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention
The schematic diagram of the time domain waveform simulation result of rear end；
Fig. 4 (b) is radiometer in a kind of simulation example of total power type micro-wave radiometer system emulation mode of the invention
The schematic diagram of the frequency-domain waveform simulation result of rear end.
Specific embodiment
Now in conjunction with attached drawing, the invention will be further described.
As shown in Figure 1, the invention proposes a kind of total power type micro-wave radiometer system emulation mode, this method is specifically wrapped
It includes:
Firstly, simulation generates calibration cold source input signal and calibration respectively according to the heat radiated noise model pre-established
Heat source input signal；
Specifically, the heat radiated noise model that the basis pre-establishes, simulation generates calibration cold source input signal respectively
With calibration heat source input signal；It specifically includes:
When the radiation spectrum of observed object is constant, for example, high and low temperature source when calibration, heat radiated noise is with limit
White Gaussian noise.Wherein, white Gaussian noise is generated by pseudo random number, and mean value and standard deviation are determined by formula (1):
μ=0
σ=kT (1)
Wherein, k is Boltzmann constant；T is the bright temperature of heat radiated noise；μ is the mean value of white Gaussian noise；σ is Gauss
The standard deviation of white noise；Wherein, the bright temperature T of heat radiated noise is the bright temperature for calibrating heat source or the bright temperature for calibrating heat source；
For white Gaussian noise, time domain and frequency-region signal all Normal Distributions:
S (t)~N (0, σ)
S (f)~N (0, π σ) (2)
Wherein, s (t) is the time domain of white Gaussian noise；S (f) is the frequency domain of white Gaussian noise；
If rectangular window function is C (f), then the white Gaussian noise S with limitb(f) are as follows:
Sb(f)=C (f) S (f) (3)
Under actual conditions, power of the broadband signal that the antenna in total power type micro-wave radiometer receives on each frequency point
It is to be determined by the radiation spectrum of observed object.Assuming that observed object radiation spectrum is A (f), then the frequency spectrum S of heat radiated noiseA(f)
Are as follows:
SA(f)=A (f) Sb(f) (4)
Wherein, according to Gaussian Profile, SA(f) distribution function are as follows:
SA(f)~N (0, A (f) π σ) (5)
Therefore, the frequency spectrum S of heat radiated noiseA(f) be heat radiated noise model, each frequency point obey mean value be zero,
Variance is the Gaussian Profile of A (f) π σ, carrys out the Realization of Simulation using in the pseudo random number of Gaussian Profile；
Wherein, the time domain for the white Gaussian noise signal that Fig. 2 (a) and Fig. 2 (b) are respectively target heat radiated noise when being 95K
And frequency domain representation.The mean value of white Gaussian noise is μ, standard deviation is that σ is calculated by formula (1)；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating heat sourceHWhen；According to the heat radiated noise model of foundation, simulation
Generate calibration heat source input signal, i.e. the spectrum of heat source S of heat radiated noiseA(f)；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating cold sourceCWhen；According to the heat radiated noise model of foundation, simulation
Generate calibration cold source input signal, i.e. the cold source frequency spectrum S of heat radiated noiseA(f)。
Then, above-mentioned input signal is separately input into total power type micro-wave radiometer system, accordingly output calibration
Heat source output voltage and calibration cold source output voltage, calculate the simulation performance index of total power type micro-wave radiometer system；
Specifically, the total power type micro-wave radiometer system includes five cascade low noise, frequency mixer, radio frequency amplification
Device, filter, wave detector；Parametric modeling is carried out to each device in total power type micro-wave radiometer system, obtains low noise
Parameterized model, the parameterized model of frequency mixer, the parameterized model of radio frequency amplifier, the parameterized model of filter and inspection
The parameterized model of wave device, and it is arranged in correspondence with the design parameter of each device in total power type micro-wave radiometer system.
It is described obtain the parameterized model of low noise, the parameterized model of frequency mixer, radio frequency amplifier parameterized model,
The parameterized model of filter and the parameterized model of wave detector；It specifically includes:
The parameterized model S of low noisel(f) are as follows:
Sl(f)=Hl(f)SA(f)+Nl(f) (6)
Wherein, Hl(f) it is the transmission function of low noise, indicates the gain of low noise, for receiving input signal, and will be defeated
Enter the transmission function that signal is transferred to frequency mixer；NlIt (f) is the noise signal of low noise；
Consider that frequency mixer self-noise contributes Nm(f), and it is uncorrelated to input signal, the parameterized model S of frequency mixerm(f)
Are as follows:
Sm(f)=Sl(f)Hm(f)+Nm(f) (7)
Wherein, HmIt (f) is the transmission function of frequency mixer；NmIt (f) is frequency mixer self-noise；
Wherein, the transfer function H of frequency mixerm(f) are as follows:
Hm(f)=Am(f)δ(f-f0-Δf) (8)
Wherein, Δ f indicates the offset of local frequency；δ () is unit impulse response；AmIt (f) is conversion loss；F is frequency
Rate；f0For local frequency；
The transfer function H of frequency mixerm(f), for receive by low noise transmission function transmitting input signal, and by its
It is transferred to the transmission function of radio frequency amplifier；
The major parameter of radio frequency amplifier has gain and flatness, noise coefficient and linear zone.Since microwave radiometer connects
What is received is heat radiation faint in nature, and power is very small, and in the linear zone in amplifier, therefore radio frequency amplifier is not
Nonlinearity erron can be generated.
The parameterized model S of radio frequency amplifiera(f) are as follows:
Sa(f)=Ha(f)Sm(f)+Na(f) (9)
Wherein, Ha(f) it is the transmission function of radio frequency amplifier, indicates the gain of radio frequency amplifier；Na(f) amplify for radio frequency
The noise signal of device；
The transfer function H of radio frequency amplifieraIt (f), will for receiving by the input signal of the transmission function transmitting of frequency mixer
Its transmission function for being transferred to filter；
For practical bandpass filter, it is difficult to realize the frequency response of rectangular window.If the frequency response of bandpass filter is
Hf(f), the self-noise of filter is Nf(f), then the parameterized model S of filterf(f) are as follows:
Sf(f)=Hf(f)Sa(f)+Nf(f) (10)
Wherein, Hf(f) it is the transmission function of bandpass filter, indicates the frequency response of bandpass filter；
NfIt (f) is the self-noise of filter；
The transfer function H of filterfIt (f), will for receiving by the input signal of the transmission function transmitting of radio frequency amplifier
Its parameterized model for being transferred to wave detector；
Wherein, by cascading low noise, the transmission function of mixing, amplification and filtering, the radio-frequency part of microwave radiometer is obtained
The transmission function divided.Fig. 3 (a) and 3 (b) is respectively time domain waveform and frequency-domain waveform of the noise signal after radio frequency part.Its
In, the gain of low noise is 30dB, noise coefficient 5dB；The conversion loss of frequency mixer is 2dB；The gain of radio frequency amplifier is
45dB, noise coefficient 6dB；The passband of filter is 1.5GHz, and the Out-of-band rejection at 1.5 times of bandwidth is 35dB.
In realistic model, the non-linear effects of transistor, the parameterized model of wave detector are considered are as follows:
Vd(t)=c0{IFFT(Sf(f))}2e(p) (11)
Wherein, c0For detection coefficient；IFFT is inverse Fourier transform；E (p) is linear factor, the function as input signal
Rate function；When input signal power reaches the inelastic region of wave detector, e (p) is less than 1；When input power continues to increase, it is more than
When the inelastic region of wave detector, e (p) is equal to zero, and wave detector reaches saturation region；VdIt (t) is the output voltage of wave detector.
Fig. 4 (a) and 4 (b) is respectively signal by post-detector time domain waveform and frequency-domain waveform.The detection system of wave detector
Number is 88.85mV/mW.After quadratic detection, radiofrequency signal is rectified into vision signal.
Total power type micro-wave radiometer uses quadratic detection, indicates signal power value with detecting circuit value.By detection
Signal is essentially direct current signal after integral, and the time-domain description of the mathematical model of wave detector is relatively simple, thus the model by when
Domain representation.Acceleration geophone parameter model receives the noise signal by filter parameter Model Transfer, by inverse Fourier transform,
The voltage for exporting the noise signal, using the voltage value can computer sim- ulation radiometer sensitivity, the linearity and dynamic range
Performance indicator.Specifically, the input signal is by above-mentioned each parameterized model and its corresponding transfer function, by calibration heat
Source signal and calibration cold source signal are successively finally transmitted in acceleration geophone parameter model, and pass through the acceleration geophone parameter mould
Type utilizes Vd(t), calibration heat source signal and calibration cold source signal are converted into corresponding calibration heat source output voltage VHAnd calibration
Cold source output voltage VC, according to calibration heat source output voltage VHWith calibration cold source output voltage VC, the radiometer of computer sim- ulation is sensitive
The performance indicator of degree, the linearity and dynamic range.
Finally, the design parameter of each device in adjustment total power type micro-wave radiometer is until total power type micro-wave radiometer
The simulation performance index of system is met the requirements.
Specifically, the simulation performance index of the total power type micro-wave radiometer system includes: that the radiometer of emulation is sensitive
Spend Δ T, linearity R and dynamic range Δ V.
The radiometer sensitivity Δ T of the emulation for calculating total power type micro-wave radiometer system；It specifically includes:
The input signal is finally transmitted to the parameterized model of wave detector, and will by the parameterized model of the wave detector
Input signal is converted to corresponding output voltage；Specifically, by inverse Fourier transform, calibration cold source input signal is converted to
Calibrate cold source output voltage VC；Calibration heat source input signal is converted into calibration heat source output voltage VH；
The radiometer sensitivity Δ T of the emulation specifically:
The variation for comprehensively considering calibration heat source and cold source, by the bright temperature value and wave detector output voltage of heat source and cold source and
Its standard deviation carrys out the radiometer sensitivity Δ T of computer sim- ulation:
Wherein, THFor the bright temperature for calibrating heat source；TCFor the bright temperature for calibrating cold source；VHTo calibrate heat source output voltage, that is, calibrate
The corresponding wave detector output voltage of heat source；VCTo calibrate cold source output voltage, that is, calibrate the corresponding wave detector average voltage of cold source；
Standard difference operation is sought in STD () expression；Wherein, STD (VH)2For the flat of the corresponding wave detector output voltage standard deviation of calibration heat source
Side；STD(VC)2For square of the corresponding wave detector output voltage standard deviation of calibration cold source.
The linearity R of the emulation for calculating total power type micro-wave radiometer system；The linearity of radiometer is defined as examining
Linearly related degree between the output voltage and input noise temperature of wave device, with linearly dependent coefficient R, specifically:
Wherein, N is measurement points；For the wave detector output voltage of i-th measurement；Represent wave detector output voltage
Mean value；TiFor the input noise temperature of i-th measurement；Represent the mean value of input noise temperature.
The dynamic range Δ V of the emulation for calculating total power type micro-wave radiometer system；The dynamic range of radiometer is fixed
Justice is the dynamic range of radiometer output voltage when the antenna of microwave radiometer is directed toward to be become calibrating cold source from calibration heat source
Amount；Specifically:
Wherein, mean () expression is averaged；For the wave detector output voltage of the calibration heat source of i-th measurement；It is
The wave detector output voltage of the calibration cold source of i measurement.
Wherein, the design parameter of each device of total power type micro-wave radiometer is adjusted until system performance index is met the requirements；
It specifically includes:
It is corresponding to judge whether radiosusceptibility Δ T, the linearity R of emulation and dynamic range Δ V performance indicator all meet
Pre-set desired value；
If radiosusceptibility Δ T, the linearity R and dynamic range Δ V performance indicator of emulation meet corresponding preparatory
The desired value of setting is then completed signal processing, and is terminated；
If radiosusceptibility Δ T, the linearity R and dynamic range Δ V performance indicator of emulation are unsatisfactory for corresponding preparatory
The desired value of setting then repeats above-mentioned signal processing method, iterates to input signal, until the radiosusceptibility of emulation,
The linearity and dynamic range performance index meet corresponding pre-set desired value, complete signal processing, and terminate.
Specifically, if the radiosusceptibility Δ T of emulation is less than pre-set desired value, and the linearity R emulated is big
It is greater than pre-set desired value, the then radiation-sensitive emulated in the dynamic range Δ V of pre-set desired value, and emulation
Degree, the linearity and dynamic range performance index meet corresponding pre-set desired value, complete signal processing, and terminate；?
In the present embodiment, comparison sheet 2 and table 1, the system performance of emulation are all satisfied design expectation, and emulation terminates.
If the radiosusceptibility Δ T of emulation is greater than pre-set desired value, or the linearity R of emulation is less than in advance
The desired value of setting, the dynamic range Δ V of emulation are less than pre-set desired value, then repeat above-mentioned signal processing method, directly
Radiosusceptibility Δ T to emulation is less than pre-set desired value, and the linearity R emulated is greater than pre-set expectation
Value, and the dynamic range Δ V of emulation are greater than pre-set desired value, complete signal processing, and terminate.
Wherein, the pre-set desired value is the design desired value of total power type micro-wave radiometer index；Specific packet
It includes:
The main indicator of microwave radiometer includes radiosusceptibility, the receiver linearity and dynamic range, with wind and cloud three
For the channel 1 of microwave Hygrothermograph, pre-set expectation are as follows:
The pre-set expectation of 1 radiometer of table
Wherein, the calibration heat source signal and calibration cold source signal are to be emitted by reference source, and believe as input
Number it is input to heat radiated noise model.
Utilize formula (12)~(14) computer sim- ulation performance indicator, calculated result are as follows:
The performance indicator that table 2 emulates
It should be noted last that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting.Although ginseng
It is described the invention in detail according to embodiment, those skilled in the art should understand that, to technical side of the invention
Case is modified or replaced equivalently, and without departure from the spirit and scope of technical solution of the present invention, should all be covered in the present invention
Scope of the claims in.
Claims (9)
1. a kind of total power type micro-wave radiometer system emulation mode, which is characterized in that this method comprises:
According to the heat radiated noise model pre-established, simulation generates calibration cold source input signal and calibration heat source input letter respectively
Number；
Above-mentioned input signal is separately input into total power type micro-wave radiometer system, accordingly output calibration heat source output electricity
Pressure and calibration cold source output voltage, calculate the simulation performance index of total power type micro-wave radiometer system；
The parameter of total power type micro-wave radiometer system is adjusted until simulation performance index is met the requirements.
2. the method according to claim 1, wherein the heat radiated noise model that the basis pre-establishes, divides
Calibration cold source input signal and calibration heat source input signal Mo Ni not generated；It specifically includes:
When the radiation spectrum of observed object is constant, heat radiated noise is the white Gaussian noise with limit:
μ=0
σ=kT (1)
Wherein, k is Boltzmann constant；T is the bright temperature of heat radiated noise；μ is the mean value of white Gaussian noise；σ is Gauss white noise
The standard deviation of sound；Wherein, the bright temperature T of heat radiated noise is the bright temperature for calibrating heat source or the bright temperature for calibrating heat source；
For white Gaussian noise, time domain and frequency-region signal all Normal Distributions:
S (t)~N (0, σ)
S (f) N (0, π σ) (2)
Wherein, s (t) is the time domain of white Gaussian noise；S (f) is the frequency domain of white Gaussian noise；
If rectangular window function is C (f), then the white Gaussian noise S with limitb(f) are as follows:
Sb(f)=C (f) S (f) (3)
Assuming that observed object radiation spectrum is A (f), then the frequency spectrum S of heat radiated noiseA(f) are as follows:
SA(f)=A (f) Sb(f) (4)
Therefore, the frequency spectrum S of heat radiated noiseA(f) be heat radiated noise model, each frequency point obey mean value be zero, variance is
The Gaussian Profile of A (f) π σ carrys out the Realization of Simulation using in the pseudo random number of Gaussian Profile；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating heat sourceHWhen；According to the heat radiated noise model of foundation, simulation is generated
Calibrate heat source input signal, the spectrum of heat source as heat radiated noise；
When the bright temperature T of heat radiated noise is the bright temperature T for calibrating cold sourceCWhen；According to the heat radiated noise model of foundation, simulation is generated
Calibrate cold source input signal, the cold source frequency spectrum as heat radiated noise.
3. according to the method described in claim 2, it is characterized in that, the total power type micro-wave radiometer system includes five grades
Low noise, frequency mixer, radio frequency amplifier, filter and the wave detector of connection；
The parameterized model S of the low noisel(f) are as follows:
Sl(f)=Hl(f)SA(f)+Nl(f) (6)
Wherein, HlIt (f) is the transmission function of low noise；HlIt (f) is the noise signal of low noise；
The parameterized model S of the frequency mixerm(f) are as follows:
Sm(f)=Sl(f)Hm(f)+Nm(f) (7)
Wherein, HmIt (f) is the transmission function of frequency mixer；NmIt (f) is frequency mixer self-noise；
Wherein, the transfer function H of frequency mixerm(f) are as follows:
Hm(f)=Am(f)δ(f-f0-Δf) (8)
Wherein, Δ f indicates the offset of local frequency；δ () is unit impulse response；AmIt (f) is conversion loss；F is frequency；
f0For local frequency；
The parameterized model S of the radio frequency amplifiera(f) are as follows:
Sa(f)=Ha(f)Sm(f)+Na(f) (9)
Wherein, HaIt (f) is the transmission function of radio frequency amplifier；NaIt (f) is the noise signal of radio frequency amplifier；
The parameterized model S of the filterf(f) are as follows:
Sf(f)=Hf(f)Sa(f)+Nf(f) (10)
Wherein, HfIt (f) is the transmission function of bandpass filter；NfIt (f) is the self-noise of filter；
The parameterized model of the wave detector are as follows:
Vd(t)=c0{IFFT(Sf(f))}2e(p) (11)
Wherein, c0For detection coefficient；IFFT is inverse Fourier transform；E (p) is linear factor, the power letter as input signal
Number；When input signal power reaches the inelastic region of wave detector, e (p) is less than 1；When input power continues to increase, more than detection
When the inelastic region of device, e (p) is equal to zero, and wave detector reaches saturation region；VdIt (t) is the output voltage of wave detector.
4. the method according to claim 1, wherein described be separately input into total power formula for above-mentioned input signal
In microwave radiation meter systems, accordingly heat source output voltage and calibration cold source output voltage are calibrated in output；It specifically includes:
The input signal is finally transmitted to the parameterized model of wave detector, and will be inputted by the parameterized model of the wave detector
Signal is converted to corresponding output voltage；Specifically, by inverse Fourier transform, calibration cold source input signal is converted into calibration
Cold source output voltage VC；Calibration heat source input signal is converted into calibration heat source output voltage VH。
5. the method according to claim 1, wherein the simulation performance of the total power type micro-wave radiometer system
Index includes: radiometer sensitivity Δ T, the linearity R and dynamic range Δ V of emulation.
6. according to the method described in claim 5, it is characterized in that, the emulation for calculating total power type micro-wave radiometer system
Radiometer sensitivity Δ T；It specifically includes:
Wherein, THFor the bright temperature for calibrating heat source；TCFor the bright temperature for calibrating cold source；Standard difference operation is sought in STD () expression；Wherein, STD
(VH)2For square of the corresponding wave detector output voltage standard deviation of calibration heat source；STD(VC)2For the corresponding wave detector of calibration cold source
Square of output voltage standard deviation.
7. according to the method described in claim 5, it is characterized in that, the emulation for calculating total power type micro-wave radiometer system
Linearity R；Specifically:
Wherein, N is measurement points；For the wave detector output voltage of i-th measurement；Represent the equal of wave detector output voltage
Value；TiFor the input noise temperature of i-th measurement；Represent the mean value of input noise temperature.
8. according to the method described in claim 5, it is characterized in that, the emulation for calculating total power type micro-wave radiometer system
Dynamic range Δ V specifically:
Wherein, mean () expression is averaged；For the wave detector output voltage of the calibration heat source of i-th measurement；For i-th survey
The wave detector output voltage of the calibration cold source of amount.
9. according to the method described in claim 5, it is characterized in that, the specific ginseng of adjustment each device of total power type micro-wave radiometer
Number is until system performance index is met the requirements；It specifically includes:
It is corresponding preparatory to judge whether radiosusceptibility Δ T, the linearity R of emulation and dynamic range Δ V performance indicator all meet
The desired value of setting；
If the radiosusceptibility Δ T of emulation is less than pre-set desired value, and the linearity R emulated is greater than pre-set
Desired value, and the dynamic range Δ V of emulation are greater than pre-set desired value, then the radiosusceptibility Δ T emulated, the linearity
R and dynamic range Δ V performance indicator all meet corresponding pre-set desired value, terminate；
Otherwise, then radiosusceptibility Δ T, the linearity R and dynamic range Δ V performance indicator emulated is unsatisfactory for corresponding setting in advance
The desired value set then repeats above-mentioned signal processing method, iterates to input signal, until the radiosusceptibility of emulation, line
Property degree and dynamic range performance index all meet corresponding pre-set desired value, terminate.
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