CN106841824B - Signal source comprehensive parameter on-site measuring device - Google Patents
Signal source comprehensive parameter on-site measuring device Download PDFInfo
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Abstract
The invention discloses a signal source comprehensive parameter field measuring device, which comprises: the system comprises a radio frequency front-end module, a frequency measurement module, an attenuation measurement module, a modulation degree measurement module, a spectrum purity measurement module and a display control module; the input end of the radio frequency front-end module is used as the input end of a signal to be measured of the signal source comprehensive parameter on-site measuring device, the output end of the radio frequency front-end module is respectively connected with the input ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectrum purity measuring module, and the output ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectrum purity measuring module are all connected with the input end of the display control module. The invention can realize the measurement of various technical indexes of the signal source.
Description
Technical Field
The present invention relates to radio measuring instruments. And more particularly, to a signal source comprehensive parameter field measuring device.
Background
The signal source is a radio instrument which is most widely applied, and is widely used in the field of radio communication scientific research and test, active equipment (radars, missiles, airplanes, navigation satellites and the like) of troops, test fields, target ranges and other occasions. Its performance index has important influence on various application systems. However, in general, the test environment conditions of the test field, the target range and other fields are relatively severe and are often performed outdoors, the voltage fluctuation of the temperature and humidity environment and the power supply is large, and the zero-voltage sometimes can reach about 20VPP, which are factors that are easy to cause irreversible serious damage to the used instruments during the test or greatly affect the measurement data, resulting in inaccurate and unreliable measurement results. Currently, the internationally commercialized signal source comprehensive parameter measuring devices mainly include an FSMR measuring receiver manufactured by R & S company in germany and an N5530S measuring receiver manufactured by Agilent company in the united states. The working principle of the device is realized by software on the basis of a spectrum analyzer, but the device has higher requirements on test conditions and environmental conditions and cannot meet field test tasks such as a test field and a target range.
Therefore, it is desirable to provide a signal source integrated parameter field measurement device.
Disclosure of Invention
The invention aims to provide a signal source comprehensive parameter on-site measuring device, which solves the problem of on-site measurement of a signal source in a severe environment and obtains various technical indexes of frequency, attenuation, modulation degree, spectrum purity and the like of a signal to be measured output by the signal source. The technical indexes required to be achieved by the invention are as follows:
(1) frequency measurement range: 10MHz to 40 GHz;
frequency measurement resolution: 1 Hz;
allowable error limit: 5X 10-8;
(2) attenuation measurement range:
(10-2000) MHz: (0-120) dB, allowable error limit: +/-0.02 dB/10 dB;
(2-26.5) GHz: (0-100) dB, allowable error limit: +/-0.02 dB/10 dB;
(26.5-40) GHz: (0-80) dB, allowable error limit: +/-0.05 dB/10 dB;
(3) and (3) modulation degree measurement:
modulation frequency: 20Hz to 200 kHz;
amplitude modulation measurement range: 0% -99%, allowable error limit: plus or minus 1 percent;
frequency modulation frequency deviation measurement range: 0 Hz-1 MHz, allowable error limit: plus or minus 1 percent;
phase modulation phase deviation measurement range: 0-400 rad, allowable error limit: plus or minus 3 percent;
(4) spectral purity (harmonics, clutter) range: (-20-80) dBc
Allowable error limit: 1.0 dB.
In order to achieve the purpose, the invention adopts the following technical scheme:
a signal source integrated parameter field measurement device, comprising: the system comprises a radio frequency front-end module, a frequency measurement module, an attenuation measurement module, a modulation degree measurement module, a spectrum purity measurement module and a display control module;
the input end of the radio frequency front-end module is used as the input end of a signal to be measured of the signal source comprehensive parameter on-site measuring device, the output end of the radio frequency front-end module is respectively connected with the input ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectrum purity measuring module, and the output ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectrum purity measuring module are all connected with the input end of the display control module.
Preferably, the radio frequency front end module further comprises: the system comprises a YIG filter, a first SPDT radio frequency coaxial switch, a first SP3T radio frequency coaxial switch, a second SP3T radio frequency coaxial switch, an 8 GHz-40 GHz microwave amplifier, a first microwave attenuator, a third SP3T radio frequency coaxial switch, an 8 GHz-40 GHz mixer, a second SPDT radio frequency coaxial switch, a 10 MHz-8 GHz microwave amplifier, a second microwave attenuator, a fourth SP3T radio frequency coaxial switch, a 10 MHz-8 GHz mixer, a local oscillator signal source and a third SPDT radio frequency coaxial switch;
the input end of the YIG filter is used as the input end of a signal to be detected of the radio frequency front-end module, and the output end of the YIG filter is connected with the input end of the first SPDT radio frequency coaxial switch;
the first output end of the first SPDT radio frequency coaxial switch is connected with the input end of the first SP3T radio frequency coaxial switch, and the second output end of the first SPDT radio frequency coaxial switch is connected with the input end of the second SP3T radio frequency coaxial switch;
the first output end of the first SP3T radio frequency coaxial switch is connected with the input end of the 8 GHz-40 GHz microwave amplifier, the second output end of the first SP3T radio frequency coaxial switch is connected with the input end of the first microwave attenuator, and the third output end of the first SP3T radio frequency coaxial switch is connected with the third input end of the third SP3T radio frequency coaxial switch;
the output end of the 8 GHz-40 GHz microwave amplifier is connected with the first input end of the third SP3T radio frequency coaxial switch, and the output end of the first microwave attenuator is connected with the second input end of the third SP3T radio frequency coaxial switch;
the output end of the third SP3T radio frequency coaxial switch is connected with the input end of the 8 GHz-40 GHz mixer;
a first output end of the second SP3T radio frequency coaxial switch 104 is connected with an input end of a 10 MHz-8 GHz microwave amplifier, a second output end is connected with an input end of a second microwave attenuator, and a third output end is connected with a third input end of a fourth SP3T radio frequency coaxial switch;
the output end of the 10 MHz-8 GHz microwave amplifier is connected with the first input end of a fourth SP3T radio frequency coaxial switch, and the output end of the second microwave attenuator is connected with the second input end of a fourth SP3T radio frequency coaxial switch;
the output end of the fourth SP3T radio frequency coaxial switch is connected with the input end of the 10 MHz-8 GHz mixer;
the output end of the local oscillator signal source is connected with the input end of the third SPDT radio frequency coaxial switch;
the first output end of the third SPDT radio frequency coaxial switch is connected with the local oscillator end of the 8 GHz-40 GHz frequency mixer, and the second output end of the third SPDT radio frequency coaxial switch is connected with the local oscillator end of the 10 MHz-8 GHz frequency mixer;
the output end of the 8 GHz-40 GHz mixer is connected with the first input end of the second SPDT radio frequency coaxial switch, and the output end of the 10 MHz-8 GHz mixer is connected with the second input end of the second SPDT radio frequency coaxial switch;
and the output end of the second SPDT radio frequency coaxial switch is used as the intermediate frequency signal output end of the radio frequency front-end module.
Preferably, the attenuation measuring module includes a low noise preamplifier, a band-pass filter, a program-controlled step-by-step standard attenuator, and a lock-in amplifier, which are connected in sequence, wherein an input end of the low noise preamplifier is used as an input end of the attenuation measuring module, and an output end of the lock-in amplifier is used as an output end of the attenuation measuring module.
Preferably, the modulation degree measurement module further includes: the device comprises an AD data acquisition unit, an AM demodulator, an FM demodulator, a selection switch, an FIR low-pass filter and a DSP data processor;
the input end of the AD data acquisition device is used as the input end of the modulation degree measurement module, and the output end of the AD data acquisition device is respectively connected with the input ends of the AM demodulator and the FM demodulator;
the output end of the AM demodulator is connected with the first input end of the selection switch, and the output end of the FM demodulator is connected with the second input end of the selection switch;
the output end of the selection switch is connected with the input end of the FIR low-pass filter, and the output end of the FIR low-pass filter is connected with the input end of the DSP data processor;
and the control end of the DSP data processor is connected with the control end of the selection switch, and the output end of the DSP data processor is used as the output end of the modulation degree measuring module.
The invention has the following beneficial effects:
the technical scheme of the invention has compact and reliable structure, small volume, complete measurement parameters, indexes reaching the level of similar products abroad, realization of the localization target, capability of meeting the field measurement requirement, guarantee of the fighting capacity of high-technology weaponry, guarantee of the quality of the developed products and convenience of daily maintenance, and guarantee of the signal source to measure and calibrate the key indexes and key parameters of the signal source before use or in the maintenance period. In the attenuation measurement, because a correlation detection method of a phase-locked amplifier is adopted, when large attenuation is measured, an input weak signal is amplified to a level which is enough to meet the work of a correlation detector, and the interference and noise of the input signal are inhibited and filtered by the correlation detection method of the phase-locked amplifier, so that when a signal with a poor signal-to-noise ratio is measured, a useful signal can be still extracted from the noise and effectively measured, the measurement stability of the balance level is greatly improved, and the measurement accuracy, stability and repeatability of the attenuation are greatly improved.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Fig. 1 shows a schematic diagram of a signal source integrated parameter field measurement device.
Fig. 2 shows a schematic diagram of a radio frequency front end module.
Fig. 3 shows a schematic diagram of an attenuation measurement module.
Fig. 4 shows a schematic diagram of the frequency measurement module performing the frequency calculation.
Fig. 5 shows a schematic diagram of a modulation degree measurement module.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
As shown in fig. 1, the signal source comprehensive parameter on-site measuring device disclosed by the present invention comprises a radio frequency front end module 100 and an intermediate frequency measuring receiver, wherein the intermediate frequency measuring receiver comprises a frequency measuring module 200, an attenuation measuring module 300, a modulation degree measuring module 400, a spectrum purity measuring module 500 and a display control module 600. The main function of the rf front-end module 100 is to convert the signal to be measured to an intermediate frequency without distortion and output an intermediate frequency signal with a stable frequency. The function of the intermediate frequency measurement receiver is to form a complete signal source comprehensive parameter measurement receiver system through the cooperation of each measurement module and the display control module 600.
In the signal source comprehensive parameter on-site measuring device disclosed by the invention, the input end of a radio frequency front end module 100 is used as the input end of a signal to be measured of the signal source comprehensive parameter on-site measuring device, the output end of the radio frequency front end module 100 is respectively connected with the input ends of a frequency measuring module 200, an attenuation measuring module 300, a modulation degree measuring module 400 and a spectrum purity measuring module 500, and the output ends of the frequency measuring module 200, the attenuation measuring module 300, the modulation degree measuring module 400 and the spectrum purity measuring module 500 are all connected with the input end of a display control module 600.
In this scheme, the rf front-end module 100 performs spectrum shifting on a signal to be measured (usually, a high-frequency broadband microwave signal) to convert the signal to be measured into an intermediate-frequency signal that is easy to process, and the method of performing spectrum shifting is to perform down-conversion on the rf signal to be measured by using a mixer and a local oscillator signal. Because the mixer is a nonlinear device, the influence of nonlinearity is considered, the signal input into the mixer cannot be too large to generate nonlinear compression to cause measurement error, and when the signal to be measured is too small, the signal to be measured may be buried in noise due to the limitation of the noise floor of the mixer to be unmeasured. Therefore, both factors should be considered together when processing the signal to be measured in the rf front-end module 100. When the power level of the signal to be measured is too strong, a microwave attenuator is added at the front end of the mixer in the radio frequency front end module 100 to reduce the level of the input signal and reduce the nonlinear compression of the mixer; when the power level of the signal to be measured is very weak, a microwave broadband amplifier is added to the front end of the mixer in the radio frequency front end module 100 to improve the power level of the input signal, reduce the noise influence and improve the signal-to-noise ratio, so that the mixer always works in a good state, the signal-to-noise ratio is improved while the nonlinear distortion of the signal is not caused, and the dynamic range of measurement is effectively improved.
As shown in fig. 2, to implement the above functions, the rf front-end module 100 further includes:
a YIG filter 101, a first SPDT radio frequency coaxial switch 102, a first SP3T radio frequency coaxial switch 103, a second SP3T radio frequency coaxial switch 104, an 8 GHz-40 GHz microwave amplifier 105, a first microwave attenuator 106, a third SP3T radio frequency coaxial switch 107, an 8 GHz-40 GHz mixer 108, a second SPDT radio frequency coaxial switch 109, a 10 MHz-8 GHz microwave amplifier 110, a second microwave attenuator 111, a fourth SP3T radio frequency coaxial switch 112, a 10 MHz-8 GHz mixer 113, a local oscillator signal source 114 and a third SPDT radio frequency coaxial switch 115;
an input end of the YIG filter 101 is used as an input end of a signal to be detected of the radio frequency front-end module 100, and an output end of the YIG filter is connected with an input end of the first SPDT radio frequency coaxial switch 102;
a first output end of the first SPDT rf coaxial switch 102 is connected to an input end of the first SP3T rf coaxial switch 103, and a second output end is connected to an input end of the second SP3T rf coaxial switch 104;
the first output end of the first SP3T radio frequency coaxial switch 103 is connected with the input end of the 8 GHz-40 GHz microwave amplifier 105, the second output end is connected with the input end of the first microwave attenuator 106, and the third output end is connected with the third input end of the third SP3T radio frequency coaxial switch 107;
the output end of the 8 GHz-40 GHz microwave amplifier 105 is connected with the first input end of the third SP3T radio frequency coaxial switch 107, and the output end of the first microwave attenuator 106 is connected with the second input end of the third SP3T radio frequency coaxial switch 107;
the output end of the third SP3T radio frequency coaxial switch 107 is connected with the input end of the 8 GHz-40 GHz mixer 108;
a first output end of the second SP3T rf coaxial switch 104 is connected to the input end of the 10 MHz-8 GHz microwave amplifier 110, a second output end is connected to the input end of the second microwave attenuator 111, and a third output end is connected to the third input end of the fourth SP3T rf coaxial switch 112;
the output end of the 10 MHz-8 GHz microwave amplifier 110 is connected with the first input end of a fourth SP3T radio frequency coaxial switch 112, and the output end of the second microwave attenuator 111 is connected with the second input end of the fourth SP3T radio frequency coaxial switch 112;
the output end of the fourth SP3T radio frequency coaxial switch 112 is connected with the input end of the 10 MHz-8 GHz mixer 113;
the output end of the local oscillator signal source 114 is connected with the input end of the third SPDT radio frequency coaxial switch 115;
a first output end of the third SPDT radio frequency coaxial switch 115 is connected with a local oscillation end of the 8 GHz-40 GHz mixer 108, and a second output end is connected with a local oscillation end of the 10 MHz-8 GHz mixer 113;
the output end of the 8 GHz-40 GHz mixer 108 is connected with the first input end of the second SPDT radio frequency coaxial switch 109, and the output end of the 10 MHz-8 GHz mixer 113 is connected with the second input end of the second SPDT radio frequency coaxial switch 109;
the output end of the second SPDT rf coaxial switch 109 serves as the if signal output end of the rf front-end module 100.
If measurement receivers generally use if substitution methods for measurement, and all perform substitution at a lower fixed if. In order to ensure high measurement accuracy, the receiver is required to have good linearity, excellent stability and fine if gain control. The linearity depends mainly on the detector operating level of the measurement receiver part, so the rf and if gain is adjusted by properly selecting the if circuit gain to fall within the optimal linear region of the detector. The measuring receiver part adopts an intermediate frequency amplifier with a narrow passband, so that the measuring range of the lower limit of level measurement can be improved, and a narrow-band filter circuit is adopted to ensure that the intermediate frequency is at the optimal position of the intermediate frequency bandwidth, the narrower the bandwidth is, the higher the stability of signal measurement is, the smaller the measurable level is, and the higher the sensitivity of the receiver is.
In the scheme, the attenuation measuring module 300 adopts a series low-intermediate frequency substitution method, and is characterized in that the attenuation measurement accuracy is high, the dynamic range is large, the working principle is that firstly, calibration is carried out during zero attenuation, then, the attenuator to be measured is accessed, and the attenuation of the attenuator to be measured is replaced by changing the attenuation of the program-controlled step standard attenuator to achieve rebalance again. In order to further improve the system performance, the scheme adopts a method of combining radio frequency series connection and low-intermediate frequency series connection replacement to improve the system, introduces a method of relevant detection of a phase-locked amplifier, and uses the phase-locked amplifier as an intermediate frequency receiving and indicating device. The phase-locked amplifier adopts the relevant detection technology according to the principle that the reference signal is relevant to the test signal and is irrelevant to the noise, so that the bandwidth is compressed to the maximum extent, the noise is suppressed, and the measurement stability and the dynamic range of the system are greatly improved. The functional block diagram of the single-channel serial low-intermediate frequency substitution method using the phase-locked amplifier is shown in fig. 3. In the attenuation measurement system, the radio frequency source, the local vibration source and the function generator are used for time base sharing, the reference signal is generated by the function generator, the test system is simple in structure, and the measurement accuracy is higher due to the fact that the crosstalk problem of the test channel and the reference channel does not exist.
As shown in fig. 3, the attenuation measuring module 300 includes a low noise preamplifier 301, a band pass filter 302, a programmable step standard attenuator 303, and a lock-in amplifier 304, which are connected in sequence, wherein an input end of the low noise preamplifier 301 serves as an input end of the attenuation measuring module 300, and an output end of the lock-in amplifier 304 serves as an output end of the attenuation measuring module 300. The technical principle of a series low-intermediate frequency substitution method is adopted, radio frequency and microwave signals are linearly converted into intermediate frequency signals in a frequency conversion mode, the attenuation of the detected radio frequency and microwave attenuators is substituted by the change amount of a high-accuracy standard attenuator, and therefore the purpose of accurately and effectively measuring the attenuation is achieved, and the high-accuracy low-intermediate frequency linear attenuator has high sensitivity and a dynamic range exceeding 100 dB. In order to ensure high measurement accuracy, the receiver is required to have good linearity, excellent stability and fine if gain control. The linearity depends mainly on the operating level, so various combinations of rf front-end circuit gain and if circuit gain are properly selected to adjust the rf and if gain to fall within the optimal linear region of the mixer and detector.
The attenuation measurement process is that firstly, the intermediate frequency signal is pre-amplified with low noise, and is subjected to substitution compensation by the program control step standard attenuator 303, and then the intermediate frequency signal is amplified, filtered and related detection processing by the phase lock amplifier 304 and is sent to the display control module 600 for final display. The specific process is to calibrate the system to obtain a balanced level, then change the attenuation of the intermediate frequency signal, and simultaneously change the attenuation of the program control standard step attenuator 303 in the system to make the system reach secondary balance, wherein the change of the program control standard step attenuator 303 is the attenuation of the intermediate frequency signal. The error measured depends on the sensitivity and accuracy of the lock-in amplifier 304.
When different attenuation amounts are measured, because an intermediate frequency substitution method is adopted, the total attenuation amount of the system is fixed and unchanged, the gain of each part is reasonably distributed, so that the system does not generate nonlinear distortion and compression when amplifying signals, and can meet the signal-to-noise ratio when the signals are very small, and the technical indexes of circuit distribution of each part under the principle are as follows:
low noise pre-amplification 301:
center frequency: 50 kHz; amplification gain: 20 dB; output impedance:
programmed step standard attenuator 303:
center frequency: 50 kHz; attenuation range: 0-110 dB, 0.1dB step; input/output impedance:
the lock-in amplifier 304:
center frequency: 50 kHz; amplification gain: 90 dB; bandwidth of: 500 Hz; input impedance:
in the design process of the circuit, the suppression capability of the lock-in amplifier 304 on temperature drift and power supply frequency interference is also effectively ensured.
In this scheme, the frequency measurement module 200 adopts a direct measurement method for signals smaller than 150MHz, and for radio frequency signals larger than 150MHz, the intermediate frequency signals after the mixer are shaped and denoised by the comparator, and then the frequency is measured by using the frequency meter formed by the FPGA, and finally the measured radio frequency is obtained according to the relevant local oscillation frequency. In the signal conditioning process, because the harmonic wave is at least 20dB weaker than the fundamental wave, in order to eliminate the influence of the spurious frequency after frequency mixing in the measuring process, the circuit adopts a small direct current offset (about 50mV) on the basis of the comparison level, so that the comparison level deviates from the amplitude central point of the measured signal and does not respond to the small harmonic signal interference, thereby eliminating the harmonic wave interference in the shaping process and improving the measuring accuracy.
During signal processing, the method of scanning and controlling the local oscillator signal source is adopted to make the intermediate frequency after frequency mixing fall within the measurable range of the frequency, then frequency measurement is performed by changing a small variation of the local oscillator, an accurate value actually measured can be obtained according to the variation of the measured frequency and the local oscillator quantity, and a calculation schematic diagram is shown in fig. 4. When the local oscillator signal frequency fL is greater than the measured signal fx, changing the local oscillator signal frequency by a conversion amount' f, so that the frequency fI of the measured intermediate frequency signal changes in the same direction, and obtaining the measured signal frequency as fL-fI; when the local oscillation signal fL is smaller than the measured signal fx, the frequency of the measured intermediate frequency signal fL changes in the opposite direction by changing the local oscillation signal frequency by a conversion amount "f, so that the measured signal frequency fL + fL is obtained.
In this embodiment, the modulation degree measuring module 400 has the capability of measuring amplitude modulation, frequency modulation, and phase modulation, and can demodulate a frequency modulation/amplitude modulation/phase modulation signal. The modulation degree measurement module 400 performs high-speed data acquisition on the intermediate frequency signal and performs software demodulation. And performing software demodulation, filtering and data processing analysis on the acquired signals through a microprocessor to obtain a related modulation degree measurement result. Specifically, high-speed data acquisition is carried out on an intermediate frequency signal, an amplitude modulation wave obtained by digitizing an amplitude modulation signal is subjected to absolute value calculation and low-pass filtering to obtain a modulation signal; the information carried by the frequency modulation wave is contained in the change of the instantaneous frequency, the zero-crossing information contains the modulation information, the demodulation of the frequency modulation signal is realized by adopting a zero-crossing information counting method, and the counting method is a method for obtaining the original modulation signal by demodulating the frequency modulation wave by utilizing the uniqueness, accuracy, wide range and high efficiency of the zero point of the frequency modulation wave. The uniqueness of the zero-crossing point means that the zero-crossing point of the frequency modulation wave corresponds to the instantaneous amplitude of the modulation signal. Firstly, the frequency modulation wave is subjected to A/D conversion to form data stream, and the counter is added with 1 every time the data stream crosses zero. After counting the pulses, low-pass filtering is carried out, and then a modulation signal can be obtained.
As shown in fig. 5, to implement the above functions, the modulation degree measurement module 400 further includes:
an AD data collector 401, an AM demodulator 202, an FM demodulator 403, a selection switch 404, an FIR low-pass filter 405 and a DSP data processor 406;
an input end of the AD data collector 401 is used as an input end and an output end of the modulation degree measuring module 400, and the input ends are respectively connected with the input ends of the AM demodulator 402 and the FM demodulator 403;
the output end of the AM demodulator 402 is connected with the first input end of the selection switch 404, and the output end of the FM demodulator 403 is connected with the second input end of the selection switch 404;
the output end of the selection switch 404 is connected with the input end of the FIR low-pass filter 405, and the output end of the FIR low-pass filter 405 is connected with the input end of the DSP 406;
a control terminal of the DSP data processor 406 is connected to a control terminal of the selection switch 404, and an output terminal of the DSP data processor 406 serves as an output terminal of the modulation degree measurement module 400.
In this scheme, the spectral purity measuring module 500 has a function of measuring second harmonic, third harmonic and subharmonic output by the signal source. The spectral purity measuring module 500 works in such a way that a YIG band-pass filter is added at the front end of the mixer to filter out fundamental waves to eliminate the nonlinear influence of the fundamental waves on the intermediate frequency signals when measuring harmonic waves on the basis of attenuation measurement, and the measured attenuation amount relative to the fundamental waves is much higher than that of direct measurement. The method for measuring the spectral purity comprises the steps of firstly calibrating the frequency of a fundamental wave, then taking the frequency as a reference, changing the center frequency of the YIG band-pass filter to the frequency points of subharmonics and harmonics, measuring to obtain the attenuation relative to the fundamental wave, and correcting error components introduced by the frequency responses of the YIG band-pass filter and a mixer to obtain a final measurement result.
As mentioned above, the signal source comprehensive parameter on-site measuring device disclosed by the invention has the following advantages:
(1) the device can be used for field calibration of a signal source in severe electromagnetic and temperature environments, has compact and reliable structure, small volume and complete measurement parameters, and is used for calibrating and calibrating various technical indexes of the signal source such as frequency, attenuation, modulation degree, spectral purity and the like.
(2) A phase-locked amplifier is introduced to calibrate and verify weak signals in the aspect of attenuation measurement, so that the measurement accuracy and the dynamic range are greatly improved, and the problem of interference of various noises in the process of measuring large attenuation quantity is solved.
(3) In the aspect of frequency measurement, after an intermediate frequency signal after a mixer is adopted to shape and de-noise a signal through a comparator for a radio frequency signal larger than 150MHz, in the process of signal conditioning, because a harmonic wave is at least 20dB weaker than a fundamental wave, in the process of measurement, in order to eliminate the influence of a parasitic frequency after mixing, a circuit is additionally provided with a small direct current offset (about 50mV) on the basis of a comparison level, so that the comparison level deviates from the amplitude central point of a measured signal, no response is generated to small harmonic wave signal interference, the harmonic wave interference is eliminated in the shaping process, and the accuracy of measurement is improved. When the measurement result is processed, the method of scanning and controlling the local oscillator signal source is adopted to enable the intermediate frequency after frequency mixing to fall within the measurable range of the frequency, then the frequency measurement is carried out by changing a small variation of the local oscillator, and the final actually measured accurate value can be obtained according to the variation of the measured frequency and the amount of the local oscillator.
(4) In the aspect of spectral purity measurement, the attenuation relative to the fundamental wave is directly measured on a frequency point to be measured by changing the central frequency of the YIG band-pass filter, and a final measurement result is obtained by error correction.
(5) The digital demodulation method adopted in the aspect of modulation degree measurement replaces the traditional analog circuit to carry out the measurement, so that the measurement accuracy is improved.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (3)
1. A signal source integrated parameter field measurement device, the device comprising: the system comprises a radio frequency front-end module, a frequency measurement module, an attenuation measurement module, a modulation degree measurement module, a spectrum purity measurement module and a display control module;
the input end of the radio frequency front-end module is used as the input end of a signal to be measured of the signal source comprehensive parameter on-site measuring device, the output end of the radio frequency front-end module is respectively connected with the input ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectral purity measuring module, and the output ends of the frequency measuring module, the attenuation measuring module, the modulation degree measuring module and the spectral purity measuring module are all connected with the input end of the display control module;
the radio frequency front end module further comprises: the system comprises a YIG filter, a first SPDT radio frequency coaxial switch, a first SP3T radio frequency coaxial switch, a second SP3T radio frequency coaxial switch, an 8 GHz-40 GHz microwave amplifier, a first microwave attenuator, a third SP3T radio frequency coaxial switch, an 8 GHz-40 GHz mixer, a second SPDT radio frequency coaxial switch, a 10 MHz-8 GHz microwave amplifier, a second microwave attenuator, a fourth SP3T radio frequency coaxial switch, a 10 MHz-8 GHz mixer, a local oscillator signal source and a third SPDT radio frequency coaxial switch;
the input end of the YIG filter is used as the input end of a signal to be detected of the radio frequency front-end module, and the output end of the YIG filter is connected with the input end of the first SPDT radio frequency coaxial switch;
the first output end of the first SPDT radio frequency coaxial switch is connected with the input end of the first SP3T radio frequency coaxial switch, and the second output end of the first SPDT radio frequency coaxial switch is connected with the input end of the second SP3T radio frequency coaxial switch;
the first output end of the first SP3T radio frequency coaxial switch is connected with the input end of the 8 GHz-40 GHz microwave amplifier, the second output end of the first SP3T radio frequency coaxial switch is connected with the input end of the first microwave attenuator, and the third output end of the first SP3T radio frequency coaxial switch is connected with the third input end of the third SP3T radio frequency coaxial switch;
the output end of the 8 GHz-40 GHz microwave amplifier is connected with the first input end of the third SP3T radio frequency coaxial switch, and the output end of the first microwave attenuator is connected with the second input end of the third SP3T radio frequency coaxial switch;
the output end of the third SP3T radio frequency coaxial switch is connected with the input end of the 8 GHz-40 GHz mixer;
a first output end of the second SP3T radio frequency coaxial switch 104 is connected with an input end of a 10 MHz-8 GHz microwave amplifier, a second output end is connected with an input end of a second microwave attenuator, and a third output end is connected with a third input end of a fourth SP3T radio frequency coaxial switch;
the output end of the 10 MHz-8 GHz microwave amplifier is connected with the first input end of a fourth SP3T radio frequency coaxial switch, and the output end of the second microwave attenuator is connected with the second input end of a fourth SP3T radio frequency coaxial switch;
the output end of the fourth SP3T radio frequency coaxial switch is connected with the input end of the 10 MHz-8 GHz mixer;
the output end of the local oscillator signal source is connected with the input end of the third SPDT radio frequency coaxial switch;
the first output end of the third SPDT radio frequency coaxial switch is connected with the local oscillator end of the 8 GHz-40 GHz frequency mixer, and the second output end of the third SPDT radio frequency coaxial switch is connected with the local oscillator end of the 10 MHz-8 GHz frequency mixer;
the output end of the 8 GHz-40 GHz mixer is connected with the first input end of the second SPDT radio frequency coaxial switch, and the output end of the 10 MHz-8 GHz mixer is connected with the second input end of the second SPDT radio frequency coaxial switch;
and the output end of the second SPDT radio frequency coaxial switch is used as the intermediate frequency signal output end of the radio frequency front-end module.
2. The signal source comprehensive parameter field measuring device according to claim 1, wherein the attenuation measuring module comprises a low noise preamplifier, a band pass filter, a programmable step standard attenuator and a phase-locked amplifier which are connected in sequence, an input end of the low noise preamplifier serves as an input end of the attenuation measuring module, and an output end of the phase-locked amplifier serves as an output end of the attenuation measuring module.
3. The signal source integrated parameter field measurement device of claim 1, wherein the modulation degree measurement module further comprises: the device comprises an AD data acquisition unit, an AM demodulator, an FM demodulator, a selection switch, an FIR low-pass filter and a DSP data processor;
the input end of the AD data acquisition device is used as the input end of the modulation degree measurement module, and the output end of the AD data acquisition device is respectively connected with the input ends of the AM demodulator and the FM demodulator;
the output end of the AM demodulator is connected with the first input end of the selection switch, and the output end of the FM demodulator is connected with the second input end of the selection switch;
the output end of the selection switch is connected with the input end of the FIR low-pass filter, and the output end of the FIR low-pass filter is connected with the input end of the DSP data processor;
and the control end of the DSP data processor is connected with the control end of the selection switch, and the output end of the DSP data processor is used as the output end of the modulation degree measuring module.
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