CN112436906B - Wireless modulation signal modulation quality parameter calibration equipment - Google Patents
Wireless modulation signal modulation quality parameter calibration equipment Download PDFInfo
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- CN112436906B CN112436906B CN202011257514.7A CN202011257514A CN112436906B CN 112436906 B CN112436906 B CN 112436906B CN 202011257514 A CN202011257514 A CN 202011257514A CN 112436906 B CN112436906 B CN 112436906B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/11—Monitoring; Testing of transmitters for calibration
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
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Abstract
The application discloses wireless modulation signal modulation quality parameter calibration equipment includes: the wireless modulation signal acquisition device is used for acquiring wireless modulation signals; the signal analysis device is used for analyzing the acquired wireless modulation signals to obtain modulation quality parameters of the wireless modulation signals; and the modulation quality uncertainty evaluation device is used for evaluating the uncertainty of the modulation quality parameter, so that the source of the error in the wireless modulation signal modulation quality calibration process can be determined through the modulation quality uncertainty evaluation device.
Description
Technical Field
The application relates to the field of communication technology measurement, in particular to wireless signal modulation quality parameter calibration equipment.
Background
In the prior art, a wireless communication system widely adopts a digital communication mode. Such as mobile communication systems, satellite communication systems, electronic countermeasure systems, and the like. The digital communication mainly uses a vector signal generator, a digital communication comprehensive tester and other devices to generate wireless modulation signals so as to test the performance of the base station, the terminal and other devices. The main calibration parameters of the digital wireless modulation signal include frequency, power, and modulation quality parameters.
In the process of realizing the prior art, the inventor finds that:
the modulation quality parameters are mainly calibrated by a vector signal analyzer at present, and the source of errors in the wireless modulation signal modulation quality calibration process cannot be determined.
Therefore, it is necessary to provide a calibration apparatus for the modulation quality parameters of wireless modulation signals, which can be directly traced.
Disclosure of Invention
The embodiment of the application provides wireless modulation signal modulation quality parameter calibration equipment capable of directly tracing to a source.
The application provides a wireless modulation signal modulation quality parameter calibration device, which comprises:
the wireless modulation signal acquisition device is used for acquiring wireless modulation signals;
the signal analysis device is used for analyzing the acquired wireless modulation signals to obtain modulation quality parameters of the wireless modulation signals;
and a modulation quality uncertainty evaluation device for evaluating uncertainty of the modulation quality parameter.
Further, in a preferred embodiment provided by the present application, the modulation quality uncertainty evaluation device is configured to evaluate that the modulation quality parameter is derived from at least one of uncertainty of the wireless modulation signal acquisition device and uncertainty of the signal analysis device.
Further, in a preferred embodiment provided by the present application, evaluating the uncertainty derived from the wireless modulation signal acquisition device comprises:
and evaluating at least one of uncertainties caused by noise, jitter and nonlinearity.
Further, in a preferred embodiment provided herein, evaluating the uncertainty derived from the signal analysis device comprises:
algorithm error, amplitude error, phase estimation error.
Further, in a preferred embodiment provided by the present application, the wireless modulation signal acquisition device is clock-synchronized with the wireless modulation signal generator.
Further, in a preferred embodiment provided by the present application, an attenuator is connected between the wireless modulation signal acquisition device and the wireless modulation signal generator.
Further, in a preferred embodiment provided by the present application, the signal analysis device performs digital down-conversion processing on the acquired wireless modulation signal.
Further, in a preferred embodiment provided by the present application, the calibration apparatus for wireless modulation signal modulation quality parameters expands the frequency range of the wireless modulation signal to be calibrated by expanding the bandwidth and the sampling rate of the wireless modulation signal acquisition device.
Further, in a preferred embodiment provided by the present application, the calibration apparatus for wireless modulation signal modulation quality parameters further includes a down converter interface, which is used for externally connecting a down converter to expand a frequency range of a wireless modulation signal to be calibrated.
Further, in a preferred embodiment provided by the present application, the bandwidth of the wireless modulation signal acquisition apparatus is not less than 3 times of the highest frequency of the wireless modulation signal to be calibrated, and the sampling rate is not less than 4 times of the highest frequency of the wireless modulation signal to be calibrated.
The embodiment provided by the application has at least the following beneficial effects:
the source of the error in the wireless modulation signal modulation quality calibration process can be determined by the modulation quality uncertainty evaluation device.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic structural diagram of a device for calibrating a modulation quality parameter of a wireless modulation signal according to an embodiment of the present application.
100 wireless modulation signal modulation quality parameter calibration equipment
11 wireless modulation signal acquisition device
12 signal analysis device
13 modulation quality uncertainty evaluation device
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
Referring to fig. 1, the present application discloses a wireless modulation signal modulation quality parameter calibration apparatus 100, which includes:
the wireless modulation signal acquisition device 11 is used for acquiring a wireless modulation signal;
the signal analysis device 12 is used for analyzing the acquired wireless modulation signals and obtaining modulation quality parameters of the wireless modulation signals;
modulation quality uncertainty evaluation means 13 for evaluating the uncertainty of the modulation quality parameter.
The wireless modulation signal modulation quality parameter calibration equipment 100 provided in the application is used for calibrating a vector signal generator and a wireless communication comprehensive tester, and has the characteristics of high accuracy and traceability.
The wireless modulation signal acquisition device 11 is used for acquiring digital modulation signals in real time and displaying acquired waveforms. In a specific embodiment provided in the present application, the wireless modulation signal acquisition device 11 may be a digital oscilloscope. The bandwidth and sampling rate of a digital oscilloscope need to meet the nyquist criterion.
Further, in a preferred embodiment provided by the present application, the wireless modulation signal acquisition device 11 is clock-synchronized with the wireless modulation signal generator.
Specifically, the digital oscilloscope is synchronized with a wireless modulation signal generator, namely a vector signal generator, through a 10MHz reference clock, and is triggered by a symbol synchronization signal of the vector signal generator.
Further, in a preferred embodiment provided by the present application, an attenuator is connected between the wireless modulation signal acquisition apparatus 11 and the wireless modulation signal generator.
Specifically, in order to reduce the influence of impedance mismatch, a 6dB attenuator is connected to the output end of the wireless modulation signal generator.
Further, in a preferred embodiment provided in the present application, the bandwidth of the wireless modulation signal acquisition device 11 is not less than 3 times of the highest frequency of the wireless modulation signal to be calibrated, and the sampling rate is not less than 4 times of the highest frequency of the wireless modulation signal to be calibrated.
The signal analysis device 12 is configured to analyze the acquired wireless modulation signal to obtain a modulation quality parameter of the wireless modulation signal.
The signal analysis device 12 is configured to perform vector analysis on the wireless modulation signal acquired by the wireless modulation signal acquisition device 11. The signal analysis device 12 calculates a modulation quality parameter from parameters such as a frequency, a sampling rate, a symbol rate, and a filter coefficient, and displays a frequency spectrum and a vector diagram.
The signal analysis device 12 can implement functions through software, and is mainly divided into three parts, namely signal preprocessing, signal demodulation and EVM measurement.
The signal preprocessing mainly comprises down-conversion and spectrum calculation of a wireless modulation signal. The signal preprocessing mainly includes digital down-conversion of radio frequency signals modulated wirelessly, demodulation of orthogonal information of the I path and the Q path by coherent demodulation technology, and calculation of frequency domain characteristics by an FFT (fast Fourier transform) method.
The signal demodulation comprises filter design, optimal sampling time and phase correction, and the accuracy of a baseband signal of a demodulated wireless modulation signal is ensured.
Signal modulation utilizes baseband filtering to limit bandwidth and reduce intersymbol interference. At the same time, the signal demodulation baseband filtering must be configured to match the system under test to accurately demodulate the signal. This again requires that the filter type be matched to the filter bandwidth coefficients.
Sampling judgment must be carried out on the wireless modulated baseband signal at the optimal sampling moment after the wireless modulated baseband signal passes through the filter, otherwise, constellation points of the wireless modulated signal output by demodulation are diffused, and the error rate is increased, so that the measurement of the error vector amplitude is inaccurate. The optimal sampling algorithm adopted here is a nonlinear timing error estimation algorithm proposed based on the maximum likelihood estimation theory, and the output signal of the matched filter is subjected to nonlinear transformation, so that the symbol timing error is derived, and the optimal sampling time is obtained.
Phase errors in different forms are generated in the wireless modulation signal generation and receiving processes, for example, a phase error caused by an initial phase of a radio frequency oscillator, a phase error caused by imperfect frequency of the radio frequency oscillator, a phase error caused by noise added in a signal measurement process, and the like, and the sources and the sizes of the errors have great randomness and need to be eliminated by adopting a phase correction algorithm. The optimal sampling algorithm adopted here is a phase rotation algorithm based on minimum distance, and an initial phase difference of the received signals is obtained.
EVM (vector magnitude error) measurements may further include generation and optimization of ideal wireless modulation signals. When analyzing the radio modulated signal, it is necessary to input parameters such as a carrier frequency, a modulation scheme, and a symbol rate that match the calibrated radio modulated signal to the signal analyzer 12.
And recalculating the reference signal by using the data recovered from the received wireless modulation signal after demodulation and judgment to calculate the modulation quality parameter. A multidimensional function extreme value solving method based on a Nelder-Mead simplex method is used for optimizing IQ data to minimize an error vector.
Further, in a preferred embodiment provided in the present application, the signal analysis device 12 performs digital down-conversion processing on the acquired wireless modulation signal.
In the specific embodiment provided by the present application, the signal analysis device 12 performs digital signal processing such as digital down conversion on the radio frequency signal acquired by the oscilloscope to obtain the modulation quality parameter, so that the error magnitude generated by each link of acquisition, frequency conversion, filtering, symbol synchronization, phase recovery, IQ waveform generation, etc. of the radio frequency signal can be definitely analyzed, and finally the source tracing of the modulation quality parameter is realized by evaluating the uncertainty generated by the introduction of these errors.
The modulation quality uncertainty evaluation means 13 is used to evaluate the uncertainty of the modulation quality parameter.
Further, in a preferred embodiment provided by the present application, the modulation quality uncertainty evaluation device 13 is configured to evaluate that the modulation quality parameter is derived from at least one of uncertainty of the wireless modulation signal acquisition device 11 and uncertainty of the signal analysis device 12.
Further, in a preferred embodiment provided by the present application, the evaluating the uncertainty derived from the wireless modulation signal acquisition apparatus 11 includes:
and evaluating at least one of uncertainties caused by noise, jitter and nonlinearity.
The error of the wireless modulation signal acquisition device 11 mainly originates from aspects such as noise, jitter, nonlinearity and the like.
The noise is caused by the low sampling resolution of the wireless modulation signal acquisition device 11 and the broadband devices such as the front-end amplifier. The noise generally follows a gaussian distribution.
Jitter is the time error of the wireless modulation signal acquisition device 11, and includes sampling clock jitter and trigger jitter. Wherein, the trigger jitter can be eliminated by an optimal sampling algorithm, and the sampling clock jitter is mainly considered in the uncertainty analysis.
The non-linearity is analyzed by evaluating the linearity of the wireless modulation signal acquisition device 11 itself. And evaluating the linearity of the wireless modulation signal acquisition device 11 in the frequency range of the calibrated line modulation signal and the amplitude range of 100 mV-400 mV by using a power meter and a power divider.
Further, in a preferred embodiment provided herein, evaluating the uncertainty derived from the signal analysis device 12 comprises:
algorithm error, amplitude error, phase estimation error.
The error generated by the signal analysis device 12 mainly comes from the root raised cosine filter model and the optimization algorithm such as phase correction. In order to calculate the error in the signal processing of the signal analysis device 12, the rf signal may be generated by digitally up-converting the desired signal and then calculated by the same signal processing algorithm.
In a typical configuration, a computer may include one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement or the like made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.
Claims (4)
1. A wireless modulation signal modulation quality parameter calibration apparatus, comprising:
the wireless modulation signal acquisition device is used for acquiring wireless modulation signals;
the signal analysis device is used for analyzing the acquired wireless modulation signals to obtain modulation quality parameters of the wireless modulation signals;
modulation quality uncertainty evaluation means for evaluating uncertainty of the modulation quality parameter;
the modulation quality uncertainty evaluation device is used for evaluating at least one of uncertainty of a wireless modulation signal acquisition device and uncertainty of a signal analysis device of modulation quality parameters;
the wireless modulation signal acquisition device adopts a digital oscilloscope with the bandwidth and the sampling rate meeting the Nyquist criterion;
the wireless modulation signal acquisition device and the vector signal generator carry out 10MHz clock synchronization and are triggered by a symbol synchronization signal of the vector signal generator;
a 6dB attenuator is connected between the wireless modulation signal acquisition device and the vector signal generator;
the wireless modulation signal modulation quality parameter calibration equipment expands the frequency range of a wireless modulation signal to be calibrated by expanding the bandwidth and the sampling rate of a wireless modulation signal acquisition device;
the wireless modulation signal modulation quality parameter calibration equipment also comprises a down converter interface which is used for externally connecting a down converter and expanding the frequency range of the wireless modulation signal to be calibrated;
the bandwidth of the wireless modulation signal acquisition device is not less than 3 times of the highest frequency of the wireless modulation signal to be calibrated, and the sampling rate is not less than 4 times of the highest frequency of the wireless modulation signal to be calibrated.
2. The wireless modulation signal modulation quality parameter calibration apparatus according to claim 1, wherein evaluating the uncertainty derived from the wireless modulation signal acquisition device comprises:
and evaluating at least one of uncertainty caused by noise, jitter and nonlinearity.
3. The wireless modulation signal modulation quality parameter calibration apparatus of claim 1, wherein evaluating the uncertainty derived from the signal analysis means comprises:
algorithm error, amplitude error, phase estimation error.
4. The wireless modulation signal modulation quality parameter calibration apparatus according to claim 1, wherein the signal analysis means performs digital down-conversion processing on the acquired wireless modulation signal.
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