CN105137182A - Measuring and calibrating method for signal amplitudes in SDR applications - Google Patents
Measuring and calibrating method for signal amplitudes in SDR applications Download PDFInfo
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- CN105137182A CN105137182A CN201510582398.9A CN201510582398A CN105137182A CN 105137182 A CN105137182 A CN 105137182A CN 201510582398 A CN201510582398 A CN 201510582398A CN 105137182 A CN105137182 A CN 105137182A
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Abstract
The present invention belongs to the technical field of electronic measurement, and relates to a measuring and calibrating method for signal amplitudes in SDR applications. The method includes the steps as follows: confirming a local oscillator amplitude of a complex digital in digital mixing; multiplying a sampled signal by a complex local oscillation so as to realize frequency mixing, eliminating a high-frequency component by digital filtering and retaining a complex baseband signal only; detecting wave in time domain and detecting a signal instantaneous power by a baseband signal; performing a FFT transformation to the complex baseband signal so as to acquire a signal frequency spectrum component; and measuring the oscillator amplitude or power of various frequency spectrum components of the complex baseband signal in time domain. According to the above calculation method, an accuracy of signal amplitude expression in various links in the SER process is ensured, and the result can be directly applied to an occasion for measuring and detecting signal amplitudes.
Description
Technical field
The invention belongs to electronic measuring technology field, relate to signal amplitude metering calibrating method in a kind of SDR application.
Background technology
Along with the development of computing technique, software and radio technique (Software-DefinedRadio, be called for short SDR) apply increasingly extensive, no matter in Large-Scale Equipment, or in general apparatus measures, directly digitizing is carried out to higher frequency signals, then utilize SDR to realize the situation of test function more prevalent.In instrument metrology and measurement, many instruments provide real-time sampling data and export, professional radio signal analysis software (the 89600 Vector Signal Analysis softwares as Agilent company) can be utilized to analyze, but these professional softwares are expensive, and sometimes need that some format conversion are carried out to collection signal and could be identified by software, directly utilize and there is larger difficulty.Usual signal processing algorithm primary study signal trace, modulation /demodulation, loop filterings etc. on the other hand, do not pay close attention in metrology and measurement the signal absolute amplitude needing to measure.
Summary of the invention
In order to overcome existing technical matters, the invention provides a kind of signal amplitude metering calibrating method in SDR application, technical scheme is as follows:
In a kind of SDR application, signal amplitude metering calibrating method, comprises the steps:
(1) this amplitude of complex digital in digital mixing is determined;
(2) real sampled signal and duplicate shake directly to be multiplied and realize mixing, and eliminate high fdrequency component by digital filtering, only retain complex baseband signal; First set signal impedance as 1, the amplitude of digital local oscillator is dimensionless unit 2, and namely local oscillation signal is 2e again
-j ω t, in formula: e is constant, represent the end of natural logarithm, value is about 2.7182818; J is unit imaginary number, is worth to be
ω is angular frequency, and value is 2 π f, f is signal frequency; T is time variable;
(3) time domain is carried out to complex baseband signal and carry out detection, detection signal instantaneous power;
(4) FFT conversion is carried out to complex baseband signal, draw signal spectrum component;
(5) at frequency domain measurement complex baseband signal different spectral component amplitude or power.
Preferably, the real sampled signal of input and the duplicate signal multiplication that shakes realizes mixing in described step (2), by digital filtering, eliminates high fdrequency component, only reservation low frequency baseband signal b=A (t) e
j θ=A (t) cos θ+jA (t) sin θ=I+jQ, in formula: s is real sampled signal; A (t) representation signal changes in amplitude; ω is angular frequency; θ (t) representation signal phase place changes; J is unit imaginary number; I represents complex signal real component; Q represents signal imaginary.
Preferably, in described step (3), the power detection method of complex baseband signal is p=(I
2+ Q
2)/2, in formula: p is signal transient power; I represents complex baseband signal real component; Q represents complex baseband signal imaginary.
Preferably, in described step (5), different frequency component m place signal amplitude-scaled is Y (m)=fft (x (n))/N, and for the effective value of this frequency content of complex baseband signal is
power is
in formula: Y is signal amplitude; M is signal frequency component; Fft represents and carries out Fast Fourier Transform (FFT) to signal; X (n) represents the digitised signal series after mixing and filtering, and n is time sequence number; N is the number of data points of burst.
Beneficial effect:
The present invention relates to signal amplitude metering calibrating method in a kind of SDR application, this amplitude, time domain instantaneous power detection algorithm, signal different spectral component amplitude computing method when this method giving digital mixing, ensure the accuracy that different link signal amplitude is expressed in SDR process, its result can directly apply to the occasion needing signal amplitude to be carried out to metrology and measurement.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is principle of the invention process flow diagram;
Fig. 2 is embodiment 1 original sampled signal time domain beamformer;
Fig. 3 is that embodiment 1 adopts time domain detection of the present invention to obtain calibrated signal power variations;
Fig. 4 is embodiment 2 original sampled signal time domain beamformer;
Fig. 5 is that embodiment 2 adopts the present invention to obtain the calibrated amplitude of spectrum component.
Embodiment
For making the object of the embodiment of the present invention, technical scheme and advantage clearly, be clearly and completely described below to the technical scheme in the embodiment of the present invention, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
In a kind of SDR application, signal amplitude metering calibrating method, comprises the steps:
(1) this amplitude of complex digital in digital mixing is determined;
(2) real sampled signal and duplicate shake directly to be multiplied and realize mixing, and eliminate high fdrequency component by digital filtering, only retain complex baseband signal; First set signal impedance as 1, the amplitude of digital local oscillator is dimensionless unit 2, and namely local oscillation signal is 2e again
-j ω t, in formula: e is constant, represent the end of natural logarithm, value is about 2.7182818; J is unit imaginary number, is worth to be
ω is angular frequency, and value is 2 π f, f is signal frequency; T is time variable;
(3) time domain is carried out to complex baseband signal and carry out detection, detection signal instantaneous power;
(4) FFT conversion is carried out to complex baseband signal, draw signal spectrum component;
(5) at frequency domain measurement complex baseband signal different spectral component amplitude or power.
The real sampled signal of input and the duplicate signal multiplication that shakes realizes mixing in step (2), by digital filtering, eliminates high fdrequency component, only reservation low frequency baseband signal b=A (t) e
j θ=A (t) cos θ+jA (t) sin θ=I+jQ, in formula: s is real sampled signal; A (t) representation signal changes in amplitude; ω is angular frequency; θ (t) representation signal phase place changes; J is unit imaginary number; I represents complex signal real component; Q represents signal imaginary, and in step (3), the power detection method of complex baseband signal is p=(I
2+ Q
2)/2, in formula: p is signal transient power; I represents complex baseband signal real component; Q represents complex baseband signal imaginary, and in step (5), different frequency component m place signal amplitude-scaled is Y (m)=fft (x (n))/N, and for the effective value of this frequency content of complex baseband signal is
power is
in formula: Y is signal amplitude; M is signal frequency component; Fft represents and carries out Fast Fourier Transform (FFT) to signal; X (n) represents the digitised signal series after mixing and filtering, and n is time sequence number; N is the number of data points of burst.
Embodiment 1:
For the amplitude jump of carrier frequency 10Hz shown in Fig. 2 continuous wave signal, signal initial magnitude is 2V, middle 2 seconds amplitudes are 1V, and last amplitude becomes 3V, adopts the method for the invention in time domain measurement signal power variations, comprises the steps:
(1) the duplicate amplitude indicated according to this method requires to generate digital copy and to shake signal 2e
-j ω t, local frequency is chosen as 10Hz;
(2) real signal sampling obtained and duplicate shake signal multiplication mixing, digital filtering is adopted to eliminate high fdrequency component: digital filter adopts 12 joint Butterworth wave filters, 3dB point is ± 16Hz, script center is shifted to the base band centered by zero-frequency at the signal at 10Hz carrier frequency place, and by the high fdrequency component filtering near complex frequency domain-20Hz;
(3) time domain instantaneous power detection algorithm is provided according to this method
measuring-signal time-domain power changes, and Output rusults, as Fig. 3, changes consistent with actual signal.
Embodiment 2:
For signal shown in Fig. 4, signal comprises the signal of two frequency contents, a frequency 8Hz, amplitude 3V, another frequency 12Hz, amplitude 2V, adopts the method for the invention measuring-signal frequency spectrum, provides calibrated signal amplitude value, comprise the steps:
(1) the duplicate amplitude indicated according to this method requires to generate digital copy and to shake signal 2e
-j ω t, local frequency is chosen as 10Hz;
(2) real signal sampling obtained and duplicate shake signal multiplication mixing, digital filtering is adopted to eliminate high fdrequency component: digital filter adopts 8 rank Butterworth wave filters, 3dB point is ± 8Hz, script center is shifted to the base band centered by zero-frequency at the signal at 10Hz carrier frequency place, and by the high fdrequency component filtering of two near complex frequency domain-20Hz;
(3) Fast Fourier Transform (FFT) fft (x (n)) is carried out to complex baseband signal;
(4) provide spectrum component computing method measuring-signal different spectral component amplitude according to this method, frequency spectrum calculate and calibration result as Fig. 5, the difference on the frequency of base band and amplitude corresponding consistent with actual signal.
The present invention relates to signal amplitude metering calibrating method in a kind of SDR application
in formula: Y is signal amplitude; M is signal frequency component; Fft represents and carries out Fast Fourier Transform (FFT) to signal; X (n) represents the digitised signal series after mixing and filtering, and n is time sequence number; N is the number of data points of burst, this amplitude, time domain instantaneous power detection algorithm, signal different spectral component amplitude computing method when this method giving digital mixing, ensure the accuracy that different link signal amplitude is expressed in SDR process, its result can directly apply to the occasion needing signal amplitude to be carried out to metrology and measurement
Above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature; And these amendments or replacement, do not make the essence of appropriate technical solution depart from the spirit and scope of various embodiments of the present invention technical scheme.
Claims (4)
1. a signal amplitude metering calibrating method in SDR application, is characterized in that, comprise the steps:
(1) this amplitude of complex digital in digital mixing is determined;
(2) real sampled signal and duplicate shake directly to be multiplied and realize mixing, and eliminate high fdrequency component by digital filtering, only retain complex baseband signal; First set signal impedance as 1, the amplitude of digital local oscillator is dimensionless unit 2, and namely local oscillation signal is 2e again
-j ω t, in formula: e is constant, represent the end of natural logarithm, value is about 2.7182818; J is unit imaginary number, is worth to be
ω is angular frequency, and value is 2 π f, f is signal frequency; T is time variable;
(3) time domain is carried out to complex baseband signal and carry out detection, detection signal instantaneous power;
(4) FFT conversion is carried out to complex baseband signal, draw signal spectrum component;
(5) at frequency domain measurement complex baseband signal different spectral component amplitude or power.
2. signal amplitude metering calibrating method in SDR application as claimed in claim 1, be characterised in that, the real sampled signal of input and the duplicate signal multiplication that shakes realizes mixing in described step (2), pass through digital filtering, eliminate high fdrequency component, only retain low frequency baseband signal b=A (t) e
j θ=A (t) cos θ+jA (t) sin θ=I+jQ, in formula: s is real sampled signal; A (t) representation signal changes in amplitude; ω is angular frequency; θ (t) representation signal phase place changes; J is unit imaginary number; I represents complex signal real component; Q represents signal imaginary.
3. signal amplitude metering calibrating method in SDR application as claimed in claim 1, be characterised in that, in described step (3), the power detection method of complex baseband signal is p=(I
2+ Q
2)/2, in formula: p is signal transient power; I represents complex baseband signal real component; Q represents complex baseband signal imaginary.
4. signal amplitude metering calibrating method in SDR application as claimed in claim 1, be characterised in that, in described step (5), different frequency component m place signal amplitude-scaled is Y (m)=fft (x (n))/N, and for the effective value of this frequency content of complex baseband signal is
power is
in formula: Y is signal amplitude; M is signal frequency component; Fft represents and carries out Fast Fourier Transform (FFT) to signal; X (n) represents the digitised signal series after mixing and filtering, and n is time sequence number; N is the number of data points of burst.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107942137A (en) * | 2017-11-16 | 2018-04-20 | 成都玖锦科技有限公司 | A kind of method based on the accurate estimating carrier frequency of scanning |
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| CN107942137A (en) * | 2017-11-16 | 2018-04-20 | 成都玖锦科技有限公司 | A kind of method based on the accurate estimating carrier frequency of scanning |
| CN107942137B (en) * | 2017-11-16 | 2019-11-19 | 成都玖锦科技有限公司 | A method of based on the accurate estimating carrier frequency of scanning |
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Application publication date: 20151209 |