CN105282086B - The double-tone orthogonal measuring method of frequency change system group delay - Google Patents
The double-tone orthogonal measuring method of frequency change system group delay Download PDFInfo
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- CN105282086B CN105282086B CN201510568426.1A CN201510568426A CN105282086B CN 105282086 B CN105282086 B CN 105282086B CN 201510568426 A CN201510568426 A CN 201510568426A CN 105282086 B CN105282086 B CN 105282086B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/36—Modulator circuits; Transmitter circuits
- H04L27/366—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator
- H04L27/367—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion
- H04L27/368—Arrangements for compensating undesirable properties of the transmission path between the modulator and the demodulator using predistortion adaptive predistortion
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
- H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
- H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
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Abstract
The double-tone orthogonal measuring method of frequency change system group delay, the two-tone signal that frequency difference is Δ f is generated by vector signal source, then the signal passes through power splitter, signal inputs the first A/D converters all the way, another way signal enters frequency conversion system after centainly decay, the output signal of frequency conversion system is after centainly decaying, the input as the 2nd A/D converters；During measurement, two A/D converter synchronized samplings after A/D samplings are carried out with output signal to input signal, carry out digital quadrature processing to input signal and output signal, obtain the tone signal that two frequencies are Δ f respectively；Finally, the group delay value of frequency conversion system is obtained by comparing the phase for the tone signal that frequency is Δ f；In the case where maintaining two-tone signal frequency difference Δ f constant, the frequency values of synchronous change two-tone signal can be achieved with the measurement of each frequency point group delay in frequency conversion system bandwidth；The precision of measurement result depends on the phase estimation precision for the tone signal that frequency is Δ f.
Description
Technical field
The present invention relates to a kind of double-tone orthogonal measuring method of frequency change system group delay, for the essence of frequency change system group delay
Close measurement.
Background technology
Group delay is to describe an important indicator of medium and receive-send system performance, and mistake during system is passed through with signal
True and time delay size is closely related.Since the input terminal of frequency conversion system is different from output terminal working frequency, during frequency conversion system group
The measurement prolonged is the difficult point in Group Delay Measurement field.Document " Group delay and phase measurements at
converters and multistage converters without LO access”(Proceedings ofIEEE
International Conference on Microwaves,Communications,Antennas and
Electronics Systems, Tel Aviv, 2009, pp.1-5.) a kind of double-tone Group Delay Measurement method is proposed in.In profit
With this method measurement frequency conversion system group delay when, it is only necessary to know that the frequency in local oscillation signal source, without provide or obtain it is any with
The related signal of system under test (SUT) local oscillator.However, due to the influence of the factors such as device aging and working environment variation, frequency conversion system
Local frequency unknown drift may occur.The drift of local frequency will influence the measurement accuracy of double-tone method.Especially exist
When carrying out digit phase estimation using Fast Fourier Transform (FFT) (FFT) and its innovatory algorithm, the drift of local frequency will cause
The frequency of output two-tone signal is in the non-integral multiple position of algorithm frequency resolution, and signal spectrum is caused to be revealed.When signal frequency
When composing existing leakage, the estimate of phase will be two-tone signal each the interaction of phase true value as a result, and then serious shadow
Ring the measurement accuracy of group delay.
The content of the invention
In order to overcome technical disadvantages during existing double-tone method measurement frequency change system group delay, it is an object of the invention to provide
A kind of double-tone orthogonal measuring method of frequency change system group delay, the measuring method and system under test (SUT) local oscillation signal are completely irrelevant, gram
The influence that local oscillation signal drifts about to Group Delay Measurement precision is taken.
The present invention technical solution be：Pass through orthogonal processing, when double-tone method is measured group delay, two-tone signal phase
The estimation of difference is converted to the phase estimation for the tone signal that frequency is two-tone signal frequency difference.
In order to achieve the above object, the technical solution adopted by the present invention is：
The double-tone orthogonal measuring method of frequency change system group delay, includes the following steps：
(1), using vector signal source, it is respectively f to generate frequency1And f2, frequency difference be Δ f two-tone signal：
(2), the two-tone signal of generation is divided into two-way, inputs the first A/D converters all the way, another way is suitably being declined
Input frequency conversion system after subtracting, and using the output signal of frequency conversion system after centainly decaying as the input of the 2nd A/D converters；
Then the input signal of the first A/D converters of synchronized sampling and the 2nd A/D converters；
(3), the data that the first A/D converters obtain are multiplied by sin (2 π f ' respectively0And cos (2 π f ' t)0T), wherein f '0
Local frequency when being handled for digital mixing, t are time variable, and it is (high then to filter out in signal and frequency using low-pass filter
Frequently part), and squared and computing is carried out to filtered signal, it obtains than the single-tone that the frequency of phase is Δ f joining for number
Examine signal
Wherein Δ f=f1-f2
Wherein：a1、f1、Respectively input amplitude, frequency and the phase of first sound in two-tone signal；a2、f2、
Respectively input amplitude, frequency and the phase of second sound in two-tone signal；T is time variable；
The orthogonal processing identical with the first A/D converters is carried out to the data that the 2nd A/D converters obtain, obtains counting
Word than phase frequency be Δ f single-tone measuring signal：
Wherein Δ f=f1-f2
Wherein：f1For the frequency of first sound in input two-tone signal；f2For the frequency of second sound in input two-tone signal
Rate；a′1、Respectively export the amplitude and phase of first sound in two-tone signal；a′2、Respectively export in two-tone signal
The amplitude and phase of second sound；T is time variable；
(4), by it is squared and after obtained data subtract its average, to inhibit the DC component in data；Then utilize
Digit phase method of estimation estimates carry out after direct current inhibition that frequency is the phase of Δ f components in data respectivelyWithAnd then realize the estimation of group delay：
(5), maintain two-tone signal frequency difference Δ f constant, synchronous change two-tone signal frequency f1And f2Value, obtain frequency conversion system
The group delay value of each frequency point in regiment commander's width.
The present invention has the following advantages compared with prior art：
1st, the measurement of frequency change system group delay is completely unrelated with the local oscillator of system under test (SUT), overcomes local oscillation signal drift to group
The influence of latency measurement precision.
2nd, by orthogonal processing, the estimation of the phase difference of two-tone signal when double-tone method is measured frequency change system group delay is asked
The Technology of Precision Measurement of tone signal phase can easily be applied to by topic conversion for the phase estimation problem of tone signal
The accurate measurement of frequency change system group delay.
Description of the drawings
Fig. 1 is the principle of the present invention block diagram.
Fig. 2 is the waveform of the two-tone signal that vector signal source generates in the embodiment of the present invention.
Fig. 3 is waveform of the input with output two-tone signal after orthogonal processing in the embodiment of the present invention.
Fig. 4 is the precision improvement figure in the embodiment of the present invention.
Fig. 5 is the improvement figure of the measurement variance in the embodiment of the present invention.
Specific embodiment
The present invention is described in further detail with reference to the accompanying drawings and detailed description.
The double-tone orthogonal measuring method of frequency change system group delay of the present invention, includes the following steps：
1st, using vector signal source, it is respectively f to generate frequency1And f2, frequency difference be Δ f two-tone signal；
2nd, then, the two-tone signal of generation is divided into two-way, inputs the first A/D converters all the way, another way is being fitted
Input frequency conversion system after attenuation, and using the output signal of frequency conversion system after centainly decaying as the 2nd A/D converters
Input；The input signal of two A/D converters of synchronized sampling.In synchronized sampling, lack sampling is such as carried out, it is desirable that input double-tone letter
Number frequency f1And f2Average, frequency conversion system output two-tone signal frequency f '1With f '2Average be not sample rate fsIt is whole
Several times.In addition, sample rate fsIt must is fulfilled for：fs2 Δ f of ＞.
3rd, the data that the first A/D converters obtain are multiplied by sin (2 π f ' respectively0And cos (2 π f ' t)0T), then using low
Bandpass filter filters out in signal and frequency (high frequency) part, and carries out squared and computing to filtered signal；To the 2nd A/D
The data that converter obtains carry out the orthogonal processing identical with the first A/D converters.It filters out and is multiplied by for the ease of subsequent filter
sin(2πf′0And cos (2 π f ' t)0T) after and frequency component, in non-lack sampling, in the data to the first A/D converters
When being handled, f '0The value of frequency conversion system input center frequency is chosen for, is handled in the data to the 2nd A/D converters
When, f '0It is chosen for the value of frequency conversion system output center frequency；In lack sampling, to the data of the first A/D converters into
During row processing, f '0It is chosen for the value divided by sample rate f of frequency conversion system input center frequencysRemainder afterwards；It is converted to the 2nd A/D
When the data of device are handled, f '0It is chosen for the value divided by sample rate f of frequency conversion system output center frequencysRemainder afterwards.In addition,
Input must utilize identical low-pass filter with output terminal.
4th, by it is squared and after obtained data subtract its average, to inhibit the DC component in data；Then number is utilized
Word phase estimation method estimates carry out after direct current inhibition that frequency is the phase of Δ f components in data respectively, and then when realizing group
The estimation prolonged.
5th, maintain two-tone signal frequency difference Δ f constant, synchronous change two-tone signal frequency f1And f2Value, obtain frequency conversion system
Each frequency point group delay value in bandwidth.
Embodiment
The input center frequency of the frequency conversion system of simulation is 1225MHz, and corresponding output center frequency is 50MHz.Simulation
The bandwidth of system is 2MHz, and sample rate is fixed as 1GHz.Ideally, the local oscillation signal frequency of frequency conversion system should be
1075MHz.For influence caused by simulation local oscillation signal frequency drift, the frequency of local oscillation signal is set to 1075.0002MHz.
1st, it is respectively the random two-tone signal of 1224MHz and 1224.01MHz, initial phase that simulation, which generates frequency, such as Fig. 2
It is shown.
2nd, then, the two-tone signal of generation is divided into two-way, inputs the first A/D converters all the way, another way is being fitted
Input frequency conversion system after attenuation, and using the output signal of frequency conversion system after centainly decaying as the 2nd A/D converters
Input；The input signal of two A/D converters of synchronized sampling.
3rd, f ' is chosen0The data that first A/D converters obtain are multiplied by sin (2 π f ' by=225MHz respectively0And cos (2 π t)
f′0T), then by bandwidth be 8MHz quadravalence number Butterworth LPF.
4th, to carrying out squared and computing by the signal of low-pass filter, and operation result is subtracted into its average, with suppression
DC component processed.
5th, f ' is chosen0=50MHz carries out and step 3,4 identical processing the data that the 2nd A/D converters obtain.It is defeated
It is as shown in Figure 3 with exporting the waveform that signal obtains after orthogonal processing to enter signal.As can be seen from the figure：Two-tone signal is passing through
After step 2 to the processing of step 4, the tone signal that frequency is 10kHz is converted to；
6th, the phase for the component that frequency in final data is 10kHz is asked for using fft algorithm, and then realizes the survey of group delay
Amount；
7th, the Frequency Synchronization of two-tone signal is increased into 10kHz, repeats step 2~6, and then obtain frequency conversion system bandwidth of operation
Interior group delay, as shown in Figure 4.As can be seen from the figure：By orthogonal processing, the phase difference measurement of two-tone signal is converted to
The phase measurement of tone signal effectively overcomes the influence that local oscillation signal drifts about to Group Delay Measurement precision；
8th, change the size of local vibration source frequency shift amount, and repeat step under specific frequency shift amount and play 1~5, obtain different local oscillator frequencies
Statistical result under drift, as shown in Figure 5.As can be seen from the figure：In the group of the method measurement frequency conversion system using the present invention
Delay, measurement accuracy is only determined by the phase estimation precision of tone signal, unrelated with the frequency drift of local oscillation signal.
Claims (1)
1. the double-tone orthogonal measuring method of frequency change system group delay, it is characterised in that：Include the following steps：
(1) two-tone signal that frequency difference is Δ f is generated using vector signal source；
(2) two-tone signal that frequency difference is Δ f is divided into two-way, inputs the first A/D converters all the way, another way is defeated after being decayed
Enter frequency conversion system, and using the output signal of frequency conversion system after centainly decaying as the input of the 2nd A/D converters；Then it is same
The input signal of step the first A/D converters of sampling and the 2nd A/D converters in synchronized sampling, such as carries out lack sampling, it is desirable that defeated
Enter the frequency f of two-tone signal1And f2Average, frequency conversion system output two-tone signal frequency f '1With f '2Average be not to adopt
Sample rate fsIntegral multiple；In addition, sample rate fsIt must is fulfilled for：fs>2Δf；
(3) data that the first A/D converters obtain are multiplied by sin (2 π f ' respectively0And cos (2 π f ' t)0T), wherein f '0For number
Local frequency during Frequency mixing processing, t are time variable；Then in signal and frequency i.e. radio-frequency head is filtered out using low-pass filter
Divide, and a square summation is carried out to the signal after low-pass filter, obtain than the single-tone reference that the frequency of phase is Δ f believing for number
Number：
Wherein Δ f=f1-f2
Wherein：a1、f1、Respectively input amplitude, frequency and the phase of first sound in two-tone signal；a2、f2、Respectively
Input amplitude, frequency and the phase of second sound in two-tone signal；T is time variable；
The orthogonal processing identical with the first A/D converters is carried out to the data that the 2nd A/D converters obtain, is obtained for digital ratio
The frequency of phase is the single-tone measuring signal of Δ f
Wherein Δ f=f1-f2
Wherein：f1Input the frequency of first sound in two-tone signal；f2Input the frequency of second sound in two-tone signal；a′1、
Respectively export the amplitude and phase of first sound in two-tone signal；a′2、Respectively export second sound in two-tone signal
Amplitude and phase；
(4) the squared data obtained with after are subtracted into its average, to inhibit the DC component in data；Then digital phase is utilized
Position method of estimation estimates and carries out after direct current inhibition that frequency is the phase of Δ f components in dataWithIt is and then real
The estimation of existing group delay；
(5) the frequency difference Δ f of maintenance two-tone signal is constant, and the frequency values of synchronous change two-tone signal are obtained in frequency conversion system bandwidth
The group delay value of each frequency point.
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| CN109813962B (en) * | 2018-12-27 | 2021-04-13 | 中电科思仪科技股份有限公司 | Frequency conversion system group delay measurement method and system based on Hilbert transform |
| CN113055108B (en) * | 2021-01-18 | 2022-06-17 | 浙江大学 | Method and device for measuring group delay of frequency mixer |
| CN113805182B (en) * | 2021-09-18 | 2023-05-02 | 四川轻化工大学 | Object motion monitoring method based on vector operation |
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| CN102231620A (en) * | 2010-09-06 | 2011-11-02 | 刘郁林 | Power amplifier linearization method and device based on baseband digital predistortion technology |
| EP2733871A1 (en) * | 2012-11-20 | 2014-05-21 | Tektronix, Inc. | Amplitude flatness and phase linearity calibration for rf sources |
| CN103973321A (en) * | 2013-02-06 | 2014-08-06 | 中国电子科技集团公司第十研究所 | Method for increasing flexibility of multi-tone frequency modulated signal receiver |
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| WO2008137204A1 (en) * | 2007-03-20 | 2008-11-13 | Massachusetts Institute Of Technology | Modulator for frequency-shift keying of optical signals |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102231620A (en) * | 2010-09-06 | 2011-11-02 | 刘郁林 | Power amplifier linearization method and device based on baseband digital predistortion technology |
| EP2733871A1 (en) * | 2012-11-20 | 2014-05-21 | Tektronix, Inc. | Amplitude flatness and phase linearity calibration for rf sources |
| CN103973321A (en) * | 2013-02-06 | 2014-08-06 | 中国电子科技集团公司第十研究所 | Method for increasing flexibility of multi-tone frequency modulated signal receiver |
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