CN104777495B - A kind of QPSK modulation I/Q path quadrature method of testings based on distribution histogram - Google Patents
A kind of QPSK modulation I/Q path quadrature method of testings based on distribution histogram Download PDFInfo
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- 238000010998 test method Methods 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 16
- 238000010606 normalization Methods 0.000 claims description 6
- 238000007781 pre-processing Methods 0.000 claims description 6
- 239000000284 extract Substances 0.000 claims description 5
- 238000005070 sampling Methods 0.000 claims description 5
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- 238000003199 nucleic acid amplification method Methods 0.000 claims description 2
- 230000001186 cumulative effect Effects 0.000 abstract description 2
- 238000011156 evaluation Methods 0.000 abstract description 2
- 238000012544 monitoring process Methods 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 8
- 230000005856 abnormality Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 230000000631 nonopiate Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000001568 sexual effect Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
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Abstract
The invention discloses a kind of QPSK modulation I/Q path quadrature method of testings based on distribution histogram, belong to signal quality monitoring and evaluation field.I branch road of the method with the receiver tracking digital medium-frequency signal, outgoing carrier phase place, carrier frequency and navigation message data；Secondly, digital medium-frequency signal is demodulated using carrier frequency and carrier phase information in locally generated carrier wave, generate the baseband signal of two branch roads of I/Q, recycle navigation message data to peel off the text in two branch road baseband signals of I/Q.The present invention does not need the pseudo-code of two branch roads of I, Q, it is known that having widened the range of application of the orthogonal judgement of I, Q；The deviation caused by external noise, the thermal noise of device and undesirable property is insensitive so that the result of the orthogonal judgement of I, Q has robustness；The cumulative mode of usage cycles, improves signal to noise ratio, so as to improve the precision of I, Q orthogonality judged result.
Description
Technical field
The invention belongs to signal quality monitoring and evaluation field, is related to modulation domain calculating, is directed to high-gain parabola antenna
The satellite-signal of reception, carries out post processing, calculates the orthogonality of I/Q branch roads.The present invention is modulated suitable for QPSK at present, is specifically related to
And a kind of method of testing based on I/Q branch road baseband signal distribution histograms.
Background technology
The method of the calculating orthogonality for commonly using at present has two kinds, is planisphere and based on the orthogonal of track loop respectively
Property test.Planisphere test is to judge that signal is different with the presence or absence of orthogonality by assessing the phase error of planisphere and range error
Normal and non-orthogonal degree, but its phase error is not the phase contrast of I/Q branch roads truly, and due to actual rings
There is noise under border, cause data point to fall around constellation point is entopic, form the shape as cloud, along with Base-Band Processing
When wave filter undesirable cause Chip Waveform vibration, signal discontinuity point there is intermediate zone etc., can all bring measurement planisphere
Larger with ideal constellation error, so the result of calculation of its index can not truly reflect the modulating performance of I/Q branch roads.
Based on the orthogonality method of testing of track loop, be using receiver tracking loop circuit in code ring and carrier wave ring, point
Two branch roads of I/Q are not carried out with carrier phase measurement in synchronization, I/Q two-way carrier phase differences is calculated, you can draw tested
Signal I/Q path quadratures.This method can be used in the case where signal to noise ratio is low, but is required known to pseudo-code.For GPS
The Q branch road pseudo-codes of No. two phase signals of P (Y) codes and the Big Dipper are unknown, and this method is inapplicable.
Content of the invention
The drawbacks of present invention is for both the above method, proposes a kind of QPSK based on baseband signal distribution histogram
(Quadrature Phase Shift Keyin) modulates I/Q path quadrature method of testings.The method allows Q branch roads pseudo-code not
Know, and calculation error is less.Measured signal can be calculated with the presence or absence of orthogonal sexual abnormality, and detect orthogonal sexual abnormality
Degree.
The signal for realizing utilizing radio-frequency front-end collection satellite to be measured of the method, obtains digital medium-frequency signal and stores,
What Data processing afterwards was used is this digital medium-frequency signal.First, with I of the receiver tracking digital medium-frequency signal
Road, outgoing carrier phase place, carrier frequency and navigation message data；Secondly, using carrier frequency and carrier phase information local
Carrier wave is produced, digital medium-frequency signal is demodulated, the baseband signal of two branch roads of I/Q is generated, recycles navigation message data to peel off I/Q
Text in two branch road baseband signals.When two branch roads of I/Q have nonopiate, i.e., the phase contrast of two branch roads is not 90 °,
Two branch road baseband signal waveforms can deviate preferable chip shape, and relative amplitude can also change, and extract the spy of waveform
Levy and can be calculated the relative skew of phase place.Here uses the amplitude characteristic for being characterized in that waveform, and the extraction of amplitude is exactly
Obtained using the counts peaks of distribution histogram.In order that feature extraction is more accurate, signal to noise ratio is improved using the cycle addition method, when
Accumulation period long enough, can make Chip Waveform clear, and feature is obvious.
Above-mentioned method of testing is based on, the present invention also provides a kind of test device for realizing above-mentioned method of testing, described survey
Trial assembly is put including four modules, respectively：Satellite-signal acquisition module, Digital Down Converter Module, data preprocessing module and just
The property handed over computing module；
Satellite-signal acquisition module is by high-gain aerial, preamplifier, low-converter, A/D converter and data disk
Array is constituted, and high-gain aerial receives satellite to be measured signal, the filter of the signal of reception through prefilter and preamplifier
Ripple is amplified into low-converter, is mixed with local carrier in low-converter, generates analog if signal, then changes through A/D
Analog if signal is converted into digital medium-frequency signal by device, and this digital medium-frequency signal is designated as r (nTS)；Collection a period of time
Digital medium-frequency signal is stored in data disk array, is ready for sending Digital Down Converter Module；
Digital Down Converter Module include receiver tracking loop circuit, local oscillator, the first multiplier, the second multiplier,
Digital medium-frequency signal r (the nT that the tracking of one low pass filter and the second low pass filter, first receiver tracking loop circuit has been gatheredS)
I branch roads, export carrier frequency w of tenacious tracking, carrier phase phi and navigation message data D (nTs)；
Carrier frequency and carrier phase in conjunction with output produces the carrier wave letter with I branch road carrier wave homophases in local oscillator
Number cos (w nTs+ φ), and carrier signal sin (the w nT with I branch road multicarrier orthogonalss+φ)；Carrier signal cos (w
nTs+ φ) in the first multiplier with digital medium-frequency signal r (nTs) after multiplication, I roadbed is obtained through the first low pass filter
Band signal, is designated as Ir(nTs), in the same manner, carrier signal sin (w nTs+ φ) in the second multiplier with digital medium-frequency signal r
(nTs) after multiplication, obtain Q branch road baseband signals through the second low pass filter, be designated as Qr(nTs), Ir(nTs)、Qr(nTs) for originally
The baseband signal of ground reduction；
Data preprocessing module includes text strip module, cycle laminating module and normalized module, described electricity
Literary strip module is used for the navigation message data for peeling off two roads, then carries out data segment superposition in cycle laminating module, most
Calculating is normalized afterwards in normalized module；
Described orthogonality computing module carries out the level value of distribution histogram and extracts and orthogonality calculating.
Advantages of the present invention and good effect are：
(1) pseudo-code of two branch roads of I, Q is not needed all, it is known that having widened the range of application of the orthogonal judgement of I, Q；
(2) deviation for external noise, the thermal noise of device and undesirable property being caused is insensitive so that I, Q are orthogonal to be sentenced
Disconnected
Result there is robustness；
(3) the cumulative mode of usage cycles, improves signal to noise ratio, so as to improve the precision of I, Q orthogonality judged result.
Description of the drawings
Fig. 1 is the QPSK modulation I/Q path quadrature method of testing flow charts based on distribution histogram that the present invention is provided.
Specific embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
The present invention provides a kind of QPSK modulation I/Q path quadrature method of testings based on distribution histogram, also provides one
The test device of the method for testing for realizing described is planted, described test device includes four modules, respectively：Satellite-signal is gathered
Module, Digital Down Converter Module, data preprocessing module and orthogonality computing module, below will be to modules and its test side
Method describes in detail.
1. satellite-signal acquisition module carries out signals collecting；
As shown in Figure 1, satellite-signal acquisition module is by high-gain aerial, preamplifier, low-converter, A/D (moulds
Intend/numeral) transducer and data disk array composition, mainly complete the off-line data collecting to satellite navigation signals, for rear
Face resume module and analysis.High-gain aerial receives satellite to be measured signal, and the signal of reception is through prefilter and front storing
Low-converter is entered after the filter and amplification of big device, is mixed with local carrier in low-converter, generated analog if signal, then pass through
Analog if signal is converted into digital medium-frequency signal by A/D converter, and this digital medium-frequency signal is designated as r (nTS).One section of collection
The digital medium-frequency signal of time is stored in data disk array, is ready for sending Digital Down Converter Module.
In the digital medium-frequency signal for not considering that the ideally QPSK of noise etc. is modulated, expression formula is as follows：
Sequence numbers of the wherein n for sample sequence, TsFor the sampling period, w is IF-FRE, and φ is initial phase, PIFor I branch roads
The power of signal, PQFor the power of Q tributary signals, c (nTS) for I branch road pseudo-codes sampled value, P (nTS) adopting for Q branch road pseudo-codes
Sample value, D (nTs) for navigation message sampled value.Under normal circumstances, the carrier phase difference of I/Q branch roads is 90 °, when the number of modulation
When word intermediate-freuqncy signal occurs nonorthogonality exception, existAngle skew, signal can be expressed as：
Above formula (2) can be arranged as follows：
2. Digital Down Converter Module completes signal demodulation, obtains I/Q two-way baseband signals.
(1) the digital medium-frequency signal r (nT for having been gathered first with receiver tracking loop circuit trackingS) I branch roads (assume I
Known to branch road pseudo-code), export carrier frequency w, carrier phase phi and the navigation message data D (nT of tenacious trackings).
(2) carrier frequency and carrier phase for combining output produces the load with I branch road carrier wave homophases in local oscillator
Ripple signal cos (w nTs+ φ), and carrier signal sin (the w nT with I branch road multicarrier orthogonalss+φ).Carrier signal cos
(w·nTs+ φ) in the first multiplier with digital medium-frequency signal r (nTs) after multiplication, I is obtained through the first low pass filter
Roadbed band signal, is designated as Ir(nTs), the cut-off frequency of first low pass filter is greater than c (nTs) and P (nTs) two puppets
The bandwidth of code, it is ensured that include both pseudo-codes in time domain.In the same manner, carrier signal sin (w nTs+ φ) in the second multiplier with
Digital medium-frequency signal r (nTs) after multiplication, obtain Q branch road baseband signals through the second low pass filter, be designated as Qr(nTs), described
The cut-off frequency of the second low pass filter is more than P (nTs) pseudo-code bandwidth.Ir(nTs)、Qr(nTs) it is the local base for reducing
Band signal, notes the difference with satellite end baseband signal.
Now have：
3. data preprocessing module is normalized to two-way baseband signal；
Data preprocessing module is that data are done with some conversion, and the signal processing after being does early-stage preparations, refers here to
Stripping baseband signal navigation message, the cycle addition method are arrived and have improved signal to noise ratio and normalized, as shown in Figure 1.
For the satellite-signal being an actually-received, if the gain of reception antenna is not enough, after will be unable to clearly distinguish demodulation
Signal, can make orthogonality abnormality detection error very big.Theory analysis shows that (data segment, length can be according to pseudo-code by R data segment
Cycle selects, such as optional to GPS L1 signals 1ms) it is superimposed, signal to noise ratio can improve R times, i.e. 10log10R dB.But base band now
Signal modulation has navigation message, the number of times of this meeting restrictive cycle superposition, it is desirable to effectively using cycle superposition raising signal to noise ratio, need
Navigation message is peeled off before superposition.Due to having used receiver tracking loop circuit tracking I tributary signals in Digital Down Converter Module,
It is not difficult to obtain navigation message data D (nTs), with D (nTs) and Ir(nTs) corresponding multiplication, that is, peel off the navigation message number of I branch roads
According to D (nTs) and Qr(nTs) corresponding multiplication, that is, peel off the navigation message data of Q branch roads.
Now have：
Baseband signal data after text in two branch roads is peeled off enters line period superposition, the base after the cycle is superimposed respectively
Band signal is designated as Ia(nTs), Qa(nTs).
For QPSK is modulated, navigation baseband signal has two kinds of values：- 1 and+1.In order that the baseband signal after cycle superposition
The true amplitude characteristic of signal can more be reflected, facilitate data handling procedure, the signal normalization process after the cycle is superimposed.Generally
In the case of on the basis of I tributary signals, normalized factor D is calculated as follows：
Sampling numbers of the wherein N for the data segment of I branch road baseband signals.
Shown in normalized method such as formula (9)～(10)：
Q(nTs)=Qa(nTs)/D (10)
WhereinFor I branch road normalization (counting afterwards) evidences, Q (nTs) it is data after Q branch road normalization.
4. orthogonality computing module carries out the level value extraction of distribution histogram and orthogonality is calculated；
The orthogonality computing module provides the core algorithm of the orthogonal sexual abnormality of detection, is divided into two parts：Based on distribution Nogata
The level value of figure is extracted and orthogonality is calculated.
(1) the level probability distribution that distribution histogram counts two branch road baseband signals of I/Q is utilized respectively, and extracts counting peak
Value level value.
Because the value of pseudo-code is -1 or 1, in the ideal caseThere are 4 level values { I is designated as respectively1,
I2,I3,I4, Q (nTs) there are two level values{ Q is designated as respectively1,Q2, can be with
Find out in the relation that nonopiate information just lies in this 6 level values.
But in the actual signal for receiving, can noisy presence, and in loop is received low pass filter characteristic
Rectangle square-wave signal can be made to produce overshoot in discontinuity point, round and smooth gradual change, so actualNot there was only 4 level
Value, Q (nTs) also not 2 level, this causes difficulty to the acquisition of information.Average in view of additive noise is 0, first
The waveform edge Jitter Attenuation that low pass filter and the filtering of the second low pass filter are caused is very fast, the electricity of most of chip samples point
Level values can still be in preferable level value, it is possible to use the distribution histogram of I branch roads finds out the corresponding level value of counts peaks,
As { I1,I2,I3,I4, the corresponding level value of counts peaks is found out with the distribution histogram of Q branch roads, be designated as { Q1,Q2, so
Efficiently reduce impact of the other factors to result of calculation.
(2) the relative deviation angle of Q branch roads can be calculated using this 6 level values.Computational methods are as follows：
Wherein,It is according to I1And I2The deviation angle of calculating,According to I3And I4The deviation angle of calculating, both can be anti-
Reflect the relative deviation angle of Q branch roads, both are numerically very close in theory, in nonorthogonality test, can be with them equal
ValueCharacterize nonopiate degree.
Claims (2)
1. a kind of QPSK based on distribution histogram modulates I/Q path quadrature method of testings, it is characterised in that：
The first step, satellite-signal acquisition module carry out signals collecting；
High-gain aerial receives satellite to be measured signal, and the signal of reception is through prefilter and the filter and amplification of preamplifier
Enter low-converter afterwards, be mixed with local carrier in low-converter, generate analog if signal, then through A/D converter by mould
Intend intermediate-freuqncy signal and be converted into digital medium-frequency signal, this digital medium-frequency signal is designated as r (nTS)；In the numeral of collection a period of time
Frequency signal is stored in data disk array, is ready for sending Digital Down Converter Module；
In the digital medium-frequency signal for not considering that the ideally QPSK of noise is modulated, expression formula is as follows：
Sequence numbers of the wherein n for sample sequence, TsFor the sampling period, w is IF-FRE, and φ is initial phase, PIFor I tributary signals
Power, PQFor the power of Q tributary signals, c (nTS) for I branch road pseudo-codes sampled value, P (nTS) for Q branch road pseudo-codes sampling
Value, D (nTs) for navigation message sampled value；Under normal circumstances, the carrier phase difference of I/Q branch roads is 90 °, when the numeral of modulation
When intermediate-freuqncy signal occurs nonorthogonality exception, existAngle skew, signal can be expressed as：
Above formula (2) can be arranged as follows：
Second step, Digital Down Converter Module complete signal demodulation, obtain I/Q two-way baseband signals；
First with the digital medium-frequency signal r (nT that receiver tracking loop circuit tracking has been gatheredS) I branch roads, in conjunction with digital intermediate frequency believe
Number r (nTS) carrier frequency and carrier phase produce in local oscillator and carrier signal cos of I branch road carrier wave homophases
(w·nTs+ φ), and carrier signal sin (the w nT with I branch road multicarrier orthogonalss+φ)；Carrier signal cos (w nTs+φ)
With digital medium-frequency signal r (nT in the first multipliers) after multiplication, I branch road baseband signals are obtained through the first low pass filter,
It is designated as Ir(nTs), in the same manner, carrier signal sin (w nTs+ φ) in the second multiplier with digital medium-frequency signal r (nTs) be multiplied
Afterwards, Q branch road baseband signals are obtained through the second low pass filter, is designated as Qr(nTs)；Ir(nTs)、Qr(nTs) it is local reduction
Baseband signal；
Now have：
3rd step, data preprocessing module are normalized to two-way baseband signal；
With D (nTs) and Ir(nTs) corresponding multiplication, that is, the navigation message data of I branch roads are peeled off, with D (nTs) and Qr(nTs) corresponding
It is multiplied, that is, has peeled off the navigation message data of Q branch roads；
Now have：
Baseband signal data after text in two branch roads is peeled off enters line period superposition respectively, the base band letter after the cycle is superimposed
Number it is designated as Ia(nTs), Qa(nTs)；
Signal normalization process after cycle is superimposed, on the basis of I tributary signals, normalized factor D is calculated as follows：
Sampling numbers of the wherein N for the data segment of I branch road baseband signals；
Shown in normalized method such as formula (9)～(10)：
Q(nTs)=Qa(nTs)/D (10)
WhereinFor data after I branch road normalization, Q (nTs) it is data after Q branch road normalization；
4th step, orthogonality computing module carry out the level value of distribution histogram and extract and orthogonality calculating；
(1) the level probability distribution that distribution histogram counts two branch road baseband signals of I/Q is utilized respectively, and extracts counts peaks electricity
Level values；
Because the value of pseudo-code is -1 or 1, in the ideal caseThere are 4 level values { I is designated as respectively1,
I2,I3,I4, Q (nTs) there are two level values{ Q is designated as respectively1,Q2}；
The corresponding level value that counts peaks are found out using the distribution histogram of I branch roads, used as { I1,I2,I3,I4, with Q branch roads
Distribution histogram finds out the corresponding level value of counts peaks, is designated as { Q1,Q2}；
(2) the relative deviation angle of Q branch roads is calculated using this 6 level values, and computational methods are as follows：
2. a kind of QPSK based on distribution histogram according to claim 1 modulates I/Q path quadrature method of testings, its
It is characterised by：The cut-off frequency of first low pass filter is more than c (nTs) and P (nTs) two pseudo-codes bandwidth, it is ensured that time domain
Interior comprising both pseudo-codes；The cut-off frequency of second low pass filter is more than P (nTs) pseudo-code bandwidth.
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| CN105337915B (en) * | 2015-09-30 | 2018-09-18 | 电信科学技术第一研究所有限公司 | The acquisition methods of π/4-QPSK demodulator base band sample data optimum sampling points |
| CN106226793B (en) * | 2016-07-29 | 2019-01-15 | 北京空间飞行器总体设计部 | A kind of in-orbit navigation signal IQ phase equalization scaling method |
| CN107104914B (en) * | 2017-04-19 | 2020-01-07 | 中电科（宁波）海洋电子研究院有限公司 | Digitalized phase demodulation method of position indication signal |
| CN109729037B (en) * | 2017-10-27 | 2020-03-20 | 华为技术有限公司 | Signal generation method and electronic equipment |
| CN108873025B (en) * | 2018-06-05 | 2022-04-01 | 上海司南卫星导航技术股份有限公司 | GNSS satellite signal tracking method, carrier tracking loop and receiver |
| CN110471091B (en) * | 2019-08-29 | 2021-05-25 | 北京航空航天大学合肥创新研究院 | Deception jamming detection method based on orthogonal component of correlator |
| CN112051532A (en) * | 2020-08-04 | 2020-12-08 | 中电科仪器仪表有限公司 | Intermediate frequency calibration method based on vector network analyzer |
| CN114297117B (en) * | 2021-12-28 | 2024-05-03 | 北京和利时系统工程有限公司 | Modulation method, modulation device, demodulation method and storage medium |
| CN117200813B (en) * | 2023-11-07 | 2024-03-15 | 成都飞机工业（集团）有限责任公司 | Method and system for detecting burst signal of radio navigation system |
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