CN102801671B - Carrier tracking device capable of adaptively adjusting parameters - Google Patents
Carrier tracking device capable of adaptively adjusting parameters Download PDFInfo
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- CN102801671B CN102801671B CN201210252373.9A CN201210252373A CN102801671B CN 102801671 B CN102801671 B CN 102801671B CN 201210252373 A CN201210252373 A CN 201210252373A CN 102801671 B CN102801671 B CN 102801671B
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Abstract
The invention discloses a carrier tracking device capable of adaptively adjusting parameters, comprising an A/D (Analogue/Digital) converter, an orthogonal down convertor, a digital control oscillator, an estimation module, an integrator, a main carrier frequency demodulation and phase demodulation device and a loop filter, wherein an orthogonal down convertor module utilizes a local reference signal to carry out digital down conversion on a sampling signal output by the A/D converter to generate a baseband signal; the digital control oscillator generates the local reference signal according to a carrier frequency offset control word and a carrier tracking frequency control word; the carrier frequency offset control word is generated by the estimation module according to the baseband signal; the carrier tracking frequency control word is generated by the loop filter according to a frequency demodulation and phase demodulation error signal; the main carrier frequency demodulation and phase demodulation device generates the frequency demodulation and phase demodulation error signal according to an integrated signal; and the integrator and the loop filter determine the integrated time and loop filtering parameter according to selected parameters and the selected parameters are determined according to a signal to noise rate of the baseband signal by the estimation module. The carrier tracking device disclosed by the invention can realize the self-adaptive tracking on an upstream carrier signal according to the estimation of the baseband signal of an input signal.
Description
Technical field
The invention belongs to communication technical field, relate to a kind of carrier track device of Automatic adjusument parameter.
Background technology
China has carried out the detector that development upgrades at present, for detecting remoter celestial body, comprises Venus, Mars, Jupiter etc.The moon is to the maximum distance about 400,000 kilometers of the earth, and Mars is to the maximum distance about 400,000,000 kilometers of the earth, and distance has expanded 1000 times.In survey of deep space, the signal to noise ratio dynamic range of Received signal strength is very large, the 20dBHz of C/N0 from the 117dBHz of high s/n ratio to low signal-to-noise ratio, and the excursion of the Algorithm for Doppler Frequency Rate-of-Change of Received signal strength is very large, from more than 5KHz/s during high s/n ratio, to about 20Hz/s during low signal-to-noise ratio, the carrier tracking technique of answering machine on star is had higher requirement.And the tracking sensitivity of answering machine only reaches more than 47dBHz on the moonik CE-1/2 flown at present, the demand of farther survey of deep space can not be met.
Summary of the invention
Technology of the present invention is dealt with problems and is: for the deficiencies in the prior art, provides a kind of carrier track device of Automatic adjusument parameter, can according to the adaptive tracing realized the estimation of input signal baseband signal up-link carrier signal.
Technical solution of the present invention is:
A carrier track device for Automatic adjusument parameter, comprises A/D converter, quadrature frequency conversion, digital controlled oscillator, estimation module, integrator, main carrier phase frequency detector and loop filter,
The sampled signal of generation is outputted to quadrature frequency conversion module by input signal after A/D converter; The local reference signal that described quadrature frequency conversion module utilizes digital controlled oscillator to produce carries out down-conversion to sampled signal and produces baseband signal; Described digital controlled oscillator produces local reference signal according to the carrier wave frequency deviation control word of input and carrier track frequency control word, and carrier wave frequency deviation control word is produced according to baseband signal by estimation module; The frequency and phase discrimination error signal that carrier track frequency control word is exported according to main carrier phase frequency detector by loop filter produces, and described main carrier phase frequency detector produces described frequency and phase discrimination error signal according to the integrated signal of described integrator to baseband signal; Wherein, described loop filter comprises second-order PLL and third order pll.
Described integrator and described loop filter determine the time of integration and loop filtering parameter according to the Selection parameter that described estimation module produces, and described Selection parameter is determined by the signal to noise ratio of described estimation module according to baseband signal.
Further, different Selection parameter corresponds to different choice parameter area, and when the signal to noise ratio of described baseband signal is among certain Selection parameter scope, then estimation module exports the Selection parameter corresponding to this Selection parameter scope.
Further, in described Selection parameter scope, adjacent Selection parameter scope has the end points scope overlapped.
The present invention compared with prior art tool has the following advantages:
The present invention adopts Doppler and signal-to-noise ratio (SNR) estimation, selects suitable initial loop parameter.Estimate to determine Selection parameter according to signal power, and the time of integration of filtering parameter sum-product intergrator according to Selection parameter determination loop filter, thus the feature of upward signal can be adapted to, complete carrier track function.The signal of high s/n ratio, high-doppler rate of change can be adapted to, also can be adapted to the signal of Arctic ice area, low rate doppler changing rate.Be adapted to the measurement and control signal with very big excursion in survey of deep space task.
Accompanying drawing explanation
Fig. 1 is carrier track device of the present invention composition schematic diagram;
Fig. 2 is the composition schematic diagram of loop filter;
Fig. 3 is the schematic diagram of Selection parameter scope.
Embodiment
Just by reference to the accompanying drawings the present invention is described further below.
As shown in Figure 1, the carrier track device of Automatic adjusument parameter of the present invention comprises: A/D converter, quadrature frequency conversion, digital controlled oscillator NCO, estimation module, integrator, main carrier phase frequency detector and loop filter.
Input signal leads to A/D converter samples, and forms intermediate frequency digital sample sequence and outputs to quadrature frequency conversion module.The orthogonal local reference signal of the two-way that quadrature frequency conversion module utilizes digital controlled oscillator NCO to provide is down-converted to base band to intermediate frequency digital sample sequence, obtains the baseband signal that I, Q two-way is orthogonal.
Estimation module carries out Nonlinear Transformation in Frequency Offset Estimation to the baseband signal that two-way is orthogonal, doppler changing rate is estimated and signal power is estimated, forms Nonlinear Transformation in Frequency Offset Estimation control word.Adopt FFT computing to carry out spectrum analysis to the baseband signal that I, Q two-way is orthogonal in the estimation module, search the peak-peak of baseband signal.The position of peak value represents frequency offset, and the size of peak value represents signal power, can embody signal to noise ratio snr.Carry out twice FFT computing continuously, the variable quantity measuring peak for twice just reflects doppler changing rate.NCO utilizes Nonlinear Transformation in Frequency Offset Estimation control word to control the frequency exporting reference signal, makes the local reference signal of output identical with input IF signal frequency.
Integrator carries out integration to the baseband signal that I, Q two-way is orthogonal, and the two-way integrated signal exported after integration sends into main carrier phase frequency detector.Carry out frequency discrimination and phase demodulation by main carrier phase frequency detector to input signal, rear generation outputs to the frequency and phase discrimination error signal of loop filter.Loop filter forms carrier track frequency control word after carrying out loop filtering to frequency and phase discrimination error signal, and the intermediate frequency digital sample sequence of the reference signal that control NCO makes it export and input, with frequency homophase, completes carrier lock.
The Selection parameter that the time of integration of described integrator and the loop filtering parameter of described loop filter are exported by estimation module is determined.Integrator and loop filter complete the carrier track to baseband signal according to Selection parameter.The effect of carrier track is the frequency difference constantly eliminating local carrier and baseband signal carrier wave, makes the carrier wave of local reference signal and input signal with frequency homophase, also namely eliminates the Doppler contribution of carrier signal.Carrier track is estimated as basis with Nonlinear Transformation in Frequency Offset Estimation and signal power.Estimate to eliminate signal overwhelming majority Doppler component by frequency deviation, the frequency deviation of signal carrier and local carrier is controlled in the traction bandwidth of track loop.
Integrator carries out integration accumulation to baseband signal, and the time span T of accumulation is the time of integration of integrator.Baseband signal after integration obtains the frequency and phase discrimination error signal for characterizing instantaneous frequency difference and instantaneous phase difference respectively by frequency discrimination and phase demodulation.
As shown in Figure 2, be loop filter schematic diagram.The basic structure of loop filter adopts second order FLL to assist third order pll.Difference on the frequency and phase difference calculate tracking loop frequency control word by five multipliers, two T time delayers and three integrators.
In tracing process, the structure of loop filter remains unchanged, but loop filtering parameter wherein can dynamically change.Comprise the T1 time of integration of integrator, delayer T2 time of delay, FLL and phase-locked loop coefficient Cf1, Cf2, Cp1, Cp2, Cp3.If arrange Cf1=Cf2=0, then form third order pll PLL.If select Cp3=0, then form second-order PLL PLL.Usually for the signal of strong signal to noise ratio, adopt the parameter with wider loop bandwidth and the shorter time of integration, thus accelerate locking; For weak signal-noise ratio signal, select the parameter with the longer time of integration and narrower loop bandwidth, thus improve signal to noise ratio; For the signal had compared with high-doppler rate of change, adopt second-order loop to assist the structure on third order PLL road, thus reduce to follow the tracks of phase difference; For the signal with lower doppler changing rate, the parameter forming second-order loop can be selected, thus improve stability.
The Selection parameter that estimation module exports comprises (T1, Cf1, Cf2, Cp1, Cp2, Cp3), and wherein, T1 is the time of integration of integrator; Cf1, Cf2 are the loop parameter of 2 rank FLL; Cp1, Cp2, Cp3 are the loop parameter of 3 rank phase-locked loops.Multiple Selection parameter preset forms Selection parameter collection, and each Selection parameter corresponds to a Selection parameter scope.As shown in Figure 3, Selection parameter 1 condition is selected to be that the scope that phase-locked loop normally works is SNR > thresholding 1-; The condition of Selection parameter 2 is selected to be that the scope that phase-locked loop normally works is thresholding 2+ > SNR > thresholding 2-; The condition of Selection parameter 3 is selected to be that the scope that phase-locked loop normally works is thresholding 3+ > SNR > thresholding 3-; The condition of Selection parameter 4 is selected to be that the scope that phase-locked loop normally works is thresholding 4+ > SNR > thresholding 4-.
And correspond in the Selection parameter scope of Selection parameter 1 ~ Selection parameter 4, adjacent Selection parameter scope has certain overlap at end points place, i.e. thresholding 1-< thresholding 2+.Thresholding 2+ > thresholding 1-, thresholding 3+ > thresholding 2-, thresholding 4+ > thresholding 3-.
In the estimation module, adopt the formula of I*I+Q*Q to continue to carry out calculating to baseband signal power and observe, estimate as SNR.According to the current residing state of loop filter, the end points of SNR and Selecting parameter scope is made comparisons.If phase-locked loop is current have employed Selection parameter 1, then, in tracing process, SNR should be on thresholding 1-.If SNR < thresholding 1-, and SNR > thresholding 2-, then change (T, Cf1, Cf2, Cp1, Cp2, Cp3), adopt Selection parameter 2.If rediscover SNR > thresholding 2+, then become Selection parameter 1, if SNR < thresholding 2-, and SNR > thresholding 3-, then adopt Selection parameter 3.
By that analogy, along with the height of signal to noise ratio changes, phase-locked loop switches according to the Selection parameter determined between adjacent Selection parameter scope, thus realizes seamlessly transitting.And each adjacent Selection parameter scope has the end points scope (end points being crosses one another) overlapped, ensure that loop parameter can not equal the end points place of some Selection parameter scopes and oscillate just due to signal to noise ratio.When switching between two Selection parameter scopes, only change the T and the filter coefficient time of integration of frequency and phase discrimination integrator, retain the accumulated value of the delay cumulative unit in loop, thus memory effect when guaranteeing that loop switches before maintenance, can not undergo mutation.
The unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.
Claims (1)
1. a carrier track device for Automatic adjusument parameter, comprises A/D converter, quadrature frequency conversion, digital controlled oscillator, estimation module, integrator, main carrier phase frequency detector and loop filter,
The sampled signal of generation is outputted to quadrature frequency conversion module by input signal after A/D converter; The local reference signal that described quadrature frequency conversion module utilizes digital controlled oscillator to produce carries out down-conversion to sampled signal and produces baseband signal; Described digital controlled oscillator produces local reference signal according to the carrier wave frequency deviation control word of input and carrier track frequency control word, and carrier wave frequency deviation control word is produced according to baseband signal by estimation module; The frequency and phase discrimination error signal that carrier track frequency control word is exported according to main carrier phase frequency detector by loop filter produces, and described main carrier phase frequency detector produces described frequency and phase discrimination error signal according to the integrated signal of described integrator to baseband signal; Wherein, described loop filter comprises second-order PLL and third order pll,
It is characterized in that: the Selection parameter that estimation module exports comprises (T1, Cf1, Cf2, Cp1, Cp2, Cp3), and wherein, T1 is the time of integration of integrator; Cf1 and Cf2 is respectively the loop parameter of 2 rank FLL; Cp1, Cp2 and Cp3 are the loop parameter of 3 rank phase-locked loops; The parameter value that each Selection parameter presets by 4, the corresponding Selection parameter scope of each parameter value of presetting, selects the condition of preliminary setting parameter 1 to be: the scope that phase-locked loop normally works is SNR > thresholding 1-; The condition of preliminary setting parameter 2 is selected to be: the scope that phase-locked loop normally works is thresholding 2+ > SNR > thresholding 2-; The condition of preliminary setting parameter 3 is selected to be: the scope that phase-locked loop normally works is thresholding 3+ > SNR > thresholding 3-; The condition of preliminary setting parameter 4 is selected to be: the scope that phase-locked loop normally works is thresholding 4+ > SNR > thresholding 4-; Described thresholding 2-< thresholding 1-< thresholding 2+, thresholding 3-< thresholding 2-< thresholding 3+, thresholding 4-< thresholding 3-< thresholding 4+;
In the estimation module according to the SNR estimated and the current residing state of loop filter, SNR and thresholding are compared, determine Selection parameter value, be specially:
If phase-locked loop is current selected preliminary setting parameter 1, then in tracing process, SNR should be on thresholding 1-, if SNR < thresholding 1-, and SNR > thresholding 2-, then change (T, Cf1, Cf2, Cp1, Cp2, Cp3), select preliminary setting parameter 2, if find SNR > thresholding 2+, then become and select preliminary setting parameter 1, if SNR < thresholding 2-, and SNR > thresholding 3-, then adopt Selection parameter 3, by that analogy.
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| CN103036589A (en) * | 2012-12-24 | 2013-04-10 | 哈尔滨工业大学 | Spread spectrum communication combination carrier synchronization method based on signal to noise ratio (SNR) |
| CN104320201B (en) * | 2014-09-23 | 2017-01-25 | 西安空间无线电技术研究所 | Spatial coherent optical communication high-dynamic carrier capture tracking loop |
| CN107040488B (en) * | 2016-11-11 | 2019-09-24 | 上海航天测控通信研究所 | The carrier wave tracing method and tracking device of Arctic ice area based on FPGA |
| CN108712190B (en) * | 2018-04-25 | 2020-10-27 | 西安宇飞电子技术有限公司 | Multi-carrier tracking method and tracking device |
| CN110501728B (en) * | 2018-05-16 | 2022-03-29 | 清华大学 | Frequency discrimination method and device for time hopping signal of positioning base station |
| CN111431557B (en) * | 2020-06-12 | 2020-09-11 | 长沙北斗产业安全技术研究院有限公司 | Signal tracking method and signal tracking system suitable for multi-mode modulation system |
| CN112684480B (en) * | 2020-12-14 | 2023-07-07 | 中山大学 | High-dynamic carrier combined loop tracking method and system |
| CN113093238B (en) * | 2021-03-25 | 2024-01-30 | 中国人民解放军国防科技大学 | Carrier wave numerical control oscillator, optimization method thereof and navigation receiver |
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| CN101329390B (en) * | 2007-06-21 | 2011-12-21 | 凹凸科技（中国）有限公司 | GPS receiver and method for detecting GPS receiver tracking loop circuit state |
| CN101183149B (en) * | 2007-12-07 | 2010-09-01 | 清华大学 | Double replacement rate carrier tracking loop circuit |
| CN101435866B (en) * | 2008-11-26 | 2012-04-04 | 苏州莱迪斯特电子有限公司 | Carrier wave tracking system and method of GPS coarse / capturing code signal |
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Inventor after: Ji Xin Inventor after: Ren Jingwei Inventor after: Di Shenghua Inventor after: Qin Yufeng Inventor after: Zhang Zongpan Inventor before: Ji Xin Inventor before: Ren Jingwei Inventor before: Di Shenghua Inventor before: Zhang Zongpan |
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