CN1529421A - Digital demodulating-receiving device - Google Patents
Digital demodulating-receiving device Download PDFInfo
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- CN1529421A CN1529421A CNA031264743A CN03126474A CN1529421A CN 1529421 A CN1529421 A CN 1529421A CN A031264743 A CNA031264743 A CN A031264743A CN 03126474 A CN03126474 A CN 03126474A CN 1529421 A CN1529421 A CN 1529421A
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Abstract
The receiving device comprises real time demodulation module for carrying out real time demodulation, modulating transmission system and module for predicting characteristic parameters of channel, and generation module of synchronized clock. The modulating transmission system and module for predicting characteristic parameters of channel through off line computational analysis recovers out the carrier wave in same frequency and same phase to received signal, tapping coefficient of filter utilized in balanced channel, and timing information etc., which are sent to real time demodulation module to control demodulation of received signal synchronistically. The invented device separates modulating transmission system and module for predicting characteristic parameters of channel from demodulation so as to reduce operation quantity, and realize demodulation in real time.
Description
Technical field
The present invention relates to a kind of digital demodulation receiver, relate in particular to a kind of device of in digital demodulation, launching modulating system and channel characteristics parameter prediction.
Background technology
In digital communication, digital baseband signal arrives radio frequency by the modulators modulate of transmitting terminal, sends to certain channel by transmitter then and transmits.In the process of modulate emission, digital signal can be subjected to the influence of frequency deviation, phase noise, output amplitude error and the modulation error etc. of local oscillator; In the process of transmission, because the undesirable situation of real channel, signal also can be subjected to the influence as interference such as white Gaussian noise, multipath reflection, channel interference, undesirable amplifier nonlinearity distortions.Therefore, when receiving terminal carries out demodulation, must carry out a series of activities such as carrier frequency recovery, carrier phase recovery, channel equalization, regularly recovery, noise filtering to signal, obtain again digital modulation signals separate the necessary carrier information of timing, timing information, to channel compensate with information and noise filter parameter information etc.Therefore, in the process of digital demodulation, one of most important task is exactly that the characteristic parameter of modulation emission system and the characteristic parameter of channel are extracted, and sets up the model of emission system and transmission channel.The extraction of characteristic parameter comprises the prediction of noise prediction, regularly prediction, carrier frequency prediction, carrier phase prediction and channel transfer function etc.
But in the reality design, modulate emission modulating system characteristic parameter and channel characteristics parameter extraction need recover not pass through the primary signal of Channel Transmission accurately, launch the prediction of modulating system and channel as a reference with this.Accomplish this point, must relate to very complex calculations and processing, brought a series of problem thus:
Need powerful real time digital signal disposal ability, with high costs; Power consumption is big, the heat radiation difficulty;
Again produce primary signal and relate to suitable complex calculations, be difficult to accomplish real-time processing; If can not handle in real time, then need very big memory space, for the real-time digital processor, be difficult to accomplish, if add memory device in addition, increased cost again.
In many patents in the past, the method for some relevant digital demodulations has been proposed also.But, all fail to solve the above problem that proposes, can not well carry out the real time data demodulation.
As at United States Patent (USP) " DSP implementation of a Cellular base stationreceiver ", US Patent No.5,764,704 June 9,1998, in a kind of digital demodulator is disclosed, be to adopt traditional digital modulation and demodulation structure, the simple directly carrier recovering method of utilization.Like this, in the Channel Transmission that noise and distortion are arranged, can not carry out the generation of carrier frequency recovery, carrier phase recovery, equalizer coefficients and noise filter coefficient exactly.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of digital demodulation receiver, can launch the prediction of modulating system characteristic parameter and channel characteristics parameter exactly, can reduce the operand of real-time demodulation module simultaneously.
For this reason, the invention provides a kind of digital demodulation receiver to digital modulation signals, comprise real-time demodulation module, modulate emission system and channel characteristics parameter prediction module and synchronised clock generation module, wherein: described real-time demodulation module, receive described digital modulation signals, and it is carried out real-time demodulation, obtain the digital signal after the demodulation; Described modulate emission system and channel characteristics parameter prediction module receive described digital modulation signals, by the computational analysis of off-line, dope the characteristic parameter of modulate emission system and channel, and deliver to the described real-time demodulation module control demodulating process that desynchronizes; Described synchronised clock generation module is used to produce the reference clock that the parameters such as carrier frequency, carrier phase and timing information of the time that depends on when recovering provide.
Device of the present invention is separated the prediction of modulate emission system and channel characteristics parameter according to modulate emission system and the metastable characteristic of each characteristic parameter of channel from real-time demodulation module.So both can alleviate the computational burden of digital processing device, accomplish real real-time demodulation, and because data are processed offline, can reuse image data, on the basis of tentatively setting up modulate emission system and channel model by the mode of loop control, the adjustment modulate emission system that does not stop and the various features parameter of channel, match actual conditions, up to the value that reaches near actual conditions, thus the accurate signal of demodulation digital modulation.
Description of drawings
Fig. 1 is a system construction drawing of the present invention;
Fig. 2 is the structure chart of the modulate emission system and the channel characteristics parameter prediction module of off-line of the present invention;
Embodiment
Though modulate emission system and channel characteristics Parameter Extraction be difficulty quite, the parameters of most of modulate emission system is relatively stable; The noise major part of communication system transmits channel satisfies normal distribution or other noise model, and the distortion situation of channel is relative fixed also, and channel becomes or time-invariant system when always a parameters is metastable.
At this situation, the designed entire system structure of the present invention as shown in Figure 1, the digital receiver of the embodiment of the invention has been divided into three functional modules: the one, carry out the real-time demodulation module 1 that real time digital signal is handled, the 2nd, carry out the modulate emission system and the channel characteristics parameter prediction module 2, three of processed offline, synchronised clock generation module 3 to modulating emission system and channel characteristics parameter.The structure of Fig. 1 is applicable to quadrature and non-orthogonal modulating system.
As shown in the figure, the digital modulation signals of reception enters real-time demodulation module 1 and modulate emission system and channel parameter prediction module 2 respectively.Modulate emission system and channel parameter prediction module 2 are by the computational analysis of off-line, obtain modulate emission system and Channel Models, parameters such as employed filter tap coefficients and timing information when the carrier wave of the same homophase frequently of the digital modulation signals that recovers and receive, channel equalization.Then, by the control of synchronised clock generation module 3, these parameter informations are delivered to the desynchronize demodulation of control received signal of real-time demodulation module 1, demodulate at last the digital modulation signals that is subjected to modulate emission systematic error and channel distortion influence exactly.
To describe the function and the realization of each module below in detail.
Real-time demodulation module, this part is the digital demodulation part of real-time digital modulation signal, comprising noise filtering and channel filtering.Owing in the design of native system, will from the digital demodulation module, separate, carry out processed offline to the prediction of modulation emission system and each characteristic parameter of channel.Therefore, alleviate the computational burden of this digital demodulation module greatly, can carry out the real-time digital demodulation at an easy rate.Below, with reference to Fig. 1 the handling process of digital signal in this module is described below:
At first the digital modulation signals and its carrier signal with the frequency homophase that receive are carried out mixing, obtain containing the signal of base band data.Wherein, carrier wave is obtained by the modulate emission system and the channel characteristics parameter prediction module of off-line;
Signal after the mixing by baseband filtering unit 11, is taken out the baseband signal that digital solution accesses.The noise filtering parameter of the fine setting of its median filter and compensation, interchannel and the compensating parameter of third-order non-linear distortion are by the modulate emission system and 2 decisions of channel characteristics parameter prediction module of off-line;
The baseband digital signal that demodulates enters regularly decision unit 12,, samples the original symbol that obtains transmitting at correct timing position according to symbol rate.Wherein Cai Yang timing information is determined by the modulate emission system and the channel characteristics parameter prediction module 2 of off-line;
Equalization filtering unit 13, the equalizing coefficient of the equalizer real part (perhaps real part and imaginary part) that obtains by the modulate emission system and the channel characteristics parameter prediction module 2 of off-line, form the equalization filtering unit 13 of described channel, numerical chracter through the demodulation sampling is carried out further channel equalization filtering, the influence of suffered channel distortion in the influence of the modulate emission systematic error that compensating signal is received and the Channel Transmission, and the deviation that remedies phase place in some carrier waves recoveries, obtain better demodulation effect.
According to different modulation systems and channel situation, not every demodulating system all needs above all functional modules.In the design of native system, modulate emission system and channel characteristics parameter prediction module can be informed real-time demodulation module those are necessary function, to simplify demodulating process, save power consumption.For example, in antireflecting modulating system, channel equalization is exactly unwanted.
Fig. 2 promptly is the structural representation of the modulate emission system and the channel characteristics parameter prediction module 2 of off-line.Referring now to Fig. 2 each submodule of this module is described below:
Transmission data recovery module 21: receive the digital modulation signals of coming, under the situation of certain channel, the modulation signal that receives is carried out demodulation, recover base band data through the channel distortion influence by Channel Transmission.Demodulating process belongs to the content of prior art, can comprise processes such as noise jamming filtering, carrier frequency recovery, carrier phase recovery, regularly recovery, nonlinear distortion verification, adaptive equalization, forward error correction, automatic gain control usually.
Digital modulation module 22: the data that demodulate are modulated into radiofrequency signal again according to the modulation system of transmitting terminal, send into then in modulate emission system and the channel model 23;
Modulate emission system and channel model 23: obtain the interchannel noise size, channel reflection distortion situation of modulate emission system and channel and to the frequency and the parameters such as phase pushing figure, timing slip of carrier wave by characteristic parameter prediction module 25, simulate a modulate emission system and channel model, will be modulated to the digital signal of radio frequency again by this modulate emission system and channel;
Analyze comparison module 24: will compare and analyze by the modulating data of modulate emission system and channel model 23 and the modulating data that passes through actual channel that receives, if the channel characteristics parameter prediction gets very accurate, the two paths of data statistical property should be similar or very approaching.Give characteristic parameter prediction module 25 with analyzing result relatively;
Characteristic parameter prediction module 25, according to the comparative result of analyzing comparison module, in characteristic parameter prediction module 25, adjust the parameters of modulate emission system and channel module 23 adaptively, as crosstalk and other noise jamming, linearity or nonlinear channel distortion, carrier frequency shift, carrier phase offset, timing slip etc., so that the modulation signal that produces is again carried out the simulation of actual modulated emission system and channel.
Above all functions are processes of a dynamic loop control, constantly adjust the various characteristic parameters of channel, finally reach the accurate estimation of parameter, realize correct demodulation.
Synchronised clock generation module 3 is to depend on the reference clock that the parameter of time provides when produce recovering.These parameters that depend on the time comprise carrier frequency, carrier phase and timing information etc.Under clock control accurately, real-time demodulation module 1 can correctly be recovered and be used for to these information.In system, mainly containing following two kinds of situations needs Synchronization Control: a kind of is that real-time demodulation module 1 and modulate emission system and channel characteristics parameter prediction unit 2 are undertaken synchronously by synchronised clock generation module 3; Another kind is to recover the transmission of baseband signal afterwards through modulate emission system and channel model 23, when the modulation signal that passes through actual channel that enters analysis comparison module 24 and receive compares, will be synchronous for this two-way input of analyzing comparison module 24 by 3 of synchronised clock generation modules.
Synchronization Control of the present invention is to carry out in the mode of beating timestamp to signal.
As seen, the present invention utilizes modulate emission system and the metastable characteristics of channel parameters, the prediction of modulation emission system and channel characteristics parameter is adopted the processing mode of off-line, replace the real-time characteristic parameter of channel with one group of characteristic parameter that data doped, thereby modulate emission system and channel characteristics parameter prediction are separated from demodulation, reduce the operand of demodulation module, real-time processing unit can be provided with according to the situation of channel and transmitter, only carry out necessary demodulation function, can improve performance, reduce unnecessary processing and power consumption, realize real real-time demodulation.Though offline mode is adopted in the above-mentioned parameter prediction, but be continuous deal with data, and the parameter of demodulated data and prediction is controlled by a master clock, adopts the mode of beating timestamp to signal to carry out, make carrier frequency, wave phase, timing information etc. can with the demodulating data synchronised.
Claims (9)
1, a kind of digital demodulation receiver comprises real-time demodulation module, it is characterized in that, also comprises modulate emission system and channel characteristics parameter prediction module and synchronised clock generation module, wherein:
Described real-time demodulation module receives described digital modulation signals, and it is carried out real-time demodulation, obtains the digital signal after the demodulation;
Described modulate emission system and channel characteristics parameter prediction module receive described digital modulation signals, by the computational analysis of off-line, dope the characteristic parameter of modulate emission system and channel, and deliver to the described real-time demodulation module control demodulating process that desynchronizes;
Described synchronised clock generation module is used to produce the reference clock that the parameters such as carrier frequency, carrier phase and timing information of the time that depends on when recovering provide.
2, digital demodulation receiver as claimed in claim 1, it is characterized in that, described modulate emission system and channel characteristics parameter prediction module comprise transmission data recovery module, digital modulation module, modulate emission system and channel model, analysis comparison module and characteristic parameter prediction module, wherein:
Described transmission data recovery module: be used to receive the described digital modulation signals of coming, under the situation of certain channel, the modulation signal that receives carried out demodulation, recover base band data through the channel distortion influence by Channel Transmission;
Described digital modulation module: be used for the base band data that to demodulate and be modulated into radiofrequency signal again, send into then in described modulate emission system and the channel model according to the modulation system of transmitting terminal;
Described modulate emission system and channel model: parameter simulations such as the interchannel noise that is obtained by described characteristic parameter prediction module, channel reflection distortion, carrier frequency shift, carrier phase offset, timing slip go out this modulate emission system and channel model, and the digital signal that will be modulated to radio frequency again is by this modulate emission system and channel model input;
Described analysis comparison module: be used for the digital modulation signals of described modulate emission system and channel model output and the described digital modulation signals by actual channel are compared and analyze, and give described characteristic parameter prediction module with the result;
Described characteristic parameter prediction module: the comparative result of the modulation signal that modulation signal that produces again according to described modulate emission system and channel model and actual reception arrive, in this module, adjust the parameter such as Channel Transmission, noise, carrier frequency-phase, timing information of modulate emission system and channel module adaptively.
3, digital demodulation receiver as claimed in claim 1, it is characterized in that the described modulate emission system that dopes and the characteristic parameter of channel comprise: the whole or part wherein of the timing information of the noise filtering parameter of the fine setting of carrier frequency, carrier phase, baseband filter and compensating parameter, interchannel, the compensating parameter of third-order non-linear distortion, sampling and the equalizing coefficient of channel equalization filter.
As claim 1,2 or 3 described new digital demodulate reception devices, it is characterized in that 4, described modulate emission system and channel characteristics parameter prediction module are handled the digital demodulation signal that receives, and may further comprise the steps to digital modulation signals:
(1) digital modulation signals that receives is carried out demodulation under the situation of certain channel, recover baseband signal;
(2) characteristic parameter that obtains according to described modulate emission system and channel characteristics parameter prediction module, a modulate emission system and channel model are set up in simulation;
(3) baseband signal that demodulates is modulated into radiofrequency signal again according to the modulation system that sends signal end, sends into then in modulate emission system and the channel model;
(4) will compare analysis with the digital modulation signals that passes through actual channel that receives by the modulation signal of model modulate emission system and channel;
(5) according to the result of comparative analysis, adjust modulate emission system and channel characteristics parameter adaptively, again this characteristic parameter is sent into modulate emission system and channel model, the modulation signal that produces is again carried out the simulation of actual modulated emission system and channel.
5, the new digital demodulate reception device to digital modulation signals as claimed in claim 1 is characterized in that, described real time digital signal is handled demodulation module and comprised:
The noise jamming filtration module is used for filtering noise jamming wherein when transmission of digital signals;
The carrier frequency recovery module is used for the demodulation of FM signal, promptly recovers the modulation signal that is reflected on the frequency change from incoming carrier;
The carrier phase recovery module is used for the demodulation of phase-modulated signal, promptly recovers the modulation signal that is reflected on the phase change from incoming carrier;
Regularly recover module, be used for determining correct timing position;
The correction of non-linear distortions module is used for the correction in the distortion of transmission of digital signals non-linear hour;
Adaptive balance module is used for reducing intersymbol interference, i.e. time domain equilibrium when transmission of digital signals;
Forward error correction block is used for error control, i.e. the coding of correctable error; And
The automatic gain control module is used to control the noise robustness of demodulation module.
As claim 1,3 or 5 described new digital demodulate reception devices, it is characterized in that 6, described real time digital signal is handled demodulation module the digital demodulation signal that receives is carried out the real-time digital demodulation, may further comprise the steps to digital modulation signals:
(1) digital modulation signals and its carrier signal with the frequency homophase that receive are carried out mixing, obtain containing the signal of base band data;
(2) signal that contains base band data after the mixing is passed through baseband filter, the baseband signal that obtains demodulating;
(3) with the baseband signal that demodulates at correct timing position, sample the original figure symbol that obtains transmitting according to symbol rate;
(4) will obtain exportable digital demodulation signal through the original figure symbol of the transmission of demodulation sampling by the channel equalization filter.
7, the new digital demodulate reception device to digital modulation signals as claimed in claim 1 is characterized in that, described clock synchronization module provides reference clock for generation recovers to depend on the parameter of time, thereby carries out Synchronization Control, and its Synchronization Control comprises:
Real time digital signal is handled demodulation module and modulate emission system and channel characteristics parameter prediction module carry out clock synchronization; And
To carry out clock synchronization by the modulation signal of model modulate emission system and channel and the digital modulation signals that passes through actual channel that receives.
8, the new digital demodulate reception device to digital modulation signals as claimed in claim 7 is characterized in that, the Synchronization Control that described clock synchronization module carries out is to carry out in the mode of beating timestamp to signal.
9, the new digital demodulate reception device to digital modulation signals as claimed in claim 7 is characterized in that, described generation recovers to depend on the parameter of time and comprises: carrier frequency, carrier phase and timing information.
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| CNA031264743A CN1529421A (en) | 2003-09-28 | 2003-09-28 | Digital demodulating-receiving device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102484488A (en) * | 2009-09-04 | 2012-05-30 | 日本电气株式会社 | Radio communication device having carrier phase noise elimination function and radio communication method |
| CN109691046A (en) * | 2016-09-15 | 2019-04-26 | 索尼半导体解决方案公司 | Sending device and system |
| CN110224721A (en) * | 2015-03-27 | 2019-09-10 | 意法半导体(鲁塞)公司 | To the analog signal from transmission channel, the signal delivered especially by power line communication, the method handled |
| CN112949328A (en) * | 2019-12-11 | 2021-06-11 | 上海烨煊信息技术有限公司 | Industrial ultrahigh frequency RFID read-write device and RFID radio frequency identification system |
-
2003
- 2003-09-28 CN CNA031264743A patent/CN1529421A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102484488A (en) * | 2009-09-04 | 2012-05-30 | 日本电气株式会社 | Radio communication device having carrier phase noise elimination function and radio communication method |
| US8798549B2 (en) | 2009-09-04 | 2014-08-05 | Nec Corporation | Radio communication device having carrier phase noise elimination function, and radio communication method |
| CN102484488B (en) * | 2009-09-04 | 2014-08-06 | 日本电气株式会社 | Radio communication device having carrier phase noise elimination function and radio communication method |
| CN110224721A (en) * | 2015-03-27 | 2019-09-10 | 意法半导体(鲁塞)公司 | To the analog signal from transmission channel, the signal delivered especially by power line communication, the method handled |
| CN110224721B (en) * | 2015-03-27 | 2021-06-04 | 意法半导体(鲁塞)公司 | Method and receiver for processing an analog signal from a transmission channel |
| CN109691046A (en) * | 2016-09-15 | 2019-04-26 | 索尼半导体解决方案公司 | Sending device and system |
| CN112949328A (en) * | 2019-12-11 | 2021-06-11 | 上海烨煊信息技术有限公司 | Industrial ultrahigh frequency RFID read-write device and RFID radio frequency identification system |
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