CN1472903A - CDMA receiver system (II) with digital AGC - Google Patents
CDMA receiver system (II) with digital AGC Download PDFInfo
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- CN1472903A CN1472903A CNA03121116XA CN03121116A CN1472903A CN 1472903 A CN1472903 A CN 1472903A CN A03121116X A CNA03121116X A CN A03121116XA CN 03121116 A CN03121116 A CN 03121116A CN 1472903 A CN1472903 A CN 1472903A
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Abstract
A CDMA receptor system adopting full-digital AGC comprises an intermediate frequency decoding unit and a base band signal processing unit. Said intermediate frequency decoding unit receives analog intermediate frequency signal and outputs digital base band signal, comprising the successively connected A/D converter, orthogonal decoder, digital filter for down frequency conversion and formation, characterized in that this unit further comprises a signal power detector, an automatic generator for gain controlling parameters and a quantification table; said signal power detector and automatic generator for gain controlling parameters are connected successively; said signal power detector measures the energy of the power collecting signal in digital base band output by the filter of formation, said automatic generator for gain controlling parameters outputs AGC parameters
Description
Technical field
The invention belongs to wireless mobile communications wireless access technology field, relate to a kind of wireless intermediate-frequency receiver, more definite will be a kind of cdma receiver system that adopts digital AGC.
Background technology
Accompanying drawing 1 demonstrates wireless intermediate-frequency receiver, mainly comprise radio frequency amplification and down-converter unit, intermediate frequency demodulation unit and baseband signal processing unit, the radio frequency that is connected with reception antenna amplifies and down-converter unit output intermediate-freuqncy signal, intermediate frequency demodulation unit output baseband signal.Early stage wireless intermediate-frequency receiver all adopts analogy method to realize, have problems such as costing an arm and a leg, debug complexity, along with the development of technology and technology, wireless intermediate-frequency receiver develops into digital receiver from analog receiver gradually.
Initial digital receiver just partly adopts digital technology to handle at baseband signal processing unit, be called the analog intermediate frequency digital receiver, can realize the work that most of data-signal is handled, but base band and intermediate frequency analogue device such as baseband filter still can't be realized digitlization.Along with further developing of technology, the intermediate frequency demodulation part also adopts digital signal technique to handle, and is called digital if receiver.
Shown in the accompanying drawing 2, be to amplify and the down-converter unit part at radio frequency, promptly in the amplifier 21 that is linked in sequence, frequency mixer 22, band pass filter 23 and 24 dynamic ranges of controlling intermediate frequency AGC by the employing radio frequency power detector of simulation variable gain amplifier, signal excursion when promptly reducing the A/D sampling by simulation AGC is controlled accurately to signal.In this technical scheme, the analogue signal amplitude that requires simulation variable gain amplifier 24 to export can not surpass the scope of A/D conversion incoming level, otherwise will cause the blasting of quantification, also require the analog signal of simulation variable gain amplifier 24 outputs could guarantee follow-up processing accuracy as far as possible near the maximum input level of A/D conversion.This scheme exists AGC to control step-length, precision is not accurate enough, and AGC is difficult to keep the problem of linearity in great dynamic range.
Accompanying drawing 3 is depicted as the another kind of automatic gain controlling schemes of digital if receiver, be at the intermediate frequency demodulation cell mesh, promptly the simulation variable gain amplifier 31 that is linked in sequence, A/D converter 32, if demodulator 33 and down 34 of samplers be the amplification quantity of behind base band demodulating, controlling AGC by adopting intermediate frequency power detector 35 to control the amplification quantity of variable gain amplifier 31 (AGC) according to the power of digital baseband signal.In this scheme, need to adopt the A/D converter of great dynamic range to satisfy the demand of dynamic range of signals, can realize than analogue system more accurately, control flexibly, but have the relatively large problem of data-signal treating capacity.
Summary of the invention
The objective of the invention is to design the cdma receiver system that adopts digital AGC, with simple, practicality is the invention aim, reduce the Digital Signal Processing amount significantly, in digital AGC, adopt the feed-forward AGC mode, in the AGC loop, cancelled the variable gain amplifier of simulation, reduce cost, reached the purpose of accurate control simultaneously.
Technical scheme of the present invention is as follows:
Technical scheme of the present invention is achieved in that a kind of cdma receiver system that adopts digital AGC, comprise intermediate frequency demodulation unit and baseband signal processing unit: described intermediate frequency demodulation unit receives the intermediate-freuqncy signal of simulation, the output digital baseband signal, comprise the A/D converter, quadrature demodulator, Digital Down Convert and the formed filter that are linked in sequence, it is characterized in that: also include signal power detector, automatic gaining controling parameter maker and quantization table; Described signal power detector and automatic gaining controling parameter maker are linked in sequence; Described signal power detector is to measure the energy of power collecting signal of the digital baseband of formed filter output, described automatic gaining controling parameter maker is to described quantization table output AGC parameter, be used to guarantee baseband signal output within certain scope, export behind the power collecting signal inquiry quantization table of the digital baseband signal of described intermediate frequency demodulation unit output by the digital baseband of formed filter output.Whole system adopts digital AGC, has cancelled original analog gain amplifier;
Described signal power detector receives the baseband signal of formed filter output, is used to measure the energy of digital baseband signal, adopts after the demodulation of QPSK (quaternary PSK) signal, and the energy of digital baseband signal is a quadrature two paths of signals energy sum, by I
2+ Q
2Algorithm generates, or adopts | I|+|Q| algorithm (wherein I is the in-phase branch data, and Q is the quadrature branch data);
Described automatic gaining controling parameter maker (AGC parameter generators) is added up by distributing to received signal, calculate the mean square deviation (SIGMA) that received signal distributes, to guarantee that most of received signal is in the scope that quantizes once more, and according to received signal distribution generation correction factor, final generation rank offer described quantization table.
Also include DC filter, be arranged between Digital Down Convert and formed filter; Also be provided with filter between described signal power detector and described automatic gaining controling parameter maker.
Described DC filter is the digital filter of isolated DC.
The dynamic range that analog if signal had before the A/D converter of the great dynamic range that described A/D converter is the N bit, described A/D converter needs M significant bit data at least, then N＞M should be arranged.
Common digital if receiver adopts in A/D converter front, increases the AGC of simulation, and the size by the signal amplitude before the adjustment A/D conversion guarantees that the signal amplitude after the A/D conversion meets the requirement of base band signal process to signal energy.And the cdma receiver system of the digital AGC of employing of the present invention, then different with common digital if receiver, on whole radio frequency and middle frequency link, all there is not the AGC of simulation to exist, but finish the function of whole AGC by the digital feed forward mode, owing to adopt feed-forward mode, so locking time is quick, there is not the self-excitation problem, advantages such as adopting the cdma receiver system of digital AGC to have does not need debugging, and link is stable, and is with low cost.
Description of drawings
Fig. 1 is the principle structure block diagram of common wireless intermediate-frequency receiver
Fig. 2 is the principle structure block diagram of analog intermediate frequency digital receiver AGC scheme
Fig. 3 is the principle structure block diagram that adopts the digital if receiver AGC scheme of base band control
Fig. 4 is the structured flowchart that the present invention adopts the cdma receiver system of digital AGC
Specific implementation
Referring to Fig. 4, adopt the structure of the cdma receiver system of digital AGC shown in the figure, form by antenna element 41, radio frequency amplification and down-converter unit 42, intermediate frequency demodulation unit 43 and baseband signal processing unit 44.Radio frequency amplifies and down-converter unit 42 output analog if signals, intermediate frequency demodulation unit 43 output digital baseband signals.The cdma receiver system that then forms the digital AGC of employing of the present invention by intermediate frequency demodulation unit 43 and baseband signal processing unit 44.
Intermediate frequency demodulation unit 43 includes A/D converter 4301, quadrature demodulator 4302, digital down converter 4303, DC filter 4304, formed filter 4305, quantization table 4306, signal power detection 4307, filter 4308, AGC parameter generators 4309.Analog if signal inputs to A/D converter 4301, by quantization table 4306 output digital baseband signals.
Quadrature demodulator 4302 in the intermediate frequency demodulation unit 43, digital down converter 4303 and formed filter are the necessary link of Digital IF Processing, and be identical with traditional processing method.
The present invention is divided into four parts with AGC, i.e. signal power detection 4307, filtering 4308, the generation 4309 of AGC parameter and quantization table 4306, and this four part integrates and finishes the AGC function jointly.
Signal power detector 4307 receives the baseband signal of formed filter 4305 outputs, be used to measure the energy of digital baseband signal, if quadrature demodulator adopts the demodulation of QPSK (quaternary PSK) signal, then the energy signal of digital baseband signal is a quadrature two paths of signals energy sum, can be by I
2+ Q
2Algorithm generates (wherein I is the in-phase branch data, and Q is the quadrature branch data), and the significant bit number of establishing I, Q is M, then I
2+ Q
2The significant bit number be 2M+1 because I, Q be the great dynamic range signal, therefore adopt I
2+ Q
2Algorithm measurement signal energy data computation amount is very huge.In order to reduce the data computation amount, also can adopt | I|+|Q| substitutes sqr (I
2+ Q
2), carry out the baseband signal energy measurement, adopt | when I|+|Q| measures the baseband signal energy, its | the significant bit number of I|+|Q| is the M+1 position, thereby has effectively reduced the digital operation amount.
Filter 4308 also has anti-stop signal and is subjected to the effect that burst noise disturbs except the effect with conventional power detection filter device.
AGC parameter generators 4309 is added up by distributing to received signal, calculate the mean square deviation (SIGMA) that received signal distributes, to guarantee most of received signal, as 99.9%, be in the scope that quantizes once more, and according to received signal distribution generation correction factor, final generation rank offer quantization table 4306.In wireless technical field, wireless signal is generally described with the Gaussian channel model, the n one-bit data signal of AGC output obey N (O, in the time of SIGMA), SIGMA
2Be the average energy of received signal.
Final digital baseband signal is determined quantization table 4306 by digital baseband signal.Digital baseband signal through quantization table 4306 definite outputs as in cdma system, should be I, the Q signal of 4bit, and the energy of baseband signal should remain on I
2+ Q
2=18.
DC filter 4304 is digital filters of an isolated DC, and the interference that can isolated DC signal be caused can be accepted or rejected according to whether DC offset circuit being arranged.
Signal flow of the present invention following (referring to Fig. 4):
The wireless signal that reception antenna unit 41 receives from travelling carriage, delivering to radio frequency amplifies and down-converter unit 42, after carrying out radio frequency amplification and down-conversion, with RF signal transformation is intermediate-freuqncy signal, deliver to intermediate frequency demodulation unit 43, A/D converter 4301 is at first with the analog signal of intermediate frequency in intermediate frequency demodulation unit 43, after being transformed to digital signal, in delivering to quadrature demodulator 4302, carry out quadrature demodulation, generate the I of quadrature, Q signal, digital down converter 4303 is with the I of digital quadrature, Q signal carries out Digital Down Convert, to the baseband signal of down-conversion after carrying out DC filtering 4304 and molding filtration 4305, carry out AGC and handle, AGC mainly detects 4307 by signal power, filter 4308, AGC parameter generators 4309 and quantization table 4306 are formed.Baseband signal at first is sent to carries out power detection in the signal power detector 4307, and then after delivering to filter 4308 and carrying out filtering and anti-bursty interference filtering, deliver to generation rank in the AGC parameter generators 4309, the amount rank are sent in the quantization table, digital baseband signal is quantized, and final output meets the baseband signal that baseband signal processing unit 44 requires.
Claims (7)
1, a kind of cdma receiver system that adopts digital AGC, comprise intermediate frequency demodulation unit and baseband signal processing unit: described intermediate frequency demodulation unit receives the intermediate-freuqncy signal of simulation, the output digital baseband signal, comprise the A/D converter, quadrature demodulator, Digital Down Convert and the formed filter that are linked in sequence, it is characterized in that: also include signal power detector, automatic gaining controling parameter maker and quantization table; Described signal power detector and automatic gaining controling parameter maker are linked in sequence; Described signal power detector is to measure the energy of power collecting signal of the digital baseband of formed filter output, described automatic gaining controling parameter maker is to described quantization table output AGC parameter, be used to guarantee baseband signal output within certain scope, export behind the power collecting signal inquiry quantization table of the digital baseband signal of described intermediate frequency demodulation unit output by the digital baseband of formed filter output.Whole system adopts digital AGC, has cancelled original analog gain amplifier.
2, the cdma receiver system of the digital AGC of employing as claimed in claim 1, it is characterized in that: described signal power detector receives the baseband signal of formed filter output, be used to measure the energy of digital baseband signal, adopt after the demodulation of QPSK (quaternary PSK) signal, the energy of digital baseband signal is a quadrature two paths of signals energy sum, by I
2+ Q
2Algorithm generates, or adopts | I|+|Q| algorithm (wherein I is the in-phase branch data, and Q is the quadrature branch data).
3, the cdma receiver system of the digital AGC of employing as claimed in claim 1, it is characterized in that: described automatic gaining controling parameter maker (AGC parameter generators) is added up by distributing to received signal, calculate the mean square deviation (SIGMA) that received signal distributes, to guarantee that most of received signal is in the scope that quantizes once more, and according to received signal distribution generation correction factor, final generation rank offer described quantization table.
4, the cdma receiver system of the digital AGC of employing as claimed in claim 1 is characterized in that: also include DC filter, be arranged between Digital Down Convert and formed filter.
5, the cdma receiver system of the digital AGC of employing as claimed in claim 4 is characterized in that: described DC filter is the digital filter of isolated DC.
6, as the cdma receiver system of claim 1 or the digital AGC of 5 described employings, it is characterized in that: also be provided with filter between described signal power detector and described automatic gaining controling parameter maker.
7, as the cdma receiver system of claim 1,2,3, the digital AGC of 4 or 5 described employings, it is characterized in that: the A/D converter of the great dynamic range that described A/D converter is the N bit, the dynamic range that analog if signal had before the described A/D converter needs M significant bit data at least, then N＞M should be arranged.
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| Application Number | Priority Date | Filing Date | Title |
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| CNA03121116XA CN1472903A (en) | 2003-03-27 | 2003-03-27 | CDMA receiver system (II) with digital AGC |
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| CNA03121116XA CN1472903A (en) | 2003-03-27 | 2003-03-27 | CDMA receiver system (II) with digital AGC |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101207428B (en) * | 2006-12-21 | 2011-08-10 | 京信通信技术(广州)有限公司 | Method for anti-self excitation of straight amplification station system |
| CN104601266A (en) * | 2015-02-13 | 2015-05-06 | 东南大学 | System and method for monitoring broadcast signals in online manner and parallelly demodulating same |
| CN108599805A (en) * | 2018-07-06 | 2018-09-28 | 航天恒星科技有限公司 | A kind of forward communications circuit based on baseband radio integrated design |
| CN109120292A (en) * | 2018-08-06 | 2019-01-01 | 电子科技大学 | A kind of digital automatic gain control system and method |
-
2003
- 2003-03-27 CN CNA03121116XA patent/CN1472903A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101207428B (en) * | 2006-12-21 | 2011-08-10 | 京信通信技术(广州)有限公司 | Method for anti-self excitation of straight amplification station system |
| CN104601266A (en) * | 2015-02-13 | 2015-05-06 | 东南大学 | System and method for monitoring broadcast signals in online manner and parallelly demodulating same |
| CN104601266B (en) * | 2015-02-13 | 2017-11-07 | 东南大学 | A kind of system of broadcast singal on-line monitoring and parallel demodulation |
| CN108599805A (en) * | 2018-07-06 | 2018-09-28 | 航天恒星科技有限公司 | A kind of forward communications circuit based on baseband radio integrated design |
| CN109120292A (en) * | 2018-08-06 | 2019-01-01 | 电子科技大学 | A kind of digital automatic gain control system and method |
| CN109120292B (en) * | 2018-08-06 | 2019-11-05 | 电子科技大学 | A kind of digital automatic gain control system and method |
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Effective date of registration: 20060310 Address after: No. 398, Hangzhou, Wensanlu Road Applicant after: Dongfang Communication Co., Ltd. Address before: Upper two street, Beijing, Haidian District Applicant before: Dongfang Communication Sci. & Tech. Dev. Co., Ltd. |
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