CN1330456A - Automatic gain control (AGC) method for digital base band - Google Patents
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Abstract
An automatic gain control (AGC) method for digital baseband includes such steps as digitalizing the received signals, calculating the energy of received signals, the convertion from signal energy to signal amplitude, creating dynamic quantized AGC table, quantizing AGC by mapping method and outputting the AGC. Its advantages include high regulatino precision, short response time and real-time regulation of resolution.
Description
Signal processing technology in the present invention relates to communicate by letter refers to the high-precision automatic gain control (AGC) method for digital base band of a kind of dynamic adjustable resolution to signal processing in all high-speed signal acquisitions especially.
In the narrow-band FM receiver of simulation, normally utilize FM demodulator to obtain the phase information of moment waveform.Present FM receiver normally adds a frequency discriminator behind amplitude limiter, wherein, the effect of amplitude limiter is to make the energy of input signal keep a definite value, thereby the signal that guarantees the frequency discriminator input has maximum signal to noise ratio.Yet, such analog signal processing technology generally includes meticulous filter circuit, and these circuit normally are made of some discrete electronic devices and components, thereby the whole system reaction speed is slow, low precision, and existing result shows that the systematic function of employing linear digital demodulation techniques can be better than the analog demodulator technology.
Therefore, in existing receiving system, all adopt digital receiver mostly.General digital receiver comprises the amplifier of a variable gain, the variation of its gain is that outer signal controlled, this process of utilizing a control signal to adjust the received signal processing gain just is called automatic gain control (Automatic Gain Control abbreviates AGC as).The AGC function is absolutely necessary in the practical application of digital receiver, because the signal excursion that receiver receives is big, because the higher sampling rate and the restriction of A-D converter resolution, the function that receiver must have AGC just can overcome the signal fadeout that declines slowly and decline and cause soon.This shows that adopting the purpose of AGC in system is exactly when the power of radio-frequency input signals changes, keep output signal to be roughly steady state value.Typical A GC system comprises the radio frequency amplifier or the intermediate frequency amplifier of integrator on range detector, the feedback path or filter, one or more controllable gain.
In conjunction with Fig. 2 as can be seen, in digital receiver, the processing procedure of AGC: at first be that signal is converted to digital signal through A-D converter, this signal being outputed to the measurement of carrying out signal power in the module 21 calculates again, then signal power that measures and predefined desired signal power value are compared in module 22, resulting error signal just can obtain the control signal of amplifier after module 23 process Threshold detection.The difference of signal power that is actually signal power that utilize to measure and expectation is adjusted signal strength signal intensity as the control signal of variable gain amplifier.In the processing procedure of above-mentioned AGC, when the generated error signal, the signal of being imported will compare with predefined reference signal; Signal when the Threshold detection also can with set threshold value and compare, and this reference signal value and threshold value preestablish and choose, and can not change because of the difference of equipment institute running environment thereupon, so will influence the precision of adjusting.
In sum as can be seen, in current existing AGC technology, simulation AGC is owing to system response is slow, low precision is unfavorable for signal processing.Though common digital AGC has the difference of matter with simulation AGC, but owing to what adopt usually in digital AGC is that staged is regulated to adapt to hard-wired requirement, it is slow equally also can to produce system response, the problem of low precision is such as when quantizing, because the restriction of hardware, quantization table can only be regulated generation step by step, its step-length can only be adjusted certain amplitude at every turn, so can cause the whole system delay of response, and owing to through step degree of regulation is affected.In addition, though existing digital AGC can Adjustable real-time when handling, it can not make a response when channel model changes at once, and certain time-delay is arranged, and real-time is not strong.Have to be exactly, precision is not high as a result owing to the influence of environment makes entire process probably in when operation for existing digital AGC, because the restriction that can be subjected to running environment is chosen in the setting of some of them threshold value again.
In view of this, purpose of the present invention just is to propose a kind of automatic gain control (AGC) method for digital base band, make its all advantages that not only have digital AGC, and degree of regulation is higher, and the error rate is lower, and the reaction time is short, and resolution also can be according to the channel model real-time regulated.
For achieving the above object, the invention provides a kind of automatic gain control (AGC) method for digital base band, this method is realized by following step:
(1) handles by the mould/transformation of variables of A-D converter, the base-band analog signal of handling through the base band pulse shaping filter that receives is converted to digital signal;
(2) above-mentioned digital signal is sent simultaneously to AGC quantization modules and received signal intensity indicating module (RSSI), calculate the energy of the baseband digital signal receive, flow to a filter as the output signal of RSSI module by received signal intensity indicating module;
(3) filter to the received signal energy make a ranking operation; Simultaneously, the energy valuation of received signal is converted to the amplitude valuation of signal, and the amplitude peak of received signal is sent to dynamic AGC quantization table module;
(4) amplitude peak in the output signal of filter and the existing dynamic AGC quantization table is compared, if the amplitude peak of received signal greater than the amplitude peak of existing quantization table, then increases the amplitude peak of existing quantization table, the amplitude of increase can be regulated; If less than the amplitude of existing quantization table, then reduce the amplitude peak of existing quantization table, the value of change also can be regulated;
(5) output signal that is generated by dynamic AGC quantization table adopts mapping mode directly to obtain final output signal with the data-signal of process AGC after straight filter process with quantization table.
This method also further may further comprise the steps: remove with the DC component in automatic gain control (AGC) digital signal after straight filter is with analog to digital conversion, and the digital signal after will handling is passed to AGC quantization modules and received signal intensity indicating module (RSSI) simultaneously.
Wherein, dynamically the generative process of AGC quantization table is to determine jointly that according to the signal of AGC resolution control signal and filter output its resolution is determined by the channel model that is adopted.
The test point of AGC control signal is at digital baseband, and the quantizing process of whole AGC also is to carry out at digital baseband.
Can realize the signal processing apparatus of said method, at least comprise an analog to digital conversion module, it is characterized in that: comprise further that also an AGC is every straight filtration module, a received signal intensity indicating module, a filtration module, a dynamic AGC quantization table module, an AGC quantization modules and an AGC resolution control signal module.
One base-band analog signal outputs to AGC every straight filtration module after the analog to digital conversion module converts is digital signal, through the processing of AGC every straight filtration module isolated DC component, output signal is delivered to received signal intensity indicating module and AGC quantization modules simultaneously, received signal intensity indicating module calculates the energy of this digital signal, and output to filtration module as output signal, filtration module is made a ranking operation to signal, energy valuation with signal simultaneously is converted into the amplitude valuation, and the amplitude peak of signal sent to dynamic AGC quantization table module, dynamically AGC quantization table module dynamically generates up-to-date dynamic AGC quantization table according to the signal amplitude value, and the signal that signal that the AGC quantization modules is sent dynamic AGC quantization table module here and AGC send here every straight filtration module adopts mapping mode directly to draw final output signal.
A kind of automatic gain control (AGC) method for digital base band provided by the present invention, can be under input signal variation situation greatly, keep the amplitude of output signal to reach full scale as far as possible, can make digital receiver have best signal to noise ratio like this, thereby the quantizing noise and the error rate have been reduced, improve the resolution of signal, also improved reliability; In system's actual motion, may adopt different channel models, the amplitude of its input signal is also just different so, the present invention can be very fast the difference according to input signal amplitude, regulate according to different signal resolution, shortened the reaction time, make its real-time stronger, react faster; In this method,, can handle according to the frequency of input signal fully because the generative process of quantization table does not relate to the high-speed sampling of signal, thus the precision of quantization table can do very high, thereby improved degree of regulation, further improved the performance of system.
Relevant detailed description of the present invention and technology contents, conjunction with figs. is described as follows:
Fig. 1 is a receiving system model schematic diagram.
Fig. 2 is a kind of processing block diagram of existing AGC technology.
Fig. 3 is the realization block diagram of Dynamic High-accuracy controlled resolution digital baseband AGC.
Fig. 1 has provided digital Auto Gain and has been controlled at residing position in the receiver.As shown in Figure 1, receiver antenna 11 at first receives high-frequency wireless signals, converts high-frequency received signal to baseband signal by Frequency mixing processing 12, in order to overcome intersymbol interference, allow the baseband signal that receives through receiving the processing of base band pulse shaping filter 13, reduce intersymbol interference.Its output signal is input to the automatic gain control circuit 14 of numeral, finish the automatic gain control function of received signal, the output signal of digital automatic gain control circuit is input in multipath (RAKE) receiver 15 and is merged processing, the output signal that obtains is sent into channel decoder 16, thereby be reduced to original source signal, handle obtaining original voice or data-signal 18 again through the decoding of source decoder 17.Wherein, RAKE receiver can be used to overcome the influence of multipath fading in the channel.
As seen from Figure 1, the radiofrequency signal that receives is at first passed through the processing procedure of mixing, and high-frequency signal is transformed into intermediate frequency, baseband signal, and baseband signal just enters the automatic gain control module through handling with the shaping of the pulse shaping filter that is complementary of making a start.
So, can see that in conjunction with Fig. 3 the concrete implementation of Dynamic High-accuracy controlled resolution digital baseband AGC provided by the present invention is such:
The baseband signal 31 through the processing of base band pulse shaping filter that 1, at first will receive is input to A-D converter 32 and carries out the analog to digital conversion processing, is digital signal with the analog signal conversion that receives.In order to guarantee bigger dynamic range, adopt A-D converter (A/D) converter 32 of 12 bits even more bits.When base band demodulating, as long as just can guarantee the result that searches for when satisfying significant bit and being 4 bits, mainly be because the dynamic range redundancy that the size change of signal can cause in the middle of this, thereby when choosing the concrete precision of A/D conversion, should adopt more bit number as far as possible, also to consider hardware complexity certainly.
2, to be in harmonious proportion the operand of filtering in order reducing to separate in the back, and to keep sufficient significant bit, before demodulation, add an AGC every straight filter 34.AGC is a digital filter that is used for isolated DC every straight filter, mainly is to be used for the DC component in the digital signal after the analog to digital conversion 33 is removed.Because in the environment of reality, can there be the part DC component in the process of signal transmission, be exactly the DC component that isolates out in the signal every the main effect of straight filter, thereby reduce The noise, because have noise in the DC component.
3, be transported to two modules simultaneously through the digital signal 35 behind the AGC filter filtering, that is: AGC quantization modules 312 among Fig. 3 and received signal intensity indicating module 36 (RSSI:ReceivedSignal Strength Indicator).Received signal intensity indicating module 36 is mainly used to calculate the power (being signal energy) of the baseband digital signal that receives, corresponding variation can take place according to the difference of the modulation system that is adopted in the computational methods of its signal power, for example system adopts 4 phase phase-shift keying (QPSK) modulation systems, then the generating mode of RSSI module output signal be in-phase component I square add quadrature component Q square, the two and promptly: I
2+ Q
2, with this output signal 37 as the RSSI module.
4, the output signal 37 of received signal volume indicator 36 is input to a filter 38, and the main effect of filter 38 is that energy is made a ranking operation to the received signal, and the main cause of using this filter is the correlation of signal between the sampled point of front and back.Be actually in the concrete processing procedure of filter and calculate according to following formula (1):
S (n)=aS (n-1)+(1-a) S (n) (1) is in formula (1), and S (n) represents the intensity of current sampled signal, the intensity of the sampled signal of S (n-1) expression previous moment, and a represents weighted factor.Can clearly be seen that by formula (1), the energy valuation of current demand signal and the energy valuation of front signal are closely related, thus through being equivalent to increase the timing statistics of signal strength signal intensity after so handling, and, do the destabilizing factor that this ranking operation can happen suddenly according to the correlation filtering of front and back signal, guarantee the stability of signal, improved the reliability of signal energy valuation.
Processing procedure in filter 38 is except above-mentioned weighting operation, the conversion process that also comprises a signal energy and signal amplitude, because the amount of measuring in received signal volume indicator 36 is the energy of signal, rather than the amplitude of signal, and the amount that need quantize when quantizing is the amplitude of received signal, therefore in this filter 38, also the energy valuation of received signal will be converted to the amplitude valuation of signal, and the amplitude peak of received signal is sent to AGC dynamic quantization table module 311, and wherein range value equals the energy value extraction of square root.
5, the output signal 39 of filter 38 is input to dynamic AGC quantization table module 311.The resolution of AGC quantization table module is determined by the channel model that is adopted, because can reduce quantizing noise like this and reduce the error rate.The output signal 39 of filter 38 compares with the amplitude peak of existing quantization table, if the amplitude peak of received signal greater than the amplitude peak of existing quantization table, then increases the amplitude peak of existing quantization table, the amplitude of increase can be regulated; If less than the amplitude of existing quantization table, then reduce the amplitude peak of existing quantization table, the value of change also can be regulated; Therefore the generative process of whole AGC dynamic quantization table is to determine jointly according to the signal of AGC resolution control signal 310 and filter output.Owing to all be frequency processing in the generative process of quantization table according to input signal, do not relate to the high-speed sampling of signal, thereby the precision of quantization table can do very high.
6, the quantization table that is promptly generated by the output signal 312 of dynamic AGC quantization table generation module is sent into AGC quantization modules 313, also be input to AGC quantization modules 313 through the data-signal 35 of AGC after straight filter 34 is handled simultaneously, amplitude according to the data-signal of importing, adopt mapping mode directly to obtain final output signal with quantization table, thereby avoided signal is done the multiplication and division computing.The bit number of final output signal might not be 4 bits, can determine jointly according to the requirement of hardware and to the requirement of precision.
The test point of AGC control signal is at digital baseband, and the quantizing process of whole AGC also is to carry out in base band.
Said method has solved the problem of existing digital AGC, makes that the digital AGC degree of regulation is higher, and the reaction time is shorter, and real-time is stronger.
See also shown in Figure 3ly again, realize that the device of above-mentioned automatic gain control (AGC) method for digital base band comprises at least: analog to digital conversion, AGC are every straight filtering, the indication of received signal intensity, filtering, dynamically AGC quantization table, AGC quantize and modules such as AGC resolution control signal.
The concrete processing procedure of this device is such: a base-band analog signal outputs to AGC every straight filtration module after the analog to digital conversion module converts is digital signal, by AGC after straight filtration module is done the isolated DC component and is handled, deliver to received signal intensity indicating module and AGC quantization modules simultaneously, received signal intensity indicating module is used to calculate the energy of this digital signal, and energy value outputed to filtration module, filtration module is made a ranking operation to signal, energy valuation with signal simultaneously is converted into the amplitude valuation, so that use when quantizing, at last the amplitude peak of signal is sent to dynamic AGC quantization table module, dynamically AGC quantization table module dynamically generates up-to-date dynamic AGC quantization table according to the signal amplitude value, and the signal that signal that the AGC quantization modules is sent dynamic AGC quantization table module here and AGC send here every straight filtration module adopts mapping mode directly to draw final output signal.In addition, AGC resolution control signal module mainly is when setting up in system, the environmental aspect around the test, the situation of controlled signal after treatment.This control signal is to leave among the register of FPGA, uses in order to dynamic AGC quantization table as parameter.
The specific implementation of this device can adopt multiple mode: one, analog to digital conversion module in the device is directly finished with A-D converter, AGC adopts an AGC every straight filter every straight filtration module, and other module is all realized by a programmable logic device (FPGA).Its two, the analog to digital conversion in the device, AGC are directly realized every straight filter and filter by A-D converter, AGC every straight filtering and filtration module, and other module is realized by FPGA.The third mode is exactly that this device is realized its repertoire by a FPGA fully.Above-mentioned three kinds of modes all are consistent to the Signal Processing process, and are just different on the comfort level of processing time speed and realization, can be according to user's needs in different ways.
In sum, the present invention is not only applicable to the digital demodulation of various digital radiocommunication receivers such as digital cellular wireless communication system, and its notion and method are applicable to the signal processing in all wired and radio communication high speed signals collecting simultaneously.Above-mentioned example only is a preferred embodiment of the present invention, is not to be used for limiting protection scope of the present invention.
Claims (13)
1, a kind of automatic gain control (AGC) method for digital base band is characterized in that the realization of this method is made up of following step:
(1) handles by the mould/transformation of variables of A-D converter, the base-band analog signal of handling through the base band pulse shaping filter that receives is converted to digital signal;
(2) this digital signal is sent simultaneously to AGC quantization modules and received signal intensity indicating module (RSSI), calculate the energy of the baseband digital signal receive, flow to a filter as the output signal of RSSI module by received signal intensity indicating module;
(3) filter to the received signal energy make a ranking operation; Simultaneously, the energy valuation of received signal is converted to the amplitude valuation of signal, and the amplitude peak of received signal is sent to dynamic AGC quantization table module;
(4) amplitude peak in the output signal of filter and the existing dynamic AGC quantization table is compared, if the amplitude peak of received signal greater than the amplitude peak of existing quantization table, then increases the amplitude peak of existing quantization table, the amplitude of increase can be regulated; If less than the amplitude of existing quantization table, then reduce the amplitude peak of existing quantization table, the value of change also can be regulated;
(5) output signal that is generated by dynamic AGC quantization table adopts mapping mode directly to obtain final output signal with the data-signal of process AGC after straight filter process with quantization table.
2, method according to claim 1, it is characterized in that this method also further may further comprise the steps: remove with the DC component in automatic gain control (AGC) digital signal after straight filter is with analog to digital conversion, and the digital signal after will handling is passed to AGC quantization modules and received signal intensity indicating module (RSSI) simultaneously.
3, method according to claim 1 is characterized in that: the test point of described AGC control signal is at digital baseband, and the quantizing process of whole AGC also is to carry out at digital baseband.
4, method according to claim 1 is characterized in that: corresponding variation takes place according to the difference of the modulation system that is adopted in the computational methods of the signal energy described in the step 2.
5, according to claim 1 or 4 described methods, it is characterized in that: described signal energy computation is in 4 phase phase-shift keying modulating systems, and the mode that the output signal of RSSI module generates is square (I of in-phase component
2) add square (Q of quadrature component
2).
6, method according to claim 1 is characterized in that: the generative process of the dynamic AGC quantization table described in the step 4 is to determine jointly according to the signal of AGC resolution control signal and filter output.
7, method according to claim 6 is characterized in that: the resolution of described dynamic AGC quantization table module is determined by the channel model that is adopted.
8, method according to claim 1 is characterized in that: the bit number of the final output signal described in the step 5 is determined jointly according to the requirement of hardware and to the requirement of precision.
9, a kind of signal processing apparatus of realizing the described method of claim 1, at least comprise an analog to digital conversion module, it is characterized in that: comprise further that also an AGC is every straight filtration module, a received signal intensity indicating module, a filtration module, a dynamic AGC quantization table module, an AGC quantization modules and an AGC resolution control signal module;
One base-band analog signal outputs to AGC every straight filtration module after the analog to digital conversion module converts is digital signal, through the processing of AGC every straight filtration module isolated DC component, output signal is delivered to received signal intensity indicating module and AGC quantization modules simultaneously, received signal intensity indicating module calculates the energy of this digital signal, and output to filtration module as output signal, filtration module is made a ranking operation to signal, energy valuation with signal simultaneously is converted into the amplitude valuation, and the amplitude peak of signal sent to dynamic AGC quantization table module, dynamically AGC quantization table module dynamically generates up-to-date dynamic AGC quantization table according to the signal amplitude value, and the signal that signal that the AGC quantization modules is sent dynamic AGC quantization table module here and AGC send here every straight filtration module adopts mapping mode directly to draw final output signal;
Wherein, dynamically AGC quantization table ground generative process is to determine jointly according to the output signal of AGC resolution control module and the output signal of filtration module.
10, device according to claim 9 is characterized in that: described analog to digital conversion module can be an A-D converter, and its bit number that adopts is greater than the output bit number of AGC, and choosing by hard-wired complexity of bit number determined.
11, device according to claim 10 is characterized in that: described A-D converter can adopt 12 bits even more bits.
12, device according to claim 9 is characterized in that: described AGC can be an AGC every straight filter every straight filtration module, is one to be used for isolating out the digital filter of DC component in the signal.
13, device according to claim 9 is characterized in that: described filtration module can be a filter.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100372343C (en) * | 2004-08-02 | 2008-02-27 | 北京天碁科技有限公司 | Controlling device for digital pulse formed filter output gain |
| CN100459793C (en) * | 2005-04-13 | 2009-02-04 | 大唐移动通信设备有限公司 | Method and apparatus for whole channel primary searching |
| CN1777073B (en) * | 2004-11-15 | 2011-05-11 | 中兴通讯股份有限公司 | Device for realizing multi-carrier receiving signal strength indication |
| CN103369659A (en) * | 2012-03-27 | 2013-10-23 | 马维尔国际有限公司 | Method and device used for carrying out automatic gain control (AGC) to received signal |
| CN104283514A (en) * | 2014-10-29 | 2015-01-14 | 中国电子科技集团公司第二十九研究所 | Digital FM signal demodulator with instant AGC |
| CN104954032A (en) * | 2015-05-22 | 2015-09-30 | 豪威科技(上海)有限公司 | Wireless receiver and application method thereof |
| CN112398454A (en) * | 2021-01-21 | 2021-02-23 | 上海擎昆信息科技有限公司 | Method and device for adjusting amplification factor of analog amplification circuit |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101039293B (en) * | 2006-03-15 | 2010-06-23 | 华为技术有限公司 | Apparatus, method and receiver for initial timing synchronization in communication system |
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- 2000-06-23 CN CNB001094246A patent/CN1140967C/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100372343C (en) * | 2004-08-02 | 2008-02-27 | 北京天碁科技有限公司 | Controlling device for digital pulse formed filter output gain |
| CN1777073B (en) * | 2004-11-15 | 2011-05-11 | 中兴通讯股份有限公司 | Device for realizing multi-carrier receiving signal strength indication |
| CN100459793C (en) * | 2005-04-13 | 2009-02-04 | 大唐移动通信设备有限公司 | Method and apparatus for whole channel primary searching |
| CN103369659A (en) * | 2012-03-27 | 2013-10-23 | 马维尔国际有限公司 | Method and device used for carrying out automatic gain control (AGC) to received signal |
| CN104283514A (en) * | 2014-10-29 | 2015-01-14 | 中国电子科技集团公司第二十九研究所 | Digital FM signal demodulator with instant AGC |
| CN104283514B (en) * | 2014-10-29 | 2017-02-15 | 中国电子科技集团公司第二十九研究所 | Digital FM signal demodulator with instant AGC |
| CN104954032A (en) * | 2015-05-22 | 2015-09-30 | 豪威科技(上海)有限公司 | Wireless receiver and application method thereof |
| CN112398454A (en) * | 2021-01-21 | 2021-02-23 | 上海擎昆信息科技有限公司 | Method and device for adjusting amplification factor of analog amplification circuit |
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| CN1140967C (en) | 2004-03-03 |
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