CN204031125U - Three grades of automatic gain control equipments - Google Patents
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Abstract
The utility model provides a kind of three grades of automatic gain control equipments, comprise: variable gain amplifier, analog/digital converter and feedback circuit, described feedback circuit comprises: look-up table means, THRESHOLD ESTIMATION module, thresholding error module, gain step update module, gain counter and digital/analog converter, gain step update module is by thresholding error and three grades of threshold value comparisons, obtain the gain step of next update cycle, thresholding error is less, and gain step is less.Three grades of automatic gain control equipments that the utility model provides, adopt three grades of threshold values, are divided into tertiary treatment according to thresholding error, obtain the gain step of next different update cycles, thereby realize quick adjustment and the stable regulation of gain; Reference thresholds is set to the update cycle 33%, can reach optimum signal-noise ratio loss, is applicable to low signal-noise ratio data processing; Be applicable to 2bit and above all analog/digital converters.The utility model also provides a kind of three grades of auto gain control methods.
Description
Technical field
The utility model belongs to digital telecommunication circuit technical field, relates to a kind of circuit of digital Auto Gain control, relates in particular to a kind of three grades of automatic gain control equipments that are applied to spread spectrum communication system.
Background technology
Digital integrated circuit is because its superior data processing speed, good noise resisting ability and relatively little area and low-power consumption obtain applying more and more widely, therefore, it is digital signal that large-scale data carries out analog signal Data collecting conversion while processing conventionally, carries out being converted to analog signal output after a series of processing again.
The function of analog/digital converter realizes the conversion of analog signal to digital signal.Along with the raising of data processing precision, analog/digital converter requires more bit bit wide to meet the requirement of precision.The signal that receiver receives is due to factors such as outer signals interference, multipath fading and interchannel noises, cause the signal that analog/digital converter receives to change in a larger dynamic range, simple use analog/digital converter easily causes loss of data and distortion, or even analog/digital converter itself is destroyed.
The effect of automatic gain control is the dynamic range of adjusting signal, so that signal makes full use of the dynamic range of analog/digital converter, ensures minimum snr loss and linear distortion simultaneously.
Traditional automatic gain control is to be realized by analog circuit, realize the adjustment of signal by detecting the energy of analog signal, this automatic gain control is to realize by feed forward circuit, its major defect is power consumption and the area factor intrinsic due to analog circuit, cause circuit structure complexity, power consumption large, and can cause the linear distortion of signal.
In recent years, the digital Auto Gain control based on feedback form has also obtained research extensively and profoundly.
Application number CN101005284A, name is called the Chinese invention patent of " automatic gain control equipment ", and a kind of automatic gain control loop method based on feedback is provided, and the automatic gain control equipment 1 of this section of patent is as shown in Figure 1.This automatic gain control section comprises: variable gain amplifier 11, in order to amplify an analog signal according to a gain; Analog/digital converter 12, in order to be converted to a digital signal by the analog signal after amplifying; And feedback circuit 13, this feedback circuit 13 comprises amplitude level detector 131, produces the first amplitude position standard and the second amplitude position standard according to digital signal; Range detector 132, the accurate and accurate adjustment signal that produces in the second amplitude position according to the first amplitude position; Gain controller 133, comprise gain counter 134 and digital/analog converter 135, the adjustment signal producing according to range detector 132 is adjusted gain automatically, and this invention can make full use of the input range of analog/digital converter and can effectively remove DC offset.
In automatic gain control equipment 1, gain regulated in each clock cycle, this gain control mode changes comparatively stable signal for data amplitude and has preferably regulating power, be quick on the draw, but for Low SNR signal, especially signal power is much smaller than the signal of thermal noise power, due to the stochastic behaviour of thermal noise, after adjusting, can cause the serious distortion of signal, and gain fluctuation is larger, signal stabilization is poor, easily causes larger snr loss after analog/digital converter.
Application number is CN200610138564, name is called the Chinese invention patent of " based on the digital AGC of specific lookup table ", a kind of automatic gain control loop method based on specific lookup table mode is provided, and the automatic gain control equipment 2 of this section of patent as shown in Figure 2.This automatic gain control equipment comprises: antenna 21, band pass filter 22, variable gain amplifier 23, down-conversion mixer 24, analog to digital converter 25, baseband module 26 and DAC 20, also comprise: range detector 27, to the N a receiving sampling point, adopt the method for time domain average to carry out amplitude detection; Look-up table 28, compares testing result with reference level, the error between obtaining; Loop filter 29, obtains the sequence number of corresponding gain control signal by error signal, this signal is inputted to look-up table as index, obtains the gain through DAC FEEDBACK CONTROL VGA after gain control signal.
In automatic gain control equipment 2, use look-up table 28, replaced logarithm operation and antilogarithm computing in traditional automatic gain control, reduced computation complexity, the response speed startup stage of raising.The mode of look-up table has reduced the computational complexity of circuit, improve the speed of circuit, but on the other hand, look-up table mode calculated data has the limitation of its function, first, in look-up table, data can not cover all situations, in automatic gain control equipment 2, the look-up table that 0.25dB arranges if look-up table 28 incoming signal levels successively decrease, while being less than 0.25dB for signal change precision, be not easy to obtain suitable gain control signal, secondly,, for the larger signal of dynamic range, the scale of its look-up table must cause circuit scale very large.
Therefore, be devoted to develop a kind of defect that can effectively overcome above-mentioned prior art in digital telecommunication circuit technical field in the urgent need to those skilled in the art, realize more stable and regulate fast, thering is the comparatively simple automatic gain control equipment of circuit structure simultaneously.
Summary of the invention
An object of the present utility model is to provide a kind of three grades of automatic gain control equipments, realizes and gains more stable and regulate fast, is applicable to less signal to noise ratio simultaneously, and circuit structure is comparatively simple in addition.
Another object of the present utility model is to provide a kind of three grades of auto gain control methods.
The utility model adopt three grades of threshold values, thresholding error amount is divided into tertiary treatment, obtain the gain step of next different update cycles, with realize gain more stable and fast adjusting.
The utility model is set to 33% of the update cycle with reference to threshold value,, reaches optimum signal-noise ratio loss when the ratio that makes high-amplitude Value Data is total data the 33% left and right, is applicable to low signal-noise ratio data processing.
The utility model adopts the mode of look-up table, when having reduced circuit computing complexity, has also reduced the complexity of circuit structure, and circuit structure is comparatively simple.
The utility model provides a kind of three grades of automatic gain control equipments, comprising:
Variable gain amplifier, for inputting the dynamic range of analog signal according to gain control signal adjustment;
Analog/digital converter, for the analog signal after adjusting is converted to digital signal, the input of analog/digital converter is connected with the output of variable gain amplifier;
Feedback circuit, for generation of the gain control signal of variable gain amplifier, the input of feedback circuit is connected with the output of analog/digital converter, and the output of feedback circuit is connected with an input of variable gain amplifier;
Feedback circuit comprises:
Look-up table means, for according to mode parameter, obtains three grades of threshold values that update cycle, reference thresholds and gain step are upgraded, and three grades of threshold values comprise the first order threshold value being arranged in order from big to small, second level threshold value and third level threshold value;
THRESHOLD ESTIMATION module, for adding up THRESHOLD ESTIMATION value within each update cycle;
Thresholding error module, obtains thresholding error for comparison threshold estimated value and reference thresholds;
Gain step update module, for by thresholding error and three grades of threshold value comparisons, obtains the gain step of next update cycle, and thresholding error is less, and gain step is less;
Gain counter, for adding up and carry out data encoding, to upgrade current gain control word to gain step;
Digital/analog converter, for being converted to gain control signal by current gain control word;
THRESHOLD ESTIMATION module, thresholding error module, gain step update module, gain counter and digital/analog converter connect successively, the input that is input as feedback circuit of THRESHOLD ESTIMATION module, and digital/analog converter is output as the output of feedback circuit; Look-up table means is connected with THRESHOLD ESTIMATION module, thresholding error module, gain step update module respectively.
Three grades of automatic gain control equipments that the utility model provides, adopt three grades of threshold values, be divided into tertiary treatment according to thresholding error amount, obtaining the gain step of next different update cycles, when thresholding error is more than or equal to first order threshold value, is the first order gain adjusting stage, gain step is set to the first gain step, this stage, the first gain step was also larger because thresholding error is large, thereby realized the quick adjustment of gain; When thresholding error is more than or equal to second level threshold value and is less than first order threshold value, be the second level gain adjusting stage, gain step is set to the second gain step, and the second gain step is less than the first gain step; When thresholding error is more than or equal to third level threshold value and is less than second level threshold value, be the third level gain adjusting stage, gain step is set to the 3rd gain step, and the 3rd gain step is less than the second gain step; When thresholding error is less than or equal to third level threshold value, gain step is set to 0, and gain reaches stable, does not produce adjustment signal.
Therefore, when thresholding error is larger, the gain step setting of next update cycle is larger, thereby realizes the quick adjustment of gain; And thresholding error more hour, the gain step setting of next update cycle is less is even set to 0, thereby realizes the stable regulation of gain.
Further, reference thresholds and the numerical relation between the update cycle are:
Reference thresholds=update cycle × 33%.
For low signal-noise ratio data, especially available signal power is much smaller than the reception data of thermal noise power, and useful signal is submerged in white noise.Owing to receiving the statistical property Gaussian distributed of data, theory shows, in the situation that only having white noise to disturb, in the time of 33% left and right that the ratio of high-amplitude Value Data is total data, can reach optimum signal-noise ratio loss, separating timing can complete recovery useful signal, and wherein 33% source is that white Gaussian noise signal amplitude is greater than the poor ratio of white Gaussian noise SS.
Three grades of automatic gain control equipments that the utility model provides, are set to 33% of the update cycle with reference to threshold value, can be applicable to low signal-noise ratio data processing, are particularly useful for the low signal-noise ratio data processing in spread spectrum communication system.
Further, first order threshold value is the critical value of distance reference threshold value 2dB, and second level threshold value is the critical value of distance reference threshold value 1dB, and third level threshold value is the critical value of distance reference threshold value 0.5dB.
Further, mode parameter comprises: regulate sooner pattern, quick adjustment pattern, compromise adjusting pattern and stable regulation pattern at a slow speed.
Three grades of automatic gain control equipments that the utility model provides, can adopt different adjusting patterns, and to be applicable to the needs of different application occasion, different adjusting patterns are corresponding to the different update cycles.
Further, THRESHOLD ESTIMATION module comprises counter and accumulator, and counter is for generation of periodically updating signal; Inferior high data bit of the input connecting analog of accumulator/digital quantizer output, to add up THRESHOLD ESTIMATION value within each update cycle, and exports thresholding estimated value when effective at the signal that periodically updates of counter generation.
Further, thresholding error module is subtracter, and the first input end of subtracter connects the output of thresholding estimation module, and the second input connects the reference thresholds output of table look-up module, to obtain thresholding error amount.
Further, gain step update module comprises: gain rank determining device and gain step adjuster, the first input end of gain rank determining device connects the output of thresholding error module, three grades of threshold value outputs of the second input connection and locating table module of gain rank determining device, for comparison threshold error amount and three grades of threshold values, output gain rank; The input of gain step adjuster connects the output of gain rank determining device, for according to gain rank output gain step; Gain step is the product value of gain step coefficient and thresholding error amount.
The utility model also provides a kind of three grades of auto gain control methods of three grades of automatic gain control equipments, comprises the following steps:
(1) look-up table means, according to mode parameter, is obtained three grades of threshold values that update cycle, reference thresholds and gain step are upgraded:
(2) the THRESHOLD ESTIMATION value of the digital signal of THRESHOLD ESTIMATION module statistical simulation within each update cycle/digital quantizer output;
(3) thresholding error module comparison threshold estimated value and reference thresholds obtain thresholding error;
(4) gain step update module, by thresholding error and three grades of threshold value comparisons, obtains the gain step of next update cycle, and thresholding error is less, and gain step is less;
(5) gain counter adds up gain step and carries out data encoding, upgrades current gain control word;
(6) current gain control word is converted to gain control signal by digital/analog converter; Gain control signal is input to variable gain amplifier, to adjust the dynamic range of input analog signal.
Three grades of auto gain control methods that the utility model provides, adopt three grades of threshold values, are divided into tertiary treatment according to thresholding error, obtain the gain step of next different update cycles, when thresholding error is larger, gain step setting is larger, thereby realizes the quick adjustment of gain; More hour gain step setting is less is even set to 0 for thresholding error, thereby realizes the stable regulation of gain.
Further, in step (4), gain step update module is by thresholding error and three grades of threshold value comparisons, and the method that obtains the gain step of next update cycle comprises:
(41) thresholding error is taken absolute value;
(42) absolute value of comparison threshold error and three grades of threshold values, in the time that the absolute value of thresholding error is greater than first order threshold value, gain step coefficient is set to the first gain step coefficient; In the time that the absolute value of thresholding error is less than or equal to first order threshold value and is greater than second level threshold value, gain step coefficient is set to the second gain step coefficient; In the time that the absolute value of thresholding error is less than or equal to second level threshold value and is greater than third level threshold value, gain step coefficient is set to the 3rd gain step coefficient; In the time that the absolute value of thresholding error is less than or equal to third level threshold value, gain step coefficient is set to 0, the first gain step coefficient and is greater than the second gain step coefficient, and the second gain step coefficient is greater than the 3rd gain step coefficient.
Three grades of auto gain control methods that the utility model provides, adopt three grades of threshold values, be divided into tertiary treatment according to thresholding error, obtaining the gain step of next different update cycles, when thresholding error is more than or equal to first order threshold value, is the first order gain adjusting stage, because thresholding error is large, gain step is set to the first gain step, and the first gain step is larger, thereby realizes the quick adjustment of gain; When thresholding error is more than or equal to second level threshold value and is less than first order threshold value, be the second level gain adjusting stage, gain step is set to the second gain step, and the second gain step is less than the first gain step; When thresholding error is more than or equal to third level threshold value and is less than second level threshold value, be the third level gain adjusting stage, gain step is set to the 3rd gain step, and the 3rd gain step is less than the second gain step; When thresholding error is less than or equal to third level threshold value, gain step is set to 0, and gain reaches stable, does not produce adjustment signal.
Further, in step (42), the first gain step coefficient is that 0.5, the second gain step coefficient is 0.125, the three gain step coefficient 0.0625.Corresponding gain step value is determined by following formula:
Gain step value=thresholding error amount × gain step coefficient
If employing computing, the computing meeting that comprises multiple decimal places brings the loss in computational accuracy.In order to reduce loss of significance, in side circuit is realized, gain step value obtains by arithmetic shift:
In side circuit is realized, 16 in above-mentioned formula denominator, can realize by moving to right 4, and multiple in above-mentioned formula molecule, and three, one of arithmetic shift left and keep thresholding error amount to obtain can move to left by thresholding error amount is done sums respectively.
Adopt arithmetic shift left to carry out the adjustment of multiple, can not cause the loss of computational accuracy.
Compared with prior art, the utility model provides three grades of automatic gain control equipments and three grades of auto gain control methods have following beneficial effect:
1, adopt three grades of threshold values, be divided into tertiary treatment according to thresholding error, obtain the gain step of next different update cycles, thereby realize quick adjustment and the stable regulation of gain;
2, reference thresholds is set to 33% of the update cycle, owing to receiving the statistical property Gaussian distributed of data, in the situation that only having white noise to disturb, in the time of 33% left and right that the ratio of high-amplitude Value Data is total data, can reach optimum signal-noise ratio loss, separating timing can complete recovery useful signal, thereby is applicable to low signal-noise ratio data processing, is particularly useful for the low signal-noise ratio data processing in spread spectrum communication system;
3, during due to data processing, only adopt the inferior high data bits certificate of analog/digital converter output digit signals, so be applicable to 2bit and above all analog/digital converters;
4, in side circuit is realized, gain step value obtains by arithmetic shift, can not cause the loss of computational accuracy.
Brief description of the drawings
Fig. 1 is the structural representation of a kind of automatic gain control circuit in prior art;
Fig. 2 is the structural representation of another kind of automatic gain control circuit in prior art;
Fig. 3 is the structural representation of three grades of automatic gain control equipments of an embodiment of the present utility model;
Fig. 4 is the structural representation of the THRESHOLD ESTIMATION module of three grades of automatic gain control equipments shown in Fig. 3;
Fig. 5 is the structural representation of the gain step update module of three grades of automatic gain control equipments shown in Fig. 3;
Fig. 6 is the structural representation of the gain counter module of three grades of automatic gain control equipments shown in Fig. 3;
Fig. 7 is that the circuit of the gain counter module of three grades of automatic gain control equipments shown in Fig. 3 forms schematic diagram.
Embodiment
Below with reference to accompanying drawing, the technique effect of design of the present utility model, concrete structure and generation is described further, to understand fully the purpose of this utility model, feature and effect.
As shown in Figure 3, the structural representation of three grades of automatic gain control equipments of an embodiment of the present utility model, these three grades of automatic gain control equipments comprise variable gain amplifier 31, analog/digital converter 32 and feedback circuit 33.
An input connecting analog signal 300 of variable gain amplifier 31, another input connects gain control signal 303, the analog signal of output after amplifying; The input of analog/digital converter 32 connects the output of variable gain amplifier 31, the digital signal 301 of output after analog-to-digital conversion; The inferior high data bit 304 of input connecting analog/digital quantizer 32 output digit signals 301 of feedback circuit 33, the gain control signal 303 of output to variable gain amplifier.
Feedback circuit 33 comprises look-up table means 41, THRESHOLD ESTIMATION module 42, thresholding error module 43, gain step update module 44, gain counter 45 and digital/analog converter 46.
In feedback circuit 33, the input connection mode parameter 302 of look-up table means 41, output update cycle 401, reference thresholds 402, and first order threshold value 403, second level threshold value 404, third level threshold value 405.
As shown in Figure 3, the inferior high data bit 304 of an input connecting analog/digital quantizer 32 output digit signals 301 of THRESHOLD ESTIMATION module 42, the update cycle 401 that another input connection and locating table module 41 is exported, export thresholding estimated value 423 and periodically update signal 422.
An input of thresholding error module 43 connects the THRESHOLD ESTIMATION value 423 that thresholding estimation module 42 is exported, the reference thresholds 402 that another input connection and locating table module 41 is exported, output thresholding error amount 442.
An input of gain step update module 44 connects the thresholding error amount 442 that thresholding error module 43 is exported, remaining input terminal connection and locating table module 41 is exported respectively first order threshold value 403, second level threshold value 404 and third level threshold value 405, output gain step 443.
The first input end of gain counter module 45 connects the output gain step 443 of gain step update module 44, the second input connects the output update signal 422 of thresholding estimation module 42, the 3rd input connects input signal pattern parameter 302, and control word 459 obtains gaining; The input of digital/analog converter module connects the gain control word 459 that gain counter 45 is exported, outputing gain control signal 303.
Variable gain amplifier 31 is under the control of gain control signal 303, the analog signal of input 300 is amplified, signal after amplification is converted to digital signal 301 through analog/digital converter 32 and exports, and the inferior high data bit 304 of digital signal 301 (highest order of data is sign bit) is sent into feedback circuit 33 simultaneously and obtains the gain signal gain control signal 303 to variable gain amplifier.
In feedback circuit, in initialization or each update signal 422 effectively time, look-up table means 41 is selected update cycle 401, reference thresholds 402 and three grades of threshold values according to input pattern parameter 302: first order threshold value 403, second level threshold value 404, third level threshold value 405; THRESHOLD ESTIMATION module 42 is the number of " 1 " in the inferior high data bit 304 of each update cycles 401 statistics signal 301, obtains THRESHOLD ESTIMATION value 423, sends into thresholding error module 43.
Thresholding error module 43 is subtracter, produces by reference thresholds 402 and the THRESHOLD ESTIMATION value 423 thresholding error amounts 442 that form, and sends into gain step update module 44; Gain step update module 44, according to thresholding error amount 442 and three grades of threshold values 403～405, produces corresponding gain step 443, sends into gain counter module 45.
Gain counter 45 is in the time that each update signal 422 is effective, and gain step 443 is added up and encoded obtains coding gain control word 459, sends into digital/analog converter 46; Coding gain control word 459 is converted to gain control signal 303 by digital/analog converter 46, sends into variable gain amplifier 31.
Look-up table means 41 comprises: update cycle look-up table, reference thresholds look-up table and three grades of threshold value look-up tables, be respectively used to choose corresponding update cycle 401, reference thresholds 402 and three grades of threshold values according to mode parameter 302, three grades of threshold values comprise first order threshold value 403, second level threshold value 404 and third level threshold value 405.
Three grades of automatic gain control equipments in the present embodiment provide four kinds of patterns: regulate sooner pattern, quick adjustment pattern, compromise adjusting pattern and stable regulation pattern at a slow speed, by the selection of mode parameter 302.
In the present embodiment, mode parameter 302 is adopted to 2 codings, wherein 00 corresponding to regulating sooner pattern, and 01 corresponding to quick adjustment pattern, and 10 corresponding to compromise adjusting pattern, and 11 corresponding to stable regulation pattern at a slow speed.
In update cycle look-up table, comprise four kinds of update cycle preset values 63,127,255 and 511, corresponding respectively to the update cycle is 64,128,256 and 512 system clock cycles.Minimum update cycle preset value 63 is corresponding to regulating sooner pattern, and maximum update cycle preset value 511 is corresponding to stable regulation pattern at a slow speed, be applicable to less snr loss, but renewal speed can be affected.
In reference thresholds look-up table, comprise default reference thresholds 402, reference thresholds 402 and the numerical relation between the update cycle 401 are: reference thresholds=update cycle × 33%, for four kinds of mode of operations, update cycles 401 preset value in update cycle look-up table is 63,127,255 and 511, and the analog value that corresponds to the reference thresholds 402 in reference thresholds look-up table is 21,42,84 and 169.
For low signal-noise ratio data, especially available signal power is much smaller than the reception data of thermal noise power, and useful signal is submerged in white noise.Owing to receiving the statistical property Gaussian distributed of data, in the situation that only having white noise to disturb, in the time of 33% left and right that the ratio of high-amplitude Value Data is total data, can reach optimum signal-noise ratio loss, separating timing can complete recovery useful signal.
In three grades of threshold value look-up tables, three grades of threshold values 403～405 are respectively the critical value for 2dB, 1dB and 0.5dB dynamic range apart from reference thresholds 402.Three grades of threshold values 403～405 also can be set to other values, for example: distance reference threshold value 6dB, 1dB and 0.5db and other can meet the setting of performance requirement.
Three grades of threshold values can be calculated by following formula:
If be limited to x under N stage gain convergence
d, in convergence, be limited to x
u, g
1=2dB, g
2=1dB, g
3=0.5dB, three grades of threshold values are respectively TH1, TH2, TH3 has
There is THN=max (x
d, x
u), N=1,2,3
For four kinds of mode of operations:
(1) under adjusting pattern sooner, the mode of operation that update cycle 401 is 63, reference thresholds 402 is 21, its first order threshold value 403 is 5, and second level threshold value 404 is 2, and third level threshold value 405 is 1;
(2) under quick adjustment pattern, the mode of operation that update cycle 401 is 127, reference thresholds 402 is 42, its first order threshold value 403 is 10, and second level threshold value 404 is 5, and third level threshold value 405 is 2;
(3) in compromise adjusting pattern, the mode of operation that update cycle 401 is 255, reference thresholds 402 is 84, its first order threshold value 403 is 20, and second level threshold value 404 is 10, and third level threshold value 405 is 5;
(4) at a slow speed in steady operation pattern, the mode of operation that update cycle 401 is 511, reference thresholds 402 is 169, its first order threshold value 403 is 44, and second level threshold value 404 is 20, and third level threshold value 405 is 10.
As shown in Figure 4, THRESHOLD ESTIMATION module 42 comprises counter 420 and accumulator 421.Counter 420 subtracts a counting under system clock control, count down at 1 o'clock and exports update signal 422, is automatically again written into the update cycle 401 simultaneously; Accumulator 421 adds up to input data 304 under system clock control, exports thresholding estimated value 423 in the time that update signal 422 is effective, and accumulator zero clearing simultaneously is again written into data and starts next cycle statistics.Input data 304 are inferior high data bit of digital signal 301, i.e. time high data bit bit number.
As shown in Figure 5, gain step update module 44 comprises that gain rank judge 440 and gain step adjustment 441, thresholding error amount 442 judges that by gain rank 440 produce gain stage level signal, and gain stage level signal ride gain step is adjusted 441 and produced corresponding gain step 443.Particularly, the rank that gains in this example judge 440 and gain step adjustment 441 realized by hardware in a module, be one and be similar to MUX with priority and realize.
Fig. 6 has shown the process that gain step 443 generates, step 601 is to thresholding error amount 442 computing that takes absolute value, obtain the absolute value of thresholding error amount, then turn to step 602, if this absolute value is greater than first order threshold value 403, illustrate in the first order gain adjusting stage, perform step 603 pairs of thresholding error amounts 442 and carry out arithmetic shift left 3 bit manipulations and obtain gain step, exit gain step adjustment; Otherwise turn to step 604 to judge whether this absolute value is greater than second level threshold value 404, if set up, illustrate in second level gain adjusting stage, execution step 605, thresholding error amount 442 is carried out to arithmetic shift left 1 bit manipulation and obtain gain step, exit gain step adjustment; Otherwise turn to step 606, judge whether this absolute value is greater than third level threshold value 405, if set up, illustrate that execution step 607, gets this thresholding error amount 442 and obtain gain step, exits gain step adjustment in the third level gain adjusting stage; Otherwise turn to step 608, gain step gets 0, gain step adjustment finishes.
In the present embodiment, move to right 4 and realize in the data encoding circuit of gain counter.
The circuit that Fig. 7 shows gain counter module forms, and gain counter module 45 comprises gain step accumulator 451 and data encoder 452.Gain step 443 carries out data accumulation and accumulation result is carried out to data encoding obtaining the gain signal after renewal in the time that each update signal 422 is effective.
Gain step accumulator comprises adder 453 and buffer 454, the accumulation result of a update cycle 401 on buffer 454 buffer memorys, cumulative with current gain step 443 effectively time in update signal 422, upgrade buffer data, while data are sent into data encoder 452.
Data encoder 452 comprises that complement code turns former decoding circuit 456, fixed point change-over circuit 457 and selection coding circuit 458.Complement code turns former decoding circuit 456 data in current cache is converted to former representation by complement code, and fixed point change-over circuit 457 is determined gain control word 455, and in more detail, position and the adjustable dynamic scope of decimal point determined in fixed point conversion.Decimal point number is determined by mode parameter 302.Be respectively 63,127,255 and 511 for update cycles 401 configuration, corresponding scaling position was positioned at before the 10th, 11,12,13.For most of variable gain amplifiers 31, degree of regulation 0.039dB can fully meet accuracy requirement, therefore in this example, retains 8 decimal places, and scaling position is between 8bit and 9bit data.The integer part dynamic range of the analog signal of the required processing of foundation is chosen,
In the present embodiment, choose three integer parts and a bit sign position, obtain 13bit gain control word 455.For the gain control word 455 of this 13bit, adjustable gain ranging is 79.96～-79.96dB, and degree of regulation is 0.039dB.
Select 458 of coding circuits, according to selected digital/analog converter 46 and variable gain amplifier 31 types, gain control word 455 codings are obtained to final coding gain control word 459.
Current coding gain control word 459 is converted to gain control signal 303 by digital/analog converter 46.
Three grades of automatic gain control equipments and three grades of auto gain control methods that the utility model provides, adopt three grades of threshold values, be divided into tertiary treatment according to thresholding error, obtain the gain step of next different update cycles, thereby realize quick adjustment and the stable regulation of gain; Reference thresholds is set to the update cycle 33%, owing to receiving the statistical property Gaussian distributed of data, in the situation that only having white noise to disturb, in the time of 33% left and right that the ratio of high-amplitude Value Data is total data, can reach optimum signal-noise ratio loss, separating timing can complete recovery useful signal, thereby is applicable to low signal-noise ratio data processing, is particularly useful for the low signal-noise ratio data processing in spread spectrum communication system; Be applicable to 2bit and above all analog/digital converters; In side circuit is realized, gain step value obtains by arithmetic shift, can not cause the loss of computational accuracy.
More than describe preferred embodiment of the present utility model in detail.Should be appreciated that those of ordinary skill in the art just can make many modifications and variations according to design of the present utility model without creative work.Therefore, all technical staff in the art comply with design of the present utility model on the basis of existing technology by the available technical scheme of logical analysis, reasoning, or a limited experiment, all should be in by the determined protection range of claims.
Claims (7)
1. three grades of automatic gain control equipments, comprising:
Variable gain amplifier, for inputting the dynamic range of analog signal according to gain control signal adjustment;
Analog/digital converter, for the analog signal after adjusting is converted to digital signal, the input of described analog/digital converter is connected with the output of described variable gain amplifier;
Feedback circuit, for generation of the described gain control signal of variable gain amplifier;
It is characterized in that, described feedback circuit comprises:
Look-up table means, for according to mode parameter, obtains three grades of threshold values that update cycle, reference thresholds and gain step are upgraded, and described three grades of threshold values comprise the first order threshold value being arranged in order from big to small, second level threshold value and third level threshold value;
THRESHOLD ESTIMATION module, for adding up THRESHOLD ESTIMATION value within each described update cycle;
Thresholding error module, obtains thresholding error for more described THRESHOLD ESTIMATION value and described reference thresholds;
Gain step update module, for by described thresholding error and described three grades of threshold value comparisons, obtains the gain step of next update cycle, and described thresholding error is less, and described gain step is less;
Gain counter, for described gain step being added up and carried out data encoding, to upgrade current gain control word;
Digital/analog converter, for being converted to described gain control signal by current gain control word;
Described THRESHOLD ESTIMATION module, described thresholding error module, described gain step update module, described gain counter and described digital/analog converter connect successively, the inferior high data bit of the output digit signals that is input as described analog/digital converter of described THRESHOLD ESTIMATION module, the output of described digital/analog converter is connected with an input of described variable gain amplifier; Described look-up table means is connected with described THRESHOLD ESTIMATION module, described thresholding error module, described gain step update module respectively.
2. three grades of automatic gain control equipments as claimed in claim 1, is characterized in that, described reference thresholds and the numerical relation between the described update cycle are: reference thresholds=update cycle × 33%.
3. three grades of automatic gain control equipments as claimed in claim 1, it is characterized in that, described first order threshold value is the critical value of the described reference thresholds 2dB of distance, described second level threshold value is the critical value of the described reference thresholds 1dB of distance, and described third level threshold value is the critical value of the described reference thresholds 0.5dB of distance.
4. three grades of automatic gain control equipments as claimed in claim 1, is characterized in that, described mode parameter comprises: regulate sooner pattern, quick adjustment pattern, compromise adjusting pattern and stable regulation pattern at a slow speed.
5. three grades of automatic gain control equipments as claimed in claim 1, is characterized in that, described THRESHOLD ESTIMATION module comprises counter and accumulator, and described counter is for generation of periodically updating signal; The input of described accumulator is the input of described THRESHOLD ESTIMATION module, and to add up described THRESHOLD ESTIMATION value within each update cycle, and the signal that periodically updates producing at described counter is exported described THRESHOLD ESTIMATION value when effective.
6. three grades of automatic gain control equipments according to claim 1, it is characterized in that, described thresholding error module is subtracter, the first input end of described subtracter connects the output of thresholding estimation module, the second input connects the reference thresholds output of described table look-up module, to obtain described thresholding error amount.
7. three grades of automatic gain control equipments according to claim 1, it is characterized in that, described gain step update module comprises: gain rank determining device and gain step adjuster, the first input end of described gain rank determining device connects the output of described thresholding error module, the second input of described gain rank determining device connects three grades of threshold value outputs of described look-up table means, for more described thresholding error amount and described three grades of threshold values, output gain rank; The input of described gain step adjuster connects the output of described gain rank determining device, for according to described gain rank output gain step; Described gain step is the product value of gain step coefficient and thresholding error amount.
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| CN201420465539.XU CN204031125U (en) | 2014-08-18 | 2014-08-18 | Three grades of automatic gain control equipments |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105353213A (en) * | 2015-12-15 | 2016-02-24 | 中国电子科技集团公司第四十一研究所 | Waveform integral gain distribution method for spectrum analyzer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105353213A (en) * | 2015-12-15 | 2016-02-24 | 中国电子科技集团公司第四十一研究所 | Waveform integral gain distribution method for spectrum analyzer |
| CN105353213B (en) * | 2015-12-15 | 2018-02-06 | 中国电子科技集团公司第四十一研究所 | A kind of wave complete machine gain distribution method of spectrum analyzer |
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