CN101079981B - Method and apparatus for digital automatic gain control - Google Patents

Abstract

According to the device and method for the automatic gain control, the present invention controls the received signal intensity to a constant level by the receiver which is used to receive the exerted digital broadcast signal. With this end in view, it compensates the incoming signal received by the gain error detector by the compensating signal, detects the gain error, accumulate the gain error detected by the loop filter, and the compensating signal generator compensates the accumulated gain error by the prescheduled penalty function to generate the compensating signal, and compensates the received incoming signal detected by the gain error detector according to the generated compensating signal.

Description

Equipment and the method for automatic gain, controlled

The cross reference of related application

The korean application 10-2006-0020136 that the application submitted to based on March 2nd, 2006, and require to enjoy its priority, at this in conjunction with its whole disclosures as a reference.

Technical field

The present invention relates to equipment and the method for automatic gain, controlled, more specifically, relate to for automatically adjust the broadcast singal receiving from the receiver of receiving broadcast signal gain equipment and method.

Background technology

Following description is usually directed to control (AGC) equipment and method for automatic gain, and this automatic gain is controlled for automatically adjusting the gain of the broadcast singal receiving from the receiver of receiving broadcast signal.

At present, digital broadcasting is just carried out local standardized based on multiple technologies.For example, the broadcast standard of discussing in China comprises digital ground multimedia broadcast (DTMB).The DTMB standard coming into question has adopted the new modulation scheme that is called as time-domain synchronous orthogonal frequency division multiplex (TDS-OFDM).

What Europe adopted is the service based on OFDM scheme, and OFDM scheme is one of modulation scheme transmitting with digital signal surface wave.In OFDM scheme, information is divided in several carrier waves, and provides orthogonality for minimizing the gap between divided carrier wave, and described carrier wave is re-used and then sends out.

Conventionally; in TDS-OFDM scheme; transmit data just as in Cyclic Prefix (cyclic prefix) OFDM (CP-OFDM); by inverse discrete Fourier transformer inverse-discrete (IDFT), carry out, and in protection interval (GI), use pseudo noise (PN) sequence as doing training signal (known array; pilot frequency sequence) replace Cyclic Prefix; to reduce transport overhead, increase channel efficiency, and strengthen the performance of synchronizer and channel estimator.The equation that creates PN sequence can obtain by formula 1 below.

[formula 1]

P(x)＝x ⁸+x ⁶+x ⁵+x+1

For receiving the receiver of the transmission data that transmitted by DTMB, by the Strength retention of received signal, in constant level, be very important, to allow the correlated results of PN sequence to remain steady state value always.

For by the Strength retention of received signal in constant level, at automatic gain, control the gain error value of accumulating predetermined reference signal and received signal in (AGC) equipment, and accumulated gain error value is generated as to gain control signal, for adjusting the amplitude gain of received signal.Respond the gain error value of accumulating and generate compensating signal, the signal being received to compensate.

According to the compensating signal of accumulated gain error value, with the form of exponential function, express, at this, compensating signal is pre-stored within memory as question blank, and from memory, read the compensating signal corresponding with accumulated gain error value and export this compensating signal, this will increase the capacity of memory.

Summary of the invention

[technical problem]

The disclosed object of example is to provide a kind of equipment and the method that automatic gain is controlled (AGC), and it is by reducing in fact the size of hardware not making to realize AGC in memory-aided situation.

Another object is to provide a kind of equipment and method can real-time update AGC bandwidth, that for automatic gain, control.

[technical solution]

In the example embodiment of the disclosed AGC equipment according to example, gain error detector response compensates received input signal in signal, to detect gain error value.By loop filter, accumulate detected gain error value, and utilize the default penalty function of compensating signal generator to compensate accumulated gain error value to generate compensating signal, and generated compensating signal is outputed to gain error detector to allow compensated input signal.

In the example embodiment of the disclosed AGC method according to example, in response to compensating signal, compensate received input signal, detect gain error value, cumulative detected gain control value, compensates accumulated gain error value to generate compensating signal in response to default penalty function.

[advantageous effects]

Example openly can, by optimizing the AGC of digital ground multimedia broadcast (DTMB) receiver and cancelling memory and controll block, reduce the size of hardware.In addition, may control adaptively the amplitude gain of AGC amplifier, thereby by effectively tackling the irregular change of received signal, the intensity of received signal be remained in constant level always.

Accompanying drawing explanation

By reference to the embodiment describing by example in the following description and with reference to accompanying drawing, these and other aspect of the present disclosure also will be elucidated apparition.In any possible place, in whole accompanying drawing, with identical Reference numeral, indicate same or analogous part.

Fig. 1 is the schematic diagram of structure at protection interval that illustrates the transmission frame from DTMB transmits, has 1/9 size of frame.

Fig. 2 is the block diagram of configuration that illustrates the transmitter of DTMB.

Fig. 3 is the block diagram that illustrates the configuration of the receiver in DTMB.

Fig. 4 is the block diagram that illustrates the configuration of AGC equipment.

Fig. 5 is the curve chart that illustrates the gain curve that AGC equipment adopts.

Fig. 6 is the block diagram illustrating according to the configuration of the AGC equipment of example embodiment.

Fig. 7 is the block diagram illustrating according to the configuration of the AGC equipment of another example embodiment.

Fig. 8 and Fig. 9 illustrate the curve chart changing according to the output signal of the AGC equipment of another example embodiment.

Embodiment

Described embodiment is only for illustrating but being not used in restriction.Provide the item of describing illustrated at this to contribute to understand all sidedly disclosed some example embodiment of the present invention by reference to the accompanying drawings.Therefore, those of ordinary skill in the art will recognize: can example embodiment described here be made various changes and modifications, and do not deviate from desired scope of invention and spirit.Therefore, the application is applicable to explain its General Principle and concept in the most useful and the simplest mode.

Fig. 1 be illustrate the transmission frame from DTMB transmits, the block diagram of structure that its protection interval is 1/9 frame.

With reference to figure 1, the transmission frame transmitting from DTMB comprises frame synchronization and as the frame of data break.

Frame synchronization comprises PN sequence.PN sequence for frame synchronization is for example used but is not limited to the wherein sequence of parameter m=8.In the sequence of parameter m=8, only have 255 bit streams.Therefore, when having the protection interval of 1/9 size of frame and generate, the code element of afterbody is extended to lead code, and the code element of beginning is extended to postamble (postamble), to generate the PN sequence with 420 code elements.

For example, if frame will be comprised of 3780 code elements, the protection interval with 1/9 size of frame must be comprised of 420 codes.Therefore, in order to create 420 code elements by 255 code elements, 50 code elements that are positioned at afterbody are expanded as lead code, and 155 code elements that are positioned at beginning are expanded as postamble.Now, lead code and postamble are the cyclic extensions of PN code, and PN code is in its response initial condition and from 0 to 254 variation in the phase place that generates.

Fig. 2 is the block diagram of the configuration of diagram DTMB transmitter.With reference to figure 2, in transmitter, by chnnel coding unit (200), Voice & Video (AV) signal of the data as transmitting is encoded.The data of being carried out chnnel coding by chnnel coding unit (200) are imported into quadrature amplitude modulation (QAM) unit (202), and are modulated in 4QAM, 16QAM or 64QAM.

QAM unit (202) changes from amplitude and the phase place of the numerical data of chnnel coding unit (200) input also modulates this amplitude and phase place, make the data of chnnel coding whether be modulated into 4,16 or 64QAM in one depend on numerical data is dispersed and is modulated to how many coordinates (corordinates).

By IDFT unit (204), the data of QAM unit (202) modulation are carried out to inverse discrete Fourier transform (IDFT), and be transformed to time domain data.In addition, PN generator (206) creates PN (pseudo noise) sequence as training signal.

From the time domain data of IDFT unit (204) output and the PN sequence being generated by PN generator (206), be imported into multiplexer (208), and carry out therein multiplexedly, and in square root raised cosine (SQRC) filter (210), filter to limit its bandwidth.

The transmission data of being filtered by SQRC filter (210) are mixed with carrier signal (fc) in frequency mixer (212), and are up-converted to radio frequency (RF) bandwidth of 450～860MHz, then send out.

Fig. 3 is the block diagram that illustrates the configuration of the receiver in DTMB.Now, with reference to figure 3, radio frequency (RF) the transmission data that the bandwidth that tuner (300) reception is transmitted by transmitter is 450～860MHz.The signal power receiving from tuner (300) is normalized to the constant level its gain in AGC amplifier (302), and is converted to digital signal by analog to digital converter (ADC.304).

Phase splitter (306) is separated into same-phase signal and orthogonal signalling by the output signal of ADC (304), and realizes Frequency Synchronization by frequency synchronisation (308).

Frequency synchronisation (308) mainly comprises three unit, comprising: 1. automatic frequency controller (AFC.358), and poor for compensating frequency; 2. Timing Synchronization device (360), for the PN sequence synchronously being transmitted by transmitter; And 3. tracking cell (362) and again sampler (352), the symbol error producing for compensating sampling rate difference when transmitter and receiver is converted to digital signal by analog signal.

Aforesaid operations is all as the correlated results of PN correlator (356) and realize.In other words, AFC (358) generates AFC signal as the correlated results of PN correlator (356), and this AFC signal generating is multiplied by mutually the estimated frequency error of compensation with the output signal of phase splitter (306) in multiplier (350).

In addition the correlated results of Timing Synchronization device (360) response PN correlator (356) and synchronic PN sequence.And tracker (362) is controlled sampler (352) to compensate from the symbol error of the signal of multiplier (350) output again in response to the output signal of Timing Synchronization device (360).

By SQRC filter (354), the output signal of sampler (352) is again filtered to be entered into PN correlator (356).The output signal of SQRC filter (354) is imported in AGC signal detector (310) to detect AGC signal, and the amplitude gain of AGC amplifier (302) changes according to detected AGC signal, thereby the gain of received signal can be adjusted in a constant level.

Discrete Fourier transformer (DFT.312,314) to the code element of AGC signal detector (310) output with from the channel estimating information of PN correlator (356) output, carry out DFT, and carry out channel compensation by equalizer (316), to output to channel decoder.

As mentioned above, in the receiver of DTMB, AFC (358) compensates frequency displacement according to the correlated results of PN correlator (356).Especially, Timing Synchronization device (360) thus detect and to follow a peak value of expression associative operation after effective peak to be detected, for this reason, only have the peak value over predetermined threshold to be used to Timing Synchronization.

Therefore, by the intensity of received signal is remained on always, in constant level, the correlated results of PN sequence to be remained to constant level be always very important.Therefore, DTMB receiver is equipped with the AGC equipment that comprises AGC signal detector (310) and AGC amplifier (302), thus can be always by the Strength retention of received signal in constant level.

Fig. 4 is the block diagram that illustrates the configuration of AGC equipment.

With reference to figure 4, AGC equipment is mainly comprised of gain error detector (400), loop filter (410) and compensating signal generator (420).

Gain error detector (400) comprise two multipliers (402), power checker (404), mean value computation device (406) and, subtracter (408).Two multipliers (402) multiply each other in-phase signal (I_IN) and orthogonal signalling (Q_IN) and compensating signal respectively, with compensating gain error and output to DFT (312).In addition, power checker (404) is measured the power of the output signal of multiplier (402), and utilizes mean value computation device (406) to calculate the average power measured value of measuring an image duration.Subtracter deducts default reference power to detect gain error from calculated average power content.

By the detected gain error of gain error detector (400), be imported into loop filter (410) and postponed by delayer (414).Adder (412) is added to by the detected gain error of gain error detector (400) output of delayer (414) with storage gain error.The gain error of accumulating outputs to AGC amplifier (302) as AGC signal, adjusts thus the gain amplifier of AGC amplifier (302).

In addition, the gain error of being accumulated by loop filter (410) is imported into the storage control (422) of compensating signal generator (420), at this, storage control (422) is read the compensating signal value corresponding with accumulated gain error from memory (424), and multiplier (402) multiplies each other read compensating signal and in-phase signal (I_IN) and orthogonal signalling (Q_IN) to gain error is compensated.

In other words, memory (424) is with the compensating signal value of the pre-stored gain error value in response to being accumulated of form of question blank.Storage control (422) is read the compensating signal value corresponding with the gain error value of inputting from loop filter (410) from memory (424), with compensating gain error.

With question blank form, being stored in compensating signal in memory (424) for example represents with exponential form as shown in Figure 5.Therefore, if the gain error value of accumulation is large in loop filter (410), compensating signal value becomes larger, thereby increases compensation magnitude; And if the value of the gain error of accumulating is little, compensating signal value becomes less, to reduce compensation magnitude, has strengthened thus the stability of AGC loop.

For directly, to carrying out computing as the nonlinear function of exponential function, common way is by carrying out repetitive operation, with algorithm, to converge to the value of hope.Therefore,, in the circuit of the high speed operation with high-frequency clock operation, it is very difficult when exponential function is carried out to computing, adjusting data rate, but is possible when hardware size increases.Actual use is that the form with question blank is stored in memory (424) in advance by precalculated exponential function value, rather than direct gauge index function.

At this moment, according to the quantization step of exponential function curve, determine the gain step size of AGC, thereby can greatly suppress the memory span with the bit width use distributing according to quantization step.

For example, suppose that from the input range of the exponential function of loop filter (410) input be 1024 data, and, from the exponential function of compensating signal generator (420) output, with respect to each input data, there are two byte-sized, the desired volume of memory (424) will be two kilobytes, increase thus the whole size of receiver.Therefore,, when generating compensating signal, it is very favourable with regard to hardware size, not using memory.

Now, with reference to figure 6, it is the block diagram illustrating according to the configuration of the AGC equipment of example embodiment, and this AGC equipment calculates the power of received signal and difference (the Δ δ between desirable reference power _n).And operate as follows: if the difference of calculating (Δ δ _n) large, the value of feedback of compensating signal just reduces; And if the difference of calculating (Δ δ _n) little, value of feedback just increases.

Conventionally, the deviation of the power of received signal is quite large.Therefore the result, obtaining from the power averaging of code element at the time durations corresponding with frame is used to improve the estimated performance that the power received signal is estimated.According to AGC equipment of the present disclosure, comprise gain error detector (400), loop filter (410) and compensating signal generator (600).

As mentioned above, gain error detector (400) is for detection of gain error, the gain error that wherein loop filter (410) accumulation detects, and the gain error of accumulating is for generating AGC signal to adjust the amplitude gain of AGC amplifier (302).

Compensating signal generator (600) is according to the gain error value of default penalty function cause compensation loop filter (410) accumulation, and generate thus compensating signal, and the compensating signal generating is imported into the multiplier (402) of gain error detector (400), so that gain error is compensated.

Now, suppose: because the bandpass width of loop filter (410) is than wide from the transmission data bandwidth of gain error detector (400) input, so loop filter (410) is not carried out function.Now, by describing compensating signal generator (600) in detail, in response to the gain error from gain error detector (400) output, generate the processing of compensating signal.

Following formula 2 has defined gain error value (the Δ δ that gain error detector (400) detected in the last time (n-1) _n-1), formula 3 shows gain error value (the Δ δ that gain error detector (400) detects in current time (n) _n).

[formula 2]

${\mathrm{\Δ\δ}}_{n-1}={\mathrm{\α}}_{n-1}^2\left[\underset{m=(n-1)-N}{\overset{n-1}{\mathrm{\Σ}}}(i_m^2+q_m^2)\right]-\mathrm{ref}$

[formula 3]

${\mathrm{\Δ\δ}}_n={\mathrm{\α}}_n^2\left[\underset{m=n-N}{\overset{n-1}{\mathrm{\Σ}}}(i_m^2+q_m^2)\right]-\mathrm{ref}$

Wherein, (α) defined the compensating signal being generated by compensating signal generator (600), N has defined a frame, i _mand q _mbe the power of inputted in-phase signal (I_IN) and orthogonal signalling (Q_IN), ref refers to default reference power.

Now, the performance number of last time (n-1) is defined as

Then, following formula 4 can be derived by formula 2.

Formula 4

$p(n-1)=\frac{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}{{\mathrm{\α}}_{n-1}^2}$

If it is constant in single frame to suppose to take that the impulse response of the communication channel that ofdm system is model changes, can finds out between the upper result p (n) that received signal is averaged by N of current time (n) and the result p (n-1) on the last time (n-1), received signal being averaged by N and be roughly the same.As shown in Equation 5.

Formula 5

$p(n-1)\≅p\left(n\right)$

Then, can derive the formula 6 below with respect to current time (n).

Formula 6

$p\left(n\right)=\frac{\mathrm{ref}+{\mathrm{\Δ\δ}}_n}{{\mathrm{\α}}_n^2}\⇒{\mathrm{\α}}_n^{2}p\left(n\right)=\mathrm{ref}+{\mathrm{\Δ\δ}}_n$

Now, if the value p being drawn by formula 4 (n) substitution formula 6 can obtain following formula 7.

Formula 7

${\mathrm{\α}}_n^2\left(\frac{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}{{\mathrm{\α}}_{n-1}^2}\right)=\mathrm{ref}+{\mathrm{\Δ\δ}}_n\⇒{\mathrm{\α}}_n^2=\frac{\mathrm{ref}+{\mathrm{\Δ\δ}}_n}{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}{\mathrm{\α}}_{n-1}^2$

Value (the α of the compensating signal that then, compensating signal generator (600) generates _n) can draw from following formula 8:

Formula 8

${\mathrm{\α}}_n={\mathrm{\α}}_{n-1}\sqrt{\frac{\mathrm{ref}+{\mathrm{\Δ\δ}}_n}{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}}$

The formula 8 that has defined relation between formula 2 and formula 3 can be called as the characteristic function of compensating signal generator (600).

If Negative Feedback Type AGC equipment is stable, by the detected gain error value of gain error detector (400), As time goes on diminished, and the compensating signal being generated by compensating signal generator (600) must converge to constant.

If operation of receiver is stable, following formula 9 has illustrated that the characteristic function of compensating signal generator (600) converges to constant.

Formula 9

Wherein, ignored the impact of loop filter (100), because compare little that the output signal of gain error detector (100) may be suitable with the bandwidth of loop filter (200).

In order to meet the condition of formula 9, the mode that the output of the compensating signal generator (600) in current time (n) compensation must be reduced with the absolute value of the output on gain error detector (100) is determined.

Following formula 10 represented compensating signal generator (600), for the compensating signal value generating in the last time (n-1) based on compensating signal generator (600), make gain error detector (100) minimize necessary output condition in the detected gain error value of current time (n).

Formula 10

${{\mathrm{\α}}_n}^2\left[\underset{m=n-N}{\overset{n-1}{Q}}({i_m}^2+{q_m}^2)\right]=-\mathrm{ref}={\mathrm{X\δ}}_{n}J{\mathrm{X\δ}}_{n-1}r{{\mathrm{\α}}_n}^2\left[\underset{m=n-N}{\overset{n-1}{Q}}({i_m}^2+{q_m}^2)\right]-\mathrm{ref}\%O$

In other words, if gain error (the Δ δ that hypothesis gain error detector (400) detected in the last time (n-1) _n-1) be less than significantly gain error detector (100) at gain error value (the Δ δ of current time current time (n) detection _n), the average power of input signal is multiplied by the compensating signal being generated by compensating signal generator (600), and deducts reference power from the value multiplying each other, wherein the value of deducting be to be necessary for zero gain error value.

At this moment, the compensating signal being generated by compensating signal generator (600) is that gain error detector (400) is at the function of the gain error of current time (n) detection.Therefore, only, when the power of the input signal that can accurately estimate to receive in current time, can estimate the optimal compensation signal being generated by compensating signal generator (600).

AGC equipment is for measuring average power content within a predetermined period of time, to measure the accurate power of the input signal being received, make the difference between the average power content of measuring in the last time (n-1) and the average power content of measuring in current time (n) very little.

Result, can be used on average power content that the last time (n-1) calculates as the average power estimated value of current time (n), and can be with formula 4, according to formula 11 and formula 12, set up the function relevant to compensating signal generator (600).

Formula 11

${\mathrm{\α}}_n^2=\frac{\mathrm{ref}}{\underset{m=n-N}{\overset{n-1}{\mathrm{\Σ}}}(i_m^2+q_m^2)}=\frac{\mathrm{ref}}{p\left(n\right)}\≅\frac{\mathrm{ref}}{\hat{p}\left(n\right)}\≅\frac{\mathrm{ref}}{p(n-1)}={\mathrm{\α}}_{n-1}^2\frac{\mathrm{ref}}{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}$

Formula 12

${\mathrm{\α}}_n={\mathrm{\α}}_{n-1}\sqrt{\frac{\mathrm{ref}}{\mathrm{ref}+{\mathrm{\Δ\δ}}_{n-1}}}$

Here,

the average power estimated value of p (n), here

If it is upper that the function of formula 12 is applied to compensating signal generator (600), can minimize the size variation of received signal to improve receptivity.Yet therefore, because formula 12 has adopted subduplicate form, be necessary to be equipped with independent memory and store in advance compensating signal or be equipped with independent circuit and carry out computing formula 12.

In order to solve this shortcoming, the disclosure is used Taylor series square root function to be changed to the form of linear function, thereby AGC equipment can be save for calculating the independent circuit of square root function or with the single memory of the pre-stored compensating signal of form of question blank.Formula 12 can expand to following formula 13.

Formula 13

${\mathrm{\&alpha;}}_n={\mathrm{\&alpha;}}_{n-1}\sqrt{\frac{\mathrm{ref}}{\mathrm{ref}+{\mathrm{X\&delta;}}_{n-1}}}={\mathrm{\&alpha;}}_{n-1}\sqrt{\frac{1}{1+\frac{{\mathrm{X\&delta;}}_{n-1}}{\mathrm{ref}}}},\frac{{\mathrm{X\&delta;}}_{n-1}}{\mathrm{<figure-callout\; id="1"\; label="ref\; J"\; filenames="S071C8885320070720E000051.png,S071C8885320070720E000061.png"\; state="\{\{state\}\}">ref</figure-callout>}}J1$

In formula 13

can expand to following formula 14.

Formula 14

$\sqrt{\frac{1}{1+\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}}{\mathrm{ref}}}}={(1+\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}}{\mathrm{ref}})}^{-\frac{1}{2}}={(1+y)}^{-\frac{1}{2}},\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}}{\mathrm{ref}}=y$

If replaced as in formula 14

and use as the Taylor series of formula 15, just can derive the functional form that is similar to formula 13.

Formula 15

${(1+y)}^n=1+n\&CenterDot;y+\frac{n(n-1)}{2}{y}^2+...$

Now, if be input to gain error value (the Δ δ of compensating signal generator (600) _n-1) larger, generate very large approximate error value.Yet receiver is adjusted gain amplifier for the AGC signal in response to from the output of AGC amplifier, makes to be input to gain error value (the Δ δ of compensating signal generator (600) _n-1) dynamic range be not very large.Therefore, can ignore the error producing in formula 13 is approximately to the process of linear function.

As formula 13 being carried out to the result of Taylor series expansion, compensating signal generator (600) generates the approximate penalty function of compensating signal as shown in formula 16 below.

Formula 16

${\mathrm{\&alpha;}}_n=(1-\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}}{2\mathrm{ref}})\&CenterDot;{\mathrm{\&alpha;}}_{n-1}$

Thus, compensating signal generator (600) comprising: fader (610), and for adjusting gain error value (the Δ δ that is input to compensating signal generator (600) _n-1) gain; And compensator (620), for the compensating signal value α in output of last time (n-1) by utilization _n-1come compensating gain adjuster (610) to adjust the gain error value of its gain

and the compensating signal α of generation current time (n) _n.

Fader (610) uses for example its amplitude gain to be

amplifier build.For example, compensator (620) comprising: delayer (622), and for postponing the compensating signal (α of current time (n) _n); Multiplier (624), multiplies each other the output signal of the output signal of fader (610) and delayer (622); And adder (626), the output signal of the output signal of delayer (622) and multiplier (624) is added to generate to the compensating signal α of current time (n) _n.

Invention pattern

Fig. 7 is the block diagram illustrating according to the configuration of the AGC equipment of another example embodiment.With reference now to Fig. 7,, AGC equipment also comprises gain error compensator (700), and it is inserted between gain error detector (400) and loop filter (410).This gain error compensator (700) predetermined threshold value (TH).If be less than default threshold value (TH) from the gain error value of gain error detector (400) output, the gain error value that failure of consideration is exported from gain error detector (400), but tale quale is outputed to loop filter (410).If be greater than default threshold value (TH) from the gain error value of gain error detector (400) output, utilize threshold value (TH) to proofread and correct from the gain error value of gain error detector (400) output, and the value after proofreading and correct is outputed to loop filter (410).

In other words, in this another example embodiment, as shown in formula 17, will be from gain error value (the Δ δ of gain error detector (400) output _n-1) and default threshold value (TH) compare.Result as a comparison, if | Δ δ _n-1|≤TH, compensating signal generator (600) is used gain error value (Δ δ _n-1) compensating gain error.If | Δ δ _n-1| > TH, compensating signal generator (600) is used

rather than (Δ δ _n-1) as gain error value, thus compensating gain error.

Formula 17

${\mathrm{\&alpha;}}_n=(1-\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}^{\&prime;}}{2\mathrm{ref}})\&CenterDot;{\mathrm{\&alpha;}}_{n-1}\left\{\begin{array}{c}\left|{\mathrm{\&Delta;\&delta;}}_{n-1}\right|\&le;\mathrm{TH},{\mathrm{\&Delta;\&delta;}}_{n-1}^{\&prime;}={\mathrm{\&Delta;\&delta;}}_{n-1}\\ \left|{\mathrm{\&Delta;\&delta;}}_{n-1}\right|>\mathrm{TH},{\mathrm{\&Delta;\&delta;}}_{n-1}^{\&prime;}=\frac{{\mathrm{\&Delta;\&delta;}}_{n-1}}{\mathrm{TH}}\end{array}\right.$

For this reason, in another example embodiment, gain error compensator (700) is equipped with comparator (702), in order to gain error value (Δ δ _n-1) and default threshold value (TH) compare; Adjuster (704) is equipped with and, in order to by gain error value (Δ δ _n-1) proofread and correct to be

the result that device (702) compares as a comparison, if | Δ δ _n-1|≤TH, converting unit (706) output gain error amount (Δ δ _n-1), and if | Δ δ _n-1| > TH, converting unit (706) output as gain error value.

As mentioned above, in another example embodiment, according to gain error value (Δ δ _n-1) size and utilize two functions to carry out the bandwidth of adjustment System, thereby can suppress suddenly large change or the transient response of system of input signal with imitating, can make system stability.

Fig. 8 and Fig. 9 illustrate according to another example embodiment, the curve chart that changes from the output signal of compensating signal generator (600) output, and wherein change threshold (TH) is to check the performance of using AGC equipment of the present disclosure.

Now, with reference to figure 8 and Fig. 9, can notice, when threshold value (TH) changes, the bandwidth of system also changes.In the degeneration factor such as AGC equipment of the present disclosure, if be with roomyly, the variation of output signal as shown in Figure 8.Alternatively, if bandwidth is little, the variation of output signal as shown in Figure 9.

Although the disclosure is described in conjunction with embodiment of the present disclosure, it is apparent to those skilled in the art that disclosed application can be revised according to various ways, and can suppose the many preferred embodiments except above-mentioned specific embodiment.Therefore, claims are intended to contain all open modification theing fall within true spirit of the present invention and scope.

Industrial applicibility

According to the disclosure, for the various digital broadcasting signal receivers that receive such as the digital broadcast signal of digital ground multimedia broadcast (DTMB) signal, be equipped with automatic gain to control equipment and the method for (AGC), to adjust the intensity that receives signal.

Claims (11)

1. for automatic gain, control the equipment of (AGC), comprising: gain error detector, compensates received input signal, to detect gain error value in response to compensating signal; Loop filter, the described gain error value that accumulation is detected by gain error detector, and output to AGC amplifier as AGC signal; Compensating signal generator, the output signal of compensation loop filter by response penalty function, to generate compensating signal; And the gain error compensator between gain error detector and loop filter, for compensating described gain error and output to loop filter according to the size of the detected described gain error value of gain error detector,

Wherein, described gain error compensator comprises:

Comparator, the size between the gain error value that relatively gain error detector detects and default threshold value;

Adjuster, the gain error value of utilizing default threshold value to come correct for gain error detector to detect; And

Converting unit, if the described gain error value that described gain error detector detects is less than or equal to described default threshold value, the described gain error value described gain error detector being detected outputs to described loop filter, if and the described gain error value that described gain error detector detects is greater than described default threshold value, the gain error value of described adjuster being proofreaied and correct outputs to loop filter.

2. equipment as claimed in claim 1, compensating signal generator comprises: fader, the gain of loop filter output signal is adjusted to a preset value; And compensator, the output signal of compensating gain adjuster in response to the compensating signal value in last time durations output, to generate the compensating signal of current time.

3. equipment as claimed in claim 2, wherein fader is amplifier.

4. equipment as claimed in claim 2, wherein said compensator comprises: delayer, delay compensation signal; Multiplier, multiplies each other the output signal of the output signal of fader and delayer; And adder, the described output signal of the output signal of multiplier and described delayer is added, to generate the described compensating signal of described current time.

5. equipment as claimed in claim 1, wherein said penalty function is linear function.

6. equipment as claimed in claim 1, wherein said gain error detector comprises: multiplier, is multiplied by compensating signal by the in-phase signal of described input signal and orthogonal signalling respectively; Power checker, the power of the output signal of measurement multiplier; Average value calculator, calculates the power average value of being measured by power checker; And subtracter, from the described power average value being calculated by described average value calculator, deduct default reference power.

7. equipment as claimed in claim 6, wherein said average value calculator is calculated the mean value of a frame.

8. for automatic gain, control the method for (AGC), comprise following step: in response to compensating signal, compensate received input signal, to detect gain error value; The gain error value that accumulation detects; And compensate accumulated gain error value according to default penalty function, to generate compensating signal,

Wherein said method also comprises: the size of determining the gain error value detecting; According to determined size, compensate described gain error value and accumulate,

Wherein, described according to the described gain error value of determined size compensation and accumulate and comprise the steps:

Size between the gain error value relatively detecting and default threshold value;

Utilize described default threshold value to proofread and correct detected gain error value; And

If the gain error value detecting is less than or equal to described default threshold value, select the gain error value detecting and accumulate, if the gain error value detecting is greater than described default threshold value, selects the gain error value of proofreading and correct and accumulate.

9. method as claimed in claim 8, wherein realizes by respectively the in-phase signal of input signal and orthogonal signalling being multiplied by described compensating signal the compensation of described input signal.

10. method as claimed in claim 8, wherein comprises following step to the detection of described gain error value: the power of measuring the input signal compensating; Calculate the mean value of measured power; And deduct default reference power from calculated power average value, to calculate described gain error value.

11. methods as claimed in claim 8, wherein penalty function is linear function.

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