CN1423486A - Automatic gain control device for digital television receiver and method thereof - Google Patents
Automatic gain control device for digital television receiver and method thereof Download PDFInfo
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Abstract
The invention relates to an automatic gain controller of digital television receiver with vestigial sideband (VSB) and its device, especially it makes the received VSB modulating signal accomplish the radio frequency AGC and intermediate frequency AGC by a demodulating receiving chip, and it can also detect out the power of the received signal by the AGC in receiving chip. Thus selectively regulate frequency band to get the characteristic of rapid convergence, few distortion in the instance of waveform and low noise. When two more different receiving system is to be formed, AGC can be sheared as the reference value of each radio frequency AGC can be selected in its own way. And it can detect out the power of the received signal in the way of AGC so that it can be used to more broad fields.
Description
Technical field
The present invention relates to the automatic gain control equipment and the method (AGC apparatus and method in digital TV receiver) thereof of the digital television receiver of a kind of use residual sideband (VSB) mode.It is applicable to wired, wireless communication fields such as VSB, QAM, QPSK, OFDM receiver.
Background technology
Digital Television is a kind of television system of developing in order to experience the strong atmosphere of arenas in family.Compare with present simulated television, improved the definition (example: 1080 * 1920) of picture greatly, widened horizontal width (for enabling to adopt to greatest extent vertical ratio of film, promptly 4: 3,5: 3,1.85: 1.2,4: 1, decision was adopted 16: 9), and the multichannel sound accompaniment that the CD level is provided is (for example: 5,1 channel).
About this class Digital Television, the U.S., Europe, Japan and other countries are being formulated the broadcast system and the specification that meet self respectively and are being advanced its standardization.With the U.S. is example, and delivery form has been taked residual sideband (VSB) mode by U.S. Jie Nisi (Zenith) proposition; The video compression of compressed format aspect has been taked mpeg standard; Doby AC-3 has been taked in audio compression; Display format then is defined as with existing display packing and keeps interchangeability.
On the other hand, the signal gain size of being sent by the portion of posting a letter is normally certain, still since signal arrive receiver the distance of process, and when arriving receiver, by various passages, the signal gain size can change to some extent.The signal that has so changed the gain size will be input in the receiver.But during the most of digital circuit in the design receiver, suppose that all input signal is that the gain that has a certain size is imported usually.Therefore, just be necessary to regulate the analog signal gain that is input to receiver, one of make to have a certain size gain, and then convert digital signal to maintenance.
What play this effect is exactly automatic gain control (Auto Gain Control:AGC) device.The AGC device is to judge present input signal gain according to the mean value of input signal or power (Power).And according to the gain of judging, the amplifier in control radio frequency and the intermediate frequency analog circuit makes signal have required size.
The most of AGC device that uses all utilizes delay (Delayed) AGC mode as shown in Figure 1 now.
At first, modulated VSB high frequency (radio frequency) signal is by after the antenna input, and tuner (101) is converted to intermediate frequency then by the tuning frequency of selecting required passage, outputs to intermediate frequency AGC enlarging section (102).Above intermediate frequency in intermediate frequency AGC enlarging section (102), gain controlled after, output to VSB demodulation section (103).
VSB demodulation section (103) will carry out the controlled intermediate-freuqncy signal of gain to be exported after the VSB demodulation, so that carry out digitlization.And the signal of VSB demodulation will output to charge pump and filter (104) for AGC.
Charge pump and filter (104) are storing receiver and are initially using the information of regulating from working till now.The VSB restituted signal of input with the gain information of having deposited relatively, if the signal gain that receives is little, will generate the signal that increases gain so; If gain is big, will generate the signal that reduces gain; Signal feedback with these generations arrives on the intermediate frequency AGC enlarging section (102) then.
The signal that can gain according to the lifting or the reduction of feedback in intermediate frequency AGC enlarging section (102) increases or reduces the gain of intermediate-freuqncy signal, and then makes the signal gain of intermediate frequency remain on required state.
That is, the method for regulating actual gain is at first in opening power or when changing passage, it is set in receives the maxgain value that function reaches, and at first in intermediate frequency AGC enlarging section (102), regulates gain according to the gain size of input signal then.
If, the gain-adjusted ability of intermediate frequency AGC enlarging section (102) has reached the limit, but, if the output signal of VSB demodulation section (103) does not still reach required size, will go to regulate the gain of tuner (101) with this from intermediate frequency AGC enlarging section (102) again to tuner (101) propagation delay AGC signal so.Be that tuner (101) compares by the radio frequency AGC fiducial value that postpones the AGC signal and deposited, automatically go to control the gain of radiofrequency signal then.
But more than Shuo Ming AGC mode exists following problem.
The first, because the leakage current that takes place in the charge pump will cause AGC to produce the moment shake of waveform.Therefore, also must proceed the pumping operation even if crossed long time.
The second, because charge pump and filter all be made up of analog element, so, being difficult for removing to regulate AGC annular frequency band selectively, circuit is also complicated, also has limitation.
The 3rd, when forming plural different receiving system, because will use oneself radio frequency AGC fiducial value respectively, so, realize that total AGC is relatively more difficult.
The 4th, the power ratio of going to detect received signal from AGC is difficulty.
Summary of the invention
The present invention develops in order to solve the above problems, and purpose is to provide a kind of AGC devices and methods therefor that can directly control the digital television receiver of radio frequency and intermediate frequency AGC in the digital received chip.
Another object of the present invention is to provide a kind of AGC devices and methods therefor that detects received signal level from AGC.
The object of the present invention is achieved like this: the technical essential of this digital television receiver AGC device is: comprise tuning portion, intermediate frequency AGC enlarging section, demodulation section, wherein tuning will be from the radiofrequency signal that receives by antenna, only de-tuned specific radiofrequency signal, and by the rf gain control signal of importing, automatically regulate tuning radiofrequency signal gain, be converted into intermediate-freuqncy signal then; Intermediate frequency AGC enlarging section will automatically adjust to the intermediate-freuqncy signal gain by tuner output by the intermediate-frequency gain control signal of input, is exported then, so that carry out demodulation; Demodulation section will be to carrying out demodulation by the intermediate-freuqncy signal of intermediate frequency AGC enlarging section output; Also be provided with an AGC portion, it will try to achieve the error of AGC gain from the signal of demodulation, it is accumulated, and by the gain error size of accumulating, from a plurality of working ranges, determine one of them working range, export rf gain control signal and intermediate-frequency gain control signal by its working range to tuner and intermediate frequency AGC enlarging section again.
AGC portion has following characteristics, that is: by the big wisp working range of gain error of accumulation be divided into highfield on a large scale, the middle scope of middle electric field, weak electric field among a small circle; In on a large scale, regulate the gain of intermediate-freuqncy signal, make the gain of radiofrequency signal maintain the state that reduces to greatest extent; In middle scope, regulate the gain of radiofrequency signal, to keep the gain of intermediate-freuqncy signal; In among a small circle, regulate the gain of intermediate-freuqncy signal, make the gain of radiofrequency signal maintain enlarging state to greatest extent.
AGC portion also has following characteristics, is provided with an AGC error detector that is:, and it carries out the signal of demodulation after square processing, the difference between the performance number of asking for and having set, and exported as the gain error value.Be provided with a radio frequency loop filter, it goes to accumulate after the gain error that the AGC error detector tries to achieve, whether the gain error of checking accumulation exceeds position critical value or the next critical value on the radiofrequency signal of having set in the working range that has determined, and exports its radio-frequency region control signal; In addition, the gain error value of also finding accumulation is the upper critical value that exceeds radiofrequency signal, and the expression of still the next critical value, and output exceeds the radio frequency direction control signal of direction.Also be provided with an intermediate frequency loop filter, it will be accumulated after the gain error that the AGC error detector tries to achieve, whether the gain error of checking accumulation exceeds position critical value or the next critical value on the intermediate-freuqncy signal of having set in the working range that has determined, and exports its intermediate frequency range control signal; In addition, the gain error value of also finding accumulation is the upper critical value that exceeds intermediate-freuqncy signal, or the next critical value, and exports the intermediate frequency direction control signal that a demonstration exceeds direction.Also be provided with a FILTER TO CONTROL portion, it will receive from radio frequency, intermediate frequency direction control signal and radio frequency, the intermediate frequency range control signal of radio frequency, the output of intermediate frequency loop filter, and determine its working range, and corresponding work scope controlling value is outputed to radio frequency, intermediate frequency loop filter with this.
The technical essential of digital television receiver AGC method of the present invention is: it was made up of the following stage, that is: the phase I is that signal to demodulation carries out a square processing, from the signal of square processing, deduct the reference power value of having set then and try to achieve gain error, and then go the stage of accumulating again; Another stage is the size of gain error according to accumulation, goes to determine the some working ranges in a plurality of working ranges, and directly goes to control according to the working range of decision the stage of the gain and the intermediate-freuqncy signal gain of radiofrequency signal.
Also having a feature is in the gain controlling stage, by the big wisp working range of gain error be divided into highfield on a large scale, the middle scope of middle electric field, weak electric field among a small circle; And on a large scale in, get off to regulate the gain of intermediate-freuqncy signal with keeping the state that reduces radiofrequency signal gain to greatest extent; In middle scope, keep the state of intermediate-freuqncy signal gain to regulate the gain of radiofrequency signal down; In among a small circle, the state that keeps increasing the radiofrequency signal gain is to greatest extent got off to regulate the gain of intermediate-freuqncy signal.
The another one feature is that the above gain controlling stage is again by following forming stage by stage, that is: if present working range among a small circle, and the gain error of accumulation is judged as the next critical value that all exceeds the radiofrequency signal that sets among a small circle and the next critical value of intermediate-freuqncy signal, then working range just determines to be middle scope, and remaining situation all is decided to be among a small circle; If present working range is middle scope, and be judged to be all exceed in the next critical value of the radiofrequency signal that sets of scope and the next critical value of intermediate-freuqncy signal, then working range just decision on a large scale; And remaining situation all is decided to be among a small circle; The upper critical value of the radiofrequency signal that scope set during if the gain error of accumulation was judged as and all exceeds and the upper critical value of intermediate-freuqncy signal, then working range just is decided to be among a small circle; And remaining situation is decided to be middle scope; If present working range is on a large scale, and judge that the gain error of accumulating all exceeds the upper critical value of the radiofrequency signal that sets and the upper critical value of intermediate-freuqncy signal on a large scale, then working range just is decided to be middle scope, and remaining situation is decided to be on a large scale.
In sum, the AGC device and method of digital television receiver of the present invention can be carried out radio frequency AGC and intermediate frequency AGC with receiving chip, and the AGC in the receiving chip detects the power of received signal, therefore, following some benefit is arranged.
The first, by optionally regulating AGC annular frequency band, can be restrained the very little characteristic of jittering noise rapidly with waveform moment pettiness.
The second, because form, so than being easier to realize single chipization with digital form.Especially when forming two or more different receiving system, the fiducial value of radio frequency AGC can be gone to select, therefore AGC can be had by mode.
The 3rd, can detect the power of received signal by the mode of AGC, thereby can be widely used.
The other objects and features of the invention and benefit can be by being understood the detailed description of appended drawings example.
Description of drawings
Below in conjunction with accompanying drawing the present invention is further described.
Fig. 1 is a general A GC device composition frame chart.
Fig. 2 is an AGC device composition frame chart of the present invention.
Fig. 3 is the actuating range of AGC portion in Fig. 2 and the illustration that gain curve changes with signal intensity.
Fig. 4 is the detailed diagram of AGC portion among Fig. 2.
Fig. 5 is the detailed diagram of gain error detector and the circulation gain selector of Fig. 4.
Fig. 6 is the filter controller detailed diagram of Fig. 4.
Fig. 7 is the workflow diagram of the filter controller of Fig. 4.
Fig. 8 is the detailed diagram of the radio frequency loop filter of Fig. 4.
Fig. 9 is the detailed diagram of the intermediate frequency loop filter of Fig. 4.
Figure 10 is the repeatedly ear tower of Fig. 4, the detailed diagram of sigma 1 bit DAC.
Figure 11 is the detailed diagram of the signal power test section of Fig. 4.
Figure 12 is the workflow diagram of the signal power test section of Fig. 4.
Main sequence number explanation among the figure
201: antenna system 202: tuner
203: intermediate frequency AGC 204:VSB demodulation section
204-1 AGC portion 301: signal power test section
302: antenna control part 401:AGC error detector
402: circulation gain selector 403:AGC locking control part
404: filter controller 405: the radio frequency loop filter
406: the radio frequency ear tower that changes, sigma DAC (D-A converter)
407: the intermediate frequency loop filter
408: the intermediate frequency ear tower that changes, sigma DAC (D-A converter)
Specific implementation method
Below, to example of the present invention, described in detail with reference to accompanying drawing.
Fig. 2 is the composition frame chart of digital television receiver of the present invention.Receiver VSB acceptance division (200) is made of following part.That is: regulate antenna directivity and make the signal of reception become best antenna system (201) with antenna; In the radiofrequency signal by antenna system (201) reception, the channel frequence that only tuning user selects, and go to control tuning radiofrequency signal gain, and be converted into the tuner (202) of intermediate-freuqncy signal; Control is by the intermediate-freuqncy signal gain of tuner (202) output, and the intermediate frequency AGC enlarging section (203) of amplifying; Controlled intermediate-freuqncy signal is carried out the VSB demodulation to gaining, and to tuner (202) and intermediate frequency AGC enlarging section (203) outputing gain control signal (radio frequency AGC, intermediate frequency AGC), so as to directly removing to control the VSB demodulation section (204) of radiofrequency signal gain and intermediate-freuqncy signal gain.Wherein, VSB demodulation section (204) has the AGC portion (204-1) that generates intermediate-frequency gain control signal (intermediate frequency AGC) and rf gain control signal (radio frequency AGC).
The digital television receiver of Fig. 2 has also been set up signal power test section (301) and antenna control part (302).The AGC information that provides from VSB acceptance division (200) will be provided for the former, remove to detect the power of received signal; And the latter will go to control antenna system (201) according to the size of detected signal power.Be antenna system (201), will go to regulate the directionality of antenna, make the received signal power of antenna control part (302) output become maximum.
At this moment, antenna control part (302) will go to control the AGC mode of AGC (204-1) as required, so as to selecting normal AGC detection mode and AGC detection mode fast.
Fig. 3 shows by the working range of the AGC portion (204-1) of change in signal strength of the present invention and the example of gain curve.
Working range is according to the size of signal, promptly by intensity be divided into big (large), in (middle), little (small) scope.
That is, highfield on a large scale in, will be the biglyyest reduce rf gain, and go to regulate intermediate-frequency gain, in case amplifier or frequency mixer is saturated.At this moment, go to control the gain error of radiofrequency signal, make it can not exceed predefined large-scale upper critical value and the next critical value; Also to go to control the gain error of intermediate-freuqncy signal, make it can not exceed predefined large-scale upper critical value and the next critical value.
And in middle scope, intermediate-frequency gain will keep suitable size, and removes to regulate rf gain.At this moment, go to control the gain error of radiofrequency signal, make it can not exceed the upper critical value and the next critical value of predefined middle scope; Also to go to control the gain error of intermediate-freuqncy signal, make it can not exceed the upper critical value and the next critical value of predefined middle scope.
And weak electric field among a small circle in, mention maximum to rf gain, and go to regulate intermediate-frequency gain.At this moment, go to control the gain error of radiofrequency signal, make it can not exceed predefined upper critical value and the next critical value among a small circle; Also to go to control the gain error of intermediate-freuqncy signal, make it can not exceed predefined upper critical value and the next critical value among a small circle.
Fig. 4 is the detailed block diagram that is used for directly controlling the AGC portion (204-1) of radio frequency and intermediate-freuqncy signal gain.It is changed and tower by AGC error detector (401), circulation gain selector (402), radio frequency loop filter (405), intermediate frequency loop filter (407), filter controller (404) and radio frequency and intermediate frequency 1 bit, sigma DAC (D-A converter) (406,408) forms.
Fig. 5 is the detailed diagram of AGC error detector (401) and circulation gain selector (402).AGC error detector (401) is by squarer (401-1) and subtract and calculate device (401-2) and form.At this moment, squarer (401-1) will carry out a square processing to the signal that receives, and calculate device (401-2) output to subtracting; Subtract calculation device (401-2) and will from the signal of square processing, deduct reference power value (REF), and it is outputed to circulation gain selector (402).Subtract the output valve of calculating device (401-2) in other words and just become AGC gain error value.Also have, circulation gain selector (402) is formed by subtracting the calculation device.It will deduct constant (k) afterwards from the output of AGC error detector (401), its result is outputed to radio frequency loop filter (405) and intermediate frequency loop filter (407).At this moment, constant (k) is to be provided by AGC locking control part (403).That is to say that loop filter selector (402) will go to regulate the circulation gain of radio frequency loop filter (405) and intermediate frequency loop filter (407), make it have rapid convergence and the little characteristic of dither noise.
Fig. 6 shows the input of filter controller (404), the example of output signal.Working range will decide according to IF-Ref-con, the IF-Lim-con signal that RF-Ref-con, RF-Lim-con signal and the intermediate frequency loop filter (407) of radio frequency loop filter (405) output are exported.Promptly according to the size of input signal, among a small circle, scope, determine a working range on a large scale, generate a working range controlling value (stat), and respectively to radio frequency, intermediate frequency loop filter (405,407) output corresponding to working range.The working range of radio frequency, intermediate frequency loop filter (405,407) will be subjected to the restriction of working range controlling value (stat), as shown in Figure 3.
As an example, the working range controlling value (stat) of filter controller (404) output is to be assumed to be among a small circle in 00 o'clock; 01 is middle scope; 10 on a large scale.This is a concrete instance, but also can be different with designer's difference.
Fig. 7 is the workflow diagram of filter controller (404).
At first check the gain error value that is accumulated to radio frequency and intermediate frequency loop filter (405,407) and whether exceeded its limited field, exceed, decide working range according to its result then if exceeded will check to which direction so by its working range.For this reason, radio frequency circulation filter (405) will generate RF-Ref-con signal and RF-Lim-con signal, and outputs on the filter controller (404); And intermediate frequency circulation filter (407) will generate IF-Ref-con signal and IF-Lim-con signal, and outputs on the filter controller (404).
Fig. 8 and Fig. 9 are the detailed diagram of radio frequency and intermediate frequency loop filter (405,407).By the working range controlling value (stat) (being working range) that filter controller (404) sends, it has three working ranges.Whether the gain error value of promptly going earlier to judge radio frequency and intermediate frequency loop filter (405,407) accumulation has exceeded its limited field in the corresponding work scope.If exceeded limited field, to check so and exceed, and its result is outputed on the filter controller (404) to which direction.
At first, in Fig. 8,1MUX (multiplexer) (801) if be 0 from the upper bit of the working range controlling value (stat) of filter controller (404) output, will select the critical value maxrf that set so, and export to the 1st comparator (803); If 1, to select the critical value rfthddn that set so, and export to the 1st comparator (803).To 2MUX (802), if be 0, to select the critical value rfthdup that set so, and export to the 2nd comparator (804) from the next bit of the working range controlling value (stat) of filter controller (404) output; If 1 will select the critical value minrf that set, and export to the 2nd comparator (804).That is to say 1MUX (801) will select output filter controller (404) the upper critical value of fixed working range; 2MUX (802) then will select the next critical value of output.
For example, suppose that the working range controlling value (stat) by filter controller (404) output is 00, promptly among a small circle, 1MUX (801) will select output upper threshold critical value maxrf to the 1 comparator (803) among a small circle so; 2MUX (802) then selects output the next critical value rfthdup to the 2 comparators (804) among a small circle.
The 1st comparator (803) will be to comparing by the upper critical value of 1MUX (801) output with by the actual gain error amount of the radiofrequency signal of integrator (807) output, and its result is outputed to control signal generating unit (805); The 2nd comparator (804) will be to comparing by the next critical value of 2MUX (802) output with by the actual gain error amount of the radiofrequency signal of integrator (807) output, and its result outputed to the output valve (U) of the 1st comparator (803) that control signal generating unit (805) control signal generating unit (805) will basis and the output valve (D) of the 2nd comparator (804), generate the signal RF-Lim-con signal whether direction control signal RF-Ref-con and expression exceed critical value.
For convenience of explanation, the radiofrequency signal actual gain error amount that the present invention will set the 1st comparator (803) is during greater than upper critical value, when promptly exceeding upper critical value, allows its output 1; If when not exceeding, then allow it export 0.The radiofrequency signal actual gain error amount of setting the 2nd comparator (804) in addition is during less than the next critical value, when promptly exceeding the next critical value, allows its output 1; If when not exceeding, allow it export 0.
At this moment, RF-Ref-con signal and the RF-Lim-con signal that is generated by control signal generating unit (805) will decide by following table 1.
[table 1]
In table 1, whether the actual gain error amount of RF-Ref-con signal indication radiofrequency signal exceeds
The system signal.If 0, just be set at and exceeded the next critical value; If 1, just be set at and exceed upper critical value.RF-Lim-con represents then whether the actual gain error amount of radiofrequency signal exceeds the signal of the upper or the next critical value of having set.If 0, just setting does not exceed critical value; If 1, just setting has exceeded critical value.
| The position is faced value or is denied super the next dividing value direction | The boundary is the control that to face | ||||
| ????U | ????D | ???RF-Ref-con | ????RF-Lim-con | ||
| ????0 | ????0 | ??× | ????0 | ||
| ????0 | ????1 | ??0(D) | ????1 | ||
| ????1 | ????0 | ??1(U) | ????1 | ||
| ????1 | ????1 | ??× | ????0 | ||
So will be outputed to filter controller (404) by fixed RF-Ref-con signal and RF-Lim-con signal, meanwhile the RF-Ref-con signal will be with the output of the selection signal of 3MUX (806), and the RF-Lim-con signal is then with the selection signal output of the 4MUX (807-1) of integrator (807).
3MUX (806) when the RF-Ref-con signal is 1, for the actual gain error amount radiofrequency signal is restricted to upper critical value, will select to output to 4MUX (807-1) from the upper critical value of 1MUX (801) output; If be at 0 o'clock,, will select to output to 4MUX (807-1) from the next critical value of 2MUX (802) output for the actual gain error amount radiofrequency signal is restricted to the next critical value.
4MUX (807-1) when the RF-Lim-con signal is 1, will select to output to accumulator (807-2) from the upper or the next critical value of 3MUX (806) output; If be at 0 o'clock, will be chosen in the radiofrequency signal actual gain error of being accumulated and feeding back in (807-2) in the accumulator, output to accumulator (807-2).
The gain error value of accumulation when 5MUX (808) exports, also outputs to the addometer (807-3) of integrator (807) in accumulator (807-2).
Addometer (807-3) will be to superposeing one after the gain error value of gain error detector (401) output, to 4MUX (807-1) and the 1st, the 2nd comparator (803,804) output on the gain error value that is accumulated in accumulator (807-2).
5MUX (808) will be according to the AGC-mode signal by antenna control part (302) output, remove to select to export a rf gain error amount (RF-FAST-AGC) (809) that is fixed as particular value in advance, perhaps go to select gain error value, and it is outputed to radio frequency repeatedly and tower, sigma DAC (406) from the normal radio frequency signal of integrator (807) output.
That is,, will remove to select to be fixed as in advance the rf gain error amount (RF-FAST-AGC) of particular value so under the state of fixed RF, intermediate-freuqncy signal gain by AGC-mode if the signal that receives of forming a prompt judgement out is littler or big than a particular level.
In addition, as shown in Figure 9, it is very similar to composition and the workflow of Fig. 8.In Fig. 9, also for convenience of explanation, regulation 901 is 1MUX; 902 is 2MUX; 906 is 3MUX; 907-1 is 4MUX; 908 is 5MUX; 903 is the 1st comparator; 904 is the 2nd comparator.
At this moment, select the signal generating unit (910) will be by the working range controlling value of filter controller (404) output, generate as the selection signal of following table 2 (MUX-con1, MUX-con0) respectively to the 1st and 2MUX 901 902 fail
[table 2]
| ????Stat[1∶0] | ????MUX?con1 | ????MUX?con0 |
| 00 (among a small circle) | ????0 | ????0 |
| 01 (middle scope) | ????1 | ????0 |
| 10 (on a large scale) | ????1 | ????1 |
| ????11 | ????x | ????X |
So, 1MUX (901) when being 0 by the selection signal MUX-con1 that selects signal generating unit (910) output, with the critical value maxif that selects to have set, and outputs to the 1st comparator (903); If 1, then to select the critical value rfthdup that set, and output to the 1st comparator (903).2MUX (902) when being 0 by the selection signal MUX-con0 that selects signal generating unit (910) output, with the critical value rfthddn that selects to have set, and outputs to the 2nd comparator (904); If 1, then to select the critical value minif that set, and output to the 2nd comparator (904).Promptly 1MUX (901) selects the upper critical value of output by the working range of filter controller (404) decision, and 2MUX (902) selects the next critical value of output.
For example, the working range controlling value (stat) of establishing by filter controller (404) output is 00, is among a small circle, and 1MUX (901) will select upper critical value maxif among a small circle so, and outputs to the 1st comparator (903); 2MUX (902) then selects the next critical value rfthddn among a small circle, and exports to the 2nd comparator (904).
The 1st comparator (903) will be to comparing by the upper critical value of 1MUX (901) output with by the actual gain error amount of the intermediate-freuqncy signal of integrator (907) output, and its comparative result is outputed to control signal generating unit (905); The 2nd comparator (904) is then to comparing by the next critical value of 1MUX (902) output with by the actual gain error amount of the intermediate-freuqncy signal of integrator (907) output, and its comparative result output to control signal generating unit (905) control signal generating unit (905) according to the output valve (U) of the 1st comparator (903) and the 2nd comparator (904) be output valve (D), generate direction control signal-IF-Ref-con signal and whether expression exceeds critical value signal---IF-Lim-con signal.
In Fig. 9, also for convenience of explanation, if intermediate-freuqncy signal actual gain error amount promptly exceeds upper critical value greater than upper critical value, the 1st comparator (903) is made as output 1 so; If do not exceed, then be made as output 0.Also have, if intermediate-freuqncy signal actual gain error amount promptly exceeds the next critical value less than the next critical value, the 2nd comparator (904) is made as output 1 so; If do not exceed, then be made as output 0.
At this moment, IF-Ref-con signal and the following tabulation 3 of IF-Lim-con signal that is generated by control signal generating unit (905) decides.
[table 3]
| ????U | ????D | ????IF-Ref-con | ????IF-Lim-con |
| ????0 | ????0 | ????× | ????0 |
| ????0 | ????1 | ????0(D) | ????1 |
| ????1 | ????0 | ????1(U) | ????1 |
| ????1 | ????1 | ????× | ????0 |
In table 3, whether the actual gain error amount of IF-Ref-con signal indication intermediate-freuqncy signal has exceeded upper critical value or has not exceeded a direction control signal of the next critical value.If be 0, just be set at and exceeded the next critical value; If be 1, just be set at and exceeded upper critical value.IF-Lim-con represents then whether the actual gain error amount of intermediate-freuqncy signal has exceeded the signal of the upper or the next critical value of having set.If be 0, just be set at and do not exceed critical value; If be 1, then just be set at and exceed critical value.
IF-Ref-con signal of She Dinging and IF-Lim-con signal will output to filter controller (404) like this, and meanwhile the IF-Ref-con signal will be exported with the selection signal of 3MUX (906); The IF-Lim-con signal is then exported with the selection signal of integrator (907) 4MUX (907-1).
If the IF-Ref-con signal is 1, so, 3MUX (906) is restricted to upper critical value for the actual gain error amount intermediate-freuqncy signal, will select the upper critical value by 1MUX (901) output, and output to 4MUX (907-1); If 0, then for the actual gain error amount intermediate-freuqncy signal is restricted to the next critical value, it will select the next critical value by 2MUX (902) output, and output to 4MUX (907-1).
If the IF-Lim-con signal is 1,4MUX (907-1) will select the upper or the next critical value by 3MUX (906) output so, and output to accumulator (907-2); If 0, then be chosen in the intermediate-freuqncy signal actual gain error of accumulating and feeding back in the accumulator (907-2), and it is outputed to accumulator (907-2).
Be accumulated in the gain error value of accumulator (907-2), when exporting, also output to the addometer (907-3) of integrator (907) to 5MUX (908).
Addometer (907-3) will be exported to 4MUX (907-1) and the 1st, the 2nd comparator (903,904) by the gain error value of gain error detector (401) output on the gain error value of accumulator (907-2) accumulation then in stack.
5MUX (908) will be according to the AGC-mode signal by antenna control part (302) output, remove to select to export an intermediate-frequency gain error amount (IF-FAST-AGC) (909) that has been fixed as arbitrary value in advance, or select the output of integrator (907), and it is outputed to intermediate frequency repeatedly and on the tower, sigma DAC (408).
Filter controller (404) is the RF-Ref-con signal that is generated by Fig. 8 and Fig. 9 by input, and the RF-Ref-con signal after IF-Ref-con signal and the IF-Lim-con signal, determines its working range.Below, describe its course of work in detail with reference to the flow chart of Fig. 7.
That is, filter controller (404) will be set at 00 to initial working range controlling value (stat), promptly be initialized as among a small circle (701 stage).
And, if RF-Ref-con signal and IF-Lim-con signal all were 1 (702 stage), be that radiofrequency signal and intermediate-freuqncy signal are judged as the critical value that has all exceeded setting, so, will go to judge whether its working range controlling value (stat) is 00 (among a small circle) (703 stage).
In 703 stages,, will confirm so whether RF-Ref-con signal and IF-Ref-con signal all were 0 (704 stages) if working range controlling value (stat) is 00 (among a small circle).Here, RF-Ref-con signal and IF-Ref-con signal are 0 all, and the gain error value of radiofrequency signal and intermediate-freuqncy signal is described, (be rfthdup all less than among a small circle the next critical value, rfthddn) value illustrates that promptly it has exceeded the next critical value (is rfthdup, rfthddn).At this moment, working range will convert middle scope to, and is in addition, among a small circle original with keeping as before.
That is, in 704 stages, if in RF-Ref-con signal and the IF-Ref-con signal, some is not 0, will be set at 00 to working range controlling value (stat) so, and it is outputed to radio frequency, intermediate frequency loop filter (405,407) (705 stage).It will keep among a small circle original as before in other words.But,, if RF-Ref-con signal and IF-Ref-con signal all are 0, will be converted to 01 (middle scope) to working range controlling value (stat) so, and will output to radio frequency, intermediate frequency loop filter (405,407) (706 stage) in 704 stages.
In 703 stages,, to confirm whether be 01 (middle scope) (707 stage) so if judgment task scope controlling value (stat) is not 00 (among a small circle).In 707 stages,, to confirm so whether RF-Ref-con signal and IF-Ref-con signal all were 1 (708 stages) if judgment task scope controlling value (stat) is 01.
In 708 stages,, just represent that the gain error value of radiofrequency signal and intermediate-freuqncy signal has all exceeded the upper critical value that middle scope is set if RF-Ref-con signal and IF-Ref-con signal all are 1; If 0, just represent that the gain error value of radiofrequency signal and intermediate-freuqncy signal has all exceeded the next critical value that middle scope is set.
Because, in 708 stages, if RF-Ref-con signal and IF-Ref-con signal all are 1, the gain error value of just representing radiofrequency signal and intermediate-freuqncy signal has all exceeded the upper critical value of having set, so, to be converted to 00 (among a small circle) to working range controlling value (stat), and will output to radio frequency, intermediate frequency loop filter (405,407) (712 stage).
On the one hand, in 708 stages,,, so, reaffirm whether RF-Ref-con signal and IF-Ref-con signal all were 0 (709 stages) no matter which is not 1 if judge in the middle of RF-Ref-con signal and the IF-Ref-con signal.
In 709 stages, if judge in the middle of RF-Ref-con signal and the IF-Ref-con signal, no matter which is not 0, so, make working range controlling value (stat) be maintained 01 (middle scope) state, output to radio frequency, intermediate frequency loop filter (405,407) (710 stage) then.
In 709 stages, if two signals all are 0, just represent that radio frequency, intermediate-frequency gain error amount exceed the next critical value of having set, therefore, to be converted to 10 (on a large scale) to working range controlling value (stat) and output to radio frequency, intermediate frequency loop filter (405,407) (711 stage).
On the other hand, in 707 stages,, to confirm whether be 10 (on a large scale) (713 stages) so if judgment task scope controlling value (stat) is not 01 (middle scope).In 713 stages,, confirm whether RF-Ref-con signal and IF-Ref-con signal all were 1 (714 stages) if judgment task scope controlling value (stat) is 10.
In 714 stages, RF-Ref-con signal and IF-Ref-con signal all are 1, represent that so the gain error value of radiofrequency signal and intermediate-freuqncy signal all exceeds large-scale upper critical value, therefore, at this moment to be converted to middle scope, in addition, keep on a large scale original.
If promptly in 714 stages, in the middle of RF-Ref-con signal and the IF-Ref-con signal, whichsoever not 1, keep 10 original (on a large scale) to working range controlling value (stat), and it is outputed to radio frequency, intermediate frequency loop filter (405,407) (715 stage).And,, if RF-Ref-con signal and IF-Ref-con signal all are 1, to be converted to 01 (middle scope) to working range controlling value (stat) so, and it is outputed to radio frequency, intermediate frequency loop filter (405,407) (716 stage) in 714 stages.
And, in 713 stages,, to confirm whether be 11 (717 stages) so if judgment task scope controlling value (stat) is not 10.At this moment, working range controlling value (stat) should not take place be 11 situation, but this phenomenon may take place because of reasons such as mistakes yet.Therefore,,, return to for 701 stages, and make working range controlling value (stat) be initialized as 00 if judgment task scope controlling value (stat) is 11 in 717 stages; If judge it is not 11, return to for 702 stages, the referendum of laying equal stress on is decided the process of working range controlling value (stat).
Figure 10 be radio frequency, intermediate frequency repeatedly and tower, sigma DAC (406,408) detailed diagram, the value (RF-acc of radio frequency loop filter (405) and intermediate frequency loop filter (407), IF-acc) be converted to 1 analog signal (radio frequency AGC respectively, intermediate frequency AGC), and respectively export to tuner (202) and enlarging section (203).
Promptly subtract calculate device (1011) will be (RF-acc IF-acc) with by the maximum of MUX (1016) output or the difference of minimum value, outputs to addometer (1012) by the gain error value of loop filter (405 or 407) output.Addometer (1012) will be in the value that subtracts delayer (1013) feedback that back of stack will occur in the output of calculating device (1011), and will output to delayer (1013) to it.After delayer (1013) carries out the delay of certain hour to the output of addometer (1012), only highest order is outputed to transducer (1014) and MUX (1016), feed back to addometer (1012) simultaneously.Transducer (1014) will postpone to export behind the certain hour by delayer (1015) after will being reversed the highest order of delayer (1013) again.
In addition, Figure 11 shows output, the input signal of signal power test section (301) among Fig. 2.It will come detection signal power from AGC portion (204-1) input radio frequency gain error value (RF-acc), intermediate-frequency gain error amount (IF-acc) and working range controlling value (stat).That is, radio frequency, intermediate frequency loop filter (405,407) as shown in Figure 3, will go to determine its gain error value according to the signal strength signal intensity that receives; Therefore, signal power test section (301) will receive this and be worth to come detection signal power.And, if the signal power and the actual signal power form that detect are like this compared, can correctly calculate the performance number of signal so.Here the signal power value of Jian Ceing can be used as very important channel information.
Figure 12 is the workflow diagram of signal power test section (301), if allow the state (1201 stage) of locking, to utilize so by radio frequency, intermediate frequency recursive filter (405,407) Shu Chu gain error value (RF-acc, IF-acc), remove to detect present intermediate frequency, radiofrequency signal power (1202 stage).That is, on the maximum signal power (MAX-ACC) that receiver can have, respectively addition gain error value (RF-acc, IF-acc) (MAX-ACC+RF-acc, MAX-ACC+IF-acc), just can try to achieve present received signal power (RF-PW, IF-PW).At this moment,, promptly be expressed as on a large scale (1203 stage), will reduce rf gain to greatest extent if working range controlling value (stat) is 10.This is that signal power test section (301) will remove to determine IF-PW (1204 stage) with the signal power value (Power info.) that outputs to antenna control part (302) because regulate the scope of intermediate-frequency gain.
On the one hand, in 1203 stages, not 10 if judge working range controlling value (stat), to reaffirm whether be 01 (1205 stage) so.In 1205 stages, if 01, promptly scope in the expression will go to keep intermediate-frequency gain with suitable size so; And because be the scope of regulating rf gain, signal power test section (301) will decide radio frequency-PW (1206 stage) with the signal power level (Power info.) that outputs to antenna control part (302).
And, in 1205 stages, if 00, promptly be expressed as among a small circle, this is to increase under the state of rf gain to greatest extent so, go to regulate a scope of intermediate-frequency gain, so signal power test section (301) will decide intermediate frequency-PW (1207 stage) with the signal power value (Power info.) that outputs to antenna control part (302).
Antenna control part (302) will go to control antenna system (201) according to signal power value (Power info.), regulate the directionality of antenna, make it detect maximum power.So by antenna, the signal that is received by antenna system (201) reaches optimization.
The present invention goes for wired, wireless communication fields such as VSB, QAM, QPSK, OFDM receiver.
By above explanation, if the professional so just can carry out numerous variations or correction in the technical scope that does not break away from design philosophy of the present invention.So technical scope of the present invention should not be limited to
The content that embodiment put down in writing.
Claims (8)
1, a kind of automatic gain control equipment of digital television receiver, comprise tuning portion, intermediate frequency AGC enlarging section, demodulation section, it is characterized in that: tuning will be from the radiofrequency signal that receives by antenna, only de-tuned specific radiofrequency signal, and by the rf gain control signal of importing, automatically regulate tuning radiofrequency signal gain, be converted into intermediate-freuqncy signal then;
Intermediate frequency AGC enlarging section will automatically adjust to the intermediate-freuqncy signal gain by tuner output by the intermediate-frequency gain control signal of input, is exported then, so that carry out demodulation;
Demodulation section will be to carrying out demodulation by the intermediate-freuqncy signal of intermediate frequency AGC enlarging section output;
Also be provided with an AGC portion, it will try to achieve the error of AGC gain from the signal of demodulation, it is accumulated, and by the gain error size of accumulating, from a plurality of working ranges, determine one of them working range, export rf gain control signal and intermediate-frequency gain control signal by its working range to tuner and intermediate frequency AGC enlarging section again.
2, the automatic gain control equipment of digital television receiver according to claim 1 is characterized in that: by the big wisp working range of gain error of accumulation be divided into highfield on a large scale, the middle scope of middle electric field, weak electric field among a small circle;
In on a large scale, regulate the gain of intermediate-freuqncy signal, make the gain of radiofrequency signal maintain the state that reduces to greatest extent; In middle scope, regulate the gain of radiofrequency signal, to keep the gain of intermediate-freuqncy signal; In among a small circle, regulate the gain of intermediate-freuqncy signal, make the gain of radiofrequency signal maintain enlarging state to greatest extent.
3, the automatic gain control equipment of digital television receiver according to claim 2, it is characterized in that: be provided with an AGC error detector, it carries out the signal of demodulation after square processing, the difference between the performance number of asking for and having set, and exported as the gain error value;
Be provided with a radio frequency loop filter, it goes to accumulate after the gain error that the AGC error detector tries to achieve, whether the gain error of checking accumulation exceeds position critical value or the next critical value on the radiofrequency signal of having set in the working range that has determined, and exports its radio-frequency region control signal; In addition, the gain error value of also finding accumulation is the upper critical value that exceeds radiofrequency signal, and the expression of still the next critical value, and output exceeds the radio frequency direction control signal of direction;
Be provided with an intermediate frequency loop filter, it will be accumulated after the gain error that the AGC error detector tries to achieve, whether the gain error of checking accumulation exceeds position critical value or the next critical value on the intermediate-freuqncy signal of having set in the working range that has determined, and exports its intermediate frequency range control signal; In addition, the gain error value of also finding accumulation is the upper critical value that exceeds intermediate-freuqncy signal, or the next critical value, and exports the intermediate frequency direction control signal that a demonstration exceeds direction;
Be provided with a FILTER TO CONTROL portion, it will receive from radio frequency, intermediate frequency direction control signal and radio frequency, the intermediate frequency range control signal of radio frequency, the output of intermediate frequency loop filter, and determine its working range, and corresponding work scope controlling value is outputed to radio frequency, intermediate frequency loop filter with this.
4, the automatic gain control equipment of digital television receiver according to claim 1, it is characterized in that: be provided with the signal power test section, it will go to detect the signal power value of existing reception according to radio frequency and intermediate-freuqncy signal storage gain error amount and the working range from the output of AGC portion;
Be provided with the antenna control part, it will go to export control signal according to the signal power that is detected by the signal power test section;
Also have antenna system, it will go to adjust the directionality of antenna according to the control signal of antenna control part.
5, a kind of auto gain control method of digital television receiver, it is characterized in that: from the radiofrequency signal that receives by antenna, only de-tuned specific radiofrequency signal, and being converted to by tuning radiofrequency signal after the intermediate-freuqncy signal, carry out demodulation, comprise with the next stage:
Phase I is that the signal to demodulation carries out a square processing, from the signal of square processing, deducts the reference power value of having set then and tries to achieve gain error, and then stage of row accumulation again;
Another stage is the size of gain error according to accumulation, goes to determine the some working ranges in a plurality of working ranges, and directly goes to control the gain of radiofrequency signal and the gain of intermediate-freuqncy signal according to the working range of decision.
6, the automatic gain control equipment of digital television receiver according to claim 5 is characterized in that: the gain controlling stage by the big wisp working range of gain error be divided into highfield on a large scale, the middle scope of middle electric field, weak electric field among a small circle;
And on a large scale in, get off to regulate the gain of intermediate-freuqncy signal with keeping the state that reduces radiofrequency signal gain to greatest extent; In middle scope, keep the state of intermediate-freuqncy signal gain to regulate the gain of radiofrequency signal down; In among a small circle, the state that keeps increasing the radiofrequency signal gain is to greatest extent got off to regulate the gain of intermediate-freuqncy signal.
7, the automatic gain control equipment of digital television receiver according to claim 6 is characterized in that: the gain controlling stage is again by following forming stage by stage, that is:
If present working range is among a small circle, and the gain error of accumulation is judged as the next critical value that all exceeds the radiofrequency signal that sets among a small circle and the next critical value of intermediate-freuqncy signal, then working range just decision be middle scope, and remaining situation all is decided to be among a small circle stage;
If present working range is middle scope, and be judged to be all exceed in the next critical value of the radiofrequency signal that sets of scope and the next critical value of intermediate-freuqncy signal, then working range just decision on a large scale; And remaining situation all is decided to be among a small circle; The upper critical value of the radiofrequency signal that scope set during if the gain error of accumulation was judged as and all exceeds and the upper critical value of intermediate-freuqncy signal, then working range just is decided to be among a small circle; And stage of scope during remaining situation is decided to be;
If present working range is on a large scale, and the gain error of judging accumulation all exceeds the upper critical value of the radiofrequency signal that sets and the upper critical value of intermediate-freuqncy signal on a large scale, then working range just is decided to be middle scope, and remaining situation is decided to be the large-scale stage.
8, the automatic gain control equipment of digital television receiver according to claim 5, it is characterized in that: the gain error value of accumulation, if exceed the upper critical value of radiofrequency signal or the next critical value of working range, then the gain error value with accumulation is limited in upper critical value or the next critical value.
9, the automatic gain control equipment of digital television receiver according to claim 5, it is characterized in that: the gain error value of accumulation, if exceed the upper critical value of intermediate-freuqncy signal or the next critical value of working range, then the gain error value with accumulation is limited in upper critical value or the next critical value.
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| CN 02156910 CN1423486A (en) | 2002-12-23 | 2002-12-23 | Automatic gain control device for digital television receiver and method thereof |
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| CN 02156910 CN1423486A (en) | 2002-12-23 | 2002-12-23 | Automatic gain control device for digital television receiver and method thereof |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101911480A (en) * | 2008-01-16 | 2010-12-08 | 汤姆森特许公司 | Automatic gain control with state machine controller feedback |
| US8032099B2 (en) | 2007-10-30 | 2011-10-04 | Fitipower Integrated Technology, Inc. | Automatic gain control circuit using gain shift |
| US8036618B2 (en) | 2008-09-09 | 2011-10-11 | Ali Corporation | Auto gain controller and control method thereof |
| CN102438168A (en) * | 2011-10-10 | 2012-05-02 | 北京广电天地信息咨询有限公司 | Method for measuring broadcast television signal power and system thereof |
| CN102510315A (en) * | 2011-11-23 | 2012-06-20 | 北京广电天地科技有限公司 | CMMB (China Mobile Multimedia Broadcasting) network signal monitoring terminal, monitoring server and monitoring system |
| CN103401071A (en) * | 2013-07-29 | 2013-11-20 | 深圳市金品半导体有限公司 | Automatic receiving control method for antenna |
| CN104698339A (en) * | 2015-02-11 | 2015-06-10 | 国家电网公司 | Handheld fault finding instrument of power circuit in wall |
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2002
- 2002-12-23 CN CN 02156910 patent/CN1423486A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8032099B2 (en) | 2007-10-30 | 2011-10-04 | Fitipower Integrated Technology, Inc. | Automatic gain control circuit using gain shift |
| CN101911480A (en) * | 2008-01-16 | 2010-12-08 | 汤姆森特许公司 | Automatic gain control with state machine controller feedback |
| US8457573B2 (en) | 2008-01-16 | 2013-06-04 | Thomson Licensing | Automatic gain control with state machine controller feedback |
| CN101911480B (en) * | 2008-01-16 | 2013-12-11 | 汤姆森特许公司 | Automatic gain control circuit and method |
| US8036618B2 (en) | 2008-09-09 | 2011-10-11 | Ali Corporation | Auto gain controller and control method thereof |
| CN102438168A (en) * | 2011-10-10 | 2012-05-02 | 北京广电天地信息咨询有限公司 | Method for measuring broadcast television signal power and system thereof |
| CN102510315A (en) * | 2011-11-23 | 2012-06-20 | 北京广电天地科技有限公司 | CMMB (China Mobile Multimedia Broadcasting) network signal monitoring terminal, monitoring server and monitoring system |
| CN103401071A (en) * | 2013-07-29 | 2013-11-20 | 深圳市金品半导体有限公司 | Automatic receiving control method for antenna |
| WO2015014042A1 (en) * | 2013-07-29 | 2015-02-05 | 深圳市金品半导体有限公司 | Antenna automatic reception control method |
| CN104698339A (en) * | 2015-02-11 | 2015-06-10 | 国家电网公司 | Handheld fault finding instrument of power circuit in wall |
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