CN101873288A - Method and device for code acquisition - Google Patents
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Abstract
The invention discloses a method and a device for code acquisition and relates to synchronization technology in the field of wireless digital communication. The method for code acquisition comprises steps of: associating PN local sequences with the same phase with a PN sequence of a received signal respectively, and acquiring a plurality of PN sequence related peak values; detecting the PN sequence related peak values, finding the maximum and the sub-maximum of the related peak values in each frame, and acquiring the position difference between the maximum and sub-maximum; if the absolute value of the position difference of the maximum and the sub-maximum is the same in continuous M frames, selecting the maximum peak value position and the small or big position of the sub-maximum in the M frames as code acquisition related peak value positions; performing difference on the code acquisition related peak value positions in the M frames, and acquiring the acquisition related peak value position difference, wherein the difference is realized through N-order difference operation; and processing the absolute value of the code acquisition related peak value position difference, and acquiring a phase index of the PN sequence. The invention also provides a receiver employing the method and device.
Description
Technical field
The present invention relates to the simultaneous techniques in wireless digital communication field, particularly a kind of yard method and apparatus of catching that is used for.
Background technology
In the practical application of many different digital informations such as sound, data and video communication etc., simultaneous techniques is a kind of very important technology, and synchronous losing can cause falling flat of receiver.In ground digital television receiver, simultaneous techniques mainly comprises Carrier Synchronization, timing simultaneous techniques, Phase Tracking technology, anti-with adjacent perturbation technique frequently and yard capture technique." digital television ground broadcast transmission system frame structure, chnnel coding and modulation " GB20600-2006 of issue on 08 18th, 2006 has described three kinds of data structures.The data segment of three kinds of data structures is identical, and frame head section difference is respectively: PN420, PN595, PN945.When adopting PN595 as frame head, the phase place of frame head PN sequence is constant, and when adopting PN420 and PN945, the phase place of frame head PN sequence can change.The cycle that frame head PN sequence phase changes is a superframe, and the PN sequence phase of the every frame in the superframe is all inequality.Time domain frame head PN sequence has good autocorrelation, can be used as synchronous estimation and channel estimating.Yet, utilize the autocorrelation of PN sequence, at first to discern the phase position index of PN sequence, the process of obtaining PN sequence phase index is exactly a sign indicating number capture technique.Therefore, whether the phase position index butt joint receipts machine that whether obtains the PN sequence exactly can demodulate received signal exactly and play key effect.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of code capture method and device of quick identification PN sequence phase.
In order to solve the problems of the technologies described above, the invention provides a kind of method that sign indicating number is caught that is used for, it comprises the steps: to utilize the local sequence of the identical PN of phase place to make correlation step with the PN sequence of received signal respectively, obtains several PN sequence correlation peaks; PN sequence correlation peak is detected, find the maximum and the second largest value of correlation peak in each frame, and obtain both alternate position spikes; If in the continuous N frame, maximum value position is identical with the absolute value of second largest value alternate position spike, then select peak-peak position and medium and small position of second largest peak value or big position in this M frame, catch correlation peak location as sign indicating number; Sign indicating number in the described M frame is caught correlation peak location carry out difference step, it is poor that the acquisition sign indicating number is caught correlation peak location; Wherein difference step realizes that by N difference computing N is the integer more than or equal to 1; Sign indicating number is caught the absolute value of correlation peak location difference and handle, obtain the phase position index of PN sequence.
Further, selected correlation peak location in the M frame is carried out in the difference step, N=2 i.e. this step realizes by twice difference step.
In order to solve the problems of the technologies described above, the present invention also provides a kind of device that sign indicating number is caught that is used for, and it comprises: the PN sequence generator is used to produce identical local PN sequence; Correlator, it is relevant to utilize local PN sequence that the PN sequence generator produces and received signal to carry out, and exports several PN sequence correlation peaks; And the sign indicating number capturing unit, its yard capturing unit also comprises: the correlation peak location detection module, be used for the PN sequence correlation peak that detection correlator is exported, and find the maximum and the second largest value of correlation peak in each frame, and obtain the absolute value of both alternate position spikes; Select module, select peak-peak position and the medium and small position of second largest peak value or big position in the frame that maximum value position is identical with the absolute value of second largest value alternate position spike in continuous M frame at least, output code is caught correlation peak location; Sign indicating number is caught the acquisition module of correlation peak location difference, is used for the correlation peak location in the M frame is at least made difference, and it is poor that output code is caught correlation peak location; Wherein difference realizes that by N difference computing N is the integer more than or equal to 1; The acquisition module of PN sequence phase index, the absolute value that is used for sign indicating number is caught the correlation peak location difference is handled the phase position index of output PN sequence.
Further, sign indicating number is caught the difference computing of acquisition module of correlation peak location difference by twice realization, i.e. N=2.
The present invention also provides a kind of receiver that is used for received television signal, comprises analog-digital commutator, and the TV signal that is used for receiving is converted to digital signal; And the sign indicating number acquisition equipment, be used to discern the phase position index of the PN sequence of described digital signal; It is characterized in that the sign indicating number acquisition equipment comprises: the PN sequence generator is used to produce identical local PN sequence; Correlator, it is relevant to utilize local PN sequence that the PN sequence generator produces and received signal to carry out, and exports several PN sequence correlation peaks; And the sign indicating number capturing unit, its yard capturing unit also comprises: the correlation peak location detection module, be used for the PN sequence correlation peak that detection correlator is exported, and find the maximum and the second largest value of correlation peak in each frame, and obtain the absolute value of both alternate position spikes; Select module, select peak-peak position and the medium and small position of second largest peak value or big position in the frame that maximum value position is identical with the absolute value of second largest value alternate position spike in continuous M frame at least, output code is caught correlation peak location; Sign indicating number is caught the acquisition module of correlation peak location difference, is used for the correlation peak location in the M frame is at least made difference, and it is poor that output code is caught correlation peak location; Wherein difference realizes that by N difference computing N is the integer more than or equal to 1; The acquisition module of PN sequence phase index, the absolute value that is used for sign indicating number is caught the correlation peak location difference is handled the phase position index of output PN sequence.
Further, sign indicating number is caught the difference computing of acquisition module of correlation peak location difference by twice realization, i.e. N=2.
Adopt code capture method provided by the invention and device, can realize catching in the effective time; Further, exist when channel under the situation of timing frequency deviation or white noise, the present invention can also accurately discern the phase place of PN sequence by the mode of at least twice difference, thereby obtains strong robustness, anti-timing offset and the strong signal of dynamic channel ability.
Description of drawings
To the description of embodiments of the invention, can further understand purpose, specific structural features and the advantage of its invention by following in conjunction with its accompanying drawing.Wherein, accompanying drawing is:
Fig. 1 is that frame head is the PN sequence phase change curve of PN420;
Fig. 2 is that near the PN sequence phase of Fig. 1 A point changes schematic diagram;
Fig. 3 is that near the PN sequence phase of Fig. 2 B point changes schematic diagram;
Fig. 4 is the first embodiment ascent stage and the schematic diagram of decline stage that the present invention is used for code capture method;
Fig. 5 is the wherein maximum of the correlation peak of 3 frames and the schematic diagram of second largest value of a superframe;
Fig. 6 is the schematic diagram that the present invention is used for the second embodiment ascent stage of code capture method;
Fig. 7 is the schematic diagram that the present invention is used for the second embodiment decline stage of code capture method;
Fig. 8 exists under the timing frequency deviation situation, adopts the present invention to be used for the performance chart of second embodiment of code capture method;
Fig. 9 is the structured flowchart of receiver of the present invention.
Embodiment
The present invention is applied in the digital tv ground broadcasting, and the signal of reception comprises frame head (PN sequence) and frame (data).The frame head of describing among " digital television ground broadcast transmission system frame structure, chnnel coding and modulation " GB20600-2006 has three kinds of forms, and wherein frame head is that the phase place of two kinds of structure PN sequences in a superframe of PN420 (after the preamble, PN255 sequence, synchronously) and PN945 (synchronous after the preamble, PN511 sequence) is different.For PN420, a superframe comprises 255 signal frames; For PN945, a superframe comprises 200 signal frames.This place is the various embodiment that example illustrates code capture method of the present invention and device with PN420 as frame head for convenience.What those having ordinary skill in the art will appreciate that is with the frame head that PN420 has identical or similar phase characteristic, can adopt method disclosed by the invention, device, receiver to carry out sign indicating number and catch, and all belong to protection scope of the present invention.
See also Fig. 1 to Fig. 3, Fig. 1 has represented PN sequence phase change curve in the superframe, and phase change embodies by correlation peak location, similar spindle shape.Numerical value among Fig. 2 is that PN255 carries out the correlation peak location that 2 samplings (2fs) obtain after relevant among the PN420.When selecting for use PN420 to be frame head, frame length is 4200,8400 samplings that obtain after relevant on the 2fs.The correlation peak location of first frame (signal frame) is " 0 "; The correlation peak location of second frame is " 2 ", symbol in the promptly relative first frame deflection left side (2 samplings); The position of the 3rd frame is 2, promptly relative first frame deflection the right symbol (2 samplings); So go down, along with frame number increases, the symbolic number of deflection is also increasing.Continue to consult Fig. 3, the correlation peak location of the 113rd frame is "+112 ", and subsequently, deflection is again gradually along with the increase of frame number reduces, until the A point that arrives next superframe.
According to the characteristic that above-mentioned PN sequence phase changes, yard method of catching that is used for of the present invention comprises the steps:
(1) adopt the PN sequence generator to produce the local sequence of the identical PN of phase place (the local sequence of the local sequence of same PN or several identical PN), the local sequence of the PN that the phase place that utilization produces the is identical frame head of each frame (PN sequence) to received signal is correlated with, and obtains several PN sequence correlation peaks;
(2) PN sequence correlation peak is detected, find the maximum and the second largest value of correlation peak in each frame, the maximum value position of the correlation peak of k frame is p
Max(k), the second largest value position of correlation peak is p
Sb-max(k);
(3) maximum value position and the second largest value alternate position spike of detected each frame of acquisition step (2), the absolute value of the maximum value position of k frame and second largest value alternate position spike is:
p
diff(k)＝abs[p
max(k)-p
sb-max(k)]
Abs[...] expression takes absolute value;
(4) if in the continuous N frame, described maximum value position is identical with the absolute value of second largest value alternate position spike, then select peak-peak position and medium and small position of second largest peak value or big position in this M frame, catch correlation peak location as sign indicating number;
(5) selected sign indicating number in the M frame is caught correlation peak location and carry out difference step, promptly the sign indicating number of present frame L frame is caught the sign indicating number that correlation peak location deducts former frame L-1 frame and is caught correlation peak location, and to catch correlation peak location poor thereby obtain sign indicating number; Wherein difference step realizes by N difference step; N is the integer more than or equal to 1;
(6) absolute value that sign indicating number is caught the correlation peak location difference is handled, and can obtain the phase value (phase position index) of the PN sequence of L-N+1 frame.
In conjunction with Fig. 4 to Fig. 5 yard first embodiment of the method for catching that is used for of the present invention is described.
Utilizing the PN sequence generator to generate phase place is 0 the local sequence of PN, and the PN sequence of the interior frame head (being PN420) of the local sequence of this PN and superframe of received signal is carried out 2 sampling correlation step one by one then, obtains the correlation peak of several PN sequences.Then, the correlation peak of PN sequence is detected, find out the maximum and the second largest value of correlation peak in each frame, Fig. 5 has illustrated maximum G1, G4, G5 and second largest value G2, G3, the G6 of correlation peak of 3 frame F1, F2, F3.Need to prove that real maximum of a few frames of not faithful representation of Fig. 5 and second largest value only play the effect of explaining.Further, make the maximum and the second largest value of correlation peak in each frame and make alternate position spike, for example, the alternate position spike of 3 frames is shown in Fig. 5: P2-P1, P4-P3, P6-P5.In continuous 9 frames (in actual applications, can select according to accuracy requirement, relatively good more than or equal to 5 frame range effect, but the present invention does not get rid of the situation less than 5 frames), if the absolute value of the alternate position spike of the correlation peak that obtains is identical, then select peak-peak in this 9 frame and the little position in the second largest peak value (as P1, P3, P5) or big position (as P2, P4, P6) as sign indicating number catch correlation peak location 0 ,-2 ,+2 ,-4 ,+4 ,-6 ,+6 ,-8 ,+8.Sign indicating number in 9 frames is caught correlation peak location and carried out difference step, and promptly the sign indicating number of present frame (k frame) sign indicating number of catching correlation peak location and former frame (k-1 frame) is caught correlation peak location and is subtracted each other, and it is poor to obtain yard to catch correlation peak location.
Sign indicating number is caught correlation peak location to be increased along with frame number and increases and be defined as ascent stage, and sign indicating number is caught correlation peak location to be increased along with frame number and reduce to be defined as the decline stage, as Fig. 4, Fig. 6, Fig. 7.At method first embodiment that catches of sign indicating number that is used for of the present invention,, the absolute value processing mode of correlation peak location difference is expressed as follows when PN phase place during at ascent stage:
idx(k)＝abs[p(k)-p(k-1)]/2?????????????????(1)
Idx (k) represents the PN phase position index of k frame, and the sign indicating number of p (k) expression k frame is caught correlation peak location, and the sign indicating number of p (k-1) expression k-1 frame is caught correlation peak location, abs[...] represent to take absolute value.That is to say, when PN phase place during at ascent stage, by the sign indicating number of present frame (k frame) catch correlation peak location and former frame (k-1 frame) yard to catch that correlation peak location subtracts each other (be difference step, N=1), doing an absolute value handles again divided by 2, can obtain present frame k (k-N+1, the phase position index of PN sequence N=1) fast.
Equally, for when the decline stage, the phase position index of PN sequence obtains in the following way:
idx(k)＝224-abs[p(k)-p(k-1)]/2?????????????(2)
Be understandable that when the frame head of received signal was PN945 (0-199 signal frame is a superframe), ascent stage was identical with PN420's; For when the decline stage, the PN sequence index obtains in the following way:
idx(k)＝199-abs[p(k)-p(k-1)]/2?????????????(3)
In addition, the variation of PN sequence phase, timing frequency deviation, white noise or under the channel of abominable city different Doppler frequencies or the like all can cause the change in location of PN sequence correlation peak.Error occurs in order to reduce PN sequence phase identification, the invention provides and be used for method second embodiment that sign indicating number is caught, please refer to Fig. 6, this embodiment carries out under the situation that has the timing frequency deviation.In Fig. 6, to compare shown in Fig. 4, the sign indicating number of the frame in the frame of broken lines is caught correlation peak location drift has been taken place, and sign indicating number is caught correlation peak location and odd number "+5 " and "+13 " have been occurred, and error can appear in the phase identification that do the PN sequence this moment.Along with the increase (perhaps channel situation is all the more abominable) of timing frequency deviation, sign indicating number is caught and can be become more and more difficult.Yard second embodiment of the method for catching that is used for provided by the invention can effectively reduce the error rate that above-mentioned sign indicating number is caught, and specifically describes as follows:
At first, utilizing the PN sequence generator to generate phase place is 0 the local sequence of PN, and the PN sequence of the interior frame head (being PN420) of the local sequence of this PN and superframe of received signal is carried out 2 sampling correlation step one by one then, obtains the correlation peak of several PN sequences.Then, the correlation peak of PN sequence is detected, find out the maximum and the second largest value of correlation peak in each frame, Fig. 5 has illustrated maximum G1, G4, G5 and second largest value G2, G3, the G6 of correlation peak of 3 frame F1, F2, F3.Need to prove that real maximum of a few frames of not faithful representation of Fig. 5 and second largest value only play the effect of explaining.Further, make the maximum and the second largest value of correlation peak in each frame and make alternate position spike, for example, the alternate position spike of 3 frames is shown in Fig. 5: P2-P1, P4-P3, P6-P5.In continuous 9 frames (in actual applications, can require to select according to preparation, relatively good more than or equal to 5 frame range effect, but the present invention does not get rid of the situation less than 5 frames), if the absolute value of the alternate position spike of the correlation peak that obtains is identical, then select peak-peak in this 9 frame and the little position in the second largest peak value (as P1, P3, P5) or big position (as P2, P4, P6) as sign indicating number catch correlation peak location 0 ,-2 ,+3 ,-3 ,+5 ,-5 ,+8 ,-6 ,+10.
Then, sign indicating number in 9 frames is caught correlation peak location carry out the difference step first time, be that the sign indicating number that the sign indicating number of present frame (k frame) is caught correlation peak location and former frame (k-1 frame) is caught correlation peak location and subtracted each other, it is poor to obtain for the first time yard to catch correlation peak location.Further, carry out second difference step, promptly the sign indicating number first time of the present frame sign indicating number first time of catching correlation peak location difference and former frame is caught the correlation peak location difference and is subtracted each other, and obtains quadratic code and catches relative difference in position.That is to say in a second embodiment, carried out difference step twice, i.e. N=2.
When PN phase place during, the absolute value processing mode of correlation peak location difference is expressed as follows at ascent stage:
(4)
The PN phase position index of idx (k) expression k frame, the sign indicating number of p (k) expression k frame is caught correlation peak location, and the sign indicating number of p (k-1) expression k-1 frame is caught correlation peak location, and the sign indicating number of p (k+1) expression k+1 frame is caught correlation peak location, abs[...] expression takes absolute value
Expression rounds.That is to say that when PN phase place during at ascent stage, to do twice front and back poor by sign indicating number being caught correlation peak location, does an absolute value and handle again divided by 4, rounds the phase position index of the PN sequence that just can obtain former frame (k-1 frame) then.
Equally, for when the decline stage, the phase position index of PN sequence obtains in the following way:
Be understandable that when the frame head of received signal was PN945 (0-199 signal frame is a superframe), ascent stage was identical with PN420's; For when the decline stage, the PN sequence index obtains in the following way:
Passable from top description, in a second embodiment, sign indicating number is caught two steps that comprise that the correlation peak location difference handles: at first the secondary difference is obtained sign indicating number and catch the absolute value of correlation peak location difference and handle a 2N=4, round the phase position index that step could obtain the PN sequence of former frame then.
In the code capture method of secondary difference shown in Figure 6, with " 1 " component that has more owing to timing offset in "+5 " (right value should be " 4 ") of alternate position spike share the difference difference after "+7 " and " 11 ", can eliminate this " 1 " component easily by rounding operation.Adopt this method can effectively eliminate of the influence of timing frequency deviation, so this method shows robust having under the timing offset situation for PN sequence correlation peak.
Be understandable that second embodiment is a most preferred embodiment of the present invention, but protection scope of the present invention is not limited thereto, the present invention has also protected three times or the method for more times difference.
See also Fig. 8, this curve chart is the sign indicating number capture technique performance simulation test under the 0dB white noise channel.The individual sub-carrier modulation modes of the parameter that this emulation relates to: C=3780, the mapping mode of 16QAM, LDPC0.8, symbol interleaving 720.
Because ground digital television broadcast is continuous transmission mode, and the sign indicating number capturing function of PN sequence phase identification is in case the PN phase position index that provides every frame that can continue after realizing, once the sign indicating number capturing function is just much of that so receiver is as long as finish in the incipient stage.For receiver, if can't realize catching, must cause the host state machine of system to reset in the unit interval, so go down, up in the unit interval, finishing once sign indicating number capturing function.Mean acquisition time is short more, illustrates that capture time is short more.As can be known from Fig. 8, adopt the second embodiment of the present invention can resist the white noise of 0dB.From the simulation curve figure of Fig. 8 as can be seen, the present invention can resist the timing frequency deviation up to 1800Hz, and mean acquisition time is 5.3 frames.Therefore, adopt method provided by the invention, under the situation that has the timing frequency deviation, show robust.
Table 1 is the performance (mean acquisition time) of different white noises under the Brazilian e channel.
Table 1
| White noise (dB) | Mean acquisition time (frame) |
| ??17 | ??5.1871 |
| ??18 | ??5.0701 |
| ??21 | ??5.0316 |
| ??22 | ??5.0 |
Table 2 is the performance comparison of 8 times different timing frequency departures of typical static channel Brazil E and China.
Table 2
Above-mentioned emulation is based on the sign indicating number acquisition algorithm performance of the difference of difference under the typical static channel, from data as can be seen, static channel and white noise are little for the influence of sign indicating number acquisition algorithm, and under the situation of timing frequency deviation greater than 1800Hz, sign indicating number acquisition algorithm performance descends to some extent, and this situation can solve by the number of times that increases difference.
The inventive method also can be applicable to abominable city channel (BU) commonly used in the ground digital television broadcast transmission system.Increase along with dynamic channel Doppler, because the quick variation of multipath, can't calculate the auto-correlation variations in peak rule in certain separable footpath of root accurately, the performance of comparing above-mentioned channel based on performance of the present invention descends to some extent, but still can satisfy the needs of practical application.
Fig. 9 is understandable that for using the structured flowchart that the present invention is used for the receiver 100 of code capture method this receiver 100 also can be the receiving system that is connected with television set, as set-top box, also can be digital TV integrated machine.This receiver 100 includes but not limited to as lower module: A/D module 10, frequency mixing module 11, root rise surplus filtration module 12, interpolater 13, synchronous error estimation module 17, sign indicating number trapping module 16, down-sampler 14 and the anti-single-frequency simulation co-channel interference module 15 of revolving.A/D module 10 is converted into digital signal by sampling with analog receiving signal (ground broadcast signal).The effect of frequency mixing module 11 is that the frequency departure of digital signal carrier wave is corrected, the effect of interpolater 13 is the correction that realize the timing frequency deviation, the digital signal of A/D module 10 output is undertaken after the correction of carrier deviation and interpolater 13 carry out the correction of timing offset by frequency mixing module 11, by down-sampler 14 and anti-single-frequency simulation co-channel interference module 15, carry out the elimination of single-frequency and simulation co-channel interference, export to subsequent communication channel then and estimate and balance module.Correlator is correlated with for the signal after correcting, and catches the PN sequence phase value that provides according to sign indicating number and is correlated with, and provide the phase place and the change in location of auto-correlation peak value.Synchronous error estimation module 17 is calculated by the detection of correlation peak being carried out frequency sweep control, carrier wave Error Calculation and timing error.Frequency sweep control and carrier wave Error Calculation control frequency mixing module 11, timing error calculation control interpolater 13.
Sign indicating number acquisition equipment 16 is used the PN sequence phase index that code capture method provided by the invention is discerned received signal.This yard acquisition equipment 16 comprises: PN sequence generator (not shown), be used to produce local PN sequence, and the generation phase place is 0 local PN sequence in this enforcement; Correlator is that 0 local PN sequence is relevant with phase place respectively with the signal of down-sampler 14 output, exports several PN sequence correlation peaks; And sign indicating number capturing unit.Wherein the sign indicating number capturing unit also comprises:
The correlation peak location detection module is used for PN sequence correlation peak is detected, and finds the maximum and the second largest value of correlation peak in each frame, and obtains the absolute value of both alternate position spikes;
Select module, (do not get rid of the situation that is less than 5 frames at least 5 frames continuously, being at least 5 frames is preferred embodiments) select peak-peak position and medium and small position of second largest peak value or big position in the interior maximum value position frame identical with the absolute value of second largest value alternate position spike, catch correlation peak location as sign indicating number;
Sign indicating number is caught the acquisition module of correlation peak location difference, be used for the correlation peak location at least 5 frames is made difference, be that the sign indicating number of present frame L frame is caught the sign indicating number that correlation peak location deducts former frame L-1 frame and caught correlation peak location, to catch correlation peak location poor thereby obtain sign indicating number; Wherein difference realizes that by N difference computing N is the integer more than or equal to 1;
The acquisition module of PN sequence phase index, the absolute value that is used for sign indicating number is caught the correlation peak location difference is handled the phase position index of output PN sequence.
Further, promptly carry out the acquisition module that two sign indicating numbers that go on foot the difference computing are caught the correlation peak location difference for N 〉=2, the acquisition module of this PN sequence phase index comprises divider and rounds device, wherein divider is caught the absolute value of correlation peak location difference divided by 2N to sign indicating number, this rounds device the output of divider is rounded, and its output is the phase position index of PN sequence.
Need to prove that when N=1 promptly adopted a difference computing, what round the output of device or divider was the phase position index of the PN phase place of present frame.When N=2 promptly adopted twice difference computing, what round device output was the phase position index of the PN sequence of former frame; When N=3 promptly adopted three difference computings, what round device output was the phase position index of the PN sequence of front cross frame, and the like.
The description of above preferred embodiment makes those skilled in the art can make or use the present invention.The various modifications of these embodiment are conspicuous for a person skilled in the art, and Ding Yi General Principle can be applied among other embodiment and not deviate from the spirit or scope of the present invention here.Therefore, the embodiment that the present invention is not limited to illustrate here, and will meet and the principle and the novel feature the most wide in range consistent scope that disclose here.
Claims (18)
1. one kind is used for the method that sign indicating number is caught, and it is characterized in that, comprises the steps:
Utilize the local sequence of the identical PN of phase place to make correlation step with the PN sequence of received signal respectively, obtain several PN sequence correlation peaks;
PN sequence correlation peak is detected, find the maximum and the second largest value of correlation peak in each frame, and obtain both alternate position spikes;
If in the continuous N frame, maximum value position is identical with the absolute value of second largest value alternate position spike, then select peak-peak position and medium and small position of second largest peak value or big position in this M frame, catch correlation peak location as sign indicating number;
Sign indicating number in the described M frame is caught correlation peak location carry out difference step, it is poor that the acquisition sign indicating number is caught correlation peak location; Wherein difference step realizes that by N difference computing N is the integer more than or equal to 1;
Sign indicating number is caught the absolute value of correlation peak location difference and handle, obtain the phase position index of PN sequence.
2. yard method of catching that is used for as claimed in claim 1 is characterized in that selected correlation peak location in the M frame is carried out in the difference step, and N=2 i.e. this step realizes by twice difference step.
3. yard method of catching that is used for as claimed in claim 1 is characterized in that the phase place of described received signal PN sequence in continuous 255 frames is that phase place inequality or PN sequence in continuous 200 frames is inequality.
4. as the described sign indicating number method of catching that is used for of one of claim 1-3, it is characterized in that the absolute value that step is caught the correlation peak location difference to sign indicating number is handled and comprised: carry out sign indicating number and catch the step of the absolute value of correlation peak location difference divided by 2N; And the phase division result rounded step, round the phase position index of result for the PN sequence.
5. yard method of catching that is used for as claimed in claim 1 is characterized in that the local sequence of the PN that described phase place is identical is that phase place is 0 PN sequence.
6. yard method of catching that is used for as claimed in claim 1 is characterized in that described M 〉=5.
7. one kind is used for the device that sign indicating number is caught, and it is characterized in that, comprising:
The PN sequence generator is used to produce the identical local PN sequence of phase place;
Correlator, it is relevant to utilize local PN sequence that the PN sequence generator produces and received signal to carry out, and exports several PN sequence correlation peaks; And
The sign indicating number capturing unit, wherein the sign indicating number capturing unit also comprises: the correlation peak location detection module, be used for the PN sequence correlation peak that detection correlator is exported, find the maximum and the second largest value of correlation peak in each frame, and obtain the absolute value of both alternate position spikes; Select module, select peak-peak position and the medium and small position of second largest peak value or big position in the frame that maximum value position is identical with the absolute value of second largest value alternate position spike in continuous M frame at least, output code is caught correlation peak location; Sign indicating number is caught the acquisition module of correlation peak location difference, is used for the correlation peak location in the M frame is at least made difference, and it is poor that output code is caught correlation peak location; Wherein difference realizes that by N difference computing N is the integer more than or equal to 1; The acquisition module of PN sequence phase index, the absolute value that is used for sign indicating number is caught the correlation peak location difference is handled the phase position index of output PN sequence.
8. yard device of catching that is used for as claimed in claim 7 is characterized in that sign indicating number is caught the difference computing of the acquisition module of correlation peak location difference and passed through twice realization, i.e. N=2.
9. yard device of catching that is used for as claimed in claim 7 is characterized in that the phase place of described received signal PN sequence in continuous 255 frames is that phase place inequality or PN sequence in continuous 200 frames is inequality.
10. as the described yard device of catching that is used for of one of claim 7-9, it is characterized in that, the acquisition module of PN sequence phase index comprises divider and rounds device, wherein the divider sign indicating number of sign indicating number being caught the acquisition module output of correlation peak location difference is caught the absolute value of correlation peak location difference divided by 2N, round device the output of divider is rounded the phase position index of output PN sequence.
11. yard device of catching that is used for as claimed in claim 7 is characterized in that, what the PN sequence generator was exported is that phase place is 0 the local sequence of PN.
12. yard device of catching that is used for as claimed in claim 7 is characterized in that described M 〉=5.
13. a receiver that is used for received television signal comprises analog-digital commutator, the TV signal that is used for receiving is converted to digital signal; And the sign indicating number acquisition equipment, be used to discern the phase position index of the PN sequence of described digital signal; It is characterized in that described sign indicating number acquisition equipment comprises:
The PN sequence generator is used to produce the identical local PN sequence of phase place;
Correlator, it is relevant to utilize local PN sequence that the PN sequence generator produces and received signal to carry out, and exports several PN sequence correlation peaks; And
The sign indicating number capturing unit, wherein the sign indicating number capturing unit also comprises: the correlation peak location detection module, be used for the PN sequence correlation peak that detection correlator is exported, find the maximum and the second largest value of correlation peak in each frame, and obtain the absolute value of both alternate position spikes; Select module, select peak-peak position and the medium and small position of second largest peak value or big position in the frame that maximum value position is identical with the absolute value of second largest value alternate position spike in continuous M frame at least, output code is caught correlation peak location; Sign indicating number is caught the acquisition module of correlation peak location difference, is used for the correlation peak location in the M frame is at least made difference, and it is poor that output code is caught correlation peak location; Wherein difference realizes that by N difference computing N is the integer more than or equal to 1; The acquisition module of PN sequence phase index, the absolute value that is used for sign indicating number is caught the correlation peak location difference is handled the phase position index of output PN sequence.
14. the digital television receiver that is used for received television signal as claimed in claim 13 is characterized in that, sign indicating number is caught the difference computing of the acquisition module of correlation peak location difference and is passed through twice realization, i.e. N=2.
15. the receiver that is used for received television signal as claimed in claim 13 is characterized in that, the phase place of described received signal PN sequence in continuous 255 frames is that phase place inequality or PN sequence in continuous 200 frames is inequality.
16. as the described receiver that is used for received television signal of one of claim 13-15, it is characterized in that, the acquisition module of PN sequence phase index comprises divider and rounds device, wherein the divider sign indicating number of sign indicating number being caught the acquisition module output of correlation peak location difference is caught the absolute value of correlation peak location difference divided by 2N, round device the output of divider is rounded the phase position index of output PN sequence.
17. the receiver that is used for received television signal as claimed in claim 6 is characterized in that, what the PN sequence generator was exported is that phase place is 0 the local sequence of PN.
18. the receiver that is used for received television signal as claimed in claim 6 is characterized in that, described M 〉=5.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104184524A (en) * | 2013-05-21 | 2014-12-03 | 电信科学技术研究院 | Frequency calibration method and device |
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| US8594151B2 (en) * | 2005-10-31 | 2013-11-26 | Nokia Corporation | Pilot sequence detection |
| CN100558147C (en) * | 2008-04-01 | 2009-11-04 | 北京航空航天大学 | A kind of frame head PN catching method and device thereof of terrestrial digital television system |
| CN101309251B (en) * | 2008-06-13 | 2010-12-01 | 高拓讯达（北京）科技有限公司 | PN sequence detection method and system of receiver based on DTTB standard |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104184524A (en) * | 2013-05-21 | 2014-12-03 | 电信科学技术研究院 | Frequency calibration method and device |
| CN104184524B (en) * | 2013-05-21 | 2016-09-14 | 电信科学技术研究院 | A kind of transmitting frequency calibration method and device |
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