CN107105222B - Symbol detection circuit and method - Google Patents
Symbol detection circuit and method Download PDFInfo
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- CN107105222B CN107105222B CN201610098952.0A CN201610098952A CN107105222B CN 107105222 B CN107105222 B CN 107105222B CN 201610098952 A CN201610098952 A CN 201610098952A CN 107105222 B CN107105222 B CN 107105222B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N17/00—Diagnosis, testing or measuring for television systems or their details
Abstract
The present invention proposes a kind of detection method, and applied to the receiving terminal of digital video broadcasting to detect a position of a data frame of an input signal, which includes a continuous wave CO_2 laser ingredient, and this method includes：A coherent signal is generated according to the input signal；Rolling average is carried out to the coherent signal to calculate to generate a first movement average result；The frequency shift (FS) coherent signal is to generate the coherent signal after frequency shift (FS)；Rolling average is carried out to the coherent signal after frequency shift (FS) to calculate to generate one second rolling average result；The continuous wave CO_2 laser ingredient is eliminated according to the first movement average result and the second rolling average result, and generates an output signal according to this；And the peak value according to the output signal judges the position.
Description
Technical field
The present invention relates to symbol detection circuit and methods, especially with respect to second generation digital video broadcasting (Digital
Video Broadcasting over Terrestrial 2, hereinafter referred to as DVB-T2) system symbol detection circuit and side
Method.
Background technology
Fig. 1 is the schematic diagram of a T2 data frame (frame) of second generation digital video broadcast system, each T2 data
Frame includes P1 symbols, P2 symbols and body of data.Wherein P1 symbols carry the information of some transmission ends, such as when data modulation
The pattern of used fast Fourier transform (Fast Fourier Transform, hereinafter referred to as FFT), digital communication system
For single-input single-output (Single Input Single Output, hereinafter referred to as SISO) or multiple input single output
Information such as (Multiple Input Single Output, hereinafter referred to as MISO).In addition to for carrying above-mentioned important information
Outside, P1 symbols can be utilized to certain characteristics of detection data stream, such as the initial position of T2 data frames, carrier frequency shift
(Carrier Frequency Offset, CFO), reversing spectrum (IQ swap, abbreviation IQS, i.e. sinusoidal component and cosine component
It is inverted) etc..
P1 symbols, which include data C, (has 542 sample numbers, time span TC), data A (have 1024 sample numbers,
Time span is TA) and data B (have 482 sample numbers, time span TB).Data C is preceding 542 samples of data A
(data C ') after frequency shift (FS) as a result, and data B be data A after 482 samples (data B ') after frequency shift (FS)
As a result, frequency offset fSHIt it is the sampling period of T2 data frames for 1/1024T, T.P1 symbols can indicate as follows：
Wherein, p1AFor the content of data A.
Since data B, C are to be generated after frequency shift (FS) by the partial data of data A respectively, detection unit 110
The position of P1 symbols can be found out by the correlation of comparison data B, C and data A, and then obtain the data in P1 symbols simultaneously
It can be seen that the initial position of T2 data frames.Fig. 2 is the detailed circuit diagram of known detection unit 110.It is single that input signal enters detection
After member 110, a routing multiplier 310 is multiplied by exp (- j2 π f whereinSHNT), make its generate frequency shift (FS) (offset be-
fSH), postpone 482T via delay cell 320 in another way or 542T (is corresponded to do correlation fortune using data B or data C respectively
It calculates).Later, multiplier 330 by after frequency shift (FS) signal with the conjugation of the signal after delay is multiple be multiplied after, then by filtering
Device 340 does rolling average operation (moving average, MA), flat with the movement for obtaining correlation (correlated value)
Mean value.It the position greatly located by the moving average for finding out correlation and the delay time with reference to delay cell 320, can be with
Extrapolate the initial position of P1 symbols.Due to frequency offset fSHFor 1/1024T, as the Window length (window of filter 340
When length) being equal to length (i.e. the 1024T) of data A, the continuous wave for being present in input signal can be filtered out simultaneously
(continuous wave, CW) interference (is also known as common-channel interference (co-channel interference, CCI)), avoids
Interference of the CCI to correlation, to obtain accurate initial position.However this can but cause the filtering time of filter 340 compared with
It is long；Opposite, if filter 340 uses shorter Window length (such as 482T or 542T), although phase can be obtained comparatively fast
Pass value can not but filter out continuous wave CO_2 laser completely.Such limitation forces known circuit must be in detection speed and accuracy two
It is made trade-offs between person.
Invention content
In view of the deficiencies in the prior art, of the invention one is designed to provide a kind of symbol detection circuit and method, to carry
The speed and efficiency of high detection.
The present invention proposes a kind of detection circuit, applied to the receiving terminal of digital video broadcasting to detect the one of an input signal
One position of data frame, the input signal include a continuous wave CO_2 laser ingredient, which includes：One correlation operation list
Member is used for generating a coherent signal according to the input signal；One first movement averaging unit couples the correlation operation unit,
It is calculated for carrying out rolling average to the coherent signal to generate a first movement average result；One frequency shift (FS) unit, coupling
The correlation operation unit, for the frequency shift (FS) coherent signal；One second rolling average unit couples the frequency shift (FS) list
Member calculates for carrying out rolling average to the coherent signal after frequency shift (FS) to generate one second rolling average result；One meter
Unit is calculated, the first movement averaging unit and the second rolling average unit are coupled, is used for according to the first movement average result
And the second rolling average result eliminates the continuous wave CO_2 laser ingredient, and an output signal is generated according to this；And a judging unit,
The computing unit is coupled, judges the position for the peak value according to the output signal.
The present invention separately proposes a kind of detection method, applied to the receiving terminal of digital video broadcasting to detect an input signal
One position of one data frame, the input signal include a continuous wave CO_2 laser ingredient, and this method includes：It is generated according to the input signal
One coherent signal；Rolling average is carried out to the coherent signal to calculate to generate a first movement average result；The frequency shift (FS) phase
OFF signal is to generate the coherent signal after frequency shift (FS)；To after frequency shift (FS) the coherent signal carry out rolling average calculate with
Generate one second rolling average result；The continuous wave is eliminated according to the first movement average result and the second rolling average result
Interference component, and an output signal is generated according to this；And the peak value according to the output signal judges the position.
Compared to known technology, symbol detection circuit of the invention and method use shorter filtering time, and reach
The effect of filtering out continuous wave CO_2 laser simultaneously.
Description of the drawings
For the above objects, features and advantages of the present invention can be clearer and more comprehensible, below in conjunction with attached drawing to the tool of the present invention
Body embodiment elaborates, wherein：
Fig. 1 is the schematic diagram of a T2 data frame of second generation digital video broadcast system；
Fig. 2 is the detailed circuit diagram of known detection unit 110；
Fig. 3 is the circuit diagram of an embodiment of P1 symbol detection circuits of the present invention；
Fig. 4 is the detailed circuit of the one of which embodiment of Fig. 3；
Fig. 5 is input signal X [n], the delay of input signal X [n] and signal C_II_I [n] in the correspondence on time shaft
Figure；
Fig. 6 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention；
Fig. 7 is the thin portion circuit diagram of computing unit 54；
Fig. 8 is input signal X [n], the delay of input signal X [n] and signal C_II_I [n] and signal B_II_I [n]
In the corresponding diagram on time shaft；
Fig. 9 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention；
Figure 10 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention；And
Figure 11 is that the P1 symbol detection circuits of the present invention coordinate decision circuitry showing applied to the receiving terminal of DVB-T2 systems
It is intended to.
Component label instructions are as follows in figure：
110 detection units
310,330,414,460,465,55,560,565,610 multiplier
320,412,416,420,425,440,445 delay cell
340 filters
41,51 correlation operation unit
42,43,46,52,53,56 rolling average unit
418,470,518,570,59 frequency shift (FS) unit
44,54,60,70 computing unit
49,65,66,75 decision circuitry
430,435,475,575 adder
450,455 divider
1210 registers
1220 P1 symbol detection circuits
1230 compensation circuits
1240 decision circuitries
1242,491,651,661,751 peak detection unit
1244,492,652,662,752 P1 position judgment units
1246,653,753 IQS detection units
1248,663,754 fCFO estimate unit
S1310~S1370 steps
Specific implementation mode
The disclosure content of the present invention includes symbol detection circuit and method, under the premise of being embodied as possible, this technology neck
Field technique personnel can select equivalent element or step to realize the present invention, that is, this hair according to the disclosure content of this specification
The embodiment that bright implementation is chatted after being not limited to.
Assuming that the input signal X [n] of DVB-T2 receiving terminals indicates as follows：
X [n]=P1[n-θ]·exp(j2πΦnTS)+exp(j2πfCWnTS) (1)
Wherein P1[n-θ]·exp(j2πΦnTS) be P1 symbols part, θ represent sampling delay, Φ be carrier frequency it is inclined
It moves；exp(j2πfCWnTS) be single-tone (single-tone) continuous wave CO_2 laser (frequency fCW).For convenience of description, it neglects herein
Slightly channelling effect and noise.X [n] is postponed into TC(i.e. the length of delayed data C, 542 sample numbers), then it is more with the conjugation of itself
A multiplication can obtain signal C_I_0 [n]：
C_I_0 [n]=X [n-nc]·X*[n]=exp (- j2 π fCWTC)·1+|P1[n-θ]|2·exp(-j2π(fSH+Φ)
TC)·exp(j2πfSHnTS)+…(2)
Wherein, discrepance " ... " and 1 and exp (j2 π fSHnTS) it is orthogonal.Signal C_I_0 [n] is postponed into 2T againB(prolong
The double length of slow data B, 964 sample numbers) after, signal C_I [n] can be obtained：
C_I [n]=C_I_0 [n-2nB]=exp (- j2 π fCWTC)·1+|P1[n-2nB-θ]|2·exp(-j2π(fSH+Φ)
TC)·exp(-j4πfSHTB)·exp(j2πfSHnTS)+…(3)
Equation (3) is reduced to following formula：
C_I [n]=a_C1+b_C ρn+…(4)
Wherein, a_C=exp (- j2 π fCWTC) be continuous wave CO_2 laser part, b_C=| P1[n-2nB-θ]|2·exp-j2π
FSH+ Φ TCexp (- j4 π fSHTB) are the part of P1 symbols, ρ=expj2 π fSHTS.
Next, in continuous 542 sample points, (input signal X [n] is postponed in counterparty's formula (2) by C_I [n]
Time TC) add up, signal C_S [n] can be obtained：
C_S [n]=C_I [n]+C_I [n-1]+...+C_I [n-542+1]
=542a_C+b_C ρn-(542-1)/2·(ρ(542-1)/2+ρ(542-1)/2-1+…+ρ(1-542)/2)
=542a_C+b_C ρn-(542-1)/2·λ (5)
Wherein
Wherein assume that π/1024 level off to 0, therefore can willIt is approximatelyAs L=542 or 482, λ's
Value about 324.5686967.
On the other hand, by signal C_I [n] frequency shift (FS)s-fSH(it is multiplied by exp (- j2 π f afterwardsSHnTS)), then at continuous 542
A sample point (time T that input signal X [n] is postponed in counterparty's formula (2)C) add up, signal can be obtained：
C_T1 [n]=ρ-n·C_I[n]+ρ-(n-1)·C_I[n-1]+…+ρ-(n-542+1)·C_I[n-542+1
=542b_C+a_C ρ(542-1)/2-n·(ρ(542-1)/2+ρ(542-1)/2-1+…+ρ(1-542)/2)
=542b_C+a_C ρ(542-)/2-n·λ (6)
Above-mentioned equation (5) and equation (6) can be rewritten as equation below (7) and equation (8) respectively：
ρ(542-1)/2-nC_S [n]=542a_C ρ(542-1)/2-n+b_C·λ (7)
C_T1 [n]=542b_C+a_C ρ(542-1)/2-n·λ (8)
Equation (7) and equation (8) are indicated in the matrix form：
By equation (9) it can be found that by after signal C_S [n] frequency shift (FS), it is as linear operation with signal C_T1 [n]
The component b_C of corresponding P1 symbols can be obtained, that is, can remove the component a_C of continuous wave CO_2 laser.This linear operation phase on circuit
When easy to implement, as shown in Figure 3.
Fig. 3 is the circuit diagram of an embodiment of P1 symbol detection circuits of the present invention.Correlation operation unit 41 may be implemented
Equation (2), rolling average unit 42 carries out rolling average operation to continuous 542 sample points of signal C_I_0 [n], another
Aspect, rolling average unit 43 by frequency shift (FS) by frequency shift (FS) unit 418 to (being executed, frequency shift (FS) unit 418 can be by one
Multiplier implement or by central processing unit, microcontroller etc. execute frequency shift (FS) operation and reach) signal C_I_0 [n]
Continuous 542 sample points carry out rolling average operation.Computing unit 44 calculates rolling average unit 42 and rolling average unit
43 output and the signal C_II_I [n] for having been removed continuous wave CO_2 laser.Finally, 49 basis signal C_II_I of decision circuitry
The position of one maximum of [n] counter can push away the initial position of the data A of input signal X [n].
Fig. 4 is the detailed circuit of the one of which embodiment of Fig. 3.Correlation operation unit 41 includes delay cell 412
And multiplier 414.Rolling average unit 42 includes summing elements and averaging unit, and summing elements include the delay cell of Fig. 4
420, adder 430 and delay cell 440, averaging unit is by 450 implementation of divider.Likewise, rolling average unit 43 includes
Summing elements and averaging unit, summing elements include delay cell 425, adder 435 and the delay cell 445 of Fig. 4, average single
Member is by 455 implementation of divider.Computing unit 44 include the multiplier 460 of Fig. 4, multiplier 465, frequency shift (FS) unit 470 and
Adder 475.Decision circuitry 49 includes peak detection unit 491 and P1 position judgments unit 492.
Equation (2) may be implemented in delay cell 412 and multiplier 414.Delay cell 420, adder 430 and delay are single
Continuous 542 sample points of first 440 pairs of signal C_I_0 [n] add up, and obtain signal C_S [n].On the other hand, delay cell
425, adder 435 and delay cell 445 are to the signal C_I_0 [n] by frequency shift (FS) (being executed by frequency shift (FS) unit 418)
Continuous 542 sample points add up, obtain signal C_T1 [n].After obtaining signal C_S [n] and signal C_T1 [n], side
Formula (9) can be by divider 450 (divided by 542), divider 455 (divided by 542), multiplier 460 (being multiplied by -0.934), multiplication
Device 465 (being multiplied by 1.559), frequency shift (FS) unit 470 (make signal C_S [n] generate frequency shift (FS)) and adder 475 are subject to
It realizes, finally obtains the signal C_II_I [n] for having removed continuous wave CO_2 laser.
Peak detection unit 491 detects the peak value (i.e. maximum related value) of signal C_II_I [n], and the institute of peak value is in place
It sets and is sent to P1 position judgments unit 492, P1 position judgments unit 492 prolongs according to front stage circuits to what input signal was applied again
Late (such as 542TSOr 482TS), reckoning obtains correct position of the P1 symbols in T2 data frames.
Fig. 5 is input signal X [n], the input signal X [n] after delay and signal C_II_I [n] are in pair on time shaft
Ying Tu.Since in the circuit of Fig. 3 or Fig. 4, the delay cell 412 in correlation operation unit 41 is to prolong input signal X [n]
Late 542Ts just makes the first half of data A of data C and input signal X [n] of input signal X [n] after delay Chong Die,
Therefore input signal X [n] is by correlation operation unit 41, frequency shift (FS) unit 418, rolling average unit 42, rolling average
After the calculating of unit 43 and computing unit 44, the signal C_II_I [n] of generation has a maximum with the variation of time, by
The position of the maximum counter can push away the initial position of the data A of input signal X [n].The circuit of Fig. 3 and Fig. 4 is to enable input signal X
The first half of the data A of [n] is Chong Die with data C to carry out correlation calculations, it is therefore desirable to 542TSWindow length could effectively
Generate maximum；Similarly, in another embodiment, can also be the latter half of and data B weights for the data A for enabling input signal X [n]
It folds to carry out correlation calculations, therefore only needs 482TSWindow length can effectively generate maximum.
Compared to known detection unit 110, P1 symbol detection circuits of the invention at least have following characteristics：
The Window length of the filter 340 of known detection unit 110 is necessary for 1024TSContinuous wave CO_2 laser can be just filtered out,
And the filter (i.e. rolling average unit 42 and rolling average unit 43) of Fig. 3 only needs 542TSWindow length (processing data C)
Or 482TSWindow length (processing data B), therefore the present invention can substantially save while not reducing detection accuracy
The processing time of filter；
The filtering signal that the filter 340 of known detection unit 110 the exports not no ingredient of continuous wave CO_2 laser, and this
Though the filtering signal of the filter output of invention still has the ingredient of continuous wave CO_2 laser, equation is executed by computing unit 44
(9) partial product operation and add operation, two filtering exported from rolling average unit 42 and rolling average unit 43
The component b_C of P1 symbols is taken out in signal, you can filter out the ingredient of continuous wave interference.Other than the processing of frequency shift (FS), calculate single
Coefficient is all real number used in member 44, thus it is easy to implement on circuit, and relative inexpensiveness；And
The correlation operation that known detection unit 110 is done, one of two signals have between input signal
Having frequency shift (FS), (offset is-fSH, executed by multiplier 310)；And 2 that the correlation operation unit 41 of the present invention is multiplied
Signal (i.e. 2 input signals of multiplier 414) does not have frequency shift (FS) compared to input signal X [n].
Fig. 6 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention.The circuit of Fig. 6 includes 2 paths, on
The circuit circuit as shown in fig. 4 in square path is similar (only more delay cells 416), is exported after being dealt with to input signal X [n]
Signal C_II_I [n].Also circuit as shown in fig. 4 is similar for lower path, and rear output signal B_ is dealt with to input signal X [n]
II_I[n].The thin portion circuit of correlation operation unit 51 is identical as correlation operation unit 41, but its delay cell is delay
482TSRather than 542TS.So signal B_I [n] indicates as follows：
B_I [n]=exp (- j2 π fCWTB)·1+|P1[n-θ]|2·exp(-j2πΦTB)·exp(-j2πfSHnTS)+…
(10)
Similarly, signal B_I [n] on the one hand directly carries out operation by rolling average unit 52, on the one hand inclined through overfrequency
(frequency offset f is imposed by frequency shift (FS) unit 518 after shiftingSH, and execute and be conjugated multiple operations) again by rolling average unit
53 carry out operation.It note that the Window length of rolling average unit 52 and rolling average unit 53 is all 482TSIt is (corresponding related
The delay time 482T of property arithmetic element 51S).Both last signal obtains signal B_II_I after being calculated by computing unit 54
[n].The circuit of computing unit 54 is identical as computing unit 44, but coefficient is different, as shown in fig. 7, rolling average unit 52 is defeated
Go out and is multiplied by -1.232 again by the progress frequency shift (FS) of inclined rate offset units 570 via multiplier 560；And rolling average unit 53 is defeated
Go out after being multiplied by 1.830 via multiplier 565, is added with the signal of another way in adder 575, eventually forms signal B_II_I
[n].Coefficient and frequency offset used by computing unit 54 can be derived by by below：
Equation (10) is first reduced to following formula：
B_I [n]=a_B1+b_B ρ-n+…(11)
Wherein, a_B=exp (- j2 π fCWTB) be continuous wave CO_2 laser part, b_B=| P1[n-θ]|2·exp(-j2πΦ
TB) be P1 part, ρ=exp (j2 π fSHTS)。
Next, in continuous 482 sample points, (input signal X [n] is postponed in counterparty's formula (10) by B_I [n]
Time TB=482TS) add up, signal B_S [n] can be obtained：
B_S [n]=B_I [n]+B_I [n-1]+...+B_I [n-482+1]
=482a_B+b_B (ρ*)n-(482-1)/2·λ (12)
On the other hand, by signal B_I [n] frequency shift (FS)s fSH(it is multiplied by exp (j2 π f afterwardsSHnTS)), then at continuous 482
Sample point adds up, and can obtain signal：
B_T1 [n]=ρn·B_I[n]+ρ(n-1)·B_I[n-1]+…+ρ(n-482)·B_I[n-482+1
=482b_B+a_B (ρ*)(482-1)/2-n·λ (13)
Above-mentioned equation (12) and equation (13) can be rewritten as equation below (14) and equation (15) respectively：
ρn-(482-1)/2B_S [n]=482a_B ρn-(482-1)/2+b_B·λ (14)
B_T1 [n]=482b_B+a_B ρn-(482-1)/2·λ (15)
Equation (14) and equation (15) are indicated in the matrix form：
Coefficient and frequency offset used by computing unit 54 can be so obtained, also proves computing unit 54 simultaneously
The signal B_II_I [n] finally exported has removed the component a_B of continuous wave CO_2 laser, and leaves behind the component b_B of corresponding P1 symbols.
Fig. 8 is the input signal X [n] and signal C_II_I [n] and signal B_ after input signal X [n], two groups of delays
II_I [n] is in the corresponding diagram on time shaft.The related operation that signal B_II_I [n] is done for foundation data B, so can be in the time
2TAPlace generate maximum value.Because the detection circuit of Fig. 6 includes delay cell 416, signal C_II_I's [n] is very big
Value also falls within time 2TAPlace, therefore signal C_II_I [n] be multiplied with signal B_II_I [n] after signal (i.e. signal
P1_no_IQS [n]) in 2TAPlace will have more obvious peak value, be conducive to the judgement of subsequent conditioning circuit.
The decision circuitry 66 of Fig. 6 includes that peak detection unit 661, P1 position judgments unit 662 and fCFO estimate unit
663.The peak value that peak detection unit 661 detects signal P1_no_IQS [n] (can be obtained more acurrate compared with signal C_II_I [n] at this time
Judging result), and fCFO estimation unit 663 then obtain the carrier frequency shift of input signal from signal P1_no_IQS [n],
In more detail, calculating the argument (argument) of signal P1_no_IQS [n] can obtain：
Arg (P1_no_IQS [n])=Arg (b_Cb_B)
=-2 π (TB·fSH+TA·Φ)
Therefore, fractional part (the fractional Carrier of the carrier frequency shift of input signal n [n] can be obtained
Frequency Offset,fCFO)：
As can be known from the above analysis, P1 symbol detection circuits shown in fig. 6 using upper path and lower path respectively according to
Correlation operation is done according to the data C and data B of P1 symbols and obtains signal C_II_I [n] and signal B_II_I [n].It finally will letter
Obtained signal P1_no_IQS [n] is in addition to having more after number C_II_I [n] is multiplied with signal B_II_I [n] through multiplier 55
Apparent peak value can also learn the carrier frequency of input signal X [n] according to this in favor of finding out except the position of maximum related value
The fractional part of offset.
Above discussion be it is consistent with the signal spectrum that transmitting terminal is sent out based on receiving terminal default frequency spectrum operation,
It is exactly not have the situation of spectrum frequency reversion, however the present invention also proposes that the P1 symbol detection electricity of reversing spectrum can be detected simultaneously
Road.Fig. 9 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention.This circuit in addition with rolling average unit 56 at
The signal C_I [n] (frequency shift (FS) is executed by frequency shift (FS) unit 59 and is conjugated multiple operations) Jing Guo frequency shift (FS) is managed, then is passed through
Signal C_II_II [n] is obtained after being calculated by counting circuit 60.Therefore, the decision circuitry 65 of rear class can basis signal C_II_I
[n] and signal C_II_II [n] whichever has larger maximum related value, come learn input signal X [n] whether reversing spectrum (similarly
It can be applied to signal B_II_I [n] and signal B_II_II [n]).The peak detection unit 651 of decision circuitry 65 detects letter simultaneously
The peak value of number C_II_I [n] and signal C_II_II [n], then sends the position of two peak values to P1 position judgment units
652, and send the size of two peak values (taking absolute value) to IQS detection units 653, IQS detection units 653 compare two peaks
Reversing spectrum is known whether after the size of value, the compensation circuit of rear class is again according to this information and P1 position judgments unit 652
Output determines the correct position of P1 symbols.
Figure 10 is the circuit diagram of another embodiment of P1 symbol detection circuits of the present invention.Signal C_II_I [n] and signal C_
II_II [n] (signal B_II_I [n] with signal B_II_II [n] similarly) is respectively that corresponding frequency spectrum does not invert and the phase of reversing spectrum
OFF signal, and the two has all removed the ingredient of continuous wave CO_2 laser, that is to say, that the common-channel interference warp suffered by input signal X [n]
It can be obtained after crossing the calculating of computing unit 60 and computing unit 70 (its circuit is identical as computing unit 60, and coefficient can refer to Fig. 7)
Must determine solution.The waveform of signal C_II_I [n] (or C_II_II [n]) times corresponding with signal B_II_I [n] (or B_II_II [n])
Figure is as shown in figure 8, because signal C_II_I [n] (or C_II_II [n]) delays 964TS, so with signal B_II_I [n] (or
B_II_II [n]) be multiplied after obtained signal P1_no_IQS [n] (or P1_IQS [n]) have more obvious maximum with sharp rear class
Decision circuitry interpretation.In addition, decision circuitry can be learnt defeated by the maximum for comparing P1_no_IQS [n] and P1_IQS [n]
Enter whether signal X [n] has reversing spectrum, it can also be according to any one of P1_no_IQS [n] and P1_IQS [n], to obtain input letter
The carrier frequency shift of number X [n] (such as shown in equation (17)).The decision circuitry 75 of Figure 10 includes peak detection unit 751, P1
Position judgment unit 752, IQS detection units 753 and fCFO estimate unit 754, and it is real that wherein fCFO estimates unit 754 and Fig. 6
The fCFO estimation units 663 for applying example are identical, and the carrier frequency shift of input signal can be obtained from signal P1_no_IQS [n], however
The fCFO estimation units 754 of Figure 10 embodiments more couple IQS detection units 753, therefore can correct selection signal P1_no_IQS
[n] carries out operation.Decision circuitry 75 sentences signal P1_no_IQS [n] and signal P1_IQS [n] other items carried out
It is disconnected, explanation was done in the details of each functional unit, so it will not be repeated.
Figure 11 is that the P1 symbol detection circuits of the present invention coordinate decision circuitry showing applied to the receiving terminal of DVB-T2 systems
It is intended to.Compensation circuit 1230 according to the judging result of decision circuitry 1240 come adjust/compensate be temporarily stored into it is defeated in register 1210
Enter signal, makes the circuit (such as FFT arithmetic elements etc.) of rear class that can handle correct input signal.Decision circuitry 1240 is wrapped
Each functional unit contained is in foregoing descriptions mistake, and so it will not be repeated.
Although the present invention is disclosed as above with preferred embodiment, however, it is not to limit the invention, any this field skill
Art personnel, without departing from the spirit and scope of the present invention, when can make a little modification and it is perfect, therefore the present invention protection model
It encloses to work as and is subject to what claims were defined.
Claims (20)
1. a kind of detection circuit, applied to the receiving terminal of digital video broadcasting to detect one of a data frame of an input signal
It sets, which includes a continuous wave CO_2 laser ingredient, which includes：
One correlation operation unit is used for generating a coherent signal according to the input signal；
One first movement averaging unit couples the correlation operation unit, is used for carrying out rolling average calculating to the coherent signal
To generate a first movement average result；
One frequency shift (FS) unit couples the correlation operation unit, for the frequency shift (FS) coherent signal；
One second rolling average unit couples the frequency shift (FS) unit, for being moved to the coherent signal after frequency shift (FS)
Dynamic average computation is to generate one second rolling average result；
One computing unit couples the first movement averaging unit and the second rolling average unit, is used for according to the first movement
Average result and the second rolling average result eliminate the continuous wave CO_2 laser ingredient, and generate an output signal according to this；And
One judging unit couples the computing unit, judges the position for the peak value according to the output signal.
2. detection circuit as described in claim 1, which is characterized in that the correlation operation unit be according to delay after this is defeated
Enter signal and the conjugated signal of the input signal generates the coherent signal.
3. detection circuit as described in claim 1, which is characterized in that the data frame has a symbol, and it is defeated which carries this
Enter a modulation intelligence of signal, and the first movement averaging unit and the Window length of the second rolling average unit are less than the symbol
Number time span half.
4. detection circuit as described in claim 1, which is characterized in that the first movement average result and second rolling average
The result is that including the continuous wave CO_2 laser ingredient.
5. detection circuit as described in claim 1, which is characterized in that the frequency shift (FS) unit is that first frequency offset is single
Member, the detection circuit further include：
One another correlation operation unit is used for generating an another coherent signal according to the input signal；
One third rolling average unit couples another correlation operation unit, for being moved to another coherent signal
Average computation is to generate a third rolling average result；
One second frequency offset units couple another correlation operation unit, for frequency shift (FS) another coherent signal；
One the 4th rolling average unit couples the second frequency offset units, is used for another related letter after frequency shift (FS)
Number carry out rolling average calculate to generate one the 4th rolling average result；
One another computing unit couples the third rolling average unit and the 4th rolling average unit, is used for according to the third
Rolling average result and the 4th rolling average result eliminate the continuous wave CO_2 laser ingredient, and generate an another output signal；With
And
One multiplier is coupled to the computing unit and another computing unit, is used for believing the output signal and another output
Number it is multiplied to produce an echo signal；
Wherein, which judges the position according to a peak value of the echo signal.
6. detection circuit as claimed in claim 5, which is characterized in that the judging unit more judges that this is defeated according to the echo signal
Enter a carrier frequency shift of signal.
7. detection circuit as described in claim 1, which is characterized in that the output signal is one first output signal, the frequency
Offset units are a first frequency offset units, which further includes：
One second frequency offset units couple the correlation operation unit, for the frequency shift (FS) coherent signal；
One third rolling average unit, couples the correlation operation unit, for being total to the coherent signal after frequency shift (FS)
Conjugate signal carries out rolling average and calculates to generate a third rolling average result；
Wherein, which more couples the third rolling average unit, and more according to the first movement average result and is somebody's turn to do
Third rolling average result eliminates the continuous wave CO_2 laser ingredient, and generates one second output signal, and the judging unit more foundation
First output signal and second output signal judge a reversing spectrum information of the input signal.
8. detection circuit as claimed in claim 7, further includes：
One another correlation operation unit is used for generating an another coherent signal according to the input signal；
One the 4th rolling average unit couples another correlation operation unit, for being moved to another coherent signal
Average computation is to generate one the 4th rolling average result；
One third frequency shift (FS) unit couples another correlation operation unit, for frequency shift (FS) another coherent signal；
One the 5th rolling average unit couples the third frequency shift (FS) unit, is used for another related letter after frequency shift (FS)
Number carry out rolling average calculate to generate one the 5th rolling average result；
One the 4th frequency shift (FS) unit couples another correlation operation unit, for frequency shift (FS) another coherent signal；
One the 6th rolling average unit, couples the 4th frequency shift (FS) unit, is used for another related letter after frequency shift (FS)
Number conjugated signal carry out rolling average calculate to generate one the 6th rolling average result；
One another computing unit, couples the 4th rolling average unit, the 5th rolling average unit and the 6th rolling average
Unit, for eliminating the continuous wave CO_2 laser ingredient according to the 4th rolling average result, the 5th rolling average result, and according to this
A third output signal is generated, and for eliminating the company according to the 4th rolling average result, the 6th rolling average result
Continuous wave interference ingredient, and one the 4th output signal is generated according to this；
One first multiplier is coupled to the computing unit and another computing unit, be used for by first output signal and this
Three output signals are multiplied to produce a first object signal；And
One second multiplier is coupled to the computing unit and another computing unit, be used for by second output signal and this
Four output signals are multiplied to produce one second echo signal；
Wherein, which judges the position according to a peak value of the first object signal and a peak value of second echo signal
It sets.
9. detection circuit as claimed in claim 8, which is characterized in that the judging unit more according to the first object signal and is somebody's turn to do
Second echo signal judges a carrier frequency shift of the input signal.
10. detection circuit as claimed in claim 8, which is characterized in that the judging unit more according to the first object signal and
At least one of second echo signal judges a reversing spectrum information of the input signal.
11. detection circuit as described in claim 1 is to be applied to a second generation digital video broadcast system (DVB-T2).
12. a kind of detection method, applied to the receiving terminal of digital video broadcasting to detect the one of a data frame of an input signal
Position, the input signal include a continuous wave CO_2 laser ingredient, and this method includes：
A coherent signal is generated according to the input signal；
Rolling average is carried out to the coherent signal to calculate to generate a first movement average result；
The frequency shift (FS) coherent signal is to generate the coherent signal after frequency shift (FS)；
Rolling average is carried out to the coherent signal after frequency shift (FS) to calculate to generate one second rolling average result；
The continuous wave CO_2 laser ingredient is eliminated according to the first movement average result and the second rolling average result, and is generated according to this
One output signal；And
A peak value according to the output signal judges the position.
13. detection method as claimed in claim 12, which is characterized in that this generates a coherent signal according to the input signal
Step is to generate the coherent signal according to the input signal of delay and the conjugated signal of the input signal.
14. detection method as claimed in claim 12, which is characterized in that the data frame has a symbol, which carries should
One modulation intelligence of input signal, and generate one first Window length of the first movement average result according to this and generate according to this and be somebody's turn to do
One second Window length of the second rolling average result is less than the half of the time span of the symbol.
15. detection method as claimed in claim 12, which is characterized in that the first movement average result and second movement are flat
The result is that including the continuous wave CO_2 laser ingredient.
16. detection method as claimed in claim 12, further includes：
An another coherent signal is generated according to the input signal；
Rolling average is carried out to another coherent signal to calculate to generate a third rolling average result；
Frequency shift (FS) another coherent signal is to generate another coherent signal after frequency shift (FS)；
Rolling average is carried out to another coherent signal after frequency shift (FS) to calculate to generate one the 4th rolling average result；
The continuous wave CO_2 laser ingredient is eliminated according to the third rolling average result and the 4th rolling average result, and it is another to generate one
One output signal；
The output signal and another output signal are multiplied to produce an echo signal；And
A peak value according to the echo signal judges the position.
17. detection method as claimed in claim 16 further includes the carrier wave for judging the input signal according to the echo signal
Frequency shift (FS).
18. detection method as claimed in claim 12, which is characterized in that the output signal is one first output signal, the party
Method further includes：
Rolling average is carried out to the conjugated signal of the coherent signal after the frequency shift (FS) to calculate to generate a third rolling average
As a result；
The continuous wave CO_2 laser ingredient is eliminated according to the first movement average result and the third rolling average result, and generates one the
Two output signals；And
A reversing spectrum information of the input signal is judged according to first output signal and second output signal.
19. detection method as claimed in claim 18, further includes：
An another coherent signal is generated according to the input signal；
Rolling average is carried out to another coherent signal to calculate to generate one the 4th rolling average result；
Frequency shift (FS) another coherent signal is to generate another coherent signal after frequency shift (FS)；
Rolling average is carried out to another coherent signal after frequency shift (FS) to calculate to generate one the 5th rolling average result；
It is flat to generate one the 6th movement that rolling average calculating is carried out to the conjugated signal of another coherent signal after frequency shift (FS)
Result；
The continuous wave CO_2 laser ingredient is eliminated according to the 4th rolling average result, the 5th rolling average result, and is generated according to this
One third output signal and according to the 4th rolling average result, the 6th rolling average result eliminate the continuous wave CO_2 laser at
Point, and one the 4th output signal is generated according to this；
First output signal and the third output signal are multiplied to produce a first object signal；
Second output signal and the 4th output signal are multiplied to produce one second echo signal；And
Judge the position according to a peak value of the first object signal and a peak value of second echo signal.
20. detection method as claimed in claim 12 is to be applied to a second generation digital video broadcast system (DVB-T2).
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