CN106713196A - Estimable frequency deviation receiving circuit and related method - Google Patents
Estimable frequency deviation receiving circuit and related method Download PDFInfo
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- CN106713196A CN106713196A CN201510783730.8A CN201510783730A CN106713196A CN 106713196 A CN106713196 A CN 106713196A CN 201510783730 A CN201510783730 A CN 201510783730A CN 106713196 A CN106713196 A CN 106713196A
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- peak value
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
Abstract
The invention provides an estimable frequency deviation receiving circuit and related method. The estimable frequency deviation receiving circuit comprises a front-end circuit and a calculation circuit. The front-end circuit receives a far-end signal so as to generate a receiving signal. The calculation circuit comprises a first power calculation module which calculates the power of one index of the receiving signal so as to generate a high-order signal; a frequency domain transformation module which performs frequency domain transformation on the high-order signal so as to generate a frequency spectrum; a peak searching module which searches the peak of the frequency spectrum amplitude so as to generate peak coordinate values to reflect the peak generation frequency; and a deviation estimation module which adds the peak coordinate values and a compensation value so as to generate a sum value, wherein the sum value is divided by a first divisor to generate a remainder, subtraction is performed on the remainder and the compensation value to generate a difference value, and the difference value is divided by a second divisor to generate a deviation estimation value which can reflect frequency deviation.
Description
Technical field
It is especially a kind of the invention relates to a kind of receiving circuit and correlation technique for estimating frequency shift (FS)
The receiving circuit and correlation technique of frequency shift (FS) can be correctly estimated under multipath interference.
Background technology
Reception remote signaling uses one of most common function in having turned into modernization massaging device.For receive by
The wirelessly or non-wirelessly remote signaling that distal end radiating circuit is sent, can be provided with receiving circuit in massaging device.Hair
Transmit-receive radio road can be believed the transmitting that fundamental frequency signal liter modulation is made as radio frequency with local (local) frequency of a transmitting terminal
Number, and launched propagation.Transmission signal propagates to receiving circuit as RF remote signal, by receiving electricity
Road is received, and remote signaling drop is turned into demodulation with a receiving terminal local frequency, and fundamental frequency signal is gone back to take.
But, cannot completely be matched between the local frequency of transmitting terminal and the local frequency of receiving terminal, difference is had between the two
It is different, that is, frequency shift (FS).Therefore, radiating circuit need estimate the frequency shift (FS), correctly to carry out
Drop turns demodulation and signals revivification.Furthermore, when transmission signal propagates to receiving circuit by radiating circuit, can meet with
A variety of propagation is met to disturb, including multipath interference.Propagating interference can influence the estimation of frequency shift (FS), make estimation
Misalignment.
The content of the invention
To avoid propagating interference effect Frequency offset estimation, an object of the present invention is to provide one kind and is related to
A kind of receiving circuit for estimating frequency shift (FS), it may include a front-end circuit and a counting circuit.Front end electricity
Road is used to receive remote signaling yRF (t) that a radiating circuit is transmitted, and produces one to receive signal y (t) according to this.
Counting circuit couples front-end circuit, and it may include first power computing module, a frequency domain modular converter, a peak value
Search module and a bias estimation module.The power computing module can calculate an indices P of the reception signal
Power is producing a high order signal yp(t).The frequency domain modular converter high order signal can be carried out frequency domain conversion with
Produce frequency spectrum Z (f).The peak value search module can search peak value max | the Z (f) | of the amplitude of the frequency spectrum | Z (f) |,
A peak value coordinate values fM is produced according to this, its frequency f that can reflect peak value max | Z (f) | generations.The skew is estimated
With an offset f_half can be added the peak value coordinate values to produce one and value (fM+f_half) by meter module, will
Should and value divided by one first divisor d1 to produce a remainder ((fM+f_half) %d1), by the remainder and the compensation
Value is subtracted each other to produce a difference { ((fM+f_half) %d1)-f_half }, by the difference divided by one second divisor d2
To produce a bias estimation value { ((fM+f_half) %d1)-f_half }/d2；Wherein, the bias estimation value can reflect
Frequency shift (FS) between the local frequency of the radiating circuit and the local frequency of the receiving circuit.
In one example, comprising multiple symbols in the reception signal, the plurality of symbol has a symbol frequency Fs；
For example, each symbol continues a symbol cycle T, symbol frequency Fs can then be equal to the inverse of the symbol cycle T,
That is Fs=1/T.And the bias estimation module more can set first divisor d1 according to symbol frequency Fs；Example
Such as, the bias estimation module can make the first divisor be equal to the symbol frequency.In one example, the bias estimation mould
Block more can set offset f_half according to symbol frequency Fs；For example, the bias estimation module can foundation
The half (i.e. Fs/2) in the symbol cycle sets the offset.In one example, the bias estimation module more may be used
Second divisor d2 is set according to the indices P；For example, the bias estimation module can be equal to second divisor
The index.
In one example, the radiating circuit is to move (QPSK, quadrature phase shift according to four phase keys
Keying the remote signaling) is modulated, and the indices P can be set as 4 by the power computing module.One model
In example, each symbol for receiving signal is selected first, each constellation point c [n] by multiple constellation point c [1] to c [N]
Comprising a real part re (c [n]) and imaginary part im (c [n])；The power computing module can more set the indices P, and
The totalling being set so that after the index power of these constellation points of the indices PIt is not equal to zero.
An object of the present invention is to provide a kind of method for estimating frequency shift (FS), including：Calculate and receive letter
The power of one indices P of number y (t) produces a high order signal yp(t)；The high order signal is carried out frequency domain conversion with
Produce frequency spectrum Z (f)；Peak value max | the Z (f) | of the amplitude of the frequency spectrum | Z (f) | are searched, peak value seat is produced according to this
Scale value fM, reflects the frequency that the peak value occurs；According to the peak value coordinate values and the integer of one first divisor d1
Difference between times produces a difference, makes the difference between a negative lower limit and a positive upper limit, and wherein this is just gone up
Limit is equal to the half of first divisor with the absolute value of the negative lower limit；Also, the difference is removed divided by one second
Number d2 is used to reflect the local frequency and the receiving circuit of the radiating circuit to produce a bias estimation value
Frequency shift (FS) between local frequency.
Brief description of the drawings
It is that the above objects, features and advantages of the present invention can be become apparent, below in conjunction with accompanying drawing to this hair
Bright specific embodiment elaborates, wherein：
Fig. 1 illustrates that the receiving circuit according to an example of the invention.
Fig. 2 illustrates that the flow according to an example of the invention.
Fig. 3 illustrates that an example of constellation point distribution.
Fig. 4 A and Fig. 4 B are shown in without frequency shift (FS) and receive signal in the case of being disturbed without multipath respectively
The spectrum amplitude of power spectrum density and high order signal.
Fig. 5 A and Fig. 5 B are shown in frequency shift (FS) but receive signal in the case of being disturbed without multipath respectively
The spectrum amplitude of power spectrum density and high order signal.
Fig. 6 A and Fig. 6 B are shown in frequency shift (FS) and have multipath to receive signal in the case of disturbing respectively
The spectrum amplitude of power spectrum density and high order signal.
Component label instructions in figure：
100：Radiating circuit
102：Fundamental frequency moulds wave circuit
104：Modulation circuit
106：Passage
110：Receiving circuit
112：Front-end circuit
114：Counting circuit
116：Power computing module
118：Frequency domain modular converter
120：Peak value search module
122：Bias estimation module
200：Flow
202 to 208：Step
x(t)、y(t)、yp(t)、xRF(t)、yRF(t)、ys(t)：Signal
g(t-k*T)：Time-domain function
h(t)：Response
w(t)、n(t)：Noise
ak, c [1] to c [4]：Constellation point
Z(f)：Frequency spectrum
P：Index
fM：Peak value coordinate values
f_half：Offset
d1、d2：Divisor
T：The symbol cycle
dF：Frequency shift (FS)
dT：Time difference
：Phase
df：Bias estimation value
fLO1、fLO2：Local frequency
A：Constant
Specific embodiment
Refer to Fig. 1 and Fig. 2；Fig. 1 illustrates that the receiving circuit 110, Fig. 2 according to an example of the invention
The flow 200 according to an example of the invention is illustrated that, receiving circuit 110 can be estimated with flow 200
Frequency shift (FS).As shown in figure 1, receiving circuit 110 can arrange in pairs or groups, a radiating circuit 100 forms a receive-transmit system.
For example, this receive-transmit system can be satellite or wired DVB (DVB, digital video
Broadcasting) system, radiating circuit 100 may be disposed at a satellite or a server, receiving circuit 110
May be disposed on a satellite TV set box on box or cable TV；Receiving circuit 110 can also be arranged at one
TV or portable wisdom device.
Radiating circuit 100 may include the fundamental frequency modeling modulation electricity of ripple (baseband shaping) circuit 102 and
Road 104.Fundamental frequency modeling wave circuit 102 can be directed to the numeral input to be launched and produce corresponding fundamental frequency signal x (t),
It is represented by ∑kak *g(t-k* T)；Wherein, constellation point akReflect k-th digital content of symbol, when
Domain function g (t-k*T) is then k-th wave mode of symbol, for example, say it is through square root raised cosine filter (square
Root raised cosine filter) wave mode obtained by treatment, T is then a symbol cycle, that is, a symbol is prolonged
The continuous time；The 1/T reciprocal of symbol cycle T is then symbol frequency (symbol rate) Fs.Each symbol star
Seat point akCan for example say it is Fig. 3 institutes according to the digital content of each symbol by being selected in the default constellation point of multiple
The 4 constellation point c [1] shown are to c [4].Fig. 3 illustrates that the constellation point that four phase keys are moved under (QPSK) modulation,
Each constellation point c [n] in constellation point c [1] to c [4] is represented by complex variable, comprising a real part re (c [n]) and
Imaginary part im (c [n]), represent respectively the component of parallel phase (in-phase, Fig. 3 are denoted as " I ") with it is orthogonal
The component of phase (quadrature-phase is denoted as " Q ").For example, constellation point c [1] to c [4] can divide
Not Wei A* (1+j), A* (1-j), A* (- 1-j) and A* (1-j), be used to represent two digital bit contents " 00 ",
" 10 ", " 11 " and " 01 "；Wherein, j is -1 square root, and A is a constant.
In radiating circuit 100, modulation circuit 104 can be according to the local frequency fLO1 of a transmitting terminal by fundamental frequency
Signal x (t) rises modulation and is made as wireless radio transmission signal xRF (t), and is subject to transmitting and blazes abroad.For example,
Signal xRF (t) is represented by ∑k{re(ak)*cos(2*π*fLO1*t)+im(ak)*sin(2*π*fLO1*t)}。
Signal xRF (t) turns into RF remote signal yRF (t) after propagating to receiving circuit 110, and by receiving electricity
Road 110 receives.Signal xRF (t) is propagated as the process of signal yRF (t) can be modeled as a passage 106, its
Effect to signal xRF (t) is represented by impulse response h (t), therefore signal yRF (t) is represented byWherein, item time w (t) can be additivity additive white Gaussian (additive white
Gaussian noise)。
Receiving circuit 110 may include a front-end circuit 112 and a counting circuit 114.Front-end circuit 112
Remote signaling yRF (t) can be received, and signal yRF (t) drop is turned into solution according to a receiving terminal local frequency fLO2
Adjust, and filtered, reception signal y (t) of a fundamental frequency is produced according to this.In receiving circuit 110, front end
Circuit 112 may include (do not draw) that solution downgrades shifting circuit, low pass filter and (for example resists nearby frequency bands to do
Disturb the wave filter of (ACI, adjacent channel interference)), analog-to-digital converter, drop
Sampler (decimator), symbol detection circuit etc..Due to the local frequency fLO1 of transmitting terminal and reception
Hold local frequency fLO2 cannot perfect matching, a frequency shift (FS) dF (being not illustrated in Fig. 1) is had between the two,
And basis signal y (t) calculates a bias estimation value df by counting circuit 114, it is used to reflect actual frequency
Rate offset d F.Counting circuit 114 can comprising first power computing module 116, a frequency domain modular converter 118,
One peak value search module 120 and a bias estimation module 122, respectively correspond to flow 200 in step 202,
204th, 206 and 208, it can be described as follows.
Step 202：One indices P is set by power computing module 116, and calculates the P for receiving signal y (t)
Power is producing a high order signal yp(t).Similar to signal x (t), signal y (t) also has real part re (y (t)) with void
Portion im (y (t)), i.e. y (t)=re (y (t))+j*im (y (t)), and the high order signal y that counting circuit 114 is calculatedp(t)
Then it is represented by { re (y (t))+j*im (y (t)) }P.In one example, because radiating circuit 100 is according to four phase keys
Signal xRF (t) is made in transposition, therefore indices P can be set as 4 by power computing module 116；That is,：
yp(t)=y4(t)
=re (y (t))4+4*j*re(y(t))3*im(y(t))-6*re(y(t))2
*im(y(t))2-4*j*re(y(t))*im(y(t))3+im(y(t))4
.Under the shifting of four phase keys, indices P can also be 4 multiple.
In one example, the constellation point of each symbol is to select one of them by N number of constellation point c [1] to c [N], and
The totalling that is set so that the P power of each constellation point c [n] after of the power computing module 116 to indices PIt is not equal to zero.For example, if radiating circuit 100 uses 8PSK (shifting of eight phase keys),
Indices P may be set to 8 multiple, such as 8 or 16.If radiating circuit 100 uses 16PSK (ten
Six phase keys are moved), then indices P may be set to 16 multiple, such as 16 or 32.If radiating circuit 100 makes
With 4QAM (quadrature amplitude modulation, quadrature amplitude modulation), 16QAM, 64QAM
Or 256QAM etc., indices P also may be set to 4 multiple, such as 4 or 8.
Step 204：By frequency domain modular converter 118 to high order signal ypT () carries out frequency domain conversion (such as quick
Fourier transform, fast Fourier transform, FFT) producing frequency spectrum Z (f).
Step 206：The universe (global) of the amplitude of frequency spectrum Z (f) | Z (f) | is searched by peak value search module 120
Peak value max | Z (f) |, produce the peak value coordinate values fM of a frequency domain according to this, and reflection peak value max | Z (f) | be generation
Frequency；That is, peak value coordinate values fM can reflect argmaxf|Z(f)|.In another example, peak value search module
120 can also search spectrum amplitude | Z (f) |2Peak value occurrence frequency.
Step 208：Bias estimation module 122 is according to peak value coordinate values fM, symbol frequency Fs (can be by preceding
Terminal circuit 112 is provided) calculate one with indices P (being provided by power computing module 116, step 202)
Bias estimation value df, to reflect the frequency between the local frequency fLO1 of transmitting terminal and the local frequency fLO2 of receiving terminal
Rate offset d F.In one example, to calculate bias estimation value df, bias estimation module 122 can be by peak value coordinate
Value fM is added with an offset f_half to produce one and value (fM+f_half), wherein, bias estimation module
122 can be according to symbol frequency Fs setting compensations value f_half, such as f_half=(1/2) * Fs.Then, offset
Estimation module 122 calculates and is worth remainder (fM+f_half) %d1 of (fM+f_half) divided by one first divisor d1,
Wherein, bias estimation module 122 can set divisor d1, such as d1=Fs according to symbol frequency Fs.Then,
Remainder (fM+f_half) %d1 and offset f_half are subtracted each other to produce a difference by bias estimation module 122
{ (fM+f_half) %d1-f_half }, then by difference { (fM+f_half) %d1-f_half } divided by one second divisor d2,
To produce bias estimation value df, wherein, bias estimation module 122 can set divisor d2, example according to indices P
Such as d2=P.That is, in an example, df={ (fM+Fs/2) %Fs-Fs/2 }/P.
As will be discussed later, changed through the treatment of P powers and the frequency domain of step 204 of step 202, amplitude
Peak value coordinate values fM (step 206) that peak value occurs in | Z (f) | is represented by (L*Fs+P*dF)；Wherein, Fs
It is symbol frequency；L is an integer, and dF is frequency shift (FS).In other words, peak value coordinate values fM will correlate in
The integral multiple of symbol frequency Fs adds P times of frequency shift (FS) dF；Wherein, frequency shift (FS) dF can be just
Value or negative value, product P*dF is then between frequency domain lower limit (- Fs/2) and the frequency domain upper limit (+Fs/2).
When { (fM+Fs/2) %Fs-Fs/2 }/P is calculated to produce bias estimation value df, due to peak value coordinate values
FM is represented by (L*Fs+P*dF), therefore is represented by { L*Fs+ (P*dF+Fs/2) } with value (fM+Fs/2), remaining
Number (fM+Fs/2) %Fs is then represented by (P*dF+Fs/2).Because P*dF is in frequency domain lower limit (- Fs/2) and the upper limit
(Fs/2) between, adding offset f_half=Fs/2 can make the value of (P*dF+Fs/2) fall in frequency domain 0 to Fs
Between, therefore, pair and value (fM+Fs/2) take the remainder just removable item time L*Fs divided by Fs and to retain item secondary
(P*dF+Fs/2).Then, P*dF is just can obtain after subtracting offset Fs/2 by remainder (P*dF+Fs/2), will
P*dF just can use also frequency shift (FS) dF divided by P.
Continue Fig. 1 and Fig. 2, refer to Fig. 4 A and Fig. 4 B, it is that citing is shown in without frequency shift (FS) and nothing
Multipath receives the power spectrum density and high order signal y of signal y (t) in the case of disturbingpThe spectrum amplitude of (t)
| Z (f) |, the transverse axis of two figures is frequency (unit is MHz).Without frequency shift (FS) and without the feelings of multipath interference
Under condition, signal y (t) is represented byThe namely convolution of signal x (t) and channel response h (t)
(convolution) noise n (t) is added, noise n (t) is that noise w (t) is through the LPF of front-end circuit 112
Noise afterwards；The power spectrum density that Fig. 4 A illustrate correlates the frequency spectrum of each symbol in signal y (t).In figure
In the example of 4A and 4B, radiating circuit 100 moves modulated signal according to four phase keys, and symbol frequency Fs is 20MHz,
The signal to noise ratio of noise w (t) (Fig. 1) of passage 106 is 10dB, and nearby frequency bands are resisted in front-end circuit 112
The LPF passband (pass band) of interference is 15MHz.In response to four phase key transposition systems, counting circuit 114
In power computing module 116 indices P is set as 4.Therefore, signal is received in front-end circuit 112
YRF (t) and dropping turns after filtering obtains signal y (t), and power computing module 116 will calculate high order signal y4(t)
(step 202), frequency domain modular converter 118 can be to signal y4T () carries out frequency conversion calculation and goes out frequency spectrum Z (f)
(step 204), and peak value search module 120 then in spectrum amplitude middle search peak value max | the Z (f) | of | Z (f) | with
Find out peak value coordinate values fM (step 206).
As shown in Figure 4 B, if without frequency shift (FS) and without multipath interference, the peak value coordinate of spectrum amplitude | Z (f) |
Value fM can be located at 0MHz, and the bias estimation value df=that bias estimation module 122 is calculated
{ (fM+Fs/2) %Fs-Fs/2 }/P=(0+10) %20) and -10 }/4={ 10-10 }/4=0 (step 208), can be just
Really reflect the situation without frequency shift (FS).
Continue Fig. 1 and Fig. 2, refer to Fig. 5 A and Fig. 5 B, it is that citing has been shown in frequency shift (FS) but nothing
Multipath receives the power spectrum density and high order signal y of signal y (t) in the case of disturbingpThe spectrum amplitude of (t)
| Z (f) |, the transverse axis of two figures is frequency (unit is MHz).Have frequency shift (FS) but without multipath interference feelings
Under condition, signal y (t) is represented byWherein dF is actual frequency
Rate offsets.It is identical with the example of Fig. 4 B with Fig. 4 A, in the example of Fig. 5 A and Fig. 5 B, radiating circuit
100 move modulated signal according to four phase keys, and symbol frequency Fs is 20MHz, and the signal to noise ratio of channel noise w (t) is
10dB, the low pass passband that adjacent band interference is resisted in front-end circuit 112 is 15MHz.Furthermore, frequency is inclined
Move dF and be then equal to 2MHz.In response to four phase key transposition systems, can be set as indices P by power computing module 116
4.Therefore, front-end circuit 112 receives signal yRF (t) and dropping and turns after filtering obtains signal y (t), power meter
Calculating module 116 will calculate high order signal y4T () (step 202), frequency domain modular converter 118 can be to signal y4(t)
Carry out frequency conversion calculation and go out frequency spectrum Z (f) (step 204), | the Z (f) | then in spectrum amplitude of peak value search module 120
It is middle to search peak value to find out peak value coordinate values fM (step 206).
As shown in Figure 5 B, if actual frequency offset dF=2MHz but without multipath interference, spectrum amplitude | Z (f) |
Peak value coordinate values fM can be located at 8MHz, and the bias estimation value that bias estimation module 122 is calculated
Df={ (fM+Fs/2) %Fs-Fs/2 }/P=(8+10) %20) and -10 }/4={ 18-10 }/4=8/4=2 (steps
208) the frequency shift (FS) dF of 2MH, can correctly be reflected.
On the other hand, if frequency shift (FS) dF is -2MHz (not shown) but without multipath interference, frequency spectrum width
The peak value coordinate values fM for spending | Z (f) | can be located at -8MHz (not shown), and the calculating of counting circuit 114 is inclined
Shifting estimate df={ (fM+Fs/2) %Fs-Fs/2 }/P=(- 8+10) %20) and -10 }/4={ 2-10 }/4=-8/4=
- 2 (steps 208), also can correctly reflect the actual frequency offset dF of -2MH.
Continue Fig. 1 and Fig. 2, refer to Fig. 6 A and Fig. 6 B, it is that citing has been shown in frequency shift (FS) and has had
Multipath receives the power spectrum density and high order signal y of signal y (t) in the case of disturbingpThe spectrum amplitude of (t)
| Z (f) |, the transverse axis of two figures is frequency (unit is MHz).Have frequency shift (FS) and have multipath disturb feelings
Under condition, signal y (t) is represented by ys (t)+exp (j* φ) * ys (t-dT)+n (t), and wherein ys (t) is represented byNamely single-pathway but there is the signal of frequency shift (FS),
Exp (j* φ) * ys (t-dT) then represents the signal in another path, and φ represents the extra phase on the path, and dT is represented
Time difference between different paths.It is identical with the example of Fig. 4 B with Fig. 4 A, in the example of Fig. 6 A and 6B,
Radiating circuit 100 moves modulated signal according to four phase keys, and symbol frequency Fs is 20MHz, channel noise w (t)
Signal to noise ratio is 10dB, and the low pass passband that adjacent band interference is resisted in front-end circuit 112 is 15MHz.Again
Person, actual frequency offset dF is equal to 2MHz, and phase is equal to 1.2, and time difference dT is 0.01 μ s.
In response to four phase key transposition systems, indices P can be set as 4 by power computing module 116.Therefore, front end
Circuit 112 receives signal yRF (t) and dropping and turns after filtering obtains signal y (t), and power computing module 116 is just
High order signal y can be calculated4T () (step 202), frequency domain modular converter 118 can be to signal y4T () enters line frequency
Conversion calculates frequency spectrum Z (f) (step 204), and peak value search module 120 is searched then in spectrum amplitude in | Z (f) |
Peak-seeking value is finding out peak value coordinate values fM (step 206).
As shown in Figure 6B, if frequency shift (FS) dF=2MHz and thering is multipath to disturb, spectrum amplitude | Z's (f) |
Peak value coordinate values fM can be located at 28MHz, and bias estimation module 122 calculate bias estimation value df=
{ (fM+Fs/2) %Fs-Fs/2 }/P=(28+10) %20) and -10 }/4={ 18-10 }/4=8/4=2 (step 208),
The frequency shift (FS) dF of 2MH can correctly be reflected, even if with the presence of multipath interference.On the other hand, if frequency
Rate offset d F=-2MHz and there is multipath to disturb, the peak value coordinate values fM of spectrum amplitude | Z (f) | can be located at
12MHz (is not illustrated), and the bias estimation value df=that bias estimation module 122 is calculated
{ (fM+Fs/2) %Fs-Fs/2 }/P=(12+10) %20) and -10 }/4={ 2-10 }/4=-8/4=-2 (step 208),
Still can correctly reflect the frequency shift (FS) dF of -2MHz under multipath interference.
Two examples for comparing Fig. 4 B and Fig. 5 B understand, in the high order signal y of P=4 powerspThe frequency spectrum of (t)
In Z (f), the frequency shift (FS) dF of 2MHz can be such that peak value coordinate values fM is changed to figure by the 0MHz of Fig. 4 B
8MHz in 5B, that is, fM=P*dF.Compare two examples of Fig. 5 B and Fig. 6 B it is recognized that while this
The multipath interference that the actual frequency offset dF of two examples is all equal in 2MHz, but Fig. 6 B can make peak value seat
Scale value fM is changed the 28MHz into Fig. 6 by the 8MHz of Fig. 5 B.In fact, multipath interference can make
The integral multiple of peak value coordinate values fM extra offset symbol frequencies Fs, i.e. fM=P*dF+L*Fs, wherein L
It is an integer.
It is that bias estimation value df is calculated divided by indices P with peak value coordinate values fM in a kind of prior art,
That is df=fM/P.For example, in the example of Fig. 5 B, peak value coordinate values fM=8MHz, directly divided by P=
4 can learn that frequency shift (FS) is 2MHz.But, this kind of prior art cannot correctly be applied to multipath interference；
For example, in the example of Fig. 6 B, peak value coordinate values fM=28MHz is directly drawn divided by P=4
Bias estimation value df can be equal to 28/4=7MHz, it is impossible to correctly reflect real frequency shift (FS) dF=2MHz.
In comparison, the bias estimation module 122 in the counting circuit 114 in example of the present invention can first from peak
The integral multiple (such as { (fM-Fs/2) %Fs+Fs/2 }) of removal symbol frequency Fs in value coordinate values fM, then by
Result divided by indices P, correctly to reflect real frequency shift (FS) dF (step 208).
In another example, bias estimation module 122 can also calculate { fM-Fs*round (fM/Fs) }/d to produce
Bias estimation value df, wherein, function round (r) is closest to the integer of variable r；In other words, round (fM/Fs)
Seek to calculate integral multiple L, to subtract the integral multiple of symbol frequency from peak value coordinate values fM
Fs*round(fM/Fs).For example, in the example of Fig. 6 B, peak value coordinate values fM=28, skew is estimated
Evaluation df can be calculated as { 28-20*round (28/20) }/4={ 28-20*round (1.4) }/4={ 28-20 }/4=
8/4=2.On the other hand, if actual frequency offset dF=-2MHz and thering is multipath to disturb, peak value coordinate values
FM can be located at 12MHz (not illustrating), and bias estimation value df can be calculated as { 12-20*round (12/20) }/4
={ 12-20*round (0.6) }/4={ 12-20 }/4=-8/4=-2.
In another example, bias estimation module 122 can also use periodic function and related inverse function, by peak
The integral multiple in symbol cycle Fs is removed in value coordinate values, for example, can calculate to produce bias estimation value df.
In another example, bias estimation module 122 can also use iterative calculation bias estimation value df.Bias estimation
Whether module 122 can check peak value coordinate values fM in frequency domain (- Fs/2, Fs/2), if so, can be direct
FM/P is calculated to produce bias estimation value df；If peak value coordinate values fM is more than scope (- Fs/2, Fs/2), can
One times of symbol frequency Fs is first subtracted from peak value coordinate values fM to draw the first difference (fM-Fs), and is checked
Whether the first difference (fM-Fs) is in scope (- Fs/2, Fs/2)；If so, can by the first difference (fM-Fs) divided by
Indices P is to produce bias estimation value df, if the first difference (fM-Fs) is still greater than scope (- Fs/2, Fs/2), can
One times of symbol frequency Fs is subtracted again from the first difference (fM-Fs) to draw the second difference (fM-2*Fs), and
Check the second difference (fM-2*Fs) whether in scope (- Fs/2, Fs/2)；If so, can be by the second difference
(fM-2*Fs) divided by indices P to produce bias estimation value df, if the second difference (fM-2*Fs) is still greater than scope
(- Fs/2, Fs/2), can again subtract one times of symbol frequency Fs to draw the 3rd from the second difference (fM-2*Fs)
Difference (fM-3*Fs), by that analogy.
The bias estimation value df that counting circuit 114 is produced can turn into foundation during compensating frequency deviation.Citing and
Speech, can be set a mixer (mixer, not shown) in Fig. 1 front-end circuits 112, and this mixer can be according to
According to the smear of bias estimation value compensating property of df, to offset frequency shift (FS) dF.And/or, receive electricity
Road 110 also (can for example say it is that symbol takes also) in the back segment treatment that signal y (t) is received to fundamental frequency, and compensation is frequently
Rate deviation.
Each functional module 116 to 122 of counting circuit 114 can in fact be done by special hardware circuit, it is also possible to
Realized with logical circuit of arithmetic execution software or firmware by general.For example, frequency domain modular converter 118 can
Being realized by hardware, bias estimation module 122 can be realized by general with logical circuit of arithmetic execution firmware.
Those skilled in the art be note that after described above is read, should have been had the ability with various in this area
Possible technique (including software, firmware, hardware or its combination) realizes the technology of the present invention, is repeated no more in this.
For summary, the present invention is that foundation receives signal of change high order signal, then to the frequency spectrum width of high order signal
Degree searches peak value coordinate values, and multipath can be overcome to disturb the integral multiple additionally introduced in peak value coordinate values to accord with
In first cycle, correctly estimate transmitting terminal and connect with the difference according to peak value coordinate values with integral multiple symbol during all
Frequency shift (FS) between receiving end.
Although the present invention is disclosed as above with preferred embodiment, so it is not limited to the present invention, Ren Heben
Art personnel, without departing from the spirit and scope of the present invention, when a little modification and perfect can be made,
Therefore protection scope of the present invention is when by being defined that claims are defined.
Claims (14)
1. a kind of receiving circuit for estimating frequency shift (FS), comprising：
One front-end circuit, is used to receive the remote signaling that a radiating circuit is transmitted, and produces one to receive according to this
Signal；And
One counting circuit, couples the front-end circuit, comprising：
First power computing module, calculates the power of an index of the reception signal to produce a high order signal,
One frequency domain modular converter, frequency domain conversion is carried out to the high order signal to produce a frequency spectrum；
One peak value search module, searches a peak value of the amplitude of the frequency spectrum, and the hair of the peak value is reflected to produce
One peak value coordinate values of raw frequency；And
One bias estimation module, the peak value coordinate values is added with an offset to produce one and value, by this
With value divided by one first divisor to produce a remainder, the remainder and the offset are subtracted each other to produce a difference,
And by the difference divided by one second divisor to produce a bias estimation value, wherein, the bias estimation value reflection should
Frequency shift (FS) between the local frequency of radiating circuit and the local frequency of the receiving circuit.
2. receiving circuit as claimed in claim 1, it is characterised in that accorded with comprising multiple in the reception signal
Unit, the plurality of symbol has a symbol frequency, and the bias estimation module more should according to the symbol frequency setting
First divisor.
3. receiving circuit as claimed in claim 1, it is characterised in that accorded with comprising multiple in the reception signal
Unit, the plurality of symbol has a symbol frequency, and the bias estimation module more should according to the symbol frequency setting
Offset.
4. receiving circuit as claimed in claim 1, it is characterised in that accorded with comprising multiple in the reception signal
Unit, the plurality of symbol has a symbol frequency, and the bias estimation module is more according to the half of the symbol frequency
Set the offset.
5. receiving circuit as claimed in claim 1, it is characterised in that the bias estimation module was more according to should
Index sets second divisor.
6. receiving circuit as claimed in claim 1, it is characterised in that the bias estimation module more make this
Two divisors are equal to the index.
7. receiving circuit as claimed in claim 1, it is characterised in that the radiating circuit is according to four phase keys
Move (QPSK, quadrature phase shift keying) and modulate the remote signaling, and the power calculates mould
The index is more set as 4 by block.
8. receiving circuit as claimed in claim 1, it is characterised in that the remote signaling includes multiple symbols,
Each symbol is by being selected in multiple constellation points first, each constellation point includes a real part and an imaginary part；And the power
Computing module can more set the index, and the index be set so that the index power of the plurality of constellation point after
Totalling be not equal to zero.
9. a kind of method for estimating frequency shift (FS), is applied to a receiving circuit, comprising：
The remote signaling that one radiating circuit is transmitted is received with the receiving circuit, and produces one to receive letter according to this
Number；
The power of an index of the reception signal is calculated to produce a high order signal；
Frequency domain conversion is carried out to the high order signal to produce a frequency spectrum；
A peak value of the amplitude of the frequency spectrum is searched, to produce a peak value coordinate of the occurrence frequency for reflecting the peak value
Value；
According to the peak value coordinate values and one first divisor integral multiple between difference produce a difference, the difference be situated between
Between a negative lower limit and a positive upper limit, wherein the absolute value of the positive upper limit and the negative lower limit is equal to this and first removes
Several half；And
By the difference divided by one second divisor to produce a bias estimation value, wherein, bias estimation value reflection
Frequency shift (FS) between the local frequency of the radiating circuit and the local frequency of the receiving circuit.
10. method as claimed in claim 9, it is characterised in that comprising multiple symbols in the reception signal,
The plurality of symbol has a symbol frequency, and the method is further included：According to the symbol frequency setting, this first is removed
Number.
11. methods as claimed in claim 9, further include：Second divisor is set according to the index.
12. methods as claimed in claim 9, further include：Second divisor is set to be equal to the index.
13. methods as claimed in claim 9, it is characterised in that the radiating circuit is moved according to four phase keys
The remote signaling is modulated, and the method is further included：The index is set as 4.
14. methods as claimed in claim 9, it is characterised in that the remote signaling includes multiple symbols,
Each symbol is by being selected in multiple constellation points first, each constellation point includes a real part and an imaginary part；And the method
Further include：The judgement for being not equal to zero according to the totalling after the index power of the plurality of constellation point is selected this and is referred to
Number.
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| US20140307767A1 (en) * | 2013-04-16 | 2014-10-16 | Uurmi Systems Private Limited | Methods and Systems for Modulation Classification |
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| CN101420248A (en) * | 2008-12-05 | 2009-04-29 | 北京天碁科技有限公司 | Method and device for frequency bias estimation of TD-SCDMA terminal |
| WO2011063471A1 (en) * | 2009-11-27 | 2011-06-03 | Cohda Wireless Pty Ltd | Extracting parameters from a communications channel |
| CN101895500A (en) * | 2010-07-02 | 2010-11-24 | 浙江大学 | Symbol timing method for resisting frequency deviation and multi-path environment |
| US20140307767A1 (en) * | 2013-04-16 | 2014-10-16 | Uurmi Systems Private Limited | Methods and Systems for Modulation Classification |
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