CN102118333A - Method and device for canceling DC offsets - Google Patents

Abstract

The embodiment of the invention discloses a method and a device for canceling DC (Direct Current) offsets. The method comprises the following steps: carrying out least-squares DC estimation on input signals, obtaining an estimation value of DC offsets, and obtaining compensation signals of input signals according to the estimation value of the DC offsets; unwinding the compensation signals to obtain first unwinding signals, and unwinding the input signals to obtain second unwinding signals; and comparing an SNR (Signal to Noise Ratio) estimation value of the first unwinding signals with that of the second unwinding signals; and determining the DC offsets and canceling output signals according to comparison results. Compared with the traditional technical scheme for canceling DC offsets, the technical scheme provided by the embodiment of the invention has the following advantages: output signals can be dynamically selected according to the SNR state, so that the suitability to various application scenes can be achieved and the receiving performance can be improved under various application scenes.

Description

A kind of method for eliminating dc bias and device

Technical field

The present invention relates to communication technical field, particularly relate to a kind of method for eliminating dc bias and device.

Background technology

In communication technical field, radio circuit mainly can be divided into three parts according to function, transmitter, receiver, local oscillation circuit.For receiver, mainly comprise types such as superheterodyne receiver, zero intermediate frequency reciver (homodyne receiver) and nearly zero intermediate frequency reciver.Zero intermediate frequency reciver is meant radiofrequency signal is directly become the receiver that centre frequency is zero baseband signal by mixing, the zero intermediate frequency reciver structure is owing to have the chip integration height, required external device is few, cost is low, advantage low in energy consumption, obtained extensive use, for example the radio-frequency transmitter that is adopted in GSM (Global System for Mobile communication, global system for mobile communications) is generally zero intermediate frequency reciver.But, in the course of work of zero intermediate frequency reciver, can worsen received signal at the direct voltage that base band produces, so need eliminate direct current biasing for the accuracy that improves received signal by local oscillator self-mixing and high reject signal self-mixing.

A kind of scheme of prior art is the average direct current removing method of time slot: ask average method to obtain dc-bias to the sampled point of the received signal in the same time slot, eliminate direct current biasing then to received signal.But, the influence of being launched symbol, multipath, noise etc., the determined direct current biasing error of this method is bigger, has a strong impact on the accuracy of received signal.

The another kind of scheme of prior art is LS (Least Square, a least square) direct current method of estimation: channel impulse response and direct current are united estimation, thereby obtain dc-bias according to joint estimate, eliminate direct current biasing then to received signal.But, according to simulation result as can be known, in some scene, for example low SNR (Signal to Noise Ratio, signal to noise ratio) under scene or the HT100 channel, the determined direct current biasing error of this method is bigger, may not improve with respect to the average direct current removing method of time slot, even may cause performance loss.

As seen, under different application scenarioss, existing two kinds of determined direct current biasings of method for eliminating dc bias all may exist than mistake, cause eliminating direct current biasing exactly, thereby influence receptivity.

Summary of the invention

For solving the problems of the technologies described above, the embodiment of the invention provides a kind of method for eliminating dc bias and device, and to improve the receptivity under various application scenarioss, technical scheme is as follows:

A kind of method for eliminating dc bias comprises:

Input signal is carried out the least square direct current estimate, obtain the direct current biasing estimated value,, obtain the compensating signal of described input signal according to described direct current biasing estimated value;

Described compensating signal is untwisted, obtain first de-rotated signal, and described input signal is untwisted, obtain second de-rotated signal;

The signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal are compared, determine direct current biasing elimination output signal according to comparative result.

The embodiment of the invention also provides a kind of direct current biasing cancellation element, comprising:

The direct current biasing determination module is used for that input signal is carried out the least square direct current and estimates, obtains the direct current biasing estimated value;

The compensating signal determination module is used for the direct current biasing estimated value definite according to described direct current biasing determination module, obtains the compensating signal of described input signal;

The module of untwisting is used for described compensating signal is untwisted, and obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

The output signal determination module is used for the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal are compared, and determines direct current biasing elimination output signal according to comparative result.

According to embodiment of the invention scheme, at first input signal is carried out the least square direct current and estimate to be compensated signal; Before the output direct current biasing is eliminated the result, respectively the signal to noise ratio of original input signal that untwists and the compensating signal that untwists is carried out valuation and comparison, then according to comparative result, select a road preferable signal of signal-to-noise ratio (SNR) estimation value to eliminate output signal as final direct current biasing, compare with existing direct current biasing cancellation scheme, the scheme that the embodiment of the invention provided can be according to signal to noise ratio Dynamic Selection output signal, thereby the adaptation plurality of application scenes is improved the receptivity under various application scenarioss.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do simple the introduction to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the flow chart of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 2 is the signal processing mode schematic diagram of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 3 is second kind of flow chart of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 4 is the third flow chart of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 5 is the 4th kind of flow chart of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 6 is second kind of signal processing mode schematic diagram of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 7 is the 5th kind of flow chart of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 8 is the third signal processing mode schematic diagram of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Fig. 9 is the 4th kind of signal processing mode schematic diagram of a kind of method for eliminating dc bias that the embodiment of the invention provided;

Figure 10 is the structural representation of a kind of direct current biasing cancellation element that the embodiment of the invention provided;

Figure 11 is second kind of structural representation of a kind of direct current biasing cancellation element that the embodiment of the invention provided;

Figure 12 is the third structural representation of a kind of direct current biasing cancellation element that the embodiment of the invention provided.

Embodiment

In the prior art, average direct current removing method of time slot and least square direct current method of estimation are two kinds of method for eliminating dc bias, but under some application scenarios, these two kinds of determined direct current biasings of method all may exist than mistake, cause to eliminate direct current biasing exactly, thereby influence receptivity.A kind of method for eliminating dc bias and device that the embodiment of the invention provided can improve the receptivity under various application scenarioss effectively.

At first a kind of method for eliminating dc bias that the embodiment of the invention provided is described, this method comprises:

Input signal is carried out the least square direct current estimate, obtain the direct current biasing estimated value,, obtain the compensating signal of described input signal according to described direct current biasing estimated value;

Described compensating signal is untwisted, obtain first de-rotated signal, and described input signal is untwisted, obtain second de-rotated signal;

The signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal are compared, determine direct current biasing elimination output signal according to comparative result.

According to embodiment of the invention scheme, at first input signal is carried out the least square direct current and estimate to be compensated signal; Before the output direct current biasing is eliminated the result, respectively the signal to noise ratio of original input signal that untwists and the compensating signal that untwists is carried out valuation and comparison, then according to comparative result, select a road preferable signal of signal-to-noise ratio (SNR) estimation value to eliminate output signal as final direct current biasing, compare with existing direct current biasing cancellation scheme, the scheme that the embodiment of the invention provided can be according to signal to noise ratio Dynamic Selection output signal, thereby the adaptation plurality of application scenes is improved the receptivity under various application scenarioss.

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

With reference to Fig. 1, shown in Figure 2, a kind of method for eliminating dc bias that the embodiment of the invention provided can may further comprise the steps:

S101 carries out the least square direct current to input signal and estimates, obtains the direct current biasing estimated value;

In the present embodiment, input signal is carried out can directly carrying out the least square direct current to input signal and estimating before direct current biasing eliminates, thereby obtain the direct current biasing estimated value of input signal correspondence, carry out subsequent treatment.

Wherein, input signal is carried out the least square direct current estimates, as shown in Figure 3, specifically can may further comprise the steps:

S101a modulates blind Detecting to input signal, obtains the modulation type of input signal;

Input signal is modulated the modulation type that blind Detecting can obtain current input signal, for example, for gsm system, can learn that current input signal is through GMSK modulation or 8PSK modulation, in subsequent step, will be according to the input signal of different modulation types, the different training sequence symbols of correspondence when carrying out the estimation of least square direct current.

S101b according to the modulation type of input signal, determines the training sequence symbols of least square direct current estimation function;

Still be that example describes with the gsm system:

If current input signal is then carried out training sequence symbols through the GMSK modulation

Rotation;

If current input signal is then carried out training sequence symbols through the 8PSK modulation

Rotation.

S101c carries out the least square direct current according to determined training sequence symbols to input signal and estimates.

The training sequence symbols difference that the input signal of different modulating type is determined, so after having determined training sequence symbols, the pairing least square direct current of current input signal estimation function can uniquely be determined, and then input signal carried out the least square direct current estimate.

Wherein, the computational process of least square direct current estimation is as follows:

Least square direct current method of estimation is by uniting estimation to channel impulse response and direct current biasing.Wherein, being modeled as of the input signal before that untwists that receives:

$r(61+\frac{L-1}{2}+n)=\underset{k=0}{\overset{L-1}{\mathrm{\Σ}}}{\mathrm{ts}}^{\′}(L-1-k+n)\·h^{\′}\left(k\right)+(d_I+j{d}_Q)+n_0\left(n\right)$

n＝0，1，2......26-L

Wherein, d _I+ jd _QDirect current biasing estimated value d for the I/Q road _I, d _QPlural form; Ts ' is postrotational training sequence symbols (n), and L is a channel impulse response length; H ' is a channel estimating (k); n ₀(n) be noise.

With the matrix notation input signal be:

R＝SH+N

The matrix of training sequence symbols correspondence is:

Channel impulse response and direct current biasing associating matrix are:

$H={\left[\begin{array}{c}{h}^{\′}\left(0\right)\\ h^{\′}\left(1\right)\\ .\\ .\\ .\\ h^{\′}(L-1)\\ (d_I+j{d}_Q)\end{array}\right]}_{(L+1)\×1}$

The corresponding matrix of input signal is:

$R={\left[\begin{array}{c}r(61+\frac{L-1}{2})\\ r(62+\frac{L-1}{2})\\ .\\ .\\ .\\ r(87-L+\frac{L-1}{2})\end{array}\right]}_{(26-L+1)\×1}$

The corresponding matrix of noise is:

$N={\left[\begin{array}{c}{n}_0\left(0\right)\\ n_0\left(1\right)\\ .\\ .\\ .\\ n_0(26-L+1)\end{array}\right]}_{(26-L+1)\×1}$

Therefore, the LS of H separate into:

H＝(S ^HS) ^-1S ^HR

After solving H, can obtain input signal I/Q road direct current biasing estimated value d _I, d _Q

S102 according to described direct current biasing estimated value, obtains the compensating signal of described input signal;

Utilize least square direct current method of estimation, obtain the direct current biasing estimated value d on input signal I/Q road _I, d _QAfter obtaining the direct current biasing estimated value, can directly from input signal, deduct the direct current biasing estimated value, be compensated signal.

In order further to improve the accuracy of compensating signal, can also revise to a certain extent the direct current biasing estimated value:

S102a multiplies each other the direct current biasing estimated value after obtaining gaining with the direct current biasing estimated value with the gain factor a that presets;

S102b deducts the direct current biasing estimated value after the gain from input signal, be compensated signal.

Wherein, the value of gain factor a is near numerical value 1, and it can dynamically obtain according to simulation result, and perhaps rule of thumb value is determined.For different input signals, the value of gain factor a may be different, for example, when the direct current biasing estimated value is bigger than normal with respect to default value, then can choose the gain factor less than 1; And the direct current biasing estimated value then can be chosen the gain factor greater than 1 when less than normal with respect to default value.By using suitable gain factor, can make that the direct current biasing estimated value obtains revising, thereby the compensating signal that order finally obtains is more accurate.

S103 untwists to described compensating signal, obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

After determining compensating signal according to the direct current biasing estimated value, need untwist to compensating signal, obtain first de-rotated signal; Input signal is untwisted, obtain second de-rotated signal.By subsequent step as can be known, first de-rotated signal or second de-rotated signal will be eliminated output signal as direct current biasing.

About the realization of the mode of specifically untwisting, can be referring to the relevant regulations of 3GPP, the embodiment of the invention does not elaborate to this.

S104 compares the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal, determines direct current biasing elimination output signal according to comparative result.

In the present embodiment, the input signal of the compensating signal of separating supination being conciliate supination carries out the contrast of signal to noise ratio, according to comparative result, selects a road preferable signal of signal-to-noise ratio (SNR) estimation value to eliminate output signal as final direct current biasing.Wherein, determine that according to the comparing result of the signal-to-noise ratio (SNR) estimation value of the signal-to-noise ratio (SNR) estimation value of first de-rotated signal and second de-rotated signal direct current biasing eliminates output signal, as shown in Figure 4, can comprise:

S104a carries out signal-to-noise ratio (SNR) estimation to first de-rotated signal and second de-rotated signal respectively, the corresponding first signal-to-noise ratio (SNR) estimation value SNR1 and the second signal-to-noise ratio (SNR) estimation value SNR2 of obtaining;

Wherein, the computational process of signal-to-noise ratio (SNR) estimation is as follows:

The principle of signal-to-noise ratio (SNR) estimation is to subtract each other with the reconstruction received signal with the training sequence part in the received signal to obtain noise signal, thereby obtains noise power.On the other hand, calculate available signal power with channel impulse response.According to available signal power and noise power, obtain the signal to noise ratio of signal.

Noise signal:

$d\left(n\right)=r(61+\frac{L-1}{2}+n)-\underset{k=0}{\overset{L-1}{\mathrm{\Σ}}}\mathrm{ts}(L-1-k+n)\·h\left(k\right)$

n＝0...26-L

Noise power:

${\widehat{\mathrm{\σ}}}_n^2=\frac{1}{26-L+1}\·\underset{n=0}{\overset{26-L}{\mathrm{\Σ}}}{\left|d\left(n\right)\right|}^2$

Available signal power:

$E_{\mathrm{useful}}=\underset{k=0}{\overset{L-1}{\mathrm{\Σ}}}{\left|h\left(k\right)\right|}^2$

The signal-to-noise ratio (SNR) estimation value:

$\mathrm{SNR}=\frac{E_{\mathrm{useful}}}{{\widehat{\mathrm{\σ}}}_n^2}$

Whether S104b judges the first signal-to-noise ratio (SNR) estimation value SNR1 greater than the second signal-to-noise ratio (SNR) estimation value SNR2, if, execution in step S104c then, otherwise, execution in step S104d;

S104c is defined as direct current biasing with first de-rotated signal and eliminates output signal;

S104d is defined as direct current biasing with second de-rotated signal and eliminates output signal.

In conjunction with shown in Figure 2, as the first signal-to-noise ratio (SNR) estimation value SNR1 during less than the second signal-to-noise ratio (SNR) estimation value SNR2, show error that direct current biasing the estimates real direct current biasing of excess input signal, cause signal to noise ratio through the compensating signal of DC compensation with respect to the input signal variation of not passing through DC compensation, should eliminate output signal this moment with not being defined as direct current biasing through second de-rotated signal of the input signal correspondence of DC compensation.Otherwise first de-rotated signal that the signal-to-noise ratio (SNR) estimation value is bigger is defined as direct current biasing and eliminates output signal.

Be understandable that, in S104a, first de-rotated signal and second de-rotated signal carried out signal-to-noise ratio (SNR) estimation, can not have sequencing not.

In the present embodiment, at first input signal is carried out the least square direct current and estimate to be compensated signal; Before the output direct current biasing is eliminated the result, respectively the signal to noise ratio of original input signal that untwists and the compensating signal that untwists is carried out valuation and comparison, then according to comparative result, select a road preferable signal of signal-to-noise ratio (SNR) estimation value to eliminate output signal as final direct current biasing, compare with existing direct current biasing cancellation scheme, the scheme that the embodiment of the invention provided can be according to signal to noise ratio Dynamic Selection output signal, thereby the adaptation plurality of application scenes is improved the receptivity under various application scenarioss.

Among the said method embodiment, directly utilize least square direct current method of estimation to carry out the estimation of direct current biasing to input signal, thereby be compensated signal, carry out follow-up processing.In another embodiment of the present invention, can also be before input signal being carried out the estimation of least square direct current, by certain mode, at first the direct current biasing to input signal carries out a rough estimate, to eliminate of the influence of excessive direct current biasing to dynamic range of signals, referring to shown in Figure 5, the another kind of method for eliminating dc bias that the embodiment of the invention provided can may further comprise the steps:

S201 carries out the average direct current of time slot to input signal and eliminates;

Wherein, the computational process of the average direct current removing method of time slot is as follows:

The average direct current method of estimation of time slot adopts asks average method to obtain the direct current biasing estimated value to the sampled point of the input signal in the same time slot, and formula is as follows:

$\hat{m}=\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}r\left(i\right)$

Wherein, r (i), i=0,1,2......N-1 is the sampled point of the input signal in the same time slot, wherein each symbol can be chosen a sampled point or a plurality of sampled point; N is the sampled point number;

Be the direct current biasing estimated value.

Input signal is carried out the direct current biasing compensation, and formula is as follows:

$\tilde{r}\left(i\right)=r\left(i\right)-\hat{m}$

Be the signal behind the elimination direct current biasing.

S202 carries out the DAGC processing to the signal that carries out after the average direct current of time slot is eliminated.

Carry out DAGC (Digital Auto Gain Control, digital Auto Gain control) and handle eliminating signal behind the excessive direct current biasing;

S203 carries out the least square direct current to the input signal of handling through DAGC and estimates, obtains the direct current biasing estimated value;

S204 obtains the compensating signal of input signal according to the direct current biasing estimated value;

S205 untwists to described compensating signal, obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

S206 compares the signal-to-noise ratio (SNR) estimation value of first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of second de-rotated signal, determines direct current biasing elimination output signal according to comparative result;

Wherein step S203-S206 is identical with the step S101-S104 of the last embodiment of the present invention, no longer describes in detail at this.

Referring to shown in Figure 6, in the present embodiment, eliminate by in advance input signal being carried out the average direct current of time slot, direct current biasing in the input signal is carried out rough estimate to eliminate excessive direct current biasing, carry out DAGC and handle eliminating signal behind the excessive direct current biasing, wherein, the average direct current of time slot is eliminated and can be eliminated the influence of excessive direct current biasing to dynamic range of signals, carrying out signal after DAGC handles will import direct current biasing and eliminate subsystem and do further fine tuning and handle to obtain final direct current biasing elimination output signal, thereby improve the accuracy of compensating signal, further improve the receptivity under various application scenarioss.Wherein, among Fig. 6, the operation principle that direct current biasing is eliminated part can no longer describe in detail here referring to shown in the frame of broken lines part of Fig. 2.

In another embodiment of the present invention, the mode that the least square direct current is estimated and the signal-to-noise ratio (SNR) estimation Dynamic Selection combines by iteration repeatedly realizes that direct current biasing eliminates, and makes the more accurate of direct current biasing elimination, and receptivity is better improved.Referring to shown in Figure 7, a kind of method for eliminating dc bias that present embodiment provided can may further comprise the steps:

S301 carries out the average direct current of time slot to input signal and eliminates;

S302 carries out the DACG processing to the signal that carries out after the average direct current of time slot is eliminated;

S303 carries out the least square direct current to the input signal of handling through DAGC and estimates, obtains the direct current biasing estimated value;

S304 obtains the compensating signal of input signal according to the direct current biasing estimated value;

S305 untwists to described compensating signal, obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

Because the implementation of the step S301-S305 of present embodiment and the step S201-S205 of last embodiment is basic identical, introduces no longer in detail at this.

S306, respectively to first de-rotated signal and the second de-rotated signal signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value SNR1 and the second signal-to-noise ratio (SNR) estimation value SNR2 of obtaining;

S307, judge that whether the first signal-to-noise ratio (SNR) estimation value SNR1 is greater than the second signal-to-noise ratio (SNR) estimation value SNR2, and the current least square direct current that has carried out estimates that whether number of times t is less than default iterations T, if, then with compensating signal as input signal, carry out S303, carry out iterative processing, otherwise, execution in step S308;

In the present embodiment, can for example, can disturb power to determine according to the default iterations T of actual conditions according to interchannel noise.When the least square direct current that carried out was estimated number of times t less than default iterations T, showing also needed to carry out iterative processing, execution in step S303; Otherwise iteration finishes, and directly enters step S308, exports final direct current biasing and eliminates output signal.

In addition, satisfying under the situation of t less than T, if first signal to noise ratio snr 1 is less than second signal to noise ratio snr 2, show that the error of direct current estimation has surpassed the true direct current biasing of signal, cause through the signal to noise ratio of signal after the DC compensation poor on the contrary like this, since direct current biasing eliminate output signal should be signal to noise ratio bigger a road, so this moment should finishing iteration, second de-rotated signal that signal to noise ratio is higher directly is defined as the direct current biasing erasure signal.

In sum, when t equaled T or SNR1 less than SNR2, iteration finished, and this moment is execution in step S308 directly, export final direct current biasing elimination output signal; And when t satisfied greater than these two conditions of SNR2 simultaneously less than T and SNR1, as input signal, execution in step S303 carried out next iteration and handles with the compensating signal that do not untwist.

S308 determines that according to the signal-to-noise ratio (SNR) estimation result of this iterative processing direct current biasing eliminates output signal.If the first signal-to-noise ratio (SNR) estimation value SNR1, then is defined as first de-rotated signal direct current biasing greater than the second signal-to-noise ratio (SNR) estimation value SNR2 and eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

Referring to Fig. 8 and shown in Figure 9, in the present embodiment,, input signal is carried out the elimination of direct current biasing by the mode that the least square direct current is estimated and the signal-to-noise ratio (SNR) estimation Dynamic Selection combines of iteration repeatedly.Iterative processing repeatedly makes more accurate to the elimination of direct current biasing, and receptivity is better improved.

Be understandable that when iterations T=1, be equivalent to only carry out an iterative processing, this situation promptly is equivalent to the pairing scheme of an embodiment in the present invention.

In addition, in another embodiment of the invention, can the direct current biasing in the input signal not carried out rough estimate yet, promptly only implement above-mentioned steps S303-S308 the least square direct current that input signal carries out is repeatedly eliminated iterative processing.

Description by above method embodiment, the those skilled in the art can be well understood to the present invention and can realize by the mode that software adds essential general hardware platform, can certainly pass through hardware, but the former is better execution mode under a lot of situation.Based on such understanding, the part that technical scheme of the present invention contributes to prior art in essence in other words can embody with the form of software product, this computer software product is stored in the storage medium, comprise that some instructions are with so that a computer equipment (can be a personal computer, server, the perhaps network equipment etc.) carry out all or part of step of the described method of each embodiment of the present invention.And aforesaid storage medium comprises: various media that can be program code stored such as read-only memory (ROM), random-access memory (ram), magnetic disc or CD.

Corresponding to top method embodiment, the embodiment of the invention also provides a kind of direct current biasing cancellation element, and as shown in figure 10, this device comprises:

Direct current biasing determination module 110 is used for that input signal is carried out the least square direct current and estimates, obtains the direct current biasing estimated value;

Compensating signal determination module 120 is used for the direct current biasing estimated value determined according to described direct current biasing determination module 110, obtains the compensating signal of described input signal;

The module 130 of untwisting is used for described compensating signal is untwisted, and obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

Output signal determination module 140 is used for the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal are compared, and determines direct current biasing elimination output signal according to comparative result.

As shown in figure 11, wherein, direct current biasing determination module 110 can comprise:

Modulation blind Detecting unit 111 is used for described input signal is modulated blind Detecting, obtains the modulation type of described input signal;

Training sequence determining unit 112 is used for determining the training sequence symbols of least square direct current estimation function according to the definite modulation type in modulation blind Detecting unit;

Direct current biasing obtains unit 113, according to the determined training sequence symbols of training sequence determining unit input signal is carried out the least square direct current and estimates, obtains the direct current biasing estimated value.

As shown in figure 12, wherein, output signal determination module 140 can comprise:

Signal-to-noise ratio (SNR) estimation unit 141 is used for respectively first de-rotated signal and second de-rotated signal being carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

Output signal determining unit 142, be used for the first signal-to-noise ratio (SNR) estimation value greater than the second signal-to-noise ratio (SNR) estimation value situation under, first de-rotated signal is defined as direct current biasing eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

In another embodiment of the present invention, can also be before input signal being carried out the estimation of least square direct current, by certain mode, at first the direct current biasing to input signal carries out a rough estimate, to eliminate of the influence of excessive direct current biasing to dynamic range of signals, accordingly, this device can also comprise average direct current cancellation module of time slot and gain process module:

The average direct current cancellation module of time slot is used for that described input signal is carried out the average direct current of time slot and eliminates;

The gain process module is used for the signal that the average direct current cancellation module of time slot is determined is carried out the digital Auto Gain control and treatment, and exports result to described direct current biasing determination module 110.

In another embodiment of the present invention, more accurate for what direct current biasing was eliminated, receptivity is better improved, can be by repeatedly the least square direct current estimation of iteration and the mode that the signal-to-noise ratio (SNR) estimation Dynamic Selection combines realize the direct current biasing elimination, the output signal determination module 140 so, can comprise:

The signal-to-noise ratio (SNR) estimation unit is used for respectively first de-rotated signal and second de-rotated signal being carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

The output signal determining unit, be used for estimating under the situation of number of times less than default iterations greater than the second signal-to-noise ratio (SNR) estimation value and the current least square direct current that has carried out in the first signal-to-noise ratio (SNR) estimation value, compensating signal as input signal input direct current biasing determination module 110, is carried out iterative processing; Otherwise

Signal-to-noise ratio (SNR) estimation result according to this iterative processing determines direct current biasing elimination output signal:

If the first signal-to-noise ratio (SNR) estimation value, then is defined as first de-rotated signal direct current biasing greater than the second signal-to-noise ratio (SNR) estimation value and eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

In order further to improve the accuracy of compensating signal, can also revise to a certain extent the direct current biasing estimated value, so, described compensating signal determination module 120 can comprise:

Gain unit is used for direct current biasing estimated value that described direct current biasing determination module is determined and the gain factor of presetting and multiplies each other the direct current biasing estimated value after obtaining gaining;

The compensating signal determining unit is used for deducting the direct current biasing estimated value that described gain unit is determined from input signal, obtains compensating signal.

For device embodiment, because it is substantially corresponding to method embodiment, so relevant part gets final product referring to the part explanation of method embodiment.Device embodiment described above only is schematic, wherein said unit as the separating component explanation can or can not be physically to separate also, the parts that show as the unit can be or can not be physical locations also, promptly can be positioned at a place, perhaps also can be distributed on a plurality of network element.Can select wherein some or all of module to realize the purpose of present embodiment scheme according to the actual needs.Those of ordinary skills promptly can understand and implement under the situation of not paying creative work.

In several embodiment provided by the present invention, should be understood that disclosed apparatus and method not surpassing in the application's the spirit and scope, can realize in other way.Current embodiment is a kind of exemplary example, should be as restriction, and given particular content should in no way limit the application's purpose.For example, the division of described unit or subelement only is that a kind of logic function is divided, and during actual the realization other dividing mode can be arranged, and for example a plurality of unit or a plurality of subelement combine.In addition, a plurality of unit can or assembly can in conjunction with or can be integrated into another system, or some features can ignore, or do not carry out.

In addition, the schematic diagram of institute's tracing device and method and different embodiment, in the scope that does not exceed the application, can with other system, module, technology or method in conjunction with or integrated.Another point, the shown or coupling each other discussed or directly to be coupled or to communicate to connect can be by some interfaces, the indirect coupling of device or unit or communicate to connect can be electrically, machinery or other form.

The above only is the specific embodiment of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (12)

1. a method for eliminating dc bias is characterized in that, comprising:

Steps A is carried out the least square direct current to input signal and is estimated, obtains the direct current biasing estimated value, according to described direct current biasing estimated value, obtains the compensating signal of described input signal;

Step B untwists to described compensating signal, obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

Step C compares the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal, determines direct current biasing elimination output signal according to comparative result.

2. method according to claim 1 is characterized in that, before input signal being carried out the estimation of least square direct current, also comprises:

Input signal is carried out the average direct current of time slot to be eliminated;

The signal that carries out after the average direct current of time slot is eliminated is carried out the digital Auto Gain control and treatment.

3. method according to claim 1 and 2 is characterized in that, describedly input signal is carried out the least square direct current estimates, comprising:

Described input signal is modulated blind Detecting, obtain the modulation type of described input signal;

According to the modulation type of described input signal, determine the training sequence symbols of least square direct current estimation function;

According to determined training sequence symbols input signal being carried out the least square direct current estimates.

4. method according to claim 1 is characterized in that, described the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal is compared, and determines that according to comparative result direct current biasing eliminates output signal, comprising:

Respectively first de-rotated signal and second de-rotated signal are carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

If the first signal-to-noise ratio (SNR) estimation value, then is defined as first de-rotated signal direct current biasing greater than the second signal-to-noise ratio (SNR) estimation value and eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

5. method according to claim 1 is characterized in that, described the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal is compared, and determines that according to comparative result direct current biasing eliminates output signal, comprising:

Respectively first de-rotated signal and second de-rotated signal are carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

Estimate that greater than the second signal-to-noise ratio (SNR) estimation value and the current least square direct current that has carried out as input signal, repeated execution of steps A-step C carries out iterative processing with compensating signal under the situation of number of times less than default iterations in the first signal-to-noise ratio (SNR) estimation value; Otherwise

Signal-to-noise ratio (SNR) estimation result according to this iterative processing determines direct current biasing elimination output signal:

If the first signal-to-noise ratio (SNR) estimation value, then is defined as first de-rotated signal direct current biasing greater than the second signal-to-noise ratio (SNR) estimation value and eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

6. method according to claim 1 is characterized in that, and is described according to described direct current biasing estimated value, obtains the compensating signal of described input signal, comprising:

Direct current biasing estimated value and the gain factor of presetting are multiplied each other the direct current biasing estimated value after obtaining gaining;

From input signal, deduct the direct current biasing estimated value after the gain, obtain compensating signal.

7. a direct current biasing cancellation element is characterized in that, comprising:

The direct current biasing determination module is used for that input signal is carried out the least square direct current and estimates, obtains the direct current biasing estimated value;

The compensating signal determination module is used for the direct current biasing estimated value definite according to described direct current biasing determination module, obtains the compensating signal of described input signal;

The module of untwisting is used for described compensating signal is untwisted, and obtains first de-rotated signal, and described input signal is untwisted, and obtains second de-rotated signal;

The output signal determination module is used for the signal-to-noise ratio (SNR) estimation value of described first de-rotated signal and the signal-to-noise ratio (SNR) estimation value of described second de-rotated signal are compared, and determines direct current biasing elimination output signal according to comparative result.

8. device according to claim 7 is characterized in that, also comprises: average direct current cancellation module of time slot and gain process module:

The average direct current cancellation module of time slot is used for that described input signal is carried out the average direct current of time slot and eliminates;

The gain process module is used for the signal that the average direct current cancellation module of time slot is determined is carried out the digital Auto Gain control and treatment, and exports result to described direct current biasing determination module.

9. according to claim 7 or 8 described devices, it is characterized in that described direct current biasing determination module comprises:

Modulation blind Detecting unit is used for described input signal is modulated blind Detecting, obtains the modulation type of described input signal;

The training sequence determining unit is used for determining the training sequence symbols of least square direct current estimation function according to the definite modulation type in modulation blind Detecting unit;

Direct current biasing obtains the unit, according to the determined training sequence symbols of training sequence determining unit input signal is carried out the least square direct current and estimates, obtains the direct current biasing estimated value.

10. device according to claim 7 is characterized in that, the output signal determination module comprises:

The signal-to-noise ratio (SNR) estimation unit is used for respectively first de-rotated signal and second de-rotated signal being carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

The output signal determining unit, be used for the first signal-to-noise ratio (SNR) estimation value greater than the second signal-to-noise ratio (SNR) estimation value situation under, first de-rotated signal is defined as direct current biasing eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

11. device according to claim 7 is characterized in that, the output signal determination module comprises:

The signal-to-noise ratio (SNR) estimation unit is used for respectively first de-rotated signal and second de-rotated signal being carried out signal-to-noise ratio (SNR) estimation, the corresponding first signal-to-noise ratio (SNR) estimation value and the second signal-to-noise ratio (SNR) estimation value of obtaining;

The output signal determining unit, be used for estimating under the situation of number of times less than default iterations greater than the second signal-to-noise ratio (SNR) estimation value and the current least square direct current that has carried out in the first signal-to-noise ratio (SNR) estimation value, compensating signal as input signal input direct current biasing determination module, is carried out iterative processing; Otherwise

Signal-to-noise ratio (SNR) estimation result according to this iterative processing determines direct current biasing elimination output signal:

If the first signal-to-noise ratio (SNR) estimation value, then is defined as first de-rotated signal direct current biasing greater than the second signal-to-noise ratio (SNR) estimation value and eliminates output signal; Otherwise, second de-rotated signal is defined as direct current biasing eliminates output signal.

12. device according to claim 7 is characterized in that, described compensating signal determination module comprises:

Gain unit is used for direct current biasing estimated value that described direct current biasing determination module is determined and the gain factor of presetting and multiplies each other the direct current biasing estimated value after obtaining gaining;

The compensating signal determining unit is used for deducting the direct current biasing estimated value that described gain unit is determined from input signal, obtains compensating signal.

Images