CN104619006A - GSM (global system for mobile communications) network frequency offset correcting algorithm - Google Patents

Abstract

The invention discloses a GSM network frequency offset correcting algorithm and relates to the technical field of wireless communication. The GSM network frequency offset correcting algorithm comprises determining the average value of the phase differences of the two neighboring chips of frequency correction burst (FB) by combining data actually received by a GSM receiver; according to the average value of the phase differences, performing frequency offset correction on synchronous burst (SB) and normal burst (NB). By performing frequency offset correction on the SB and the NB through the average value of the phase differences of the two neighboring chips of the FB, the GSM network frequency offset correcting algorithm can effectively improve the accuracy of data analysis of the GSM receiver.

Description

A kind of algorithm of GSM network frequency offset correction

Technical field

The present invention relates to wireless communication technology field, specifically relate to a kind of algorithm of GSM network frequency offset correction.

Background technology

According to GSM (Global System for Mobile communications, global system for mobile communications) agreement, absolute error as the equipment carrier frequency of receiver must be less than 0.1ppm, be exactly 90HZ. for GSM900 due in actual applications, the crystal oscillator of GSM receiver also can drift about by occurrence frequency in time, so in the process of GSM operation of receiver, estimation must be made to frequency deviation, then frequency offset correction be carried out to the data received. could accurate resolution data.

Gsm protocol comprises NB (Normal Burst, normal burst), FB (Frequencycorrection Burst, frequency correction burst) and SB (Synchronous Burst, synchronization burst), NB and SB includes 156 chips, FB comprises 142 chips, and there is the phase difference of pi/2 in two chips that are connected in FB, at present, it is be FFT (Fast Fourier Transform to the FB data received that common frequency deviation is estimated, fast fourier transform) conversion draw frequency deviation, but the method precision is poor. rough frequency deviation can only be completed and estimate, thus affect the correctness of resolution data.

Summary of the invention

The object of the invention is the deficiency in order to overcome above-mentioned background technology, a kind of algorithm of GSM network frequency offset correction is provided, by the mean value of two the chip phase differences that are connected in FB, frequency offset correction is carried out to SB and NB, effectively can improve the correctness of GSM receiver resolution data.

The invention provides a kind of algorithm of GSM network frequency offset correction, comprise the following steps:

The actual data received of A, combining global mobile communication system GSM receiver, obtain in frequency correction burst FB the mean value of the phase difference of two chips that are connected;

B, according to the mean value of phase difference, frequency offset correction is carried out to synchronization burst SB and normal burst NB.

On the basis of technique scheme, specifically comprise the following steps in steps A:

A1, set frequency deviation value as Δ w, if when the transmitting terminal of base station sends data a within the t time, when not considering noise, the signal that transmitting terminal signal r (t) i.e. GSM receiver receives, r (t)=I (t) cosw _ct-Q (t) sinw _ct, wherein, I (t) is transmitting terminal I road signal, and Q (t) is transmitting terminal Q road signal, w _cfor carrier angular frequencies; The phase modulation of transmitting terminal is φ (t; A), then I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A));

The computational process of I road signal:

$\begin{array}{c}r\left(t\right)\cos (w_{c}t+\mathrm{\Δwt})\\ =(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\cos (w_{c}t+\mathrm{\Δwt})\\ =I\left(t\right)\cos w_{c}t\cos (w_{c}t+\mathrm{\Δwt})-Q\left(t\right)\sin w_{c}t\cos (w_{c}t+\mathrm{\Δwt})\\ =\frac{1}{2}I\left(t\right)\{\cos \left(\mathrm{\Δwt}\right)+\cos (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\sin (2w_{c}t+\mathrm{\Δwt})-\sin \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of I road signal after low pass filter for:

$\hat{I}\left(t\right)=\frac{1}{2}I\left(t\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\sin \left(\mathrm{\Δwt}\right)---\left(1\right)$

The computational process of Q road signal:

$\begin{array}{c}-r\left(t\right)\sin (w_{c}t+\mathrm{\Δwt})\\ =-(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\sin (w_{c}t+\mathrm{\Δwt})\\ =-I\left(t\right)\cos w_{c}t\sin (w_{c}t+\mathrm{\Δwt})+Q\left(t\right)\sin w_{c}t\sin (w_{c}t+\mathrm{\Δwt})\\ =-\frac{1}{2}I\left(t\right)\{\sin \left(\mathrm{\Δwt}\right)+\sin (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\cos (2w_{c}t+\mathrm{\Δwt})-\cos \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of Q road signal after low pass filter for:

$\hat{Q}\left(t\right)=-\frac{1}{2}I\left(t\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\cos \left(\mathrm{\Δwt}\right)---\left(2\right)$

By I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A)), substitute into above-mentioned (1) (2):

$\begin{array}{c}\hat{I}\left(t\right)=\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\sin \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\cos (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array}$

$\begin{array}{c}\hat{Q}\left(t\right)=-\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\sin (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array};$

A2, adopt sampling data to calculate, in FB, the data of 142 chips are expressed as:

$\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

$\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

Wherein n represents the sequence of chip in FB, n=0, and 1 ..., 141; Ts is chip period;

According to the phase value θ of each chip in following formulae discovery FB _n:

$\tan \left({\mathrm{\θ}}_n\right)=\hat{Q}\left(\mathrm{nTs}\right)/\hat{I}\left(\mathrm{nTs}\right)=\tan (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

θ _n＝φ(nTs；a)-ΔwnTs；

According to θ _ncalculate in FB the phase difference θ of two chips that are connected _n, computing formula is:

Δθ _n＝θ _n-θ _n-1

＝φ(nTs；a)-ΔwnTs-(φ((n-1)Ts；a)-Δw(n-1)Ts)

＝φ(nTs；a)-φ((n-1)Ts；a)-ΔwTs

＝π/2-ΔwTs；

According to Δ θ _ncalculate in FB the mean value of two the chip phase differences that are connected with frequency deviation value Δ w, computing formula is:

$\mathrm{\Δ}\stackrel{\‾}{\mathrm{\θ}}=\underset{n-1}{\overset{141}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\θ}}_n/141=\mathrm{\π}/2-\mathrm{\ΔwTs}$

$\mathrm{\Δw}=(\mathrm{\π}/2-\mathrm{\Δ}\stackrel{\‾}{\mathrm{\θ}})/\mathrm{Ts}.$

On the basis of technique scheme, specifically comprise the following steps in step B:

In SB, NB, the data of 156 chips are all expressed as:

$\begin{array}{c}\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))\end{array}$

$\begin{array}{c}\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}(\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))\end{array}$

Wherein n=0,1 ..., 155;

Simultaneous two equations:

$\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)=\hat{I}\left(\mathrm{nTs}\right)$

$\frac{1}{2}(\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))=\hat{Q}\left(\mathrm{nTs}\right)$

The process of synchronization burst SB and normal burst NB being carried out to frequency offset correction is exactly known when, solve the I road signal cos (φ (nTs after frequency offset correction; A)), Q road signal sin (φ (nTs; A) process).

On the basis of technique scheme, the s of Ts=3.7 μ described in steps A 2.

Compared with prior art, advantage of the present invention is as follows:

The present invention obtains in FB the mean value of two the chip phase differences that are connected in conjunction with the actual data received of GSM receiver, and then draw frequency deviation value, then the mean value applying in the FB obtained two the chip phase differences that are connected carries out frequency offset correction to SB and NB, effectively can improve the correctness of GSM receiver resolution data.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in further detail.

The embodiment of the present invention provides a kind of algorithm of GSM network frequency offset correction, comprises the following steps:

The actual data received of A, combining global mobile communication system GSM receiver, obtain in frequency correction burst FB the mean value of the phase difference of two chips that are connected, specifically comprise the following steps:

A1, set frequency deviation value as Δ w, if when the transmitting terminal of base station sends data a within the t time, when not considering noise, the signal that transmitting terminal signal r (t) i.e. GSM receiver receives, r (t)=I (t) cosw _ct-Q (t) sinw _ct, wherein, I (t) is transmitting terminal I road signal, and Q (t) is transmitting terminal Q road signal, w _cfor carrier angular frequencies; The phase modulation of transmitting terminal is φ (t; A), then I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A));

The computational process of I road signal:

$\begin{array}{c}r\left(t\right)\cos (w_{c}t+\mathrm{\Δwt})\\ =(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\cos (w_{c}t+\mathrm{\Δwt})\\ =I\left(t\right)\cos w_{c}t\cos (w_{c}t+\mathrm{\Δwt})-Q\left(t\right)\sin w_{c}t\cos (w_{c}t+\mathrm{\Δwt})\\ =\frac{1}{2}I\left(t\right)\{\cos \left(\mathrm{\Δwt}\right)+\cos (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\sin (2w_{c}t+\mathrm{\Δwt})-\sin \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of I road signal after low pass filter for:

$\hat{I}\left(t\right)=\frac{1}{2}I\left(t\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\sin \left(\mathrm{\Δwt}\right)---\left(1\right)$

The computational process of Q road signal:

$\begin{array}{c}-r\left(t\right)\sin (w_{c}t+\mathrm{\Δwt})\\ =-(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\sin (w_{c}t+\mathrm{\Δwt})\\ =-I\left(t\right)\cos w_{c}t\sin (w_{c}t+\mathrm{\Δwt})+Q\left(t\right)\sin w_{c}t\sin (w_{c}t+\mathrm{\Δwt})\\ =-\frac{1}{2}I\left(t\right)\{\sin \left(\mathrm{\Δwt}\right)+\sin (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\cos (2w_{c}t+\mathrm{\Δwt})-\cos \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of Q road signal after low pass filter for:

$\hat{Q}\left(t\right)=-\frac{1}{2}I\left(t\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\cos \left(\mathrm{\Δwt}\right)---\left(2\right)$

By I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A)), substitute into above-mentioned (1) (2):

$\begin{array}{c}\hat{I}\left(t\right)=\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\sin \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\cos (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array}$

$\begin{array}{c}\hat{Q}\left(t\right)=-\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\sin (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array};$

A2, adopt sampling data to calculate, in FB, the data of 142 chips are expressed as:

$\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

$\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

Wherein n represents the sequence of chip in FB, n=0, and 1 ..., 141; Ts is chip period, Ts=3.7 μ s in the present embodiment;

According to the phase value θ of each chip in following formulae discovery FB _n:

$\tan \left({\mathrm{\θ}}_n\right)=\hat{Q}\left(\mathrm{nTs}\right)/\hat{I}\left(\mathrm{nTs}\right)=\tan (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

θ _n＝φ(nTs；a)-ΔwnTs；

According to θ _ncalculate in FB the phase difference θ of two chips that are connected _n, computing formula is:

Δθ _n＝θ _n-θ _n-1

＝φ(nTs；a)-ΔwnTs-(φ((n-1)Ts；a)-Δw(n-1)Ts)

＝φ(nTs；a)-φ((n-1)Ts；a)-ΔwTs

＝π/2-ΔwTs；

According to Δ θ _ncalculate in FB the mean value of two the chip phase differences that are connected with frequency deviation value Δ w, computing formula is:

$\mathrm{\Δ}\stackrel{\‾}{\mathrm{\θ}}=\underset{n-1}{\overset{141}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\θ}}_n/141=\mathrm{\π}/2-\mathrm{\ΔwTs}$

$\mathrm{\Δw}=(\mathrm{\π}/2-\mathrm{\Δ}\stackrel{\‾}{\mathrm{\θ}})/\mathrm{Ts}.$

B, according to the mean value of phase difference, frequency offset correction is carried out to synchronization burst SB and normal burst NB, specifically comprises the following steps:

In SB, NB, the data of 156 chips are all expressed as:

$\begin{array}{c}\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))\end{array}$

$\begin{array}{c}\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}(\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))\end{array}$

Wherein n=0,1 ..., 155;

Simultaneous two equations:

$\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)=\hat{I}\left(\mathrm{nTs}\right)$

$\frac{1}{2}(\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))=\hat{Q}\left(\mathrm{nTs}\right)$

The process of synchronization burst SB and normal burst NB being carried out to frequency offset correction is exactly known when, solve the I road signal cos (φ (nTs after frequency offset correction; A)), Q road signal sin (φ (nTs; A) process).

Those skilled in the art can carry out various modifications and variations to the embodiment of the present invention, if these amendments and modification are within the scope of the claims in the present invention and equivalent technologies thereof, then these revise and modification also within protection scope of the present invention.

The prior art that the content do not described in detail in specification is known to the skilled person.

Claims (4)

1. an algorithm for GSM network frequency offset correction, is characterized in that, comprises the following steps:

The actual data received of A, combining global mobile communication system GSM receiver, obtain in frequency correction burst FB the mean value of the phase difference of two chips that are connected;

B, according to the mean value of phase difference, frequency offset correction is carried out to synchronization burst SB and normal burst NB.

2. the algorithm of GSM network frequency offset correction as claimed in claim 1, is characterized in that, specifically comprise the following steps in steps A:

A1, set frequency deviation value as Δ w, if when the transmitting terminal of base station sends data a within the t time, when not considering noise, the signal that transmitting terminal signal r (t) i.e. GSM receiver receives, r (t)=I (t) cosw _ct-Q (t) sinw _ct, wherein, I (t) is transmitting terminal I road signal, and Q (t) is transmitting terminal Q road signal, w _cfor carrier angular frequencies; The phase modulation of transmitting terminal is φ (t; A), then I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A));

The computational process of I road signal:

$\begin{array}{c}r\left(t\right)\cos (w_{c}t+\mathrm{\Δwt})\\ =(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\cos (w_{c}t+\mathrm{\Δwt})\\ =I\left(t\right)\cos w_{c}t\sin (w_{c}t+\mathrm{\Δwt})+Q\left(t\right)\sin w_{c}t\sin (w_{c}t+\mathrm{\Δwt})\\ =-\frac{1}{2}I\left(t\right)\{\sin \left(\mathrm{\Δwt}\right)+\sin (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\cos (2w_{c}t+\mathrm{\Δwt})-\cos \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of I road signal after low pass filter for:

$\hat{I}\left(t\right)=\frac{1}{2}I\left(t\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\sin \left(\mathrm{\Δwt}\right)---\left(1\right)$

The computational process of Q road signal:

$\begin{array}{c}-r\left(t\right)\sin (w_{c}t+\mathrm{\Δwt})\\ =-(I\left(t\right)\cos w_{c}t-Q\left(t\right)\sin w_{c}t)\sin (w_{c}t+\mathrm{\Δwt})\\ =-I\left(t\right)\cos w_{c}t\sin (w_{c}t+\mathrm{\Δwt})+Q\left(t\right)\sin w_{c}t\sin (w_{c}t+\mathrm{\Δwt})\\ =-\frac{1}{2}I\left(t\right)\{\sin \left(\mathrm{\Δwt}\right)+\sin (2w_{c}t+\mathrm{\Δwt})\}-\frac{1}{2}Q\left(t\right)\{\cos (2w_{c}t+\mathrm{\Δwt})-\cos \left(\mathrm{\Δwt}\right)\}\end{array}$

The signal of Q road signal after low pass filter for:

$\hat{Q}\left(t\right)=-\frac{1}{2}I\left(t\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}Q\left(t\right)\cos \left(\mathrm{\Δwt}\right)---\left(2\right)$

By I (t)=cos (φ (t; A)), Q (t)=sin (φ (t; A)), substitute into above-mentioned (1) (2):

$\begin{array}{c}\hat{I}\left(t\right)=\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\cos (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array}$

$\begin{array}{c}\hat{Q}\left(t\right)=-\frac{1}{2}\cos \left(\mathrm{\φ}(t;a)\right)\sin \left(\mathrm{\Δwt}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(t;a)\right)\cos \left(\mathrm{\Δwt}\right)\\ =\frac{1}{2}\sin (\mathrm{\φ}(t;a)-\mathrm{\Δwt})\end{array};$

A2, adopt sampling data to calculate, in FB, the data of 142 chips are expressed as:

$\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

$\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

Wherein n represents the sequence of chip in FB, n=0, and 1 ..., 141; Ts is chip period;

According to the phase value θ of each chip in following formulae discovery FB _n:

$\tan \left({\mathrm{\θ}}_n\right)=\hat{Q}\left(\mathrm{nTs}\right)/\hat{I}\left(\mathrm{nTs}\right)=\tan (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})$

θ _n＝φ(nTs；a)-ΔwnTs；

According to θ _ncalculate in FB the phase difference θ of two chips that are connected _n, computing formula is:

Δθ _n＝θ _n-θ _n-1

＝φ(nTs；a)-ΔwnTs-(φ((n-1)Ts；a)-Δw(n-1)Ts)

＝φ(nTs；a)-φ((n-1)Ts；a)-ΔwTs

＝π/2-ΔwTs；

According to Δ θ _ncalculate in FB the mean value of two the chip phase differences that are connected with frequency deviation value Δ w, computing formula is:

$\mathrm{\Δ}\stackrel{\‾}{\mathrm{\θ}}=\underset{n-1}{\overset{141}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\θ}}_n/141=\mathrm{\π}/2-\mathrm{\ΔwTs}$

$\mathrm{\Δw}=(\mathrm{\π}/2-\Δ\stackrel{\‾}{\mathrm{\θ}})/\mathrm{Ts}.$

3. the algorithm of GSM network frequency offset correction as claimed in claim 2, is characterized in that, specifically comprise the following steps in step B:

In SB, NB, the data of 156 chips are all expressed as:

$\begin{array}{c}\hat{I}\left(\mathrm{nTs}\right)=\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\cos (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)\end{array}$

$\begin{array}{c}\hat{Q}\left(\mathrm{nTs}\right)=\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{\ΔwnTs})\\ =\frac{1}{2}\sin (\mathrm{\φ}(\mathrm{nTs};a)-\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\\ =\frac{1}{2}\left(\text{sin}\right(\mathrm{\φ}(\mathrm{nTs};a))\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}})\right)\end{array}$

Wherein n=0,1 ..., 155;

Simultaneous two equations:

$\frac{1}{2}\cos \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))=\hat{I}\left(\text{nTs}\right)$

$\frac{1}{2}(\sin \left(\mathrm{\φ}(\mathrm{nTs};a)\right)\cos \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right)+\frac{1}{2}\cos \mathrm{\φ}(\mathrm{nTs};a))\sin \left(\mathrm{n\Δ}\stackrel{\‾}{\mathrm{\θ}}\right))=\hat{Q}\left(\text{nTs}\right)$

The process of synchronization burst SB and normal burst NB being carried out to frequency offset correction is exactly known when, solve the I road signal cos (φ (nTs after frequency offset correction; A)), Q road signal sin (φ (nTs; A) process).

4. the algorithm of GSM network frequency offset correction as claimed in claim 2 or claim 3, is characterized in that, the s of Ts=3.7 μ described in steps A 2.