CN101873283A

CN101873283A - Carrier recovery apparatus and related method thereof

Info

Publication number: CN101873283A
Application number: CN200910135408A
Authority: CN
Inventors: 侯文生; 陈又端; 郭文同
Original assignee: RALINK TECHNOLOGY CORP
Current assignee: RALINK TECHNOLOGY CORP
Priority date: 2009-04-23
Filing date: 2009-04-23
Publication date: 2010-10-27

Abstract

A carrier recovery apparatus and related method. The carrier recovery device is used for a communication receiver and comprises an analog-to-digital converter for converting an analog signal received by the communication receiver into a digital signal; a frequency compensator, coupled to the analog-to-digital converter, for performing frequency compensation on the digital signal according to a carrier frequency offset; a filter, coupled to the frequency compensator, for filtering the digital signal to generate an output signal; and a frequency offset estimator, coupled to the filter and the frequency compensator, for estimating the carrier frequency offset of the output signal according to the output signal and providing the carrier frequency offset to the frequency compensator to achieve carrier recovery.

Description

Carrier resetting device and correlation technique thereof

Technical field

The present invention relates to a kind of carrier resetting device and correlation technique thereof, but relate in particular to a kind of carrier resetting device and correlation technique thereof of fine compensation carrier frequency shift.

Background technology

Bluetooth (Bluetooth) technology is a kind of short-distance wireless communication technology, and it is connected to the basis by near radio cheaply, sets up a radio communication link between fixing or the communication equipment that moves, with the intercommunication data information.Because bluetooth possesses low-power is arranged, low cost, characteristic such as light, thin, short, little, therefore, widely is used in the daily life.

Please refer to Fig. 1, Fig. 1 is the schematic diagram of a known bluetooth basic grouped form 10.As shown in Figure 1, bluetooth basic grouped form 10 includes an access code 102, a header 104 and a packet 106.Access code 102 is used for identification grouping identity, and header 104 is used for data of description type and length, and packet 106 is the data content of actual transmission.(Gaussian Frequency Shift Keying, GFSK) modulate by modulation technique with Gaussian Frequency Shift Keying for early stage Bluetooth technology.At Bluetooth technology 2.0+ enhanced data transfer rate (Enhance Data Rate, EDR) in the standard of version, access code 102 and the header 104 main Gaussian Frequency Shift Keying modulation techniques that adopt, (Differential Phase Shift Keying, DPSK) modulation technique is transmitted and differential phase keying (DPSK) is adopted in packet 106.

Yet; in the wireless communication system; use the signal of the modulation system on carrier wave basis, regular meeting shakes frequency because of this locality of transmission end and receiving terminal and does not match and cause carrier frequency shift (Carrier Frequency Offset) phenomenon, and then influences the receiving terminal reception result.For instance, because carrier frequency shift, may cause signal that receiving terminal receives, and can't correctly recover the signal that transmitted by follow-up filter filtering.Therefore,, must there be a good carrier wave to recover countermeasure, correctly recovers the signal that is transmitted at receiver end.

Summary of the invention

Therefore, of the present inventionly mainly be to provide a kind of carrier resetting device and correlation technique thereof, to address the above problem.

The present invention discloses a kind of carrier resetting device, is used for a communication control processor, includes an analog-to-digital converter, and an analog signal conversion that is used for this communication control processor is received is a digital signal; One frequency compensator is coupled to this analog-to-digital converter, is used for according to a carrier frequency offset this digital signal being carried out frequency compensation; One filter is coupled to this frequency compensator, is used for this digital signal is carried out filtering, to produce an output signal; And a frequency offset estimator, be coupled to this filter and this frequency compensator, be used for according to this output signal, estimate this carrier frequency offset of this output signal, and this carrier frequency offset is provided to this frequency compensator, recover to realize carrier wave.

The present invention discloses a kind of carrier recovering method in addition, is used for a communication control processor, and include: with the analog signal conversion that this communication control processor received is a digital signal; This digital signal is carried out filtering, to produce an output signal; According to this output signal, estimate a carrier frequency offset of this output signal; And, this digital signal is carried out frequency compensation according to this carrier frequency offset, recover to realize carrier wave.

Description of drawings

Fig. 1 is the schematic diagram of a known bluetooth basic grouped form.

Fig. 2 is the schematic diagram of the embodiment of the invention one carrier resetting device.

Fig. 3 is an embodiment schematic diagram of the frequency offset estimator among Fig. 2.

Fig. 4 is another embodiment schematic diagram of the frequency offset estimator among Fig. 2.

Fig. 5 is another embodiment schematic diagram of the frequency offset estimator among Fig. 2.

Fig. 6 is the schematic diagram of the embodiment of the invention one flow process.

[main element symbol description]

20 carrier resetting devices

202 analog-to-digital converters

204 frequency compensators

206 filters

208 frequency offset estimators

302,402,502 signal multiplexers

304,404 Gaussian Frequency Shift Keying discriminators

306,406 preposition frequency offset estimators

308,408 first direct current offset estimators

310,410 first direct currents are to frequency converter

400 direct current trackers

412 direct current arresters

414 polarity discriminating devices

416 second direct current offset estimators

418 second direct currents are to frequency converter

420 accumulators

504 differential phase keying (DPSK) phase decoder

506 preposition phase offset estimator

508 phase tracking devices

510 phase compensators

512 phase offset estimator

514 phase places are to frequency converter

60 flow processs

600、602、604、606、

608,610 steps

Embodiment

Please refer to Fig. 2, Fig. 2 is the schematic diagram of the embodiment of the invention one carrier resetting device 20.Carrier resetting device 20 is used for a wireless communication receiver.In the present embodiment, this wireless communication receiver preferably is a Bluetooth communication receiver, but not as limit.Carrier resetting device 20 is revised the carrier frequency that has been offset, so that wireless communication receiver can come restoring signal with correct carrier wave according to the signal that wireless communication receiver received.Carrier resetting device 20 includes an analog-to-digital converter 202, a frequency compensator 204, a filter 206 and a frequency offset estimator 208.Analog-to-digital converter 202 is used for an analog signal S that the Bluetooth communication receiver is received _ABe converted to a digital signal S _DIn other words, the embodiment of the invention is carried out conversion of signals by analog-to-digital converter 202, so that with the mode of Digital Signal Processing, reach the purpose that carrier frequency is adjusted.Frequency compensator 204 is coupled to analog-to-digital converter 202, is used for according to a carrier frequency offset Δ f _C, to digital signal S _DCarry out frequency compensation.Filter 206 is coupled to frequency compensator 204, is used for to digital signal S _DCarry out filtering, to produce an output signal S _F Frequency offset estimator 208 is coupled to filter 206 and frequency compensator 204, is used for according to output signal S _F, estimated output signal S _FCarrier frequency offset Δ f _C, and with carrier frequency offset Δ f _CProvide to frequency compensator 204, recover to realize carrier wave.In other words, the carrier frequency offset Δ f that calculated of frequency offset estimator 208 _CCan feedback offer frequency compensator 204, with to follow-up digital signal S _DCarry out frequency compensation, and repeat aforementioned program, and then adjust carrier frequency the most accurately, correctly recover transmission signals.

In brief, the embodiment of the invention is to utilize the mode of Digital Signal Processing, calculates carrier frequency offset Δ f _C, with to follow-up digital signal S _DCarry out frequency compensation, reach the purpose that carrier frequency is adjusted, and then correctly recover transmission signals.Thus, the degree that the filtered device of received signal destroys be can reduce, and then the situation of received signal distortion, elevator system usefulness improved.

Further specify, in wireless communication system, if carrier frequency shift takes place, the common signal that transmits via demodulation after, can reflect the phenomenon of direct current offset.Therefore, the present invention can utilize this characteristic, calculates carrier frequency offset Δ f _CPlease refer to Fig. 3, Fig. 3 is an embodiment schematic diagram of the frequency offset estimator 208 among Fig. 2.Frequency offset estimator 208 includes a signal multiplexer 302, a Gaussian Frequency Shift Keying discriminator 304 and a preposition frequency offset estimator 306.Signal multiplexer 302 is coupled to filter 206, is used for according to output signal S _F, select output signal S _FIn a Gaussian frequency shift key modulation signal S _GFSKBecause the signal packets of bluetooth may be with Gaussian Frequency Shift Keying modulation or the modulation of differential phase keying (DPSK) modulation system, therefore, signal multiplexer 302 can be with Gaussian frequency shift key modulation signal S _GFSKPick out, provide to Gauss's frequency shift keying discriminator 304.Gaussian Frequency Shift Keying discriminator 304 is coupled to signal multiplexer 302, is used for Gaussian frequency shift key modulation signal S _GFSKDemodulation is to produce one first restituted signal S _DEM1Preposition frequency offset estimator 306 is used for the first restituted signal S according to a preliminary estimate _DEM1First carrier frequency offset Δ f _C1In the case, preposition frequency offset estimator 306 includes one first direct current offset estimator 308 and one first direct current to frequency converter 310.Wherein the first direct current offset estimator 308 is coupled to Gaussian Frequency Shift Keying discriminator 304, is used for according to the first restituted signal S _DEM1, estimate one first dc offset DC1.First direct current to frequency converter 310 is coupled to the first direct current offset estimator 312, is used for converting the first dc offset DC1 to first carrier frequency offset Δ f _C1, and with first carrier frequency offset Δ f _C1Provide to frequency compensator 204,, realize that carrier wave recovers with the problem of compensating frequency skew.

For the first carrier frequency offset Δ f that prevents that preposition frequency offset estimator 306 is estimated _C1Incorrect and the compensation after possible frequency drift problem, the present invention provides an embodiment of frequency offset estimator 208 in addition, as shown in Figure 4.In Fig. 4, frequency offset estimator 208 includes a signal multiplexer 402, a Gaussian Frequency Shift Keying discriminator 404, one preposition frequency offset estimator 406, one first direct current offset estimator 408, one first direct current to a frequency converter 410 and a direct current tracker 400.In Fig. 3 and Fig. 4, the element cording with same names has similar function mode and function, therefore for asking description for purpose of brevity, describe in detail just and omit at this, and the connection relationship of these elements as shown in Figure 4, do not repeat them here.Direct current tracker 400 is used for estimating the first restituted signal S _DEM1One second carrier frequency offset Δ f _C2, it includes a direct current arrester 412, a polarity discriminating device 414, one second direct current offset estimator 416 and one second direct current to frequency converter 418.When preposition frequency offset estimator 406 provides first carrier frequency offset Δ f _C1Come follow-up digital signal S to frequency compensator 204 _DAfter carrying out frequency compensation.Follow the trail of the direct current offset of follow-up remnants by direct current tracker 400, to revise the carrier shift phenomenon more accurately.Direct current arrester 412 is coupled to Gaussian Frequency Shift Keying discriminator 404, is used for eliminating the first restituted signal S according to the second dc offset DC2 _DEM1Direct current offset.Polarity discriminating device 414 is coupled to direct current arrester 412, is used for judging the first restituted signal S _DEM1A polarization state PS.The second direct current offset estimator 416 is coupled to polarity discriminating device 414, is used for according to polarization state PS, estimates the second dc offset Δ f _C2, with provide second dc offset to direct current arrester 412 and second direct current to frequency converter 418.Second direct current to frequency converter 418 couples this second direct current offset estimator 416, is used for the second dc offset Δ f _C2Convert this second carrier frequency offset Δ f to _C2Be noted that the second direct current offset estimator 416 can be periodically with the second dc offset Δ f _C2Provide to second direct current to frequency converter 418.In addition, frequency offset estimator 208 also includes an accumulator 420, be coupled to first direct current to frequency converter 410 and second direct current to frequency converter 418, first carrier frequency offset Δ f is used for adding up _C1And the second carrier frequency offset Δ f _C2, to produce carrier frequency offset Δ f _C, and provide to frequency compensator 204, carry out the frequency compensation program.

Specifically, please continue with reference to figure 4.With the Bluetooth wireless technology is example, and its packet signal carries access code, header and data usually, if all modulate in the Gaussian Frequency Shift Keying mode.In the case, preposition frequency offset estimator 306 can be at preamble (preamble) the symbol unit of access code or whole or wherein a part of signal (as Barker code (barker codes) part of synchronization character) of synchronization character, calculate direct current offset mean value, to estimate the first dc offset DC1.400 signal symbol units at other of direct current tracker estimate the second dc offset DC2.In other words, preposition frequency offset estimator 306 is earlier to the first restituted signal S _DEM1A certain segment signal calculate its direct current offset mean value, through converting first carrier frequency offset Δ f to _C1, and according to this to the first restituted signal S _DEM1Follow-up signal partly compensate, through the compensation the first restituted signal S _DEM1Estimate the second carrier frequency offset Δ f by direct current tracker 400 again _C2Come frequency of amendment skew more accurately.In addition, first direct current can reach the conversion of frequency with different modes to frequency converter 408 to the frequency converter 310 and second direct current, for instance, can dc offset with respect to the ratio of the reference dc reference (as ± 1 volt) of symbol unit 1 and symbol unit 0, convert to frequency offset and frequency translation amount (as ± 160KHz).Since first direct current to frequency converter 310 and second direct current to frequency converter 408 in order to satisfy the same requirements purpose, in system design, if having identical setting, then can be general mutually.

In the standard of Bluetooth technology 2.0+EDR version, packet mainly adopts the differential phase keying (DPSK) modulation technique to transmit.In order to increase transmission speed, the transmission end can start the EDR pattern, transmits Gaussian frequency shift key modulation signal earlier, sends out the differential phase keying (DPSK) modulation signal immediately.Therefore, at the differential phase keying (DPSK) modulation signal, please refer to Fig. 5, Fig. 5 is another embodiment schematic diagram of the frequency offset estimator 208 among Fig. 2.If generation carrier frequency shift, the common signal that transmits via the differential phase keying (DPSK) demodulation after, the skew of frequency can be transformed into the phenomenon that phase deviation.As shown in Figure 5, frequency offset estimator 208 includes a signal multiplexer 502, a differential phase keying (DPSK) phase decoder 504, one preposition phase offset estimator 506 and a phase tracking device 508.Signal multiplexer 502 couples filter 206, is used for according to output signal S _F, select output signal S _FIn a differential phase keying (DPSK) modulation signal S _DPSKDifferential phase keying (DPSK) phase decoder 504 is coupled to signal multiplexer 502, is used for differential phase keying (DPSK) modulation signal S _DPSKDemodulation is to produce one second restituted signal S _DEM2Preposition phase offset estimator 506 is coupled to differential phase keying (DPSK) phase decoder 504, is used for according to the second restituted signal S _DEM2, estimate the second restituted signal S _DEM2One first phase pushing figure P ₁Wherein, preposition phase offset estimator 506 preferably can a correlator realizes, and according to this second restituted signal S _DEM2A synchronous code in the position when identical correlator be output as peaked characteristic, calculate this first phase pushing figure P ₁ Phase tracking device 508 is used for estimating the second restituted signal S _DEM2One the 3rd carrier frequency offset Δ f _C3, it includes a phase compensator 510, a phase offset estimator 512 and a phase place to frequency converter 514.Phase compensator 510 is earlier according to the first phase pushing figure P ₁After carrying out preliminary phase compensation, again by phase offset estimator 512 feedback one second phase pushing figure P constantly ₂, progressively the phase deviation correction that skew was caused of frequency is returned.Phase compensator 510 is coupled to differential phase keying (DPSK) phase decoder 504 and preposition phase offset estimator 506, is used for according to the first phase carrier side-play amount P ₁And the second phase carrier side-play amount P ₂, to the second restituted signal S _DEM2Carry out phase compensation, to produce the second restituted signal S once phase compensation _DEM2, and produce a phase carrier side-play amount P.Be noted that phase compensator 510 can be periodically with the first phase carrier side-play amount P ₁And the second phase carrier side-play amount P ₂Be summed into phase carrier side-play amount P, and provide to phase place to frequency converter 514.Phase offset estimator 512 is coupled to phase compensator 510 and is used for estimating this second restituted signal S through phase compensation _DEM2The second phase pushing figure P ₂, and provide to phase compensator 510.Phase place to frequency converter 514 is coupled to phase compensator 510, is used for converting phase carrier side-play amount P to the 3rd carrier frequency offset Δ f _C3, carry out frequency compensation for frequency compensator 510, to reach correct reinsertion of carrier frequency.

Frequency offset estimator 208 that it should be noted that Fig. 2 is one embodiment of the invention, and frequency offset estimator 208 also can use other elements and circuit, reaches the purpose of estimating carrier frequency offset.All persons that can be used to measure the carrier frequency offset all should be covered by in the scope that the present invention protects.On the other hand, when adopting the EDR pattern, can be in conjunction with the framework of Fig. 4 and Fig. 5, and integrate each application element thereof, those skilled in the art be when can doing different variations according to this, and are not limited thereto.For instance,

signal multiplexer

302 and 502 can combine, and phase place to frequency converter 514 also can be coupled to accumulator 420, with first carrier frequency offset Δ f _C1, the second carrier frequency offset Δ f _C2And the 3rd carrier frequency offset Δ f _C3Be summed into carrier frequency offset Δ f _CIn addition, because the Energy distribution of the signal after demodulation is concentrated in low frequency part usually, therefore, filter 206 preferably can be realized by a low pass filter, with the noise of filtering HFS.In addition, frequency compensator 204 can a Numerical Control oscillator (Numerical Controlled Oscillator NCO) realizes.According to the estimated frequency offset that goes out, the Numerical Control oscillator can come the frequency of amendment skew by producing sine and cosine waveform.

The function mode of the carrier resetting device 20 of Fig. 2 can further reduce a flow process 60, as shown in Figure 6.Flow process 60 is used for the carrier resetting device 20 of a Bluetooth communication receiver, and it includes following steps:

Step 600: beginning.

Step 602: the analog signal S that analog-to-digital converter 202 is received the Bluetooth communication receiver _ABe converted to digital signal S _D

Step 604: 206 couples of digital signal S of filter _DCarry out filtering, to produce output signal S _F

Step 606: frequency compensator 204 is according to carrier frequency offset Δ f _C, to digital signal S _DCarry out frequency compensation.

Step 608: frequency offset estimator estimated output signal S _FCarrier frequency offset Δ f _C, and with carrier frequency offset Δ f _CThis frequency compensator 204 is provided, recovers to realize carrier wave.

Step 610: finish.

Flow process 60 is in order to the function mode of explanation detection of packets device 20, and detailed description and associated change can not given unnecessary details at this with reference to above stated specification.

In sum, the present invention is according to the signal that communication control processor received, and by going out carrier frequency offset according to a preliminary estimate, and after the compensation according to this, utilizes the tracking and compensating mode again, with the frequency of amendment shift phenomenon.Thus, can be the most accurately with carrier resetting, reducing the degree that the filtered device of received signal destroys, and then improve the situation of received signal distortion, elevator system usefulness.

The above only is the preferred embodiments of the present invention, and all equalizations of doing according to claims of the present invention change and modify, and all should belong to covering scope of the present invention.

Claims

1. A carrier recovery device for a communication receiver, comprising:

an analog-to-digital converter for converting an analog signal received by the communication receiver into a digital signal;

A frequency compensator, coupled to the analog-to-digital converter, is used to perform frequency compensation on the digital signal according to a carrier frequency offset;

a filter, coupled to the frequency compensator, for filtering the digital signal to generate an output signal; and

A frequency offset estimator, coupled to the filter and the frequency compensator, is used to estimate the carrier frequency offset of the output signal according to the output signal, and provide the carrier frequency offset to the frequency compensator for carrier recovery.

2. The carrier recovery device according to claim 1, wherein the frequency offset estimator comprises:

A signal multiplexer, coupled to the filter, is used to select a Gaussian frequency shift keying modulation signal in the output signal according to the output signal;

a Gaussian frequency shift keying discriminator, coupled to the signal multiplexer, used to demodulate the Gaussian frequency shift keying modulated signal to generate a first demodulated signal; and

A pre-frequency offset estimator, used to preliminarily estimate a first carrier frequency offset of the first demodulated signal, comprising:

a first DC offset estimator, coupled to the Gaussian FSK discriminator, for estimating a first DC offset according to the first demodulated signal; and

A first DC-to-frequency converter, coupled to the first DC offset estimator, is used to convert the first DC offset into the first carrier frequency offset.

3. The carrier recovery device as claimed in claim 2, wherein the first DC-to-frequency converter provides the first carrier frequency offset to the frequency compensator to realize carrier recovery.

4. The carrier recovery device as claimed in claim 2, wherein the frequency offset estimator comprises:

a DC canceller, coupled to the Gaussian FSK discriminator, used to eliminate the DC offset of the first demodulated signal according to a second DC offset;

a polarity discriminator, coupled to the DC canceller, for judging a polarity state of the first demodulated signal;

A second DC offset estimator, coupled to the polarity discriminator, used to estimate the second DC offset according to the polarity state, so as to provide the second DC offset to the DC canceller;

A second DC-to-frequency converter, coupled to the second DC offset estimator, is used to convert the second DC offset into a second carrier frequency offset.

5. The carrier recovery device as claimed in claim 4, wherein the frequency offset estimator further comprises an accumulator coupled to the first DC-to-frequency converter and the second DC-to-frequency converter for The first carrier frequency offset and the second carrier frequency offset are accumulated to generate the carrier frequency offset and provided to the frequency compensator.

6. The carrier recovery device as claimed in claim 2, wherein the preamble frequency offset estimator calculates the preceding symbol or the synchronizing word according to a preceding symbol or a synchronizing word of the first demodulated signal The average value of the DC offset is used to estimate the first DC offset.

7. The carrier recovery device according to claim 2, wherein the preamble frequency offset estimator calculates the estimated preamble symbol or the synchronization word according to a preamble symbol or a sync word of the first demodulated signal The average value of the DC offset of at least a part of the word to estimate the first DC offset.

8. The carrier recovery device as claimed in claim 1, wherein the frequency offset estimator comprises:

A signal multiplexer, coupled to the filter, is used to select a differential phase shift keying modulation signal in the output signal according to the output signal;

a differential phase shift keying discriminator, coupled to the signal multiplexer, used to demodulate the differential phase shift keying modulated signal to generate a second demodulated signal; and

a pre-phase offset estimator, coupled to the differential phase shift keying discriminator, for estimating a first phase offset of the second demodulated signal according to the second demodulated signal; and

a phase tracker for estimating a third carrier frequency offset of the second demodulated signal, comprising;

a phase compensator, coupled to the differential phase shift keying discriminator and the pre-phase offset estimator, used for the first phase carrier offset according to the first phase carrier offset and a second phase carrier offset performing phase compensation on the two demodulated signals to generate a phase-compensated second demodulated signal and generate a phase-carrier offset;

a phase offset estimator, coupled to the phase compensator, for estimating the second phase offset of the phase-compensated second demodulated signal, and providing it to the phase compensator; and

A phase-to-frequency converter, coupled to the phase compensator, is used to convert the phase carrier offset into the third carrier frequency offset and provide it to the frequency compensator.

9. The carrier recovery device as claimed in claim 8, wherein the pre-phase offset estimator is a correlator, which is used to calculate the First phase offset.

10. The carrier recovery device as claimed in claim 1, wherein the frequency compensator is a numerically controlled oscillator.

11. The carrier recovery device as claimed in claim 1, wherein the filter is a low-pass filter.

12. A carrier recovery method for a communication receiver, comprising:

converting an analog signal received by the communication receiver into a digital signal;

filtering the digital signal to generate an output signal;

Estimating a carrier frequency offset of the output signal according to the output signal; and

According to the carrier frequency offset, frequency compensation is performed on the digital signal to realize carrier recovery.

13. The carrier recovery method according to claim 12, wherein the step of estimating the carrier frequency offset of the output signal according to the output signal comprises:

selecting a Gaussian frequency shift keying modulation signal in the output signal according to the output signal;

demodulating the Gaussian frequency shift keying modulated signal to generate a first demodulated signal;

Estimating a first DC offset according to the first demodulated signal; and

The first DC offset is converted into a first carrier frequency offset.

14. The carrier recovery method according to claim 13, wherein the step of performing frequency compensation to the digital signal according to the carrier frequency offset is to perform frequency compensation to the digital signal according to the first carrier frequency offset, so as to Implement carrier recovery.

15. The carrier recovery method according to claim 12, wherein the step of estimating the carrier frequency offset of the output signal according to the output signal comprises:

judging a polarity state of the first demodulated signal;

Estimating a second DC offset according to the polarity state;

eliminating the DC offset of the first demodulated signal according to a second DC offset; and

The second DC offset is converted into a second carrier frequency offset.

16. The carrier recovery method according to claim 15, wherein the step of converting the second DC offset into the second carrier frequency offset includes accumulating the first carrier frequency offset and the second The carrier frequency offset is used to generate the carrier frequency offset for frequency compensation.

17. The carrier recovery method as claimed in claim 13, wherein the step of estimating the first DC offset according to the first demodulated signal is based on a preceding symbol or a synchronization of the first demodulated signal word, calculating the average value of the DC offset of the previous symbol or the synchronization word, so as to estimate the first DC offset.

18. The carrier recovery method according to claim 13, wherein the step of estimating the first DC offset according to the first demodulated signal is based on a preamble symbol or a sync word of the first demodulated signal , calculating an average value of the DC offset of at least a part of the previous symbol or the sync word, so as to estimate the first DC offset.

19. The carrier recovery method according to claim 12, wherein the step of estimating the carrier frequency offset of the output signal according to the output signal comprises:

Selecting a differential phase shift keying modulation signal in the output signal according to the output signal;

demodulating the differential phase shift keying modulated signal to generate a second demodulated signal;

Estimating a first phase offset of the second demodulated signal according to the second demodulated signal;

performing phase compensation on the second demodulated signal according to the first phase-carrier offset and a second phase-carrier offset to generate a phase-compensated second demodulated signal;

Estimating the second phase offset according to the phase-compensated second demodulated signal;

generating a phase carrier offset according to the first phase carrier offset and the second phase offset;

The phase carrier offset is converted into a third carrier frequency offset.

20. The carrier recovery method according to claim 19, wherein the step of estimating the first phase offset of the second demodulated signal according to the second demodulated signal is based on a synchronization code of the second demodulated signal The correlation at different time points is used to calculate the first phase offset.