CN104639485B - carrier frequency offset correction method and carrier frequency offset correction system - Google Patents
carrier frequency offset correction method and carrier frequency offset correction system Download PDFInfo
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Abstract
一种载波频率偏移校正方法与载波频率偏移校正系统，适于校正具有主载波与副载波的传输信号的载波频率偏移。载波频率偏移校正方法包括依据已知主载波频率、已知副载波频率、主反馈信号以及副反馈信号，分别对传输信号进行频率解析，以取得主载波偏移值与副载波偏移值。依据主载波偏移值、副载波偏移值之间的关系而决定是否调整主反馈信号与副反馈信号。
A carrier frequency offset correction method and a carrier frequency offset correction system are suitable for correcting the carrier frequency offset of a transmission signal having a main carrier and a subcarrier. The carrier frequency offset correction method includes performing frequency analysis on the transmission signal according to a known main carrier frequency, a known subcarrier frequency, a main feedback signal, and a sub-feedback signal to obtain a main carrier offset value and a subcarrier offset value. Whether to adjust the main feedback signal and the sub-feedback signal is determined according to the relationship between the main carrier offset value and the subcarrier offset value.
Description
Technical field
The present invention relates to a kind of communication devices, and especially with regard to a kind of offset correction of carrier frequency method and carrier frequency
Rate offset correction examining system.
Background technique
Stereo (A2Stereo) system of A2 is a kind of number for being used for radio and television (Broadcast Television)
Audio transmission system.In details of the words, in order to meet the not user of cognation or be to provide stereosonic service, many TVs
Program transmission when, can take at the same transmit the form (i.e. the form of main audio channel signal and sub-channel signal) of two groups of signals for
User's selection.Also that is, other than the main carrier of carrying main sound channel audio, the subcarrier for carrying secondary channel audio can be also provided,
To realize two-channel system;Or it is to provide for stereosonic service, after the audio mix of two sound channels of left and right, respectively by main load
Wave and subcarrier transmit.In general, the frequency of main carrier and subcarrier is to be separated from each other on frequency spectrum.When receiving terminal circuit connects
When receiving transmission signal, receiving terminal circuit can obtain respectively main audio channel signal and sub-channel signal according to known carrier frequency,
And it is demodulated respectively, to obtain the audio signal of main sound channel and the audio signal of secondary sound channel;Or by main carrier with
Subcarrier demodulation, and again after audio mixing, obtain the stereo audio of L channel and right channel two-way.
However, by environmental factor when either being transmitted based on the difference (difference between transmission end and receiving end) in system
It influences, there may be offsets for the carrier frequency of transmission signal received by receiving terminal circuit, and further cause main sound channel
Signal and sub-channel signal generate mistake in demodulation.Figure 1A~1B is a kind of schematic diagram of carrier frequency shift.Please refer to figure
1A and Figure 1B transmits terminal circuit main audio channel signal S sent out0With sub-channel signal S1Carrier frequency (centre frequency) point
It Wei not carrier frequency fc0And carrier frequency fc1, but after these signals are transmitted to receiving terminal circuit, may as shown in Figure 1B,
Its main carrier and the raw carrier frequency shift of subcarrier sending and receiving, and make the main audio channel signal S in receiving end0’With sub-channel signal
S1’Carrier frequency (centre frequency) change to fc0’And fc1’。
In order to avoid the aforementioned possible carrier frequency shift occurred influences the demodulation to transmission signal S, it is known that technology often makes
Offset correction of carrier frequency is carried out with the mode of feedback.Fig. 2 be known technology in common offset correction of carrier frequency system 100
Schematic diagram.Referring to figure 2. and by taking the carrier frequency shift of Figure 1A and 1B as an example, offset correction of carrier frequency system 100 includes
Standard detectors (standard detector) 120, demodulating equipment 140 and demodulating equipment 160.Work as offset correction of carrier frequency
After system 100 receives transmission signal S, transmission signal S is detected by standard detectors 120 and belongs to any communications protocol, then will
(standard carrier frequency, such as its centre frequency are f for the known main carrier frequency of affiliated communications protocol and known subcarrier frequencyc0
And fc1) it is provided to demodulating equipment 140 and demodulating equipment 160 respectively, and demodulating equipment 140 connects more respectively with demodulating equipment 160
Receive transmission signal S.
Demodulating equipment 140 is according to known main carrier frequency (centre frequency fc0), pass through mixer (mixer) 142, low pass filtered
Wave device (low pass filter) 144 and carrier offset calculator (carrier offset calculator) 148 calculate real
Border main audio channel signal S0’Main carrier frequency fc0’And the known main carrier frequency f of main sound channelc0Between difference as main load
Wave deviant f0 nos, as shown in Figure 1B.Then, main carrier deviant f0 nosAgain the mixer 142 of demodulating equipment 140 is fed back to
To carry out carrier frequency correction to transmission signal S, then pass through low-pass filter 144, FM signal demodulator (FM
Demodulator) 146 demodulation is completed, correctly to obtain main audio channel signal S0’(centre carrier frequency fc0’).Demodulating equipment
160 equally in a similar manner, according to known subcarrier frequency (centre frequency fc1), pass through mixer 162, low-pass filter
164 calculate practical sub-channel signal S with carrier offset calculator 1681’Subcarrier frequency fc1’And the known secondary load of secondary sound channel
Wave frequency rate fc1Between difference as subcarrier offset value f1 nos, as shown in Figure 1B.Thereafter, subcarrier offset value f1 nosAgain anti-
The mixer 162 of demodulating equipment 160 is fed to complete the demodulation of transmission signal S, and then correctly obtains sub-channel signal S1’It (carries
Wave centre frequency is fc1’)。
In offset correction of carrier frequency system 100 provided by Fig. 2, demodulating equipment 140 and demodulating equipment 160 are independently
Ground carries out offset correction of carrier frequency and demodulation to transmission signal S.However, offset correction of carrier frequency system 100 can not fit
For solving all carrier frequency shift situations.The schematic diagram for the carrier frequency shift that Fig. 1 C~1D is two kinds.Please refer to figure
1A and 1C, if the received sub-channel signal S of receiving terminal circuit institute1’Than receiving terminal circuit institute on frequency spectrum due to carrier frequency shift
Received main audio channel signal S0’The main audio channel signal S that more close transmission terminal circuit is exported0, then have very much can for demodulating equipment 140
It can be corrected because of carrier frequency, and by sub-channel signal S1’It is identified as main audio channel signal S0And demodulated, so that main audio channel signal
S0’On audio signal thus lose.
On the contrary, Figure 1A and 1D are please referred to, if the received main audio channel signal S of receiving terminal circuit institute0’Because of carrier frequency shift
And it is sub-channel signal S more received than receiving terminal circuit institute on frequency spectrum1’The secondary sound channel letter that more close transmission terminal circuit is exported
Number S1, then demodulating equipment 160 probably demodulation when, by main audio channel signal S0’It is identified as sub-channel signal S1And it is solved
It adjusts, so that sub-channel signal S1’On audio signal thus lose.Therefore, how more accurate carrier frequency shift school is provided
Correction method and system, to ensure the received main audio channel signal S of receiving terminal circuit institute0’With sub-channel signal S1’On audio signal
Will not all be lost in demodulating process due to carrier frequency shift, be still many those skilled in the art effort target it
One.
Summary of the invention
The present invention provides a kind of offset correction of carrier frequency method, can compare main carrier and subcarrier in transmission signal
Carrier frequency shift situation, with correctly to transmission signal carry out carrier frequency correction process.
The present invention provides a kind of offset correction of carrier frequency system, has carrier shift coordinator to compare in transmission signal
Main carrier and subcarrier carrier frequency shift situation, and export corresponding feedback signal to main demodulating equipment and secondary demodulation and fill
It sets, and then carrier frequency correction process correctly is carried out to transmission signal.
Offset correction of carrier frequency method described in the embodiment of the present invention is suitable for being used for offset correction of carrier frequency system
System, to correct the carrier frequency shift of the transmission signal with main carrier and subcarrier.Offset correction of carrier frequency method includes
According to known main carrier frequency, known subcarrier frequency, primary feedback signal and secondary feedback signal, transmission signal is carried out respectively
Frequency resolution, to obtain main carrier deviant and subcarrier offset value.According between main carrier deviant, subcarrier offset value
Relationship and decide whether to adjust primary feedback signal and secondary feedback signal.
Offset correction of carrier frequency system described in the embodiment of the present invention is adapted to correct for having main carrier and subcarrier
Transmit the carrier frequency shift of signal.Offset correction of carrier frequency system includes standard detectors, main demodulating equipment, secondary demodulation dress
It sets and carrier shift coordinator.Standard detectors are for providing known main carrier frequency and known subcarrier frequency.Principal solution tune
Device and secondary demodulating equipment are coupled to standard detectors, according to known carrier frequency, known subcarrier frequency, primary feedback signal with
And secondary feedback signal, frequency resolution is carried out to transmission signal respectively, to obtain main carrier deviant and subcarrier offset value.Carrier wave
Offset coordinator is coupled to main demodulating equipment and secondary demodulating equipment, receives main carrier deviant and subcarrier offset value, and according to
Relationship between main carrier deviant, subcarrier offset value and decide whether to adjust primary feedback signal and secondary feedback signal.
Based on offset correction of carrier frequency method and offset correction of carrier frequency above-mentioned, that the embodiment of the present invention is proposed
System, by calculating the carrier frequency shift of transmission signal to obtain main carrier deviant and subcarrier offset value, and foundation
Relationship between main carrier deviant and subcarrier offset value carries out carrier frequency correction process to transmission signal.In other words, main
Carrier offset values and subcarrier offset value can be simultaneously as the foundations for carrying out carrier frequency correction process to transmission signal, with accurate
Ground executes carrier frequency correction.The offset correction of carrier frequency method and carrier frequency that other embodiments of the invention are proposed
Offset correction system also utilizes the multiple parameters of transmission signal, such as carrier power, mode indicators number and signal-to-noise ratio conduct
Foundation, to accurately carry out carrier frequency correction process.
To make the foregoing features and advantages of the present invention clearer and more comprehensible, special embodiment below, and cooperate institute's accompanying drawings
It is described in detail below.
Detailed description of the invention
Figure 1A~1G is the schematic diagram of carrier frequency shift.
Fig. 2 be known technology in common offset correction of carrier frequency system schematic diagram.
Fig. 3 is the schematic diagram of offset correction of carrier frequency system depicted in an embodiment according to the present invention.
Fig. 4 is the flow chart of offset correction of carrier frequency method depicted in an embodiment according to the present invention.
Fig. 5 is the detail flowchart of offset correction of carrier frequency method depicted in another embodiment according to the present invention.
Fig. 6 is the schematic diagram of offset correction of carrier frequency system depicted in another embodiment according to the present invention.
Fig. 7 A~7B is the detailed process of offset correction of carrier frequency method depicted in another embodiment according to the present invention
Figure.
Fig. 8 is the schematic diagram of offset correction of carrier frequency system depicted in another embodiment according to the present invention.
Fig. 9 A~9B is the detailed process of offset correction of carrier frequency method depicted in another embodiment according to the present invention
Figure.
Figure 10 A~10B is the detailed stream of offset correction of carrier frequency method depicted in another embodiment according to the present invention
Cheng Tu.
Figure 11 is the schematic diagram of offset correction of carrier frequency system depicted in another embodiment according to the present invention.
Figure 12 A~12B is the detailed stream of offset correction of carrier frequency method depicted in another embodiment according to the present invention
Cheng Tu.
[label declaration]
S0、S0’: main audio channel signal S1、S1’: sub-channel signal
S: transmission signal flag: flag value
fc0、fc1: centre frequency f0 nos、f0 os: main carrier deviant
f1 nos、f1 os: subcarrier offset value f0 fb: primary feedback signal
f1 fb: secondary feedback signal f0 tos: test main carrier deviant
f1 tos: test subcarrier offset value fth: frequency shift (FS) threshold value
P0、P1: carrier power
100,200,500,700,1000: offset correction of carrier frequency system
120,220,520,720,1020: standard detectors
140,160: demodulating equipment
240,540,740,1040: main demodulating equipment
545,745: main power calculator 1047: main carrier mass detector
260,560,760,1060: secondary demodulating equipment
565,765: secondary power calculator 1067: subcarrier mass detector
767: mode detector
142,162,242,262,542,562,742,762,1042,1062: mixer
144,164,244,264,544,564,744,764,1044,1064: low-pass filter
146,166,246,266,546,566,746,766,1046,1066: FM signal demodulator
148,168,248,268,548,568,748,768,1048,1068: carrier offset calculator
280,580,780,1080: carrier shift coordinator
S320~S348, S620~654, S820~S856, S920~S956, S1120~S1152: carrier frequency shift
The step of bearing calibration
Specific embodiment
Offset correction of carrier frequency method provided by the present invention and offset correction of carrier frequency system, in receiving end
Offset correction of carrier frequency is carried out to received signal.It is compared particularly in using the signal interaction on different frequency bands, and
And offset correction of carrier frequency is carried out by way of coordination.
Fig. 3 is the schematic diagram of offset correction of carrier frequency system 200 depicted in an embodiment according to the present invention.Carrier frequency
Rate offset correction system 200 includes standard detectors 220, main demodulating equipment 240, secondary demodulating equipment 260 and carrier shift association
Adjust device 280.Fig. 4 is the flow chart of offset correction of carrier frequency method depicted in an embodiment according to the present invention.Referring to figure 3.
With Fig. 4, offset correction of carrier frequency method includes the following steps.In step S320, main demodulating equipment 240 and secondary demodulating equipment
260 according to known main carrier frequency and known subcarrier frequency (centre frequency fc0And fc1, provided by standard detectors 220),
Primary feedback signal f0 fbAnd secondary feedback signal f1 fb, respectively by mixer 242,262, low-pass filter 244,264 and carry
248,268 couples of transmission signal S of wave drift computer carry out frequency resolution, to obtain main carrier deviant f0 osWith subcarrier offset
Value f1 os.Main demodulating equipment 240 is coupled to standard detectors 220 with secondary demodulating equipment 260 to receive known main carrier frequency respectively
With known subcarrier frequency (centre frequency fc0And fc1), and the device in main demodulating equipment 240 and secondary demodulating equipment 260
Can be as demodulating equipment 140 and demodulating equipment 160 in Fig. 2, therefore details are not described herein.280 coupling of carrier shift coordinator
It is connected to main demodulating equipment 240 and secondary demodulating equipment 260, and receives main carrier deviant f0 osWith subcarrier offset value f1 os.Yu Bu
In rapid S340, carrier shift coordinator 280 is according to main carrier deviant f0 osWith subcarrier offset value f1 osBetween relationship and determine
It is fixed whether to adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb。
More specifically, in one embodiment of this invention, by comparing main carrier deviant f0 os, subcarrier offset value
f1 osWith frequency shift (FS) threshold value fth, carrier shift coordinator 280 can correctly determine transmit signal S whether need to carry out carrier frequency
Rate correction process, and then decide whether to adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb.Primary feedback signal after adjusted
f0 fbWith secondary feedback signal f1 fb, can be re-used for carrying out carrier frequency correction to transmission signal S.In addition, for having carried
Whether the signal of wave frequency rate correction process, carrier shift coordinator 280 are also used to judge its carrier frequency correctly by school
Just.
Fig. 5 is the detail flowchart of offset correction of carrier frequency method depicted in another embodiment according to the present invention.Fig. 5
Illustrated embodiment is referred to the related description of Fig. 4 and analogizes it.Referring to figure 5., in step S340, carrier shift coordinator
280 are deciding whether to adjust primary feedback signal f0 fbWith secondary feedback signal f1 fbWhen, it is by main carrier deviant f0 os, subcarrier
Deviant f1 osWith frequency shift (FS) threshold value fthAs judgment basis.If main carrier deviant f0 osAbsolute value and subcarrier offset
Value f1 osAbsolute value be smaller than frequency shift (FS) threshold value fthWhen (| f0 os|<fthAnd | f1 os|<fth), then in step S341, carry
Wave offset coordinator 280 does not adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb, and main demodulating equipment 240 and secondary demodulating equipment
260 couples of transmission signal S are demodulated to obtain the multiple groups audio signal (or data-signal) in transmission signal S.Frequency is inclined
Move threshold value fth100kHz be can be set as to 120kHz.
Specifically, by setting offset threshold fthIf main carrier deviant f0 osAbsolute value and subcarrier offset value
f1 osAbsolute value be smaller than frequency shift (FS) threshold value fth, the carrier frequency shift for representing transmission signal S is serious either
It is corrected, and main demodulating equipment 240 and secondary demodulating equipment 260 can correctly demodulate multiple groups audio signal.In other words, to scheme
For the carrier frequency shift situation of 1B, i.e. main carrier deviant f0 osWith subcarrier offset value f1 osSignal demodulation is not caused
Serious influence, and transmit the main audio channel signal S in signal S0’With sub-channel signal S1’Correctly recognized.At this point, transmission letter
Number S is via main demodulating equipment 240 and the low-pass filter 244,264 and FM signal demodulator in secondary demodulating equipment 260
246, it 266 is demodulated, to obtain audio signal therein.
If main carrier deviant f0 osAbsolute value or subcarrier offset value f1 osAbsolute value be not less than frequency shift (FS) threshold value
fth, then main carrier deviant f is further examined closely0 osWith subcarrier offset value f1 osBetween relationship, to judge in Fig. 1 C and Fig. 1 D
Carrier frequency shift situation whether occur, and whether influence to transmission signal S demodulation.
By taking the carrier frequency shift in Fig. 1 C as an example, in subcarrier (sub-channel signal S1) frequency to be greater than main carrier (main
Sound channel signal S0) frequency in the case where, the received main audio channel signal S of the institute of offset correction of carrier frequency system 2000’With secondary sound channel
Signal S1’, main carrier deviant f0 osWith known main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset
Value f1 osWith known subcarrier frequency fc1And (fc1+f1 os).For example, in Fig. 1 C, the received secondary sound channel letter of receiving end institute
Number S1’Main audio channel signal S is fallen on the position of frequency spectrum0With sub-channel signal S1Between.Due to sub-channel signal S1’Carrier frequency
Rate is due to carrier frequency shift than main audio channel signal S on frequency spectrum0’Carrier frequency more close to main audio channel signal S0, thus make
Demodulating equipment is obtained in demodulating process, mistakenly by sub-channel signal S1’It is identified as main audio channel signal S0.At this point, main demodulating equipment
The 240 and resulting main carrier deviant f of secondary demodulating equipment 2600 os(fc1’-fc0) and subcarrier offset value f1 os(fc1’-fc1) can expire
Sufficient main carrier deviant and known main carrier frequency and (fc0+f0 os) it is substantially equal to subcarrier offset value and known secondary load
Wave frequency rate and (fc1+f1 os) relationship (fc0+f0 os≒fc1+f1 os)。
When the sum of main carrier deviant and known main carrier frequency is substantially equal to subcarrier offset value and known secondary load
Wave frequency rate and when, offset correction of carrier frequency method further in step S342, is checked by carrier shift coordinator 280
Test main carrier deviant f0 tosWith test subcarrier offset value f1 tosIt whether is setting initial value.In this present embodiment, test master
Carrier offset values f0 tosWith test subcarrier offset value f1 tosSetting initial value can be respectively 0, but not limited to this.If surveying
Try main carrier deviant f0 tosWith test subcarrier offset value f1 tosTo set initial value, then in step S343, carrier shift association
Device 280 is adjusted to record main carrier deviant f0 osWith subcarrier offset value f1 osTo test main carrier deviant f0 tosWith test subcarrier
Deviant f1 tos, and carrier shift coordinator 280 adjusts primary feedback signal f according to flag value flag0 fbWith secondary feedback signal
f1 fbTo test main carrier deviant f0 tosWith test subcarrier offset value f1 tosOne of them.Conversely, if test main carrier offset
Value f0 tosWith test subcarrier offset value f1 tosFor setting initial value, then in step S344, carrier shift coordinator 280 according to
Primary feedback signal f is adjusted according to flag value flag0 fbWith secondary feedback signal f1 fbTo test main carrier deviant f0 tosWith the secondary load of test
Wave deviant f1 tosOne of them.In this present embodiment, flag value flag is set as 0 and 1.If carrier shift coordinator 280 is sentenced
Disconnected flag value flag is 0 (flag=0), then in step S345, adjusts primary feedback signal f0 fbAnd secondary feedback signal f1 fbFor test
Main carrier deviant f0 tosWith test subcarrier offset value f1 tosOne of them, and flag value flag is set as 1.In this implementation
In the step S345 (Fig. 5) of example, primary feedback signal f0 fbAnd secondary feedback signal f1 fbIt is adjusted to test subcarrier offset value
f1 tos.Conversely, in step S346, being adjusted main anti-if carrier shift coordinator 280 judges flag value flag for 1 (flag=1)
Feedback signal f0 fbAnd secondary feedback signal f1 fbTo test main carrier deviant f0 tosWith test subcarrier offset value f1 tosIt is wherein another
One, and flag value is set as 0.According to previous embodiment, then in the step S346 of the present embodiment, primary feedback signal f0 fbWith
And secondary feedback signal f1 fbIt is adjusted to test main carrier deviant f0 tos.Specifically, primary feedback signal f0 fbAnd secondary feedback
Signal f1 fbThe mixer of main demodulating equipment 240 with secondary demodulating equipment 260 can be back to by carrier shift coordinator 280 respectively
242 and 262, the modified effect of carrier frequency shift is carried out to transmission signal S to reach.In other words, step is whether carried out
S345 either step S346, offset correction of carrier frequency method can come back to step S320, and main demodulating equipment 240 and secondary
Demodulating equipment 260 is again depending on known main carrier frequency, known subcarrier frequency (centre frequency fc0And fc1), main carrier it is inclined
Shifting value f0 osWith subcarrier offset value f1 os, frequency is carried out by main demodulating equipment 240 and secondary 260 couples of transmission signal S of demodulating equipment
Parsing, to obtain new main carrier deviant f0 osWith subcarrier offset value f1 os, and again in step S340, it is inclined by carrier wave
It moves coordinator 280 and compares main carrier deviant f0 os, subcarrier offset value f1 osWith frequency shift (FS) threshold value fth, to determine existing master
Feedback signal f0 fbAnd secondary feedback signal f1 fbMain demodulating equipment 240 whether can be assisted correctly to carry out with secondary demodulating equipment 260
Demodulation.In addition, carrier shift coordinator 280 also resets test main carrier deviant f after correctly being demodulated0 tos
With test subcarrier offset value f1 tosTo set initial value, to carry out carrier frequency correction again.
Offset correction of carrier frequency method and offset correction of carrier frequency system 200 proposed by the invention, can be applicable in
In the situation of a variety of carrier frequency shifts, and achieve the effect that correctly to correct carrier frequency shift.By taking Fig. 1 D as an example, connect
The main audio channel signal S of receipts0’Carrier frequency (centre frequency fc0’) in falling in main audio channel signal S on frequency spectrum0Carrier frequency (in
Frequency of heart fc0) and sub-channel signal S1Carrier frequency (centre frequency fc1) between.Offset correction of carrier frequency system 200 is connect
The sub-channel signal S of receipts1’Carrier frequency (centre frequency fc1’) maximum, and compared to the received main sound channel of institute on frequency spectrum
Signal S0’Carrier frequency (centre frequency fc0’) it is further from sub-channel signal S1.When carrying out offset correction of carrier frequency,
The carrier shift situation of Fig. 1 D still meets main carrier deviant f0 osWith known main carrier frequency fc0And (fc0+f0 os) essence
On be equal to subcarrier offset value f1 osWith known subcarrier frequency fc1And (fc1+f1 os) relationship (fc0+f0 os≒fc1+f1 os),
Thus it can correctly be recognized and be corrected.
Fig. 1 E~1F is a kind of schematic diagram of carrier frequency shift.In Fig. 1 E, on frequency spectrum, sub-channel signal S1Load
Wave frequency rate (centre frequency fc1) it is greater than main audio channel signal S0Carrier frequency (centre frequency fc0) it is greater than the received secondary sound channel letter of institute
Number S1’Carrier frequency (centre frequency fc1’) it is greater than the received main audio channel signal S of institute0’Carrier frequency (centre frequency fc0’)
(fc0’<fc1’<fc0<fc1).And in Fig. 1 F, on frequency spectrum, the received sub-channel signal S of institute1’Carrier frequency (centre frequency
fc1’) it is greater than the received main audio channel signal S of institute0’Carrier frequency (centre frequency fc0’) it is greater than sub-channel signal S1Carrier frequency
(centre frequency fc1) it is greater than main audio channel signal S0Carrier frequency (centre frequency fc0)(fc1<fc0<fc1’<fc0’).No matter however what
Kind frequency shift (FS) situation, still meets main carrier deviant f based on its carrier shift situation0 osWith known main carrier frequency fc0's
(fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known subcarrier frequency fc1And (fc1+f1 os) relationship (fc0
+f0 os≒fc1+f1 os), offset correction of carrier frequency method and offset correction of carrier frequency system 200 can correctly carry out carrier wave
Frequency offset correction.
It is worth noting that, carrier frequency shift depicted in Fig. 1 C, is with subcarrier (sub-channel signal S1) frequency
Rate is greater than main carrier (main audio channel signal S0) frequency in case where.If however, in main carrier (main audio channel signal S0) frequency
Rate is greater than subcarrier (sub-channel signal S1) frequency in the case where (fc0>fc1) (not being painted), when the main audio channel signal of receiving end
S0’With sub-channel signal S1’Carrier frequency occur carrier frequency shift when, still meet main carrier deviant f0 osWith it is known
Main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known subcarrier frequency fc1And (fc1
+f1 os) relationship (fc0+f0 os≒fc1+f1 os).For example, e.g. on frequency spectrum, main audio channel signal S0Carrier frequency (in
Frequency of heart fc0) it is greater than sub-channel signal S1Carrier frequency (centre frequency fc1) it is greater than the received main audio channel signal S of institute0’Load
Wave frequency rate (centre frequency fc0’) it is greater than the received sub-channel signal S of institute1’Carrier frequency (centre frequency fc1’)(fc1’<fc0’<
fc1<fc0) or be the received main audio channel signal S of institute e.g. on frequency spectrum0’Carrier frequency (centre frequency fc0’) be greater than
The received sub-channel signal S of institute1’Carrier frequency (centre frequency fc1’) it is greater than main audio channel signal S0Carrier frequency (center frequency
Rate fc0) it is greater than sub-channel signal S1Carrier frequency (centre frequency fc1)(fc1<fc0<fc1’<fc0’).In other words, even if in main load
Wave (main audio channel signal S0) frequency be greater than subcarrier (sub-channel signal S1) frequency under the premise of, determine how to transmission believe
The standard that number S carries out carrier frequency correction process does not need correspondingly to change.
In step S320~S346, offset correction of carrier frequency method is by adjusting primary feedback signal f0 fbIt is fed back with pair
Signal f1 fbTo carry out carrier frequency shift amendment to transmission signal S, and reaffirms whether transmission signal S properly compensates for frequency
It can be demodulated partially and correctly to obtain multiple audio signals therein.
Referring again to Fig. 1 C, when carrier shift coordinator 280 confirms main carrier deviant f0 osWith known main carrier frequency
fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known subcarrier frequency fc1And (fc1+f1 os) after,
Prior to further checking test main carrier deviant f in step S3420 tosWith test subcarrier offset value f1 tosIt whether is that setting is first
Initial value.If testing main carrier deviant f0 tosWith test subcarrier offset value f1 tosFor setting initial value (such as be all 0, it may be assumed that
f0 tos=f1 tos=0), then in step S343, carrier shift coordinator 280 records main carrier deviant f0 osWith subcarrier offset value
f1 osTo test main carrier deviant f0 tosWith test subcarrier offset value f1 tos, and further adjusted in step S345 or S346
Whole primary feedback signal f0 fbWith secondary feedback signal f1 fb(first time).Primary feedback signal f0 fbWith secondary feedback signal f1 fbTo test main load
Wave deviant (the main carrier deviant f of Fig. 1 C0 os) either test subcarrier offset value (the subcarrier offset value f of Fig. 1 C1 os)
One of the two.If carrier shift coordinator 280 is selected to test subcarrier offset value as primary feedback signal f0 fbIt is anti-with pair
Feedback signal f1 fb, then via the corresponding raising frequency processing of the progress of mixer 242 and 262 after, transmit the carrier frequency (center in signal S
Frequency fc0’And fc1’) can adjust to close to main audio channel signal S0With sub-channel signal S1Carrier frequency (centre frequency fc0
And fc1).At this point, by main demodulating equipment 240 and secondary demodulating equipment 280 acquired main carrier deviant f again0 osWith pair
Carrier offset values f1 osAbsolute value can all be less than frequency shift (FS) threshold value fth.Then, offset correction of carrier frequency method stops adjustment
Primary feedback signal f0 fbAnd secondary feedback signal f1 fb, and enter step in S341, main demodulating equipment 240 and secondary demodulating equipment 242
Known main carrier frequency, known subcarrier frequency (centre frequency f can be passed throughc0And fc1), primary feedback signal f0 fbAnd it is secondary anti-
Feedback signal f1 fbTransmission signal S is demodulated to obtain audio signal therein.
However, in the case of the carrier frequency shift of Fig. 1 D, if the selection of carrier shift coordinator 280 is to test subcarrier
Deviant (the subcarrier offset value f in Fig. 1 D1 os) it is used as primary feedback signal f0 fbWith secondary feedback signal f1 fb, then via mixer
After 242 down conversion process corresponding with 262 progress, carrier frequency (the centre frequency f of signal S is transmittedc0’And fc1’) instead can be inclined
Move more serious.Fig. 1 G is please referred to, Fig. 1 G is the schematic diagram of another carrier frequency shift.Due to transmitting the center of signal S
Frequency fc0’And fc1’Because selecting test subcarrier offset value (the subcarrier offset value f in Fig. 1 D in Fig. 1 D1 os) as main anti-
Feedback signal f0 fbWith secondary feedback signal f1 fb, and by mistakenly frequency reducing.At this point, further inclined inferior to main carrier obtained in step S320
Shifting value f0 osOr subcarrier offset value f1 osThe absolute value of one of them is possible to be greater than frequency shift (FS) threshold value fth, and main carrier is inclined
Shifting value f0 osWith known main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known subcarrier
Frequency fc1And (fc1+f1 os).In the case, due to testing main carrier deviant f0 tosWith test subcarrier offset value f1 tos
It is not setting initial value, therefore in step S344, carrier shift coordinator 280 adjusts primary feedback signal according to flag value
f0 fbAnd secondary feedback signal f1 fb(for the second time), and primary feedback signal f0 fbAnd secondary feedback signal f1 fbFor test main carrier offset
Value f0 tosWith test subcarrier offset value f1 tosIt is wherein another.
Specifically, the carrier frequency shift situation in Fig. 1 C~1D, main carrier deviant f0 osWith subcarrier offset value
f1 osIf one of them is correctly fed back, it can make the centre frequency f for transmitting signal Sc0’And fc1’It adjusts to close to master
Sound channel signal S0With sub-channel signal S1Centre frequency fc0、fc1(in Fig. 1 C, select subcarrier offset value f1 osAs feedback letter
Number carrier frequency correction correctly can be carried out to transmission signal S, and in Fig. 1 D, select main carrier deviant f0 osAs anti-
Feedback signal correctly can carry out carrier frequency correction to transmission signal S).Therefore the offset correction of carrier frequency in the present embodiment
Method is by way of feedback test, to the main carrier deviant f recorded0 osWith subcarrier offset value f1 os(test master
Carrier offset values f0 tosWith test subcarrier offset value f1 tos) surveyed, correctly to select feedback signal.
In step S343, primary feedback signal f is adjusted according to flag value flag by carrier shift coordinator 2800 fbIt is anti-with pair
Feedback signal f1 fb.In other words, carrier shift coordinator 280 judges whether flag value is 1 (flag=1) or judges flag value flag
It whether is 0 (flag=0).If flag value flag is 0, in step S345, primary feedback signal f is set0 fbWith secondary feedback signal
f1 fbTo test main carrier deviant f0 tosWith test subcarrier offset value f1 tosOne of them (such as test subcarrier offset value
f1 tos), and resetting flag value is 1.If flag value flagWhen being 1, then in step S346, primary feedback signal f is set0 fb
With secondary feedback signal f1 fbTo test main carrier deviant f0 tosWith test subcarrier offset value f1 tosWherein another (such as test
Main carrier deviant f0 tos)。
Since the step in offset correction of carrier frequency method is consecutive steps, therefore the change of flag value can be retained.Tool
For body, if generating primary feedback signal f in step S3430 fbWith secondary feedback signal f1 fbWhen, flag value 1, then carrier shift is assisted
Device 280 is adjusted to set primary feedback signal f0 fbWith secondary feedback signal f1 fbAfterwards, can reset flag value is 0.And if via step
S345 and when entering step S344, carrier shift coordinator 280 is also according to flag value (flag value is 0 at this time) setting primary feedback
Signal f0 fbWith secondary feedback signal f1 fb, and resetting flag value is 1.
In the offset correction of carrier frequency method of the present embodiment, if carrier shift coordinator 280 judges that main carrier deviates
Value f0 osAbsolute value or subcarrier offset value f1 osAbsolute value be not less than frequency shift (FS) threshold value fth, and main carrier deviant f0 os
With known main carrier frequency fc0And (fc0+f0 os) substantially unequal in subcarrier offset value f1 osWith known subcarrier frequency
fc1And (fc1+f1 os), then carrier shift coordinator 280 adjusts primary feedback signal f in step S3470 fbFor main carrier shift
Value f0 os, secondary feedback signal f1 fbFor subcarrier offset value f1 os, and in step S348, main demodulating equipment 240 and secondary demodulating equipment
260 couples of transmission signal S are demodulated to obtain the audio signal of transmission signal S.At this point, main demodulating equipment 240 is filled with secondary demodulation
260 are set also according to known main carrier frequency fc0, known subcarrier frequency fc1, primary feedback signal f0 fbWith secondary feedback signal f1 fb
And carrier frequency correction is carried out to transmission signal S respectively, and carry out signal demodulation.
Previous embodiment only by comparing main carrier deviant, the mode of subcarrier offset value and frequency shift (FS) threshold value, with
Decide whether to carry out carrier frequency correction process.However in the present invention, offset correction of carrier frequency system judges whether to carry
The mode of wave frequency rate correction process, however it is not limited to this.Fig. 6 is carrier frequency shift depicted in another embodiment according to the present invention
The schematic diagram of correction system 500.Fig. 7 A~7B is offset correction of carrier frequency side depicted in another embodiment according to the present invention
The flow chart of method.Fig. 6 and Fig. 7 A~7B illustrated embodiment are referred to the related description of Fig. 1~4 and analogize it.Please refer to Fig. 6
With Fig. 7 A~7B, offset correction of carrier frequency system 500 further includes main power calculator 545 and secondary power calculator 565, difference
It is set to main demodulating equipment 540 and secondary demodulating equipment 560, to calculate the carrier power of signal.
In this present embodiment, offset correction of carrier frequency method is more by the carrier power of signal, to determine whether carrying out
Carrier frequency correction process.In step S620, main demodulating equipment 540 and secondary demodulating equipment 560 according to known main carrier frequency,
Known subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd secondary feedback signal f1 fb, transmission is believed respectively
The method that number S carries out frequency resolution, further includes the following steps.In step S622, main demodulating equipment 540 and secondary demodulating equipment
560 more according to known main carrier frequency, known subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd it is secondary
Feedback signal f1 fb, frequency correction is carried out to transmission signal S respectively, to obtain main fundamental frequency signal and secondary fundamental frequency signal.In step
In S624, main power calculator 545 and secondary power calculator 565 are then to calculate the carrier wave of main fundamental frequency signal and secondary fundamental frequency signal
Power P0、P1.In addition, main demodulating equipment 540 calculates main fundamental frequency signal and secondary fundamental frequency with secondary demodulating equipment 560 in step S626
The main carrier deviant f of signal0 osWith subcarrier offset value f1 os。
Then, in step S640, carrier shift coordinator 580 is according to main carrier deviant f0 osWith subcarrier offset value
f1 osBetween relationship and decide whether adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb.In step S640, carrier shift
The carrier power P of the more main fundamental frequency signal more in step S641 of coordinator 5800With the carrier power P of secondary fundamental frequency signal1。
In subcarrier (sub-channel signal S1) frequency be greater than main carrier (main audio channel signal S0) frequency in the case where, if carrier shift
Coordinator 580 judges main carrier deviant f0 osAbsolute value or subcarrier offset value f1 osAbsolute value be not less than frequency shift (FS) threshold
Value fth, and main carrier deviant f0 osWith known main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value
f1 osWith known subcarrier frequency fc1And (fc1+f1 os), and the carrier power P of main fundamental frequency signal and secondary fundamental frequency signal0、P1Essence
(f when upper identicalc0+f0 os≒fc1+f1 osAnd P0≒P1), then in step S643, carrier shift coordinator 580 adjusts primary feedback letter
Number f0 fbWith secondary feedback signal f1 fbFor main carrier offset values f0 osOr subcarrier offset value f1 os(for example, subcarrier is inclined for one of them
Shifting value f1 os).Then, in step S644, main demodulating equipment 540 with secondary demodulating equipment 560 according to known main carrier frequency,
Know subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd secondary feedback signal f1 fb, respectively to transmission signal
S carries out frequency correction, corrects secondary fundamental frequency signal to obtain the main fundamental frequency signal of the first amendment and first.In addition, in step S645,
Main demodulating equipment 540 and secondary demodulating equipment 560 are more utilized respectively main power calculator 545 and secondary power calculator 565 and calculate the
The carrier power P of the main fundamental frequency signal of one amendment and the secondary fundamental frequency signal of the first amendment0、P1。
In step S646, carrier shift coordinator 580 compares the carrier power P of the main fundamental frequency signal of the first amendment0With
One corrects the carrier power P of secondary fundamental frequency signal1.If carrier shift coordinator 580 judges the carrier wave of the first main fundamental frequency signal of amendment
Power P0The carrier power P of secondary fundamental frequency signal is corrected greater than first1(P0>P1), then in step S647, carrier shift coordinator
580 no longer adjust primary feedback signal f0 fbAnd secondary feedback signal f1 fb, and main demodulating equipment 540 and secondary demodulating equipment 560 are to the
The main fundamental frequency signal of one amendment and the secondary fundamental frequency signal of the first amendment are demodulated to obtain the audio signal in transmission signal S.Conversely,
If carrier shift coordinator 580 judges the carrier power P of the first main fundamental frequency signal of amendment0Secondary fundamental frequency signal is corrected no more than first
Carrier power P1, then in step S648, carrier shift coordinator 580 adjusts primary feedback signal f0 fbWith secondary feedback signal f1 fb
For main carrier offset values f0 osOr subcarrier offset value f1 osWherein another (for example, main carrier deviant f0 os)。
In step S649, primal coordination device 540 and secondary conditioning unit 560 pass through mixer 542,562, low-pass filter
544,564, according to known main carrier frequency, known subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbWith
And secondary feedback signal f1 fb, frequency correction is carried out to transmission signal S respectively, is repaired with obtaining the second main fundamental frequency signal of amendment with second
Chief and vice fundamental frequency signal.Then, in step S650, the second amendment is calculated by main power calculator 545 and secondary power calculator 565
The carrier power P of main fundamental frequency signal0The carrier power P for correcting secondary fundamental frequency signal with second1, and in step S651, by carrier wave
Offset coordinator 580 compares the main fundamental frequency signal of the second amendment and second and corrects the carrier power P of secondary fundamental frequency signal0、P1.If carrier wave
Offset coordinator 580 judges the carrier power P of the second main fundamental frequency signal of amendment0The carrier wave function of secondary fundamental frequency signal is corrected greater than second
Rate P1(P0>P1), then in step S652, main demodulating equipment 540 respectively believes the second main fundamental frequency of amendment with secondary demodulating equipment 560
Number correcting secondary fundamental frequency signal with second is demodulated to obtain the audio signal of transmission signal S.However, if carrier shift coordinator
580 judge that the carrier power of the second main fundamental frequency signal of amendment corrects the carrier power of secondary fundamental frequency signal no more than second, then in step
Primary feedback signal f is adjusted in rapid S6530 fbWith secondary feedback signal f1 fbIt is 0, and resumes step S620, to carry out carrier frequency again
Rate offset correction method.Different from offset correction of carrier frequency method shown in fig. 5, carrier shift coordinator 580 more passes through ratio
Compared with the carrier power P between fundamental frequency signal0、P1(such as main fundamental frequency signal and secondary fundamental frequency signal, the main fundamental frequency signal of the first amendment and the
One corrects secondary fundamental frequency signal, the main fundamental frequency signal of the second amendment and second corrects secondary fundamental frequency signal), to determine in transmission signal S
Whether carrier frequency shift is not present or is correctly corrected.Offset correction of carrier frequency system and carrier frequency in the present embodiment
Remaining step and structure of rate offset correction method please refer to the offset correction of carrier frequency system and wave frequency rate of earlier figures 2~5
The explanation of offset correction method, details are not described herein.
Fig. 8 is the schematic diagram of offset correction of carrier frequency system 700 depicted in another embodiment according to the present invention.Fig. 9 A
~9B is the flow chart of offset correction of carrier frequency method depicted in another embodiment according to the present invention.Fig. 8 and Fig. 9 A~9B
Illustrated embodiment is referred to the related description of Fig. 1~7B and analogizes it.Please refer to Fig. 8 and Fig. 9 A~9B, carrier frequency shift
In correction system 700, main demodulating equipment 740 further includes main power calculator 745, and secondary demodulating equipment 760 further includes secondary power
Calculator 765 and mode detector 767.
Compared to offset correction of carrier frequency system 500 shown in Fig. 6 and 7A~7B and offset correction of carrier frequency method,
In this present embodiment, offset correction of carrier frequency method corrects secondary base by the detection of mode detector 767 first in step S845
Mode indicators number in frequency signal.If secondary fundamental frequency is corrected in 780 judgment model designated symbol of carrier shift coordinator instruction first
Signal is stereo mode (Dual Sound) or stereo channel (Stereo Sound) mode, then carrier shift coordinator 780
Primary feedback signal f is not adjusted0 fbAnd secondary feedback signal f1 fb, and main demodulating equipment 740 and secondary demodulating equipment 760 are in step
In S847, secondary fundamental frequency signal is corrected to the main fundamental frequency signal of the first amendment and first and is demodulated to obtain the audio of transmission signal S
Signal.If it is not stereo mode that secondary fundamental frequency signal is corrected in 780 judgment model designated symbol of carrier shift coordinator instruction first
Or stereo channel mode, but judge the carrier power P of the first main fundamental frequency signal of amendment0The load of secondary fundamental frequency signal is corrected greater than first
Wave power P1(P0>P1), then carrier shift coordinator 780 does not adjust primary feedback signal f equally0 fbAnd secondary feedback signal f1 fb, and
And main demodulating equipment 740 and secondary demodulating equipment 760 correct secondary base to the main fundamental frequency signal of the first amendment and first in step S847
Frequency signal is demodulated to obtain the audio signal of transmission signal S.If carrier shift coordinator 780 judges the secondary fundamental frequency of the first amendment
It is not stereo mode or stereo channel mode that secondary fundamental frequency signal is corrected in the mode indicators number instruction first of signal, and first repairs
The carrier power P of just main fundamental frequency signal0The carrier power P of secondary fundamental frequency signal is corrected no more than first1, then carrier shift coordinator
780 in step S848, adjusts primary feedback signal f0 fbWith secondary feedback signal f1 fbFor main carrier offset values f0 os.In the present embodiment
In, carrier shift coordinator 780 first adjusts primary feedback signal f in step S8420 fbWith secondary feedback signal f1 fbFor subcarrier offset
Value f1 os, and in step S848, adjust primary feedback signal f0 fbWith secondary feedback signal f1 fbFor main carrier offset values f0 os, but this hair
Primary feedback signal f in bright0 fbWith secondary feedback signal f1 fbAdjustment mode be not limited.
Specifically, mode indicators number are generally used to indicate that the acoustic pattern of the audio signal in transmission signal S.Cause
This, if mode detector 767 is corrected in first detects mode indicators number in secondary fundamental frequency signal, and mode indicators number refer to
Show the audio signal in the first amendment pair fundamental frequency signal acoustic pattern be stereo mode or stereo channel mode, then represent to
Few first corrects correctly corresponding subcarrier (the sub-channel signal S into transmission signal S of secondary fundamental frequency signal1’) frequency.At this point,
The main fundamental frequency signal of first amendment and the secondary fundamental frequency signal of the first amendment, which can be considered, is correctly carried out carrier frequency shift amendment,
And secondary fundamental frequency signal further can be corrected with first to the first main fundamental frequency signal of amendment and demodulated, to obtain transmission signal
Audio signal in S.
Similarly, offset correction of carrier frequency method is secondary by second amendment of the detection of mode detector 767 in step S851
Mode indicators number in fundamental frequency signal.It is stereo mode or stands if secondary fundamental frequency signal is corrected in mode indicators number instruction second
Body sound channel mode, then carrier shift coordinator 780 does not adjust primary feedback signal f equally0 fbAnd secondary feedback signal f1 fb, and it is main
Demodulating equipment 740 and secondary demodulating equipment 760 are corrected secondary fundamental frequency to the main fundamental frequency signal of the second amendment and second and are believed in step S853
It number is demodulated to obtain audio signal.If secondary base is corrected in 780 judgment model designated symbol of carrier shift coordinator instruction second
Frequency signal is not stereo mode or stereo channel mode, but judges the carrier power P of the second main fundamental frequency signal of amendment0Greater than
Two correct the carrier power P of secondary fundamental frequency signal1, then carrier shift coordinator 780 does not adjust primary feedback signal f equally0 fbAnd it is secondary
Feedback signal f1 fb, and main demodulating equipment 740 and secondary demodulating equipment 760 correct main fundamental frequency signal to second in step S853
Secondary fundamental frequency signal is corrected with second to be demodulated to obtain the audio signal of transmission signal S.If carrier shift coordinator 780 judges
It is not stereo mode or stereo that secondary fundamental frequency signal is corrected in the second mode indicators number instruction second for correcting secondary fundamental frequency signal
Road mode, and the carrier power P of the second main fundamental frequency signal of amendment0The carrier power P of secondary fundamental frequency signal is corrected no more than second1, then
Carrier shift coordinator 780 adjusts primary feedback signal f in step S8540 fbWith secondary feedback signal f1 fbIt is 0, and carrier frequency
Rate offset correction method comes back to step S820.Offset correction of carrier frequency system and frequency offset school in the present embodiment
Remaining step and structure of correction method, the offset correction of carrier frequency system and frequency offset for please referring to earlier figures 2~8 correct
The explanation of method, details are not described herein.
Figure 10 A~10B is the flow chart of offset correction of carrier frequency method depicted in another embodiment according to the present invention.
Offset correction of carrier frequency method depicted in Figure 10 A~10B is similarly applied to offset correction of carrier frequency depicted in Fig. 8
System 700, only offset correction of carrier frequency method have a little difference in process.In step S926, secondary 760 benefit of demodulating equipment
The mode indicators number of secondary fundamental frequency signal are detected with mode detector 767.If carrier shift coordinator 780 judges that main carrier deviates
Value f0 osAbsolute value or subcarrier offset value f1 osAbsolute value be not less than frequency shift (FS) threshold value fth, and main carrier deviant f0 os
With known main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known subcarrier frequency fc1
And (fc1+f1 os), then in step S942, carrier shift coordinator 780 adjusts primary feedback signal f0 fbWith secondary feedback signal f1 fb
For subcarrier offset value f1 os.In step S943, main demodulating equipment 740 is with secondary demodulating equipment 760 according to known main carrier frequency
Rate, known subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd secondary feedback signal f1 fb, respectively to biography
Defeated signal S carries out frequency correction, corrects secondary fundamental frequency signal to obtain the main fundamental frequency signal of the first amendment and first.
If mode indicators number detected indicate that secondary fundamental frequency signal is stereo mode or stereo in step S926
Road mode, then main demodulating equipment 740 repairs the first main fundamental frequency signal of amendment with first in step S944 with secondary demodulating equipment 760
Chief and vice fundamental frequency signal is demodulated must transmit the audio signal in signal S.Conversely, if in step S926 mode detected
Designated symbol indicates that secondary fundamental frequency signal is not stereo mode or stereo channel mode, then in step S945, main demodulating equipment
740 calculate the first main fundamental frequency signal of amendment using main power calculator 745 and secondary power calculator 765 with secondary demodulating equipment 760
The carrier power P for correcting secondary fundamental frequency signal with first0、P1, and in step S946, carrier shift coordinator 780 compares first
It corrects main fundamental frequency signal and first and corrects the carrier power P of secondary fundamental frequency signal0、P1.If carrier shift coordinator 780 judges first
Correct the carrier power P of main fundamental frequency signal0The carrier power P of secondary fundamental frequency signal is corrected greater than first1(P0>P1), then carrier shift
Coordinator 780 does not adjust primary feedback signal f0 fbAnd secondary feedback signal f1 fb, and main demodulating equipment 740 and secondary demodulating equipment
760 in step S947, corrects secondary fundamental frequency signal to the main fundamental frequency signal of the first amendment and first and is demodulated to obtain transmission letter
Audio signal in number S.On the contrary, if carrier shift coordinator 780 judges the carrier power P of the first main fundamental frequency signal of amendment0
The carrier power P of secondary fundamental frequency signal is corrected no more than first1, then carrier shift coordinator 780 adjusts main anti-in step S948
Feedback signal f0 fbWith secondary feedback signal f1 fbFor main carrier offset values f0 os.The step S949 of offset correction of carrier frequency method~
954, step S849~854 in Fig. 9 are please referred to, details are not described herein.Compared with the offset correction of carrier frequency method of Fig. 9,
Offset correction of carrier frequency method in the present embodiment detects the mode indicators in secondary fundamental frequency signal before being fed back in advance
Number.In the present embodiment, carrier shift coordinator 780 is in adjustment primary feedback signal f0 fbWith secondary feedback signal f1 fbIt is inclined for subcarrier
Shifting value f1 osOr main carrier deviant f0 osSequence might not first be subcarrier offset value f1 osIt is then main carrier offset values
f0 os.In other words, primary feedback signal f0 fbWith secondary feedback signal f1 fbAdjustment mode be not limited with aforementioned sequence.In addition, carrier frequency
The part that rate offset correction system and offset correction of carrier frequency method do not describe, please refers to the carrier frequency of 2~9B of earlier figures
The explanation of offset correction system and frequency offset bearing calibration, details are not described herein.
Figure 11 is the schematic diagram of offset correction of carrier frequency system 1000 depicted in another embodiment according to the present invention.Figure
12A~12B is the flow chart of offset correction of carrier frequency method depicted in another embodiment according to the present invention.Figure 11 and figure
12A~12B illustrated embodiment is referred to the related description of Fig. 1~10B and analogizes it.Figure 11 and Figure 12 A~12B are please referred to,
Main demodulating equipment 1040 more respectively includes main carrier mass detector (Carrier Quality with secondary demodulating equipment 1060
Meter) 1047 with subcarrier mass detector 1067 (Carrier Quality Meter).In this present embodiment, carrier frequency
Offset correction system 1000 and offset correction of carrier frequency method are more using the method for the signal-to-noise ratio (SNR) of detection signal, to sentence
It is disconnected whether to adjust primary feedback signal f0 fbAnd secondary feedback signal f1 fb.In step S1142, if carrier shift coordinator 1080 is sentenced
Disconnected main carrier deviant f0 osAbsolute value or subcarrier offset value f1 osAbsolute value be not less than frequency shift (FS) threshold value, and main carrier
Deviant f0 osWith known main carrier frequency fc0And (fc0+f0 os) it is substantially equal to subcarrier offset value f1 osWith known secondary load
Wave frequency rate fc1And (fc1+f1 os), then carrier shift coordinator 1080 adjusts primary feedback signal f0 fbWith secondary feedback signal f1 fbFor
Subcarrier offset value f1 os.In step S1143, main demodulating equipment 1040 is with secondary demodulating equipment 1060 according to known main carrier frequency
Rate, known subcarrier frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd secondary feedback signal f1 fb, respectively to biography
Defeated signal S carries out frequency correction, corrects secondary fundamental frequency signal to obtain the main fundamental frequency signal of the first amendment and first.Then, in step
In S1144, main demodulating equipment 1040 more calculates the noise of the first main fundamental frequency signal of amendment using main carrier mass detector 1047
Than (SNR), and secondary demodulating equipment 1060 more calculates the first letter for correcting secondary fundamental frequency signal using subcarrier mass detector 1067
It makes an uproar than (SNR).If carrier shift coordinator 1080 judges that the signal-to-noise ratio of the first main fundamental frequency signal of amendment is greater than signal-to-noise ratio high threshold,
Then in step S1145, carrier shift coordinator 1080 does not adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb, and principal solution tune
Device 1040 is corrected secondary fundamental frequency signal with first to the first main fundamental frequency signal of amendment with secondary demodulating equipment 1060 and is demodulated to take
Obtain audio signal.If carrier shift coordinator 1080 judges that the signal-to-noise ratio of the first main fundamental frequency signal of amendment is less than the low threshold of signal-to-noise ratio
Value, then in step S1146~1148, carrier shift coordinator 1080 adjusts primary feedback signal f0 fbWith secondary feedback signal f1 fbFor
Main carrier deviant f0 os, and main demodulating equipment 1040 and secondary demodulating equipment 1060 are according to known main carrier frequency, known subcarrier
Frequency (centre frequency fc0And fc1), primary feedback signal f0 fbAnd secondary feedback signal f1 fb, frequency school is carried out to transmission signal S
Just, secondary fundamental frequency signal is corrected to obtain the main fundamental frequency signal of the second amendment and second.In addition, main demodulating equipment 1040 more utilizes main load
Wave mass detector 1047 calculates the signal-to-noise ratio of the second main fundamental frequency signal of amendment, and secondary demodulating equipment 1060 more utilizes subcarrier matter
Amount detector 1067 calculates the second signal-to-noise ratio for correcting secondary fundamental frequency signal.
Specifically, if the main fundamental frequency signal of the first amendment detected, signal-to-noise ratio are greater than signal-to-noise ratio high threshold, then represent
The first main fundamental frequency signal of amendment includes the audio signal in transmission signal S.Conversely, if the first main fundamental frequency signal signal-to-noise ratio of amendment is
Less than signal-to-noise ratio Low threshold, then representing the main fundamental frequency signal of the first amendment only includes noise.In other words, it is led by the first amendment of detection
The signal-to-noise ratio of fundamental frequency signal, offset correction of carrier frequency system 1000 can be confirmed whether need with offset correction of carrier frequency method
Offset correction of carrier frequency is carried out to transmission signal S.Signal-to-noise ratio high threshold and signal-to-noise ratio Low threshold with environment and can be set
Surely it changes, is not limited thereto.
Similarly, if carrier shift coordinator 1080 judges that the signal-to-noise ratio of the secondary fundamental frequency signal of the second amendment is greater than signal-to-noise ratio height
Threshold value, then in step S1149, carrier shift coordinator 1080 does not adjust primary feedback signal f0 fbWith secondary feedback signal f1 fb, and
Main demodulating equipment 1040 is corrected secondary fundamental frequency signal with second to the second main fundamental frequency signal of amendment with secondary demodulating equipment 1060 and is solved
It adjusts to obtain the audio signal of transmission signal S.If second correct secondary fundamental frequency signal signal-to-noise ratio be less than signal-to-noise ratio Low threshold,
Offset correction of carrier frequency method is returned to step S1120 again.In this present embodiment, offset correction of carrier frequency system and load
The part that frequency offset bearing calibration does not describe please refers to the offset correction of carrier frequency system and wave frequency of 2~10B of earlier figures
The explanation of rate offset correction method, details are not described herein.
In conclusion offset correction of carrier frequency method provided by the present invention and offset correction of carrier frequency system, lead to
Cross the various parameters in detection transmission signal, such as carrier frequency offset values, carrier power, mode indicators number either noise
Than etc., judge to transmit whether signal needs to carry out carrier frequency shift amendment, and further check and repair through carrier frequency shift
Whether positive transmission signal can correctly be demodulated, and then obtain audio signal therein.Whereby, offset correction of carrier frequency
Method and offset correction of carrier frequency system can demodulate to avoid the signal because of the mistake caused by serious carrier frequency shift.
Although the present invention has been disclosed by way of example above, it is not intended to limit the present invention., any those skilled in the art
Without departing from the spirit and scope of the present invention, when can make some changes and embellishment, therefore protection scope of the present invention is when view by member
Subject to scope of the appended claims institute defender.
Claims (26)
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| CN1301447A (en) * | 1998-04-14 | 2001-06-27 | 弗兰霍菲尔运输应用研究公司 | Method and apparatus for fine frequency synchronization in multi-carrier demodulation systems |
| CN1264968A (en) * | 1999-02-24 | 2000-08-30 | 松下电器产业株式会社 | Frequency deviation corrector and frequency deviation correcting method |
| CN1859675A (en) * | 2006-01-04 | 2006-11-08 | 华为技术有限公司 | Frequency correcting method and device |
| CN102577128A (en) * | 2009-06-03 | 2012-07-11 | 意法爱立信有限公司 | Frequency offset correction |
| CN102790738A (en) * | 2011-05-18 | 2012-11-21 | 中兴通讯股份有限公司 | Frequency offset correcting method and device |
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