CN101197607B - Ground supplement translator and wireless digital broadcast synchronization system and method - Google Patents
Ground supplement translator and wireless digital broadcast synchronization system and method Download PDFInfo
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Abstract
The invention discloses a system and method which synchronizes with a ground supplementary transponder and wireless digital broadcast. The ground supplementary transponder is additionally provided with a synchronization module which executes synchronization adjustment of wave carrier frequency and code according to received PN code. The method comprises the following steps: a digital signal emitting system emits a data package comprising an information resource data and a system time and emits the PN code corresponding to the system time; a digital signal receiving system executes synchronization adjustment of the system wave carrier frequency and the code according to the received PN code, the digital signal receiving system modulates the received data package, and starts up the receiving system according to system time information. In the invention, the digital signal receiving system executes synchronization module of the wave carrier frequency and the code according to PN code through the digital signal emitting system being provided with the PN code capable of emitting and reflecting the system time information, so as to achieve synchronization of the system.
Description
Technical field
The present invention relates to a kind of communication technology, relate in particular to a kind of ground supplement translator, and the synchronous system and method for wireless digital broadcasting.
Background technology
The wireless digital broadcasting technology is the inevitable outcome of development communication technologies, uses this technology, can improve the covering quality of radio network, the coverage that extends the radio network.
In practical application, if directly adopt ground to cover, the construction cost of network and maintenance cost are all very big; If adopt direct satellite to cover; Rural area and remote mountain areas can directly receive, and in the city, do not have to block the zone and also can directly receive, but block many places for building in the city; Its coverage effect is very undesirable; Therefore, for the zone of these covering quality differences, the pattern that must adopt ground supplement to transmit covers.
As shown in Figure 1, carry out the system construction drawing of wireless digital broadcasting for the available technology adopting ground supplement translator.This wireless digital broadcasting system comprises digital signal emission system, satellite and digital signal receiving system.In the digital signal emission system, the information source data modulator is modulated the data of source encoder output, again through the Ku band transmitter with the Ku band emission to satellite.The Ku wave band that satellites coupling is received is transmitted.Satellite with S-band directly the terminal demodulates device in the digital signal receiving system transmit the information source data, simultaneously, satellite is also transmitted the information source data with the Ku wave band.After the satellite antenna reception of information source data with the forwarding of Ku wave band, be transmitted to the terminal demodulates device with S-band again by supplement translator.The terminal demodulates device carries out demodulation to the information source data of the S-band that receives, is decoded by source decoder again, sends to corresponding mobile terminal afterwards.
In above-mentioned wireless digital broadcasting system, ground supplement translator is net distribution, and each ground supplement translator receives the information source data of the Ku wave band that same satellite transmits, and is transmitted to corresponding terminal demodulates device with S-band.For the terminal demodulates device, the information source data that it receives the information source data of the direct S-band of transmitting of satellite simultaneously and passes through the S-band of supplement translator forwarding.Owing to there is the skew of crystal in the satellite; The perhaps multiple reasons such as processing time-delay of ground supplement translator; There is frequency in the S-band data that possibly cause direct S-band data of transmitting of satellite and ground supplement translator to be transmitted when the incoming terminal demodulator; Sign indicating number and the deviation of time, for the terminal demodulates device, these deviations will directly cause the demodulation information source data that it can not be correct.
To above-mentioned defective; Increase single frequency adapter and GPS (Global Positioning System in the wireless digital broadcasting system in the prior art; Global positioning system) key equipment such as, Frequency Synchronization, time synchronized and the sign indicating number of realizing systems by means of these equipment are synchronously.
Through utilizing GPS equipment that accurate pps pulse per second signal is provided; Utilizing single frequency adapter that the data flow of sending is carried out huge frame by the digital signal emission system handles; After the digital signal receiving system receives the data flow of transmitting; Separate huge frame and handle, thereby the time synchronized of the system of realization is synchronous with sign indicating number.
To the requirement of Frequency Synchronization, obtain reference frequency and pps pulse per second signal from GPS equipment, drive all cascade generators in every ground supplement translator with the reference frequency of GPS equipment, so realize carrier frequency synchronously.
Can find out, in the prior art carrier synchronization, time synchronized and sign indicating number all depended on independently GPS equipment synchronously, and in practical application,, will cause whole system owing to do not carry out synchronous and in paralyzed state in case lacked the information of GPS equipment.At this moment, also be of no avail even manual intervention is arranged.And, adopt GPS equipment to carry out also causing the increase of system cost synchronously, make the networking uniting and adjustment between each ground supplement translator complicated more.
Summary of the invention
The present invention is directed to the shortcoming of prior art; Provide a kind of ground supplement translator and wireless digital broadcasting synchronous system and method; PN sign indicating number (the Pseudo noise Code that is used for the recognition system time through stack in the digital signal emission system; Pseudo-Random Noise Code), in the digital signal receiving system, carry out the synchronous of whole system according to this PN sign indicating number.
Ground supplement translator according to the invention comprises up-conversion module, down conversion module, up-conversion and power amplifier module and data path module, also comprises synchronization module;
Said synchronization module comprises:
Synchronous and the tracking module of PN sign indicating number is used for carrying out according to the PN sign indicating number that receives the synchronization acquistion and the tracking of sign indicating number;
The time synchronized tracking module is used for emission source clock that local clock is traced into, and different ground supplement translators is carried out time unification, obtains system time;
The synchronized transmission control module is used for that the data based system time that receives is carried out timing and transmits.
The present invention also provides a kind of wireless digital broadcasting synchronous system, comprises digital signal emission system, satellite and digital signal receiving system;
Said digital signal emission system comprises the packet of information source data, system time and the PN sign indicating number corresponding with system time to satellites transmits;
The PN sign indicating number that said digital signal receiving system is transmitted according to satellite carries out system carrier frequency and sign indicating number adjustment synchronously, and starts receiving system according to the system time information that demodulation obtains.
Above-mentioned digital signal emission system is provided with:
Business/synchronization motivationtheory device is used to receive the information source data that the information source data modulator sends, and information source number is reached the system time packing of generation according to this, is sent to the Ku band transmitter with the PN sign indicating number stack that generates.
Be provided with data encapsulation apparatus in above-mentioned business/synchronization motivationtheory device, this device comprises:
Data split module, are used for that the data that receive are split as at least one and include the packet of setting byte length;
The header packet information generation module is used to generate the header packet information that identifies above-mentioned packet;
The data encapsulation module is used for above-mentioned header packet information is added on before all bytes of corresponding packet.
The present invention also provides a kind of wireless digital broadcasting synchronous method, and its step comprises:
Step 2, digital signal receiving system are carried out the synchronous adjustment of system carrier frequency and sign indicating number according to the PN sign indicating number that receives;
Step 3, the packet that digital signal receiving system demodulate reception arrives, and start receiving system according to wherein system time information.
In the above-mentioned steps one, during digital signal emission system emission packet data are encapsulated, its step specifically comprises:
Add corresponding packet header identification information before the step 102, all bytes in each packet.
In the above-mentioned steps two, the digital signal receiving system is carried out the method for the synchronous adjustment of system carrier frequency and sign indicating number, comprises the steps:
Step 203 is carried out the second synchronization adjustment to the carrier frequency of digital receiving system;
Step 204 is followed the tracks of the sign indicating number and the carrier frequency of digital receiving system synchronously.
Among the present invention, in the digital signal emission system, increase the PN sign indicating number of launching reflection system time information, the digital signal receiving system is carried out the synchronous adjustment of carrier frequency and sign indicating number according to its PN sign indicating number that receives, thereby the system of realization is synchronous.Compared with prior art, under the situation that does not increase receiving system equipment, realize the synchronous of system, not only saved the spending of system's construction, also improved the reliability and the convenience of system communication.
Description of drawings
Fig. 1 is the system configuration sketch map of wireless digital broadcasting in the prior art;
Fig. 2 is the system configuration sketch map of the wireless digital broadcasting among the present invention;
Fig. 3 is the structural representation of ground supplement translator of the present invention;
Fig. 4 is the structural representation of data encapsulation apparatus in the ground supplement translator among the present invention;
Fig. 5 is the synchronous method flow diagram of wireless digital broadcasting among the present invention;
The method flow diagram that when Fig. 6 launches packet for digital signal emission system among the present invention packet is encapsulated;
The packet that Fig. 7 sends for digital signal emission system among the present invention superposes compares sketch map with the amplitude of PN sign indicating number;
Fig. 8 carries out the method flow diagram of the synchronous adjustment of carrier frequency and sign indicating number for digital signal receiving system among the present invention.
Embodiment
Among the present invention, through stack emission packet and PN sign indicating number simultaneously in the up channel of emission system, receiving system realizes that according to the PN sign indicating number time synchronized of whole wireless digital broadcasting system is synchronous with sign indicating number.
Below in conjunction with accompanying drawing the present invention is further specified.
As shown in Figure 2, the synchronous system of wireless digital broadcasting according to the invention comprises digital signal emission system, satellite and digital signal receiving system.
Wherein, the digital signal emission system comprises:
The information source data modulator is used for the code signal of source encoder output is modulated, and exports the data-signal of modulation to Ku band transmitter and business/synchronization motivationtheory device;
Source encoder is used for the information source data are encoded, and exports the information source data modulator to;
Business/synchronization motivationtheory device is used to receive the information source data that the information source data modulator sends, and information source number is reached the system time packing of generation according to this, is sent to the Ku band transmitter with the PN sign indicating number stack that generates;
Above-mentioned PN sign indicating number comprises that the time cycle counts information and secondary planet frequency-difference information, can further include sync id information, checking identification information and data qualification information, perhaps further comprises frame head information, check information and data qualification information.Wherein, described:
The time cycle information of counting comprises clock count and the accumulative total periodicity information of PN sign indicating number in the PN sign indicating number.Clock count information described here is the recording clock number according to the clock generating of PN sign indicating number generation, to represent the information of a certain particular system time;
Secondary planet frequency-difference information is that produce owing to the satellite clock frequency drift and the frequency difference information reference clock frequency.After state the ground supplement translator that digital signal accepts in the system and can revise its tranmitting frequency according to this secondary planet frequency-difference information.
Time cycle according to above-mentioned PN sign indicating number comprises is counted information and secondary planet frequency-difference information; Add sync id information, checking identification information and data qualification information; Or add frame head information, check information and data qualification information, just can in the digital signal receiving system, realize the synchronous of PN sign indicating number.
Above-mentioned sync id information is used for the PN sign indicating number is carried out sync id; Above-mentioned checking identification information is used for further confirming the original position of frame synchronization; Above-mentioned frame head information is used to represent the beginning of this frame, and above-mentioned check information is used for the PN sign indicating number is carried out verification, and above-mentioned data qualification information is used for the close spoon of expression system and waits other command informations; Other extend informations such as system encryption are provided, and this data qualification information can be for reserving item.
Represented the information content that comprises in the above-mentioned PN sign indicating number in the following table 1.
Table 1
| Information category | Content and meaning |
| Sync id and checking sign or frame head and check information | Confirm sync bit |
| Time cycle is counted information | Clock count, and accumulative total periodicity |
| Secondary planet frequency-difference information | Satellite clock frequency drift and the difference on the frequency that produces in crystal drift that produces |
| Data qualification information | Reserve |
Said business/synchronization motivationtheory device is packed to information source data and system time, and is concrete, also is provided with data encapsulation apparatus in this business/synchronization motivationtheory device.
As shown in Figure 4, described data encapsulation apparatus comprises:
Data split module, are used for that the data that receive are split as at least one and include the packet of setting byte length; Said data fractionation module is split as the data that receive according to the data map mode and comprises the respective byte data package length.
Said data split module after SPI (system packet interface) interface receives the data of a time slot, and the data division in the data is split according to 180 byte lengths, and different mappings mode data length is different, so the removable bag number of telling is different.Table 2 has been listed the removable bag number of telling under the different mappings mode.
Table 2
| The Map mode | Detachable bag number |
| BPSK | 96 |
| QPSK | 192 |
| 16QAM | 384 |
The header packet information generation module is used to generate the header packet information that identifies above-mentioned packet; Said header packet information specifically comprises header packet information sign, packet frequency sign, data packet byte length mark, packet transmitting time sign, reaches the data packet transmission sign.Wherein, said data packet transmission sign comprises time slot mark, byte interleaver device sync id, the configuration change sign that sends packet.
The data encapsulation module is used for above-mentioned header packet information is added on before all bytes of corresponding packet.Still give an example as above-mentioned, data split module data are split the packet that obtains a plurality of 180 byte lengths, and said data encapsulation module was all added the header packet information that said header packet information generation module generates before all bytes of each packet after the fractionation.
The Ku band transmitter is used at the packet of the up traffic channel transmission business of receiving/synchronization motivationtheory device packing and the information source data of information source data modulator output, the PN sign indicating number that the business/synchronization motivationtheory device that receives in up synchronizing channel emission sends.
Said satellite is used for transmitting information source data, packet and the PN sign indicating number that receives to the digital signal receiving system.
Said digital signal receiving system comprises:
Ground supplement translator; Be used to receive information source data and the PN sign indicating number that satellite is transmitted; And carry out the synchronous adjustment of system carrier and sign indicating number according to the PN that receives, the system time information of confirming according to synchronous back demodulating data bag is again sent the information source data message to the terminal demodulates device;
The terminal demodulates device is used to receive the information source data message that satellite is transmitted, and the information source data message that receives is carried out demodulation output;
Source decoder is used for the data message of terminal demodulates device output is decoded.
In the said system, the digital signal emission system is when emission information source data message, and stack emission simultaneously reflects the PN sign indicating number of system time; Like this, the digital signal receiving system just can be carried out the synchronous adjustment of carrier frequency and sign indicating number according to this PN sign indicating number, after the synchronous adjustment through above-mentioned carrier frequency and sign indicating number; The demodulating data bag; Therefrom obtain system time information, all ground supplement translators are transmitted packet according to this system time information to the terminal demodulates device, thereby have realized the synchronous of whole system.
As shown in Figure 3, the ground supplement translator described in the present invention comprises up-conversion module, down conversion module, up-conversion and power amplifier module and data path module, also comprises synchronization module.
Wherein, the data path module comprises numeric data code and carrier frequency tracking module, data demodulation module and data S-band coding module;
Said numeric data code and carrier frequency tracking module, the sign indicating number that is used to realize data synchronously with tracking and carrier frequency synchronously and tracking;
Data demodulation module is used for realizing extracting data from carrier wave, and decodes;
Data S-band coding module is used for decoded data are encoded according to the desired data format of S-band.For example, encode according to CDM or OFDM.
Down conversion module is used for the carrier frequency frequency conversion intermediate frequency that receives, with convenient follow-up realization demodulation.
The up-conversion module is used for that the data that demodulation obtains are converted to S-band and sends.
Up-conversion and power amplifier module are used to accomplish with coding up-conversion to the S-band of S-band or require wave band and according to the system requirements power emission.
Said synchronization module by the PN sign indicating number synchronously and tracking module, time synchronized tracking module, synchronized transmission control module form, wherein,
Synchronous and the tracking module of PN sign indicating number is used for carrying out according to the PN sign indicating number that receives the synchronization acquistion and the tracking of sign indicating number;
The time synchronized tracking module is used for emission source clock that local clock is traced into, and different ground supplement translators is carried out time unification, obtains system time;
The synchronized transmission control module is used for that the data based system time that receives is carried out timing and transmits.
The present invention also provides a kind of wireless digital broadcasting synchronous method, and is as shown in Figure 5, comprises the steps:
Among the present invention, the digital signal emission system is divided into Traffic Channel and synchronizing channel with up channel, and emission comprises the packet of information source data, system time in Traffic Channel, the emission PN sign indicating number corresponding with system time in synchronizing channel.
Said PN sign indicating number comprises the time cycle counting number information that the accumulative total periodicity of clock number in the PN sign indicating number and PN sign indicating number is counted, and the frequency difference information that the frequency difference of satellite crystal is identified.Clock number information described here is the recording clock number according to the clock generating of PN sign indicating number generation, to represent the information of a certain particular system time.
According to the information that above-mentioned PN sign indicating number comprises, add sync id information, checking identification information and data qualification information, or add frame head information, check information and data qualification information, just can in the digital signal receiving system, realize the synchronous of PN sign indicating number.
Said system time can represent that promptly system time can be corresponding to the integral multiple in PN sign indicating number cycle through the cycle of PN sign indicating number.For example, when the PN sign indicating number that adopts 12, the cycle of this PN sign indicating number is 212-1, i.e. 4095 chip times, so, system time can equal this PN sign indicating number cycle, the i.e. time of 4095 chips.
In this step, need encapsulate data during digital signal emission system emission packet, as shown in Figure 6, step comprises:
Step 201 is split as at least one with the data that receive and includes the packet of setting byte length; In this step 201, according to the data map mode data that receive are split as and comprise the respective byte data package length.
Add corresponding packet header identification information before the step 202, all bytes in each packet.Said header packet information specifically comprises header packet information sign, packet frequency sign, data packet byte length mark, packet transmitting time sign, reaches the data packet transmission sign.Wherein, said data packet transmission sign comprises time slot mark, byte interleaver device sync id, the configuration change sign that sends packet.
Still give an example, after data are split as the packet of a plurality of 180 byte lengths, in this step 202, before all bytes of each packet after the fractionation, all add the corresponding header packet information of this packet as aforementioned.
In this step, the digital signal emission system is launched by the amplitude of setting packet and PN sign indicating number when the PN sign indicating number of emission packet and correspondence than stack simultaneously, and its amplitude ratio can be set according to network condition.For example, shown in Fig. 7, the amplitude of packet is 1, and the amplitude of PN sign indicating number also is 1, so, the digital signal emission system when stack emission packet and PN sign indicating number, 0.1 times of desirable PN sign indicating number amplitude with packet stack emission.
The digital signal emission system with packet and PN sign indicating number by the amplitude of setting than superposed and transmitted to satellite, satellite will receive packet and the PN sign indicating number is forwarded to the digital signal receiving system.
As shown in Figure 8, in this step 102, can specifically comprise the steps:
Step 301 is slightly caught the carrier frequency of digital receiving system synchronously.
In this step, carry out the pairing frequency of relevant peaks maximum that the total correlation computing obtains, carry out slightly catching synchronously of carrier frequency according to PN sign indicating number in the setpoint frequency scope.
Be specially, in the frequency range of setting receiving system carried out frequency sweep, promptly under different frequencies, PN sign indicating number copy and PN sign indicating number that the receiving system utilization is corresponding with the PN sign indicating number of emission system carry out the total correlation computing, obtain relevant peaks.For example, the frequency range of employing-400KHz～400KHz is carried out frequency sweep to system.The generation formula of the PN sign indicating number of the PN sign indicating number copy here and emission system emission is identical, and it is identical with the PN sign indicating number of transmitting terminal that this has just guaranteed that also receiving system is carried out the PN sign indicating number of total correlation computing.
Because carrier frequency is asynchronous, the PN sign indicating number is all important on I and Q passage, in order to obtain accurate relevant peaks, can adopt the form of two passage relevant peaks quadratic sums addition, is formulated as:
In the formula, Pesk
fBe current correlation peak, I
PeakBe the correlation peak of current I passage, Q
PeakCorrelation peak for current Q passage.Relevant peaks under a certain frequency f is the maximum Peak of I and Q two-way total correlation quadratic sum
f
Because there are deviation in the carrier frequency of emission system and the carrier frequency of receiving system; Under different deviations; The relevant peaks that obtains there are differences on range value, through adjusting local carrier frequency or on base band data, carrying out predetermined frequency, makes the range value of relevant peaks reach in the maximum magnitude.The roughly deviation delta f that adjusts frequency and be emission system carrier frequency and receiving system carrier frequency of this predetermined frequency or receiving system carrier wave
1According to the above-mentioned roughly deviation delta f that obtains
1Can make the carrier frequency of receiving system and the carrier frequency of emission system realize basic synchronization, promptly realize receiving slightly catching synchronously of system carrier frequency rate.
Step 302 is slightly caught the sign indicating number of digital receiving system synchronously.
In whole system, sign indicating number carries out with the general two cover crystal that adopt of carrier frequency, therefore, carries out crystal clock when catching in the relevant peaks that adopts the PN sign indicating number, not only can receive the nonsynchronous influence of carrier wave, and the while also can receive the nonsynchronous influence of PN sign indicating number.The asynchronous of PN sign indicating number tends to cause the peak value of relevant peaks not high, and on the position at irrelevant peak, produces shake, unsettled situation occurs.In order to realize stable tracking and time synchronous, the sign indicating number of the just necessary communication system of adjustment earlier synchronously.
In this step, carry out slightly catching synchronously of PN sign indicating number according to the PN sign indicating number that receives being carried out total correlation calculating.
Be specially: the PN sign indicating number that receives is carried out total correlation calculate, when the PN sign indicating number was synchronous fully, the double time gap that relevant peaks occurs was the theoretical cycle of PN sign indicating number, has also promptly accomplished slightly catching synchronously of PN sign indicating number.When the inbound pacing of receiving terminal was slow, the distance at its serial correlation peak can be greater than a theoretical cycle of PN sign indicating number; Otherwise, when the inbound pacing of receiving terminal when very fast, the distance at its serial correlation peak can be less than a theoretical cycle of PN sign indicating number.
Carrying out adopting the pointwise Calculation Method when total correlation calculates, promptly in the cycle of each PN sign indicating number, all calculate a bit, like this, accomplish the inferior PN sign indicating number cycle in whole cycle that the The whole calculations process will be carried out the PN sign indicating number.Simultaneously, under the nonsynchronous situation of the system of consideration, the position of relevant peaks can move forward and backward, and therefore, when carrying out total correlation calculating, can calculate time cycle in cycle of 4 PN sign indicating numbers at every turn.To adopt 12 PN sign indicating number is example, just needs to calculate 4 * 4095 * 4095 symbol times.
According to the distance and the PN sign indicating number difference in theoretical cycle of local PN sign indicating number relevant peaks, can reflect the difference on the frequency of local PN sign indicating number and emission system PN sign indicating number.For example, when adopting 12 PN sign indicating number, the distance that calculates local PN sign indicating number relevant peaks is 4050 symbol times, then can be according to formula:
Δf＝(4095-4050)/(4095×4095)
Can calculate the frequency departure of local PN sign indicating number and emission system PN sign indicating number, this frequency departure that calculates is write in the local PN sign indicating number generated frequency, make that the frequency of local PN sign indicating number and emission system PN code frequency are more approaching.
In the relevant peaks process of aforementioned calculation local code, adopt the form of two passage relevant peaks quadratic sums addition, be formulated as:
In the formula, Pesk is current correlation peak, I
PeakBe the correlation peak of current I passage, Q
PeakCorrelation peak for current Q passage.
The total correlation of on above-mentioned definite PN code frequency basis, proceeding the PN sign indicating number calculates, and can continue to confirm the distance of the relevant peaks of local PN sign indicating number, promptly confirms the generated frequency of local PN sign indicating number.For example, the distance of the relevant peaks of the local PN sign indicating number of confirming once more is 4070 symbol times, so, and according to formula:
Δf＝(4095-4070)/(4095×4095)
The littler frequency departure scope of local PN code frequency and emission system PN code frequency can be confirmed, and the frequency of local PN sign indicating number can be adjusted according to this frequency departure that calculates.
As stated above local PN sign indicating number is repeatedly adjusted, can be made the theoretical cycle that cycle of local PN sign indicating number relevant peaks approaches the PN sign indicating number, thereby accomplish slightly catching synchronously of PN sign indicating number.
Step 303 is carried out the second synchronization adjustment to the carrier frequency of digital receiving system.
In this step, carry out the pairing frequency of relevant peaks maximum that the total correlation computing obtains, carry out the second synchronization adjustment of carrier frequency according to PN sign indicating number in the setpoint frequency scope.
Since the relevant peaks of PN sign indicating number receive simultaneously sign indicating number synchronously with the double influence of carrier synchronization, therefore, system also needs carry out second synchronization to carrier frequency, with 1/4 cycle of assurance carrier beat less than the PN sign indicating number after above-mentioned sign indicating number slightly catches synchronously carrying out.
Receiving system is carried out the carrier frequency second synchronization and is slightly caught synchronously slightly to catch on the basis with carrier frequency at above-mentioned sign indicating number and carry out, and its main purpose is to obtain comparatively accurate frequency-splitting, reduces The noise.
Receiving system is carried out frequency sweep in the frequency departure scope when slightly catching less than carrier frequency when carrying out the carrier frequency second synchronization.For example, carry out frequency sweep at frequency departure for the scope of ± 10KHz.
Receiving system is carried out frequency sweep in the said frequencies deviation range, identical with the aforementioned method that carrier frequency is carried out slightly catching synchronously to realize the process of the second synchronization of carrier frequency, no longer goes to live in the household of one's in-laws on getting married at this and chats.
Second synchronization through to carrier frequency can obtain more accurate frequency difference Δ f
2, through this frequency difference Δ f
2Can calculate the carrier frequency of receiving system, thereby realize the second synchronization adjustment of receiving system carrier frequency.
Step 304 is followed the tracks of the sign indicating number and the carrier frequency of digital receiving system synchronously.
After the synchronous adjustment to carrier frequency and sign indicating number in above-mentioned each step; Still, there are the drift of crystal in carrier frequency and sign indicating number and the carrier frequency of emission system and sign indicating number basic synchronization in the receiving system owing to receiving system; The cycle of the PN sign indicating number relevant peaks that obtains in the receiving system and the theoretical cycle of PN sign indicating number also exist certain difference; Therefore, must carry out sign indicating number and follow the tracks of synchronously and carrier synchronization tracking, to realize the stable of system.
Adjust the phase place of receiving system crystal constantly according to the alternate position spike of relevant peaks; And according to the accumulated value of repeatedly adjusting phase place; Calculate the synchronous frequency error of receiving system crystal sign indicating number; And adjustment makes the cycle of final relevant peaks and the theoretical cycle of PN be consistent constantly, thus the synchronous tracking that realizes yard.
For example, be example to adopt 4 code-element periods, find the position of relevant peaks according to total correlation, adjust the phase place of local PN sign indicating number copy, make relevant peaks appear at the centre position of 4 code elements of calculating.Under this kind pattern, correlation computations is parallel 4 continuous phases of calculating, promptly calculates the relevant peaks of 4 code elements.Because relevant peaks is periodically to occur, after local code element is accomplished a PN sign indicating number cycle, in 4 code elements a relevant peaks can appear, because the drift of clock, some deviations may appear in the position of relevant peaks, forward or backward traveling time Δ T.According to the relation of time Δ T and system phase delay, phase deviation Δ φ is formulated as:
The sign indicating number that can obtain system according to following formula generates the phase deviation of crystal, in order to guarantee the stability of a system, reduces the influence of systematic error; System feeds back to the phase compensation ring that sign indicating number generates crystal with 1/4 of phase deviation; Accumulated phase error value simultaneously when the accumulation of phase value reaches some bigger values, is translated into frequency error; And its value fed back to the frequency compensation ring that sign indicating number generates crystal, realized the synchronous tracking of systematic code like this.
After the synchronous tracking of carrying out sign indicating number, also need do the carrier synchronization tracking of system for guaranteeing system's demodulation.
Carrier frequency is more a lot of than the frequency of sign indicating number, so to the carrier phase synchronization sign indicating number difficulty synchronously that compares, but the synchronous tracking of method and above-mentioned yard is similar, also can adopt other phase locked track modes such as Coase tower phase-locked loop.What introduce below is the carrier frequency tracking method that we carry out.
In the synchronous tracing process of above-mentioned sign indicating number, realized the tracking of relevant peaks, promptly the relevant peaks of PN sign indicating number is all the time within the PN sign indicating number of 4 code elements calculating.
The rotation that the asynchronous direct result that causes of carrier wave is a relevant peaks, its phase angle is:
φ＝atan2(I
peak，Q
peak)，
Wherein, I
PeakAnd Q
PeakBe respectively the peak value of I branch road and Q branch road relevant peaks, atan2 representes arctangent cp cp operation, and φ is (Q
Peak/ Q
Peak) arc-tangent value, its codomain be (π, π), if the result of φ, then representes the angle that is rotated counterclockwise from the I axle for just, if the result of φ then representes the angle that turns clockwise from the I axle for bearing.
Therefore, if will realize carrier synchronization tracking, and phase stabilization, just needing angle phi is the normal value φ that confirms
0
The difference DELTA φ at carrier phase angle=φ-φ
0, Δ φ/4 are fed back to the phase loop of carrier wave, then according to formula:
φ
sum＝∑Δφ，
Calculate carrier phase angular difference value sum φ
Sum
Again according to formula:
T＝n×T
pn，
Calculate the time cycle sum T of n relevant peaks, in the formula, n is the relevant peaks number of times, T
PnBe the PN sign indicating number cycle.
Work as φ
SumGreater than the normal value φ that confirms
1The time, with average phase angular speed difference Δ ω=φ
Sum/ T writes the carrier frequency tracking ring as the carrier frequency offset feedback quantity.
Behind the sign indicating number and the synchronous tracking of carrier frequency to digital receiving system, receiving system just can correctly receive and its information source data that receive of demodulation.
Through after the carrier synchronization of step 102 and the sign indicating number adjustment synchronously, the digital signal receiving system can receive satellite and transmit the packet that gets off, and the packet that receives is carried out demodulation.
The demodulating data bag can obtain system time information; Ground supplement translator in the digital signal receiving system is set the delivery time of coded data according to the said system temporal information; And coded data sent according to the delivery time of setting, thereby realize whole system synchronously.
Although embodiment of the present invention are open as above; But it is not restricted to listed utilization in specification and the execution mode; It can be applied to various suitable the field of the invention fully, for being familiar with those skilled in the art, can easily realize other modification; Therefore under the universal that does not deviate from claim and equivalency range and limited, the legend that the present invention is not limited to specific details and illustrates here and describe.
Claims (22)
1. a ground supplement translator comprises up-conversion module, down conversion module, up-conversion and power amplifier module and data path module, it is characterized in that, also comprises synchronization module;
Said synchronization module comprises:
Synchronous and the tracking module of PN sign indicating number is used for carrying out according to the PN sign indicating number corresponding with system time that receives the synchronization acquistion and the tracking of sign indicating number;
The time synchronized tracking module is used for emission source clock that local clock is traced into, and different ground supplement translators is carried out time unification, obtains system time;
The synchronized transmission control module is used for that the data based system time that receives is carried out timing and transmits.
2. the system that wireless digital broadcasting is synchronous comprises digital signal emission system, satellite, digital signal receiving system, it is characterized in that,
Said digital signal emission system comprises the packet of information source data, system time and the PN sign indicating number corresponding with system time to satellites transmits;
The PN sign indicating number that said digital signal receiving system is transmitted according to satellite carries out system carrier frequency and sign indicating number adjustment synchronously, and starts receiving system according to the system time information that the demodulating data bag obtains; Be specially: the ground supplement translator in the said digital signal receiving system receives information source data and the PN sign indicating number that satellite is transmitted; And carry out the synchronous adjustment of system carrier frequency and sign indicating number according to the PN sign indicating number that receives, the system time information of confirming according to synchronous back demodulating data bag is again sent the information source data message to the terminal demodulates device.
3. system as claimed in claim 2 is characterized in that, said PN sign indicating number comprises that the time cycle counts information and secondary planet frequency-difference information.
4. system as claimed in claim 3 is characterized in that, said PN sign indicating number also comprises sync id information, checking identification information and data qualification information, or frame head information, check information and data qualification information.
5. like claim 2 or 3 or 4 described systems, it is characterized in that said digital signal emission system is provided with:
Business/synchronization motivationtheory device is used to receive the information source data that the information source data modulator sends, and information source number is reached the system time packing of generation according to this, is sent to the Ku band transmitter with the PN sign indicating number stack that generates.
6. system as claimed in claim 5 is characterized in that, is provided with data encapsulation apparatus in said business/synchronization motivationtheory device, and this device comprises:
Data split module, are used for that the data that receive are split as at least one and include the packet of setting byte length;
The header packet information generation module is used to generate the header packet information that identifies above-mentioned packet;
The data encapsulation module is used for above-mentioned header packet information is added on before all bytes of corresponding packet.
7. system as claimed in claim 6 is characterized in that, said data fractionation module is split as the data that receive according to the data map mode and comprises the respective byte data package length.
8. system as claimed in claim 6 is characterized in that, said header packet information comprises header packet information sign, packet frequency sign, data packet byte length mark, packet transmitting time sign, reaches the data packet transmission sign.
9. system as claimed in claim 8 is characterized in that, said data packet transmission sign comprises time slot mark, byte interleaver device sync id, the configuration change sign that sends packet.
10. method that wireless digital broadcasting is synchronous is characterized in that step comprises:
Step 1, the emission of digital signal emission system comprises the packet of information source data, system time, and the PN sign indicating number corresponding with system time;
Step 2, digital signal receiving system are carried out the synchronous adjustment of system carrier frequency and sign indicating number according to the PN sign indicating number that receives; This step is specially: the ground supplement translator in the digital signal receiving system receives information source data and the PN sign indicating number that satellite is transmitted, and carries out the synchronous adjustment of system carrier frequency and sign indicating number according to the PN sign indicating number that receives;
Step 3, the packet that digital signal receiving system demodulate reception arrives, and start receiving system according to wherein system time information; This step is specially: the ground supplement translator in the digital signal receiving system sends the information source data message to the terminal demodulates device according to the system time information that synchronous back demodulating data bag is confirmed.
11. method as claimed in claim 10 is characterized in that, in the said step 1, system time is corresponding to the integral multiple in PN sign indicating number cycle.
12. method as claimed in claim 10 is characterized in that, in the said step 1, the digital signal emission system is launched by the amplitude of setting packet and PN sign indicating number than stack.
13., it is characterized in that said PN sign indicating number comprises that the time cycle counts information and secondary planet frequency-difference information like claim 10 or 11 or 12 described methods.
14. method as claimed in claim 13 is characterized in that, said PN sign indicating number also comprises sync id information, checking identification information and data qualification information, or frame head information, check information and data qualification information.
15. method as claimed in claim 10 is characterized in that, in the said step 1, during digital signal emission system emission packet data is encapsulated, step comprises:
Step 101 is split as at least one with the data that receive and includes the packet of setting byte length;
Add corresponding packet header identification information before the step 102, all bytes in each packet.
16. method as claimed in claim 15 is characterized in that, in the said step 101, according to the data map mode data that receive is split as and comprises the respective byte data package length.
17. method as claimed in claim 15; It is characterized in that; In the said step 102, packet header sign packets of information is drawn together header packet information sign, packet frequency sign, data packet byte length mark, packet transmitting time sign, is reached the data packet transmission sign.
18. method as claimed in claim 17 is characterized in that, said data packet transmission sign comprises time slot mark, byte interleaver device sync id, the configuration change sign that sends packet.
19. method as claimed in claim 10 is characterized in that, the method for adjusting synchronously in the said step 2 comprises the steps:
Step 201 is slightly caught the carrier frequency of digital receiving system synchronously;
Step 202 is slightly caught the sign indicating number of digital receiving system synchronously;
Step 203 is carried out the second synchronization adjustment to the carrier frequency of digital receiving system;
Step 204 is followed the tracks of the sign indicating number and the carrier frequency of digital receiving system synchronously.
20. method as claimed in claim 19 is characterized in that, in the said step 201, carries out the pairing frequency of relevant peaks maximum that the total correlation computing obtains according to PN sign indicating number in the setpoint frequency scope, carries out slightly catching synchronously of carrier frequency.
21. method as claimed in claim 19 is characterized in that, in the said step 202, carries out slightly catching synchronously of PN sign indicating number according to the PN sign indicating number that receives being carried out total correlation calculating.
22. method as claimed in claim 19 is characterized in that, in the said step 203, carries out the pairing frequency of relevant peaks maximum that the total correlation computing obtains according to PN sign indicating number in the setpoint frequency scope, carries out the second synchronization adjustment of carrier frequency.
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| CN110160577A (en) * | 2019-06-20 | 2019-08-23 | 广东工业大学 | A kind of angle displacement measurement method of incremental rotary encoder, device and equipment |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1536800A (en) * | 1997-07-03 | 2004-10-13 | ��ʽ���綫֥ | Satellite broadcasting system |
| CN1677909A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | Frame synchronizing method for time-domain synchronous orthogonal frequency-division duplex receiver and system |
| CN1677911A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | Carrier-wave recovering method for time-domain synchronous orthogonal frequency-division duplex receiver and system thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1536800A (en) * | 1997-07-03 | 2004-10-13 | ��ʽ���綫֥ | Satellite broadcasting system |
| CN1677909A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | Frame synchronizing method for time-domain synchronous orthogonal frequency-division duplex receiver and system |
| CN1677911A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | Carrier-wave recovering method for time-domain synchronous orthogonal frequency-division duplex receiver and system thereof |
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