CN1638314A - Signal transmission method of digital TV ground transmission system - Google Patents
Signal transmission method of digital TV ground transmission system Download PDFInfo
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- CN1638314A CN1638314A CN 200410039115 CN200410039115A CN1638314A CN 1638314 A CN1638314 A CN 1638314A CN 200410039115 CN200410039115 CN 200410039115 CN 200410039115 A CN200410039115 A CN 200410039115A CN 1638314 A CN1638314 A CN 1638314A
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Abstract
The present invention discloses one kind of signal transmission method for digital TV ground transmission system. The transmitted data flow is divided into continuous data frames for transmission, and each of the data frames includes 2048 bit long preset information, 128 bit long system information and data information of 32768 symbol length, with the data frames forming simple first order circulation. The present invention adopts simple data frame structure as the data structure in signal transmission for digital TV ground transmission system, and the data circulate in frames easily. Constituting the preset information with PN2047 can obtain fast and reliable system sync and fast and accurate channel estimation, and adopting frequency expanded system information makes the distinction and processing in the receiving end more reliable. The present invention can well support single carrier frequency domain treating technology.
Description
Technical field the invention belongs to field of signal transmissions, the method for transmission signals in particularly a kind of DTB Digital Terrestrial Broadcasting transmission.
The data structure of the present digital tv ground broadcasting of background technology generally is divided into two big classes: a class is to be the Frame/field/segment structure of the single carrier wave time domain transmission feature of representative with U.S. ATSC, and another kind of is to be the data frame structure of the multicarrier frequency domain transmission feature of representative with European DVB-T.
With reference to Fig. 1, the ATSC data structure of the U.S., be that the data segment of forming with the data message of section synchronous head and some is a minimal circulation unit, the field sync signal section of 312 data segments and 1 equal length is formed 1 data fields, and two data fields are formed 1 Frame.Data structure is carried out each self-loopa with three cycles of section, field, frame.
Segment sync signal is selected 1,0,0,1 form, helps receiving terminal and regularly recovers.Field sync signal has 1 PN511 sequence, 3 PN63 sequences of order, and suitable reservation position constitutes.Wherein second PN63 sequence got 1 time instead every 1.PN63 negate in the not negate of PN63 in the field synchronization of the 1st data fields of 1 Frame, the field synchronization of second data fields.Thereby, divided the boundary of Frame by the negate of PN63.
Data message in the data structure of ATSC system concentrates in the data segment, consider the channel coding method that the ATSC system adopts, in fact the data message of depositing in each data segment is exactly 1 data (not comprising sync byte 47H) through coding, mapping back MPEG bag.Therefore there are the relation of integral multiple in the data message that comprises in 1 data fields or the Frame and MPEG bag, and promptly 312 are wrapped through the MPEG after coding, the mapping, do not comprise field synchronization segments.Just mean that also the digital coding mode exists certain association with data structure.In fact, the degree of depth of the byte-interleaved that ATSC adopts also just in time is 52 data segments, and synchronizing signal is not participated in coding.
The ATSC system data structure is huge, and complicated.1 data fields is about 24ms, is unfavorable for following the tracks of channel variation faster.The data structure complexity, the relevance that exists with coded system has suppressed system's employing possibility of coded system more efficiently, lacks flexibility, has restricted the space of development.
Figure 2 shows that the data frame structure of the typical frequency domain transmission of DVB-T system.System with the OFDM symbol as least unit.68 OFDM symbols are formed 1 Frame, and 4 Frames are formed a data superframe.
In 1 OFDM symbol, form at interval by the data carrier of respective number and its protection.In fact protection takes from the part of data carrier at interval, and its length decision systems is to the anti-multipath interference capability.Be used to follow the tracks of the pilot frequency information of the characteristic of channel and the TPS of bearing system information, pressed certain regular-scattered in data carrier.Because the characteristics that the multicarrier area block is handled, and the pilot tone in order to track channel change is again to be present on the data carrier with discrete form, therefore influenced the ability of system keeps track channel variation, can't resemble in the above-mentioned single-carrier system to come and the pointwise tracking of data fast change of channel own with continuous P N sequence.
Summary of the invention the purpose of this invention is to provide a kind of new digital signal transmission method.This method for transmitting signals has simple data structure, but can realize system synchronization rapidly, reliably and carry out channel estimating rapidly, exactly, and this transmission method can be used for the DTB Digital Terrestrial Broadcasting transmission system.
The method for transmitting signals of the present invention's design is such: in digital terrestrial television transmission system, data flow transmitted is divided into continuous one by one Frame and transmits.Each Frame comprises 3 parts, is respectively preset information, system information and data message, and forms simple single order circulation with this.
The effect of preset information is a usefulness of making system synchronization, clock recovery, channel estimating and equalizer training.In digital terrestrial television transmission system, preset information can be selected the two level time domain PN sequences that correlation properties are good, frequency spectrum is smooth, comes the synchronous and channel estimating of auxiliary system.For ease of carrying out the fast Fourier transform (FFT) computing that frequency domain is handled, as be used for the adaptive frequency domain equilibrium, preset information length should be chosen as 2 power power.For this reason, preset information can satisfy by the two level deterministic signals that the PN sequence increases suitable figure place.
For obtain rapidly, reliably system synchronization and rapidly, channel estimating accurately, the present invention selects PN2047 as the two level PN sequences that constitute preset information.Consider that satisfying preset information length is 2 power power, PN2047 becomes the preset information that length is 2048 two level symbols after adding last 1 two level deterministic signal again.
System information is expressed by two sequence of levels.The length of system information can be selected according to the difference of business demand, and discerns automatically at receiving terminal, is 2 power power but should satisfy.Such as, under wire transmission mode, system information can be 32 or 64 long, and under wireless communication mode, can select 64 or 128 long.
System information in the data structure is the transmission mode that is used for determining this frame of data information, comprises modulation system, coded system etc., so that receiving terminal is made corresponding processing.Especially under mixed mode transmissions, the identification of system information is very important.Therefore system information can be passed through certain processing when transmission, can be discerned reliably at receiving terminal guaranteeing.The present invention takes the spread spectrum resist technology to strengthen the robustness of system information, adopts the direct sequence spread spectrum method to finish, and is used for resisting the situation that has abominable channel fading in digital TV ground transmission.
Data message can be two level datas, also can be many level datas.The length of data message is by the decision of the transmission means that comprises in the system information, is 2 power power but also should satisfy.
Three kinds of business of digital tv ground broadcasting transmission of the present invention are respectively the fixing receptions of TV signal (fixed service), TV signal moves reception (mobile service) and data-signal moves reception (data service).Wherein, fixed service can be selected the 16-OQAM transmission mode; Mobile service can be selected 4-OQAM transmission mode or its enhancement mode (4-OQAM-E), and the 4-OQAM-E transmission mode can be by realizing in conjunction with modes such as Nordstrom-Robinson sign indicating numbers in the 4-OQAM transmission mode; Data service can be selected the 4-OQAM-E transmission mode.Under mixed transmission modes, miscellaneous service modulating mode separately is that unit mixes arbitrarily with the frame, and the modulating mode of each frame is spelt out by the system information in this frame.
(application number is a patent of having filed an application to the applicant: 200310113281.3) similar, the present invention has adopted simple data frame structure as the data structure in the digital TV ground transmission, data are loop cycle with the frame only, each Frame is by preset information, system information and data message are formed, and realize simple; Preset information length, system information length and data message length are 2 power power, can support to use the single-carrier frequency-domain treatment technology well.And the present invention replaces PN1023 to constitute preset information with PN2047, can obtain more rapid, reliable system synchronization and rapidly, channel estimating accurately; The length of data message has been increased by one times, can promptly improve the effective information transmission code rate guaranteeing to significantly improve data transmission efficiency under the prerequisite of the stability of a system.
Below in conjunction with drawings and Examples the present invention is described further.
Description of drawings Fig. 1 is the method for transmitting signals of Frame/field/segment structure of U.S. ATSC.
Fig. 2 is the data transmission method of European DVB-T.
The method for transmitting signals of the data structure that Fig. 3 designs for the present invention.
Fig. 4 is generating mode and the preset value of PN2047.
Fig. 5 is generating mode and the preset value of PN127.
Embodiment is referring to Fig. 3, and in digital terrestrial television transmission system, data flow transmitted is divided into continuous one by one Frame and transmits.Each Frame comprises 3 parts, is respectively preset information, system information and data message, and forms simple single order circulation with this.
The effect of preset information is a usefulness of making system synchronization, clock recovery, channel estimating and equalizer training.For obtain rapidly, reliably system synchronization and rapidly, channel estimating accurately, the present invention selects PN2047 as the two level PN sequences that constitute preset information, adding last 1 two level deterministic signal simultaneously is 2 power power to satisfy preset information length.For the spectral characteristic of make adding the preset information after the deterministic signal still keeps smooth, selection know that it is zero that signal should guarantee to make level and (average) after the preset information mapping.For this reason, the two level deterministic signals of adding in the present embodiment are ' 0 ', and it is the preset information of 2048 two level symbols that the mapping back constitutes length.
The generator polynomial of PN2047 is: X
11+ X
9+ 1; Initial value is 00000000001.The producing method of PN2047 is seen Fig. 4.
System information is expressed by two sequence of levels.The length of system information can be selected according to the difference of business demand, and discerns automatically at receiving terminal, is 2 power power but should satisfy.
Because system information is comprising modulation system, coded system etc. to the very important information of receiver processing module, therefore, present embodiment adopts the WALSH sequence on 128 rank to become 128 two level symbol sequences, and carries corresponding system information through after the randomization.Like this, can recover system information more reliably, guarantee the operate as normal of each module of receiver at receiving terminal.
Each system information is expressed by two sequence of levels of one 128 bit.And the sequence of these two level has 128, is derived from 128 long Walsh pieces.Basic Walsh piece is seen formula 2-1, and the systematization production method of Walsh piece is seen formula 2-2.
The Walsh piece that formula 2-1 is basic
The systematization production method of formula 2-2 Walsh piece, wherein H is the Walsh piece of last single order, "-" is negate.
With above-mentioned 128 128 long Walsh vector negates, the Walsh vector can be increased to 256.For obtaining the frequency spectrum flatness, these 256 vectors and length are to obtain 256 system information vectors behind 128 the random sequence XOR.It is to add one ' 0 ' generation after 127 the 7 rank maximal-length sequences that this random sequence produces a length by the shift register of one 7 bit.The method that produces these 127 maximal-length sequences is seen Fig. 5.Its generator polynomial is: X
7+ X
3+ 1, initial value is 0000001.
In corresponding 256 the system information vectors of every kind of transmission mode one, other vectors are as retained-mode.The definition that below is each pattern is given an example:
The 1st vector keeps
The 2nd vector keeps
The 3rd vector keeps
The 4th vector keeps
The 5th vector 16-OQAM
The 6th vector keeps
The 7th vector 4-OQAM
The 8th vector keeps
The 9th vector 4-OQAM-E
The 10th vector keeps
Other vector keeps
Wherein, the even number vector all is the negate of its last odd number vector.That is to say the 6th vector=the 5th vector negate, the 8th vector=the 7th vector negate, the 10th vector=the 9th vector negate ...
When receiver receives retained-mode, signal is not dealt with, skip this frame.
Data message can be two level datas, also can be many level datas.The length of data message is by the decision of the transmission means that comprises in the system information, is 2 power power but should satisfy.Three kinds of business of digital tv ground broadcasting transmission of the present invention are respectively fixed service, mobile service and data service.Wherein, fixed service can be selected the 16-OQAM transmission mode; Mobile service can be selected 4-OQAM or 4-OQAM-E transmission mode; Data service can be selected the 4-OQAM-E transmission mode.In the present embodiment, under each transmission mode, the length of data message all is defined as 32768 symbols.But under the 16-OQAM transmission mode, data message is chosen as the data symbol of four level, and each data symbol is 2 bits; And in 4-OQAM and 4-OQAM-E transmission mode, data message is chosen as the data symbol of two level, and each data symbol is 1 bit.Like this:
Under the 16-OQAM transmission mode, each Frame comprises the preset information (PN2047+ ' 0 ') that 1 length is 2048 two level data symbols; Length is the system information (corresponding above-mentioned the 5th vector) of the spread spectrum protection of 128 two level data symbols; The data message of every frame is totally 32768 four level symbols, and each data symbol is 2 bits, four level symbols.
Under the 4-OQAM transmission mode, each Frame comprises the preset information (PN2047+ ' 0 ') that 1 length is 2048 two level data symbols; Length is the system information (corresponding above-mentioned the 7th vector) of the spread spectrum protection of 128 two level data symbols; The data message of every frame is totally 32768 two level symbols, and each data symbol is 1 bit, two level symbols.
Under the 4-OQAM-E transmission mode, each Frame comprises the preset information (PN2047+ ' 0 ') that 1 length is 2048 two level data symbols; Length is the system information (corresponding above-mentioned the 9th vector) of the spread spectrum protection of 128 two level data symbols; The data message of every frame is totally 32768 two level symbols, and each data symbol is 1 bit, two level symbols.
Under mixed transmission modes, miscellaneous service modulating mode separately is that unit mixes arbitrarily with the frame, and the modulating mode of each frame is spelt out by the system information in this frame.
Claims (10)
1. the method for transmitting signals in the digital television ground broadcast transmission system, data flow is divided into continuous one by one Frame and transmits, each Frame comprises the preset information that can be used as system synchronization, clock recovery, channel estimating and equalizer training, the system information that can be used for characterizing this frame of data information transmission mode, this three part of data message, and forms simple single order circulation with this; It is characterized in that:
Preset information is that a length is 2048 two level symbol sequences, adds last 1 two level deterministic signal again by 1 two level time domain PN sequence PN2047 and constitutes;
System information is two sequence of levels through spread spectrum protection, and it is 2 power power that length satisfies;
Data message is two sequence of levels or many sequence of levels, and it is 2 power power that length satisfies.
2. method for transmitting signals according to claim 1 is characterized in that: two sequence of levels of 128 bits of described system information after with randomization are represented;
Described data message length is 32768 symbols, and under the 16-OQAM transmission mode, data message is four level symbols, and each data symbol is 2 bits; Under 4-OQAM and 4-OQAM-E transmission mode, data message is two level symbols, and each data symbol is 1 bit;
Under mixed transmission modes, miscellaneous service modulating mode separately is that unit mixes arbitrarily with the frame, and the modulating mode of each frame is spelt out by the system information in this frame.
3. method for transmitting signals according to claim 1 and 2 is characterized in that: adopt the WALSH code word on 128 rank to generate 128 128 long WALSH vectors, synthesize 256 vectors with 128 original set of vectors after this 128 WALSH vectors negate;
Be to obtain 256 system information vectors behind 128 the random sequence XOR with aforementioned 256 vectors that obtain and length, be used to represent system information;
In corresponding 256 the system information vectors of every kind of transmission mode one, its complement vector, does not deal with signal when receiver receives retained-mode as retained-mode, skips this frame.
4. method for transmitting signals according to claim 1 and 2 is characterized in that: the generator polynomial of described PN2047 is X
11+ X
9+ 1, initial value is 00000000001.
5. method for transmitting signals according to claim 3 is characterized in that: the generator polynomial of described PN2047 is X
11+ X
9+ 1, initial value is 00000000001.
6. method for transmitting signals according to claim 4 is characterized in that: 1 the two level deterministic signal value of adding in the preset information is elected " 0 " as, so that the level after the preset information mapping and be zero.
7. method for transmitting signals according to claim 5 is characterized in that: 1 the two level deterministic signal value of adding in the preset information is elected " 0 " as, so that the level after the preset information mapping and be zero.
8. method for transmitting signals according to claim 3 is characterized in that: the length of shift register generation that adopts one 7 bit is 127 7 rank maximal-length sequences, and its generator polynomial is X
7+ X
3+ 1, initial value is 0000001;
The above-mentioned 7 rank maximal-length sequences that obtain are added one " 0 ", and to form length be 128 random sequence, be used for 256 vector XORs to obtain 256 system information vectors.
9. method for transmitting signals according to claim 5 is characterized in that: the length of shift register generation that adopts one 7 bit is 127 7 rank maximal-length sequences, and its generator polynomial is X
7+ X
3+ 1, initial value is 0000001;
The above-mentioned 7 rank maximal-length sequences that obtain are added one " 0 ", and to form length be 128 random sequence, be used for 256 vector XORs to obtain 256 system information vectors.
10. method for transmitting signals according to claim 7 is characterized in that: the length of shift register generation that adopts one 7 bit is 127 7 rank maximal-length sequences, and its generator polynomial is X
7+ X
3+ 1, initial value is 0000001;
The above-mentioned 7 rank maximal-length sequences that obtain are added one " 0 ", and to form length be 128 random sequence, be used for 256 vector XORs to obtain 256 system information vectors.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100373917C (en) * | 2006-04-24 | 2008-03-05 | 上海交通大学 | Synchronous method for channel decodable bit interleave or rescrambling code in digital television ground transmission |
| CN101286958B (en) * | 2008-04-18 | 2010-12-15 | 北京航空航天大学 | Terrestrial broadcasting channel estimating method for digital television and device thereof |
| CN101110626B (en) * | 2006-07-17 | 2012-01-04 | 上海高清数字科技产业有限公司 | Digital signal emitting and receiving system and method thereof |
| CN104202114A (en) * | 2006-07-17 | 2014-12-10 | 上海高清数字科技产业有限公司 | Digital signal transmit-receive system and transmit-receive method (III) |
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2004
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100373917C (en) * | 2006-04-24 | 2008-03-05 | 上海交通大学 | Synchronous method for channel decodable bit interleave or rescrambling code in digital television ground transmission |
| CN101110626B (en) * | 2006-07-17 | 2012-01-04 | 上海高清数字科技产业有限公司 | Digital signal emitting and receiving system and method thereof |
| CN103067117A (en) * | 2006-07-17 | 2013-04-24 | 上海高清数字科技产业有限公司 | Digital-signal transmit-receive system and transmit-receive method thereof |
| CN104202114A (en) * | 2006-07-17 | 2014-12-10 | 上海高清数字科技产业有限公司 | Digital signal transmit-receive system and transmit-receive method (III) |
| CN103067117B (en) * | 2006-07-17 | 2015-08-05 | 上海高清数字科技产业有限公司 | Digital signal receive-transmit system and receiving/transmission method |
| CN106953712A (en) * | 2006-07-17 | 2017-07-14 | 上海高清数字科技产业有限公司 | Data signal receive-transmit system and receiving/transmission method |
| CN104202114B (en) * | 2006-07-17 | 2018-11-02 | 上海高清数字科技产业有限公司 | Digital signal receive-transmit system and receiving/transmission method |
| CN106953712B (en) * | 2006-07-17 | 2020-07-24 | 上海高清数字科技产业有限公司 | Digital signal transmitting and receiving system and method |
| CN101286958B (en) * | 2008-04-18 | 2010-12-15 | 北京航空航天大学 | Terrestrial broadcasting channel estimating method for digital television and device thereof |
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