CN101494759B - Single frequency net system for multi-channel of digital television ground broadcast - Google Patents

Abstract

A digital television terrestrial broadcasting multi-channel single frequency network system adopts mature digital data signal interface and system frame structure, channel coding and modulation techniques meeting China national standard GB20600-2006 to perform source and channel processing; transmitting stations takes a frequency in the decimetric wave frequency range, configure in identical or different power in single-channel, multi-channel signal power provided in adjacent channels or alternate channel after passive device synthesis or aerial synthesis, and then perform wireless transmission to single or a plurality of broad-band transmission antennae; adopts wired or wireless transmission links back up for each other to achieve signal transmission, forms a one-point transmitting to multi-point receiving star link or bus-type branch multi-node branch-type chain to perform distance transmission and receiving, constructs multi-channel single frequency network signal transmission chain required by relay stations, and uses a variety of relay stations to form a large region multi-channel single-frequency transmitting overlay network; the client end fixedly, movably or portably receiving.

Description

The multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting

Technical field

The present invention relates to a kind of Digital Television Terrestrial Broadcasting (Digital Television Terrestrial Broadcasting, DTTB) transfers net system, particularly a kind of multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting (Multi-channel Single Frequency Network system, M-SFN).

Background technology

In order to adapt to complicated terrestrial broadcasting transmission environment, there are three kinds of DTTB standards at present in the world: (the Advanced television Systems Committee of the U.S. advanced television standard committee, ATSC), (Digital Video Broadcasting-Terrestrial is DVB-T) with Japanese ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) for the Europe digital video broadcast-terrestrial.The DTTB standard of China is being declared the 4th international standard.The operating service pattern of DTTB network has three major types: 1) national public welfare free service; 2) paid service of market economy; 3) both patterns of having concurrently.

At present, the networking technology that international DTTB is relevant has three major types: 1) " single frequency network " (Single Frequency Network, SFN): each transmitter sends same digital television program (DVB-T in Europe is used for moving the reception networking) at same television channel.2) " multiple frequency network, MFN " (Multi-Frequency Network, MFN): same digital television program is sent by the different television channels of different transmitters; And (translator) realize the conversion (ATSC of the U.S. be used for fixing receive networking) of television channel by " transponder ".3) " digital same-frequency road repeater " (DOCR): at the same program of same television channel " repeating transmission ", the receiving terminal demodulator the signal from DOCR, is used as " echo " of " main signal " on principle.

The modulation that the DTTB of various countries, Europe adopts is high bit rate 64-quadrature amplitude modulation (Quadrature Amplitude Modulation, QAM) or middle bit rate 16-QAM (this signal can move reception), the business of carrying out be high (in) bit rate is fixing receives; The independent QPSK of employing of certain country of Europe that do not appear in the newspapers as yet modulates, and carries out the business of mobile receiving mode.Singapore employs the television channel emission qpsk modulation signal of 1 8MHz bandwidth, is used for the business that low bit rate moves receiving mode; Also employ the television channel emission 64-QAM modulation signal of another one 8MHz bandwidth, be used for the fixedly business of receiving mode of high bit rate.Because they have only employed two television channels altogether and carry out ground digital television broadcast, there not be the situation of appearance " fixedly the business of the business of receiving mode and mobile receiving mode at the adjacent television channel of same transmitting station and deposit " yet.In fact the DVB-T standard is 7.61MHz owing to the signal code check takies the television channel bandwidth, the roll-off characteristic of employed before being fed to antenna " multiplexer " does not reach technical reasons such as requirement in that a plurality of adjacent channels are synthetic, generally is not suitable for adopting the adjacent setting of emission on the same stage frequently again.Moving the business of reception even if carry out, also is the SFN system of the single television channel in a urban area.

The ATSC/8VS single-carrier system of the U.S. can not support to move the business of reception; can only support that the fixing reception of single transmitting station DTTB is professional; since this system to the requirement of the protective rate (D/U) of adjacent channel up and down than the low 12dB of DVB-T multicarrier system, just than the setting of emission on the same stage that is easier to adopt neighbour's frequency.But can not support the networking of SFN and take the MFN networking mode to solve large-scale same program covering problem.

Japan's ISDB-T standard study emphasis be ground digital high definition TV (High Definition Television, HDTV) broadcasting; Just begin to utilize the centre " frequency range " of 13 frequency ranges in its 6MHz channel to carry out the tentative broadcasting of low bit rate mobile TV recently.

This shows, do not appear in the newspapers as yet in each developed country " high bit rate fixedly the business of receiving mode and business that low bit rate moves receiving mode at same transmitting station adjacent channel and deposit " and carry out the example of (or test) in certain city or area.More do not adopt this technology setting to carry out the engineering practice of big regional networking.

TV service is all accepted by the terrestrial broadcasting mode in most of cities and towns of China and rural area, accounts for more than 60% of TV user sum.According to China's actual conditions, " fixing receive " be " popularity " (majority), the trans-regional property covering of its DTTB is more intense; And " move receive " in the quite long period of history be " minority's property " (minority), but it is at home under the condition of the high speed development network of communication lines, the covering of the trans-regional property of its DTTB equally also can constantly strengthen.The business model that distinct Chinese characteristics DTTB will be practical from now on is likely: when realizing that big zone covers, promptly in same covering service area, have in 3 above DTTB television channels, having only decimal (1) television channel is the business of mobile receiving mode, and all the other majorities (more than 2) television channel all is the fixing business of receiving mode.Such market characteristics, the television channel that just needs to realize technically the mobile receiving mode of (one) high-power emission (comprising relaying) and the emission of (a plurality of) small-power fixedly receiving mode television channel on the same stage (net) set up.With regard to future world DTTB development trend, such network configuration is suitable for the overseas market equally.

Realize the homogeneity of the DTTB on a large scale network coverage of many television channels, multiple business, it is quite complicated to deal with problems technically, but its key is at link; Essence is in precision; The breach is on neighbour's frequency.The single frequency network of a plurality of television channels can be linked into a reliable and stable nerve of a covering well on a large scale, and this is crucial.This also is global technical barrier.

Realize the DTTB homogeneity network coverage on a large scale, what key breakthrough is exactly adjacent networking technology frequently.Wireless frequency particularly decimeter wave frequency is just so much, handles wireless videocast (transition stage) analog signal-digital signal again with broadcasting; Move with fixing receiving mode and the concrete requirement of implementing such as launch on the same stage.Therefore, in any case also put not open digital signal-digital signal in the wireless videocast, the technical problem of the adjacent networking frequently of digital signal-Mo word signal particularly relates to making a start and the receiving end problem of digital signal-digital signal, digital signal-Mo word signal adjacent frequency of large and small power in the middle of this.Especially fixedly realize the covering that repeats in receiving mode wants on a large scale, do not solve adjacent problem frequently and just be difficult to carry out, also just can't break away from the puzzlement that the frequency resource anxiety is presented with frequency.

Summary of the invention

The object of the present invention is to provide a kind of multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting, it is with Digital Television multichannel decimeter wave distribution system (Digital Television Multichannel UHF Distribution System, numeral MUDS) system frame structure among part technical attributes and the GB GB20600-2006, chnnel coding and modulation system merge, trend in conjunction with following DTTB market development, produced and utilized system frame structure among the GB GB20600-2006, some achievement of the technical advantage of chnnel coding and modulation system and Modern Manufacturing Technology progress, formed in the same covering service area of DTTB release be fit to high bit rate fixedly the business of receiving mode and business that low bit rate moves receiving mode in the system that is close to or separates channel and deposit.Promptly in the DTTB network system, adopt with system frame structure among the data signal interfaces (as: MPEG-2 or AVS etc.) of maturation and the GB GB20600-2006, after chnnel coding and modulation technique are carried out processing such as information source and channel, transmitting station (station) adopts the frequency of decimeter wave (UHF) frequency range (300MHz-860MHz-3000MHz), with the identical or different power configuration of single channel size, and with the neighbour frequently or every the multichannel signal power that is provided with frequently behind passive device synthetic (or aerial synthetic), be that the broadband transmitting antenna of 16-300MHz carries out the network system that the formed transmission emission of wireless transmission covers through single or multiple bandwidth again.

Single frequency network (SFN) signal of a plurality of channels of the multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting, be not rely on global positioning system (Global Position System, GPS), adopt wired (optical fiber) or wireless (the containing microwave) transmission link that backups each other to realize the signal transmission.Form and to be emitted to multiple spot on one point and to receive in star-like link or the bus type branch multinode branch type link and carry out long-distance transmissions and reception, framework relaying station desired signal transmission link, and form the emission overlay network of the multichannel single frequency network in big zone by the various relaying stations.Finally by user side with wireless receiving antenna (orientation or omnidirectional) and top box of digital machine or digital television is fixed, move or portable reception tens cover standard definition television (Standard Definition Television, SDTV) or some cover high definition TVs (High Definition Television, HDTV) program, Focus TV, data broadcasting etc. form the Radio Network System that the DTTB transmission covers.

A kind of multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting is characterized in that it comprises central front end-central transmitting station 1, signal transmission link 2, the relaying station 3, receiving unit 4 wherein:

The programme signal of the program signal input part 1-1 of described central front end-central transmitting station 1 inputs to message source process part 1-2, each road message source process passage 1-2-1 of this message source process part 1-2 ... after 1-2-n carries out source encoding-multiplexing-scrambling or not scrambling of part processing to the multiple programs signal, to satisfy each channel payload data requirement signal and export described Channel Processing part 1-3 to, each Channel Processing passage 1-3-1 of this Channel Processing part 1-3 ... 1-3-n is treated as each channel signals by chnnel coding and modulation system respectively; Each single frequency network signal of described Channel Processing part 1-3 transfers out through single frequency network signal emission part 1-6; Radiofrequency signal output is launched through emission unit-synthetic-emission antenna feeder part 1-4 in each channel of described Channel Processing part 1-3;

The data of described central front end-central transmitting station 1-part 1-5 of software administration control centre links to each other with the corresponding interface of described program signal input part 1-1, message source process part 1-2, Channel Processing part 1-3; Data such as the user management data of described Subscriber Management System 1-5-1, condition receiving system 1-5-2, Radio Data System 1-5-4, electronic program guidance system (EPG) 1-5-5, other system 1-5-6, condition receiving management control data, data broadcasting information, electronic program guide information, other video flowings and distribution control information are input to corresponding interface by the 1-5-7 of data switching exchane system; Equipment management data information is connected with described facility network guard system 1-5-3 communication interface by the 1-5-7 of data switching exchane system;

Described central front end-central transmitting station 1 also comprises single frequency network signal emission part 1-6 and upstream data receiving unit 1-7-n, this single frequency network signal emission part 1-6 comprises light emission system 1-6-1n and microwave transmission system 1-6-2n, the output of its light emission system 1-6-1n signal links to each other with optical transmission chain 2-1, and its microwave transmission system 1-6-2n employing orientation or theaomni-directional transmission mode are exported with MTL microwave transmission link 2-2 and linked to each other;

Described central front end-central transmitting station 1 also comprises the Data Receiving that upstream data receiving unit 1-7-n is up to each link, and enter the 1-5-7 of data switching exchane system and get in touch with Subscriber Management System 1-5-1, condition receiving system 1-5-2, facility network guard system 1-5-3, finish the monitoring of regional network user authorization management and operational outfit, enforcement etc.

Described signal transmission link 2 comprises mutually redundant fiber transmission link 2-1, MTL microwave transmission link 2-2; Wherein fiber transmission link 2-1 is by central front end-central transmitting station 1 light emission system 1-6-1n, link to each other with downstream signal optical relay 2-6-1, downstream signal optical receiver 2-6-3 in the link through Transmission Fibers, and the descending multichannel single frequency network signal of its downstream signal optical receiver 2-6-3 receiving demodulation enters the relaying station 3 sub-headends-trunk desk 3-1 or key trunk desk 3-2 separately; And link to each other with data-part 1-5 of software administration control centre with central front end-central transmitting station 1 upstream data receiving unit 1-7-n through the optical transmission chain of same paths by upstream data transmitter 2-7-11, upward signal optical relay 2-7-12 by the up data-signal of sub-headend-trunk desk 3-1; Wherein MTL microwave transmission link 2-2 is by microwave transmitter 1-6-2n, link to each other with microwave relay station 2-6-2, microwave receiving station 2-6-4 through microwave emission transmission link, and the single frequency network signal that the microwave receiver receiving demodulation among its microwave relay station 2-6-2 and the microwave receiving station 2-6-4 goes out a plurality of channels also enters the relaying station 3 sub-headends-trunk desk 3-1 or key trunk desk 3-2 separately.

The described relaying station 3 comprises through the transmission link 2 multichannel single frequency network signal of exporting and enters sub-headend-trunk desk 3-1 or key trunk desk 3-2, or directly carries out wireless receiving and dispatching and mend some relay station 3-3 and cover the continuity coverage rate is carried out signal transmission emission.

Described receiving unit 4 adds television set or digital television or all-in-one 4-3 by reception antenna part 4-1 and set-top box 4-2 and constitutes.

The multichannel mono-frequency network system of described a kind of Digital Television Terrestrial Broadcasting, the DTTB Project Realization is technical has at home broken through high-power adjacent be provided with on the same stage frequently for it, and further realized the adjacent frequency of big or small transmitting power or, become the new breakthrough of worldwide DTTB covering transmission group net technology every setting on the same stage frequently and big regional multichannel single frequency network foundation.On DTTB Project Realization network based on the big platform web frame of the analog transmissions station, broken through the restriction of external single frequency network distance between sites, be economically feasible, the DTTB of intensive construction China covers transmission network and expands its application space, market significantly, and implementation pattern is provided.It can melt construction altogether with the city Digital CATV Platform, with telecommunications, mobile, IP digital stream blending, for setting up the mutual broadband networks of zone digit TV, promotes the integration of three networks and lays a solid foundation.

Description of drawings

Fig. 1 is a system configuration theory diagram of the present invention;

Fig. 2 is the present invention central authorities front end-central transmitting station structured flowchart;

Fig. 3 is a transmitting station single-antenna transmission mode structured flowchart of the present invention;

Fig. 4-1 is the synthetic radiation pattern structured flowchart of transmitting station double antenna of the present invention;

Fig. 4-2 is the synthetic radiation pattern structured flowchart of the many antennas of transmitting station of the present invention;

Fig. 5 is the system block diagram of fiber transmission link of the present invention;

Fig. 6 is the system block diagram of optical wavelength-division multiplex of the present invention-multichannel SFN signal transmission link;

Fig. 7 is the system block diagram of high-speeld code-flow of the present invention-multichannel SFN flashlight transmission link;

Fig. 8 is the system block diagram of data such as the multistage SMS of the present invention link;

Fig. 9 is the system block diagram of digital microwave of the present invention-multichannel SFN signal transmissions links;

Figure 10 is sub-headend of the present invention-trunk desk structured flowchart;

Figure 11 is the key trunk desk of the present invention broadband scale-up version structured flowchart;

Figure 12 mends some relay station structured flowchart for the present invention directly carries out wireless receiving and dispatching;

Figure 13 is the receiving terminal structured flowchart.

Embodiment

Basic framework of the present invention is by central front end-central transmitting station 1 as shown in Figure 1, signal transmission link 2, and the relaying station 3 and receiving unit 4 are formed.

Wherein the formation of signal transmission link 2 is chosen in conjunction with actual by axle center branch type (2a, 2b, 2c among Fig. 1) and streptostyly (2c-2c-d, 2c-2c-e-2c-e-f among Fig. 1) basically; The basic comprising of the relaying station 3 transmits the road through difference according to signal, divides wired and wireless (containing microwave) relaying; According to the scope difference that covers, divide key (3-1 series and 3-2 series etc. among Fig. 1) and benefit point (among Fig. 1 3-3 series etc.) relaying; According to the difference between the effects that covers, divide and add program (among Fig. 1 3-1 series etc.) and direct repeating system (among Fig. 1 the serial and 3-3 series of 3-2 etc.); Also can comply with direct sending and receiving frequency difference, divide with frequency and frequency conversion relaying etc.

Receiving unit 4 adds television set or digital television or all-in-one 4-3 by reception antenna part 4-1 and set-top box 4-2 and constitutes.

Frame structure such as Fig. 2, Fig. 3, shown in Figure 4 of central authorities' front end-central transmitting station 1; Signal transmission link 2 frame structures such as Fig. 5, Fig. 6, Fig. 7, Fig. 8, shown in Figure 9; The relaying station 3 frame structures such as Figure 10, Figure 11, Figure 12, shown in Figure 4; Receiving unit 4 frame structures as shown in figure 13.

Fig. 2 is central front end-central transmitting station structured flowchart.

Central authorities' front end-central transmitting station 1 is the signal center and the control centre of system and the function that has key transmitting station concurrently, its major technique feature is to adopt ripe digital source coding and treatment technology, in the chnnel coding and the modulation treatment that the channel that is transmitted are met among the GB GB20600-2006, and, form multichannel DTTB transmission network central authorities front end-central transmitting station according to the needs of system business; Its principal character is signal center and control centre and has key transmitting station concurrently that its key transmitting station adopts launches setting on the same stage with adjacent channel or every channel, the emission on the same stage of the multichannel constant power or the transmitting power that differs in size; Its signal center is to each transmission link emission transmission multichannel single frequency network signal; Its control centre broadcasts business datum, system control information (containing the up data of each link), and network software operation etc. manages, authorizes and other a series of controls.Have concurrently thereby form professional mobile receiving mode and the fixing receiving mode etc., and form the center covering service area of the multichannel single frequency network that the repetition coverage rate can be arranged.

The programme signal of the program signal input part 1-1 of described central front end-central transmitting station 1 inputs to message source process part 1-2, each road message source process passage 1-2-1 of this message source process part 1-2 ... after 1-2-n carries out source encoding-multiplexing-scrambling or not scrambling of part processing to the multiple programs signal, to satisfy each channel payload data requirement signal and export described Channel Processing part 1-3 to, each Channel Processing passage 1-3-1 of this Channel Processing part 1-3 ... 1-3-n is treated as each channel signals by chnnel coding and modulation system respectively; Each single frequency network signal of described Channel Processing part 1-3 transfers out through single frequency network signal emission part 1-6; Radiofrequency signal output is launched through emission unit-synthetic-emission antenna feeder part 1-4 in each channel of described Channel Processing part 1-3; Wherein launching unit-synthetic-emission antenna feeder part 1-4 divides high or low power all to synthesize one the tunnel through a power combiner again, carries out radiation pattern as shown in Figure 3 through a broadband emission antenna again.

Another kind of mode is to adopt plural power combiner to synthesize multichannel, passes through plural (or broadband) transmitting antenna again and carries out radiation pattern shown in Fig. 4-1, Fig. 4-2.

As shown in Figure 2: the data of described central front end-central transmitting station 1-part 1-5 of software administration control centre is with described Subscriber Management System 1-5-1, condition receiving system 1-5-2, Radio Data System 1-5-4, electronic program guidance system (EPG) 1-5-5, the user management data of other system 1-5-6, condition receiving management control data, data broadcasting information, electronic program guide information, data such as other video flowings and distribution control information are input to message source process part 1-2 corresponding interface by the 1-5-7 of data switching exchane system; Equipment management data information is connected by the 1-5-7 of data switching exchane system facility network guard system 1-5-3 communication interface.

As shown in Figure 2: during the central front end that described central front end-central transmitting station 1 is an interconnection type-central transmitting station, comprise mutually redundant fiber transmission link 2-1, MTL microwave transmission link 2-2 for described signal transmission link 2; Wherein fiber transmission link 2-1 is by central front end-central transmitting station 1 light emission system 1-6-1n, descending multichannel single frequency network signal in the Transmission Fibers link, receive by sub-headend-up data-signals such as SMS of trunk desk 3-1 through the receiver 1-7-n of central front end-central transmitting station 1 again simultaneously, this data-signal links to each other the accurate interaction platform of construction system user management data with the data-software control core 1-5 of central front end-central transmitting station 1.Wherein MTL microwave transmission link 2-2 passes through central front end-central transmitting station 1 microwave transmission system 1-6-2n, microwave relay station 2-6-2, the descending multichannel single frequency network of the 2-6-4 of receiving station signal in microwave emission transmission link.

When described central front end-central transmitting station 1 is the front end central transmitting station of self, generally do not need to set up for described signal transmission link 2 and upstream data receiving unit 1-7-n as shown in Figure 2.

When described signal transmission link 2 adopts Optical Fiber Transmission, fiber count enough satisfy when passing channel number, can adopt single mode list core single transmit transmission means; But in bigger regional optic path, former limited with the fiber count that can squeeze usefulness in the optical fiber backbone network, or the SDH system wouldn't satisfy requirements such as time domain precision and shake, should adopt the digital signal optical fibre transmission plan of single core many (list) wavelength for this reason.

Fig. 5 is the system block diagram of fiber transmission link in the described signal transmission link 2.

As shown in Figure 5: the light emission system 1-6-1n of central front end-central transmitting station 1, link to each other with downstream signal optical relay 2-6-1, downstream signal optical receiver 2-6-3 in the link through Transmission Fibers, the descending multichannel single frequency network signal of its downstream signal optical receiver 2-6-3 receiving demodulation enters the relaying station 3 sub-headends-trunk desk 3-1 or key trunk desk separately; And link to each other with the data-part 1-5 of software administration control centre of central front end-central transmitting station 1 through the optical transmission chain of same paths by the upstream data receiving unit 1-7-n of upstream data transmitter 2-7-11, upward signal optical relay 2-7-12 and central front end-central transmitting station 1 by the up data-signal of sub-headend-trunk desk 3-1.

Fig. 6 is the system block diagram of described signal transmission link 2 optical wavelength-division multiplex-multichannel SFN signal transmission link.

As shown in Figure 6: the optical sender that is entered different wave length by the multichannel SFN signal in central front end-central transmitting station 1 smooth transmitting terminal 1-6-1n carries out light modulation, modulated different optical wavelength and identical luminous power are entered the synthetic light delivery outlet of optical multiplexer, along separate routes luminous power is divided into required link fiber number output through light again.The attenuation that wherein comprises this transmission path of light signal process of a plurality of wavelength in each road optical fiber enters this road light-repeating ship or optical receiving station.In relay station, carry out Optical Demultiplexing, after optical wavelength is carried out the luminous power amplification respectively again, enter the synthetic light delivery outlet of optical multiplexer once more, carry out the relay transmission of next stage again by optical relay 2-6-1.If the repeat transmitted station of this relay station and system 3 also is provided with optical receiver 2-6-3 with going out a place in this light-repeating ship, demodulates multichannel SFN signal and give the relaying station 3 sub-headends-trunk desk 3-1 or key trunk desk.

Adopt light wave to divide mode when single optical fibre is grown the SFN signal of Distance Transmission multiple programs, will note the inequality transmission influence that the light transmission fiber discreteness is caused especially.Be also noted that simultaneously when transmission path surpassed 500Km, the delay distortion of optical fiber also can influence laser propagation effect, should carry out handling again once more after the signal of telecommunication demodulation, and then carry out the transmission of next section.

Fig. 7 is the system block diagram of described signal transmission link 2 high-speeld code-flows-a plurality of channel SFN flashlight transmission links.This is only to need single light wave to carry out the scheme of signal transmission.

As shown in Figure 7: enter light transmitting terminal 1-6-1n port logic-processors such as routing iinformation generation separately respectively by the multichannel SFN signal in central front end-central transmitting station 1, generation high-speed data-flow signal separately enters poll and is multiplexed into the light modulation output that one road megastream enters single optical wavelength, along separate routes luminous power is divided into required link fiber number output through light again.Wherein the attenuation of single wavelength light signal (a plurality of SFN signals that comprise) process transmission path enters light-repeating ship or optical receiving station in each road optical fiber.After wherein in light-repeating ship, directly carrying out optical relay 2-6-1 amplification, enter the optical relay transmission of next stage once more.If the relaying station of this light-repeating ship and system 3 also is provided with light-receiving 2-6-3 with going out a place in this light-repeating ship, demodulates multichannel SFN signal and give the relaying station 3 sub-headends-trunk desk 3-1 or key trunk desk.

This scheme is owing to adopt the light modulation techniques of high-speed data-flow signal poll multiplexing process measure and high-speed data-flow, satisfy the needs that the time domain precision is lower than the multichannel single frequency network signal transmission of 1 * 10e-8, effectively overcome the influence of transmission multi-wavelength light transmitting discrete in single optical fibre, for improve more piece (more than 2 joints), remote (greater than 50Km) transmission SFN quality of signals and stability, the reliability effect is obvious, becomes the critical system technology that realizes the multichannel single frequency network networking more than 10,000 square kilometres.

Because the SMS signal can only adopt dedicated network to carry out data contacts, Fig. 8 is the system diagram of data link such as described signal transmission link 2 multistage SMS.

As shown in Figure 8: adopt optical fiber transmission technique to grow the system of data such as the multistage SMS link of Distance Transmission, make described signal transmission link 2 become two-way fiber-optic signal transmission link by descending one-way fashion link; When upstream data is obstructed, can give relevant user data delivery central front end-central transmitting station 1 control centre by means of telecommunications network.

Fig. 9 is the system block diagram of described signal transmission link 2 digital microwaves-multichannel SFN signal MTL microwave transmission link, the promptly general SFN signal system linked, diagram that adopts digital microwave or Digital Television Multichannel Microwave Distribution System (Digital Television Multichannel Microwave Distribution System, Digital Television MMDS or digital MMDS) technical transmission multichannel single frequency network.

As shown in Figure 9: enter microwave transmission system 1-6-2n respectively by the multichannel SFN signal in central front end-central transmitting station 1, a bit be emitted to multiple spot with various microwave relay station 2-6-2, microwave receiving station 2-6-4 formation and receive star-like link or the multinode branch type multichannel SFN of bus type branch signal MTL microwave transmission link.This is that the frontier that adopts digital microwave or digital MMDS mature technology to carry out high-speed data-flow (the SFN signal has clock synchronization information) transmission is used.And the combination by different radiation patterns (orientation or theaomni-directional transmission) of digital microwave or digital MMDS among the microwave transmission system 1-6-2n of central front end-central transmitting station 1 single frequency network signal emission part 1-6 and microwave relay station 2-6-2, form and the mutually redundant system signal transmission link 2 of fiber transmission link 2-1.

The system block diagram that has comprised the relaying station 3 structures among Fig. 1.

It is characterized in that the described relaying station 3 comprises that the SFN signal of being exported through signal transmission link 2 enters sub-headend-trunk desk 3-1 or key trunk desk 3-2, or directly carry out wireless receiving and dispatching benefit point relay station 3-3 the continuity coverage rate is carried out signal transmission emission covering.

Figure 10 is the described relaying station 3 sub-headends-trunk desk 3-1 block diagram.

As shown in figure 10: by the multichannel SFN signal of light-microwave signal relay station 2-6-1/2-6-2 output, enter the Channel Processing part 3-1-3 among sub-headend-trunk desk 3-1, particularly, carry out the synchronous time domain adjustment in the sub-channel signal coverage rate in order better to realize the mobile reception in the area of coverage (contain certain limit and repeat coverage rate); Enter emission unit-synthetic-emission antenna feeder part 3-1-4 then and launch covering by the transmitting power configuration of design.In order to guarantee the main overlapping intersection covering quality that passes program in big zone of multichannel single frequency network, must keep the signal data structure in this overlapping intersection overlay area consistent with time domain, therefore in the time will adding program, newly add a transmitting channel by sub-headend-trunk desk 3-1 and be its overlay area service, after the source encoding-multiplexing processing such as grade of the program that wherein increases newly by interpolation program-message source process part 3-11-1, the Channel Processing part 3-11-3 that enters increase carries out chnnel coding and modulation treatment, and the emission unit-synthetic-emission antenna feeder part 3-1-4 that incorporates our station again launches.Radiation pattern such as Fig. 3, Fig. 4 of wherein launching unit-synthetic-emission antenna feeder part 3-1-4 are optional, to form the sub-headend that the different radiation patterns are arranged-trunk desk 3-1 of various interpolation programs.

It adds the up data such as SMS of program-signal processing 3-11-1, enters the optical fiber return path by upstream data optical sender 2-7-11 or upstream data optical relay machine 2-7-12 and carries toward central front end-central transmitting station 1.

When the described relaying station 3 is the key trunk desk 3-2 of GENERAL TYPE, generally need not set up for described interpolation program-message source process part 3-11-1, Channel Processing part 3-11-3 and upstream data optical sender 2-7-11 or upstream data optical relay machine 2-7-12 as shown in figure 10.

Figure 11 is the described relaying station 3 key trunk desk 3-2 broadband scale-up version structured flowcharts.

As shown in figure 11: by the multichannel SFN signal of light-microwave signal relay station 2-6-1/2-6-2 output, enter the Channel Processing part 3-2-3 among the key trunk desk 3-2 (broadband scale-up version), carry out small-signal by radio frequency (RF) signal of each road upconverter output in this part and be mixed into the multichannel broadband signal, directly enter linearity wideband transmitter preferably, carry out the power amplification of multichannel broadband signal, launch by the emission antenna-feedback system again.

The described relaying station 3 of Figure 12 is directly carried out wireless receiving and dispatching and is mended some relay station 3-3 structured flowchart.

By shown in Figure 12: the master signal after described benefit point relay station 3-3 receive to be amplified by receiving terminal part 3-3-1 enters power amplifier-radiating portion 3-3-3 through handling cable and carries out launching after the power amplification of signal again.Its structure mainly is to adopt the signal directional antenna that sets up separately to receive, after the noiselike signal of anti-self-excitation amplifies master signal (should have enough signal to noise ratios), be transported to from the nearer broadband power amplification module of transmitting antenna through transmission cable, carry out again launching by transmitting antenna orientation or non-directional after the power amplification of signal.Disturb because of relating to transmitting-receiving in this scheme, adjacent frequently, do not wait specification requirement such as radiofrequency signal amplification, a joint number of mending some relay station 3-3 mode for continuous this kind of employing wireless receiving and dispatching on the engineering has certain restriction (link technology parameter height generally can surpass 4 joints).

Figure 13 is the block diagram of described receiving terminal 4.

By shown in Figure 13: the reception antenna part 4-1 of described receiving terminal part 4 adopts multiple formulas such as orientation or non-directional.Wherein fixedly the antenna formula of receiving mode and the form signal strength that can receive by user side be divided into by force, in, weak, little and disturb the multiple situation apolegamy of size.Distant fixation receives can to select the passive directional antenna of high-gain for use or to put through the low noise sky improves reception.The signal that is received by reception antenna part 4-1 is sent into and is restored video and audio signal after subscriber computer top box 4-2 handles and offer television set, or directly watches by digital television or all-in-one 4-3.

The essence of a large-scale multichannel single frequency network Construction Problems is radio frequency resources problem in short supply, can be linked into a reliable and stable nerve of a covering economically, and this is crucial.On large-scale Project Realization, two kinds of time domain precision differences that option relied on of single and multi-carrier have caused the exploitativeness that is had that substantial difference is arranged among the Chinese national standard GB20600-2006.In large tracts of land, the large-scale engineering construction, what high accuracy was brought is exactly excessive risk, with high investment.And low required precision just can obviously reduce operation risk, brings high reliability, high efficiency, brings high production.Solve the fixedly receiving mode that utilizes original broadcasting and TV emission station resource, will consider with the problem of implementation that frequently repeats to cover.Cover because the basic covering characteristics of original radio and television station are intersected exactly and repeated, what only adopt is that difference frequency covers.The fixedly reception of DTTB covers, and wants safety and tides over analog signal-digital signal with broadcasting the transitional period, just should have from the technology mode and can bear the ability that repeats to cover with frequency in big zone.

The multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting is one can carry huge operating information system engineering.Both related to high definition TV (HDTV) is the high-end development tactics of the Digital Television of sign, also relate to rural area basic model set-top box is the Digital Television scale management development tactics of the popular type consumption of sign, also relate to wireless mobile reception and mobile phone (portable) and receive, effective combination of the industry development strategy of amusement and information blending.

The technical application problem that at first needs in the networking of multichannel single frequency network to solve is the adjacent setting frequently of constant power, its key problem in technology is to overcome adjacent frequently the interference to overcome adjacent influence frequently on the basis again, and the wireless type of directly putting of multifrequency point covers with frequently mending point (active amplification) thereby help in a big way.And to satisfy bigger scope of business needs move with fixing receiving mode with in the net system, the power that differs in size that institute must run into is frequently adjacent or every frequency related technical problem to be set on the same stage more complicated.When launching unequal power on the same stage and differ a plurality of channel signals more than the 10dB, as not taking a series of technical measures, at least on same technological layer, constant power is adjacent frequently to be provided with system than adopting, and can make that this system degradation 10dB is above to be covered index and obviously influence operational effect.

The multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting is realized moving and the same net of fixing reception, adopt the synthetic and power synthetic technique that differs in size of constant power, the incoming level thresholding and the noise thresholding that are had except GB GB20600-2006 chnnel coding and modulation treatment mode are lower, outside the technical advantage condition such as anti-multipath, anti-impulse disturbances ability are strong, in engineering construction, also relate to the shared channel bandwidth of channel base band, relate to channel deviation, drift, precision, relate to the technical parameter of the adjacent channel synthesizer under the prescribed bandwidth technical conditions etc.And the fixed technical parameter of transmitting terminal institute tool is the key of total system.The shared bandwidth of information (payload rate) in each channel transmission is less than or equal under the condition of settings such as 7.56MHz, when transmitting terminal adopts the low middling channel speed (4 16-QAM or 4QAM-NR), the low limit value of the isolation of adjacent channel is greater than 34dB (concave point), the low limit value of isolation of (32-QAM or 64QAM) adjacent channel is greater than 36dB (concave point) when adopting medium above channel speed when making a start, and transmits coverage effect otherwise will obviously influence the power that differs in size synthetic back emission.

Power combiner by the small-power grade is formed (fixing receive) emission antenna-feedback system and powerful mobile emission antenna-feedback system and is taked to set up separately with tower antenna aerial synthetic, and the output of the high-power mobile transmitter of launching matches and is greater than or equals 38dBc separately.And the frequency accuracy of system, stability etc. are wanted to be lower than fixedly receiver/transmitter system.

Modulator and upconverter adopt high accuracy, and (1 * 10e-8) 10MHz phase-locked loop frequency locking locks mutually outside the control technology, for guaranteeing the transmitter operation stability, upconverter is answered built-in high accuracy, and (1 * 10e-8) 10MHz phase-locked loop frequency locking adds phase-locked and takes the precorrection adaptive control.

The multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting relies on the expansion of domestic rural market, forge into the total operation platform of program connecting system, increment service system, promote chip manufacturing, the development of enterprises such as set-top box, television set complete machine are produced, the broadcasting and TV operation and wireless broadcast network; For finally breaking away from external DTTB technology mode constraint and influence, facilitate the foundation of the independent intellectual property right system of China DTTB networking to lay the foundation.Simultaneously to promoting the development and the raising of domestic digital television devices manufacturing technology and soft, hardware device research and development system significantly, and then advance the development of China's national industry to play an important role.

The multichannel mono-frequency network system of Digital Television Terrestrial Broadcasting can make full use of the original wireless transmission station of radio, TV and film industries resource, avoids overlapping investment; Based on condition receiving system (Conditional Access System, CAS) employing, can realize really that system's commercial operation is strong to moving and fixing (containing portable reception) user watched reliable management and commercial operation, be convenient to realize personalized rating management; Realize tens cover standard definition televisions (Standard Definition Television, SDTV) the digital TV ground transmission covering of program (containing some cover HDTV programs) or Focus TV; The transmitter peak-to-average force ratio is low, and system energy consumption is little, and its electromagnetic pollution is little; Can with city digital TV platform common numbers front end system, be convenient to the scale management of regional networking.

Other wired and wireless (comprising satellite) technology replace modes have following advantage relatively: reduced investment (will be economized investment more than 90% than the HFC net in rural area, economize investment more than 60% than the MMDS net of direct broadcasting satellite net and identical scale), networking speed fast (but transmitting base station builds up just networking); TV transmission program sound spectrogram quality good (DVD or HDTV level), quantity many (tens covers); Safe (can also not allow to subject to illegal signals and attack without gps system) adopted digital condition receiving system (CAS) and Subscriber Management System (SMS), and the commercial operation of wireless network is effectively ensured; Operating cost low (having only the indivisible service maintenance of user side and the consumption of transmitting terminal), return rate height (it is recoverable base station equipment investment that two general-purpose families are generally arranged approximately), the operation of can gaining fully develops at a progressive speed; Save a large amount of radio frequency resourcess, band efficiency height (improving present uhf band utilance significantly), disturb for a short time, help utilizing the frequency planning of original simulated television emission station resource and DTTB; Effective coverage rate height (can improve coverage rate 40% in the knob) as digital relatively MMDS system, user side cost low (digital relatively MMDS economizes more than 30% approximately); Stability, reliability, fail safe all be better than other wireless networking systems (the total failare point has only 1/9 of digital MMDS and direct broadcasting satellite net, be HFC net 1/4); Compatible, expansion is strong, but with city digital TV common numbers front end system, avoid overlapping investment.

Claims (6)

1. the multichannel mono-frequency network system of a Digital Television Terrestrial Broadcasting, it is characterized in that it: in the Digital Television Terrestrial Broadcasting network system, comprise with system frame structure among the data signal interfaces of MPEG-2 or AVS maturation and the Chinese national standard GB20600-2006, chnnel coding and modulation technique are carried out information source and Channel Processing, transmitting station (station) adopts the frequency of decimeter wave (UHF) frequency range (300MHz-860MHz-3000MHz), with the identical or different power configuration of single channel size, and with the neighbour frequently or every the multichannel signal power that is provided with frequently through passive device synthetic or aerial synthetic after, be that the broadband transmitting antenna of 16-300MHz carries out wireless transmission through single or multiple bandwidth again;

Backup each other wired or wireless transmission link of employing is realized the signal transmission, form and to be emitted to multiple spot on one point and to receive in star-like link or the bus type branch multinode branch type link and carry out long-distance transmissions and reception, the required multichannel single frequency network of framework relaying station signal transmission link, and form the emission overlay network of the multichannel single frequency network in big zone by the various relaying stations;

User side is with wireless receiving antenna and top box of digital machine or digital television or all-in-one is fixed, mobile or portable reception;

The multichannel mono-frequency network system of described a kind of Digital Television Terrestrial Broadcasting comprises central front end-central transmitting station (1), signal transmission link (2), the relaying station (3), receiving unit (4), wherein:

The programme signal of the program signal input part (1-1) of described central front end-central transmitting station (1) inputs to message source process part (1-2), each road message source process passage (1-2-1 of this message source process part (1-2) ... 1-2-n) the multiple programs signal is carried out source encoding-multiplexing-scrambling or not scrambling of part and handles after, to satisfy each channel payload data requirement signal and export described Channel Processing part (1-3) to, this Channel Processing part (1-3) each Channel Processing passage (1-3-1 ... 1-3-n) be treated as each channel signals by chnnel coding and modulation system respectively; Each single frequency network signal of described Channel Processing part (1-3) transfers out through single frequency network signal emission part (1-6); Radiofrequency signal output is launched through emission unit-synthetic-emission antenna feeder part (1-4) in each channel of described Channel Processing part (1-3);

The data of described central front end-central transmitting station (1)-software administration control centre part (1-5) links to each other with the corresponding interface of described program signal input part (1-1), message source process part (1-2), Channel Processing part (1-3); The user management data of Subscriber Management System (1-5-1), condition receiving system (1-5-2), Radio Data System (1-5-4), electronic program guidance system (1-5-5), condition receiving management control data, data broadcasting information, electronic program guide information, other video flowings and distribution control information data are input to corresponding interface by data switching exchane system (1-5-7); Equipment management data information is connected with facility network guard system (1-5-3) communication interface by data switching exchane system (1-5-7);

Described central front end-central transmitting station (1) also comprises single frequency network signal emission part (1-6) and upstream data receiving unit (1-7-n), this single frequency network signal emission part (1-6) comprises light emission system (1-6-1n) and microwave transmission system (1-6-2n), the output of its light emission system (1-6-1n) signal links to each other with optical transmission chain (2-1), and its microwave transmission system (1-6-2n) employing orientation or theaomni-directional transmission mode are exported with MTL microwave transmission link (2-2) and linked to each other;

Described central front end-central transmitting station (1) also comprises the Data Receiving that upstream data receiving unit (1-7-n) is up to each link, and enter data switching exchane system (1-5-7) and get in touch with Subscriber Management System (1-5-1), condition receiving system (1-5-2), facility network guard system (1-5-3), finish the monitoring of regional network user authorization management and operational outfit;

Described signal transmission link (2) comprises mutually redundant fiber transmission link (2-1), MTL microwave transmission link (2-2);

The described relaying station (3) comprises that the signal of being exported through transmission link (2) enters sub-headend-trunk desk (3-1) or key trunk desk (3-2), or directly carries out wireless receiving and dispatching benefit point relay station (3-3) coverage rate is carried out signal transmission emission covering;

Receiving unit (4) adds television set by reception antenna part (4-1) or set-top box (4-2) or digital television (4-3) constitutes.

2. the multichannel mono-frequency network system of a kind of Digital Television Terrestrial Broadcasting as claimed in claim 1 is characterized in that described fiber transmission link (2-1) is by central front end-central transmitting station

(1) light emission system (1-6-1n), link to each other with downstream signal optical relay (2-6-1), downstream signal optical receiver (2-6-3) in the link through Transmission Fibers, the descending multichannel single frequency network signal of its downstream signal optical receiver (2-6-3) receiving demodulation enters the relaying station (3) sub-headend-trunk desk (3-1) or key trunk desk (3-2) separately; And link to each other by data-software administration control centre part (1-5) that the upstream data receiving unit (1-7-n) of upstream data transmitter (2-7-11), upward signal optical relay (2-7-12) and central front end-central transmitting station (1) passes through optical transmission chain with the central front end-central transmitting station (1) of same paths by the up data-signal of sub-headend-trunk desk (3-1).

3. as the multichannel mono-frequency network system of a kind of Digital Television Terrestrial Broadcasting of claim 1 or 2, the multichannel single frequency network signal that it is characterized in that described fiber transmission link (2-1) enters light transmitting terminal (1-6-1n) port logic-routing iinformation generation processor separately respectively, generation high-speed data-flow signal separately enters poll and is multiplexed into the light modulation output that one road megastream enters single optical wavelength, along separate routes luminous power is divided into required link fiber number output through light again.

4. the multichannel mono-frequency network system of a kind of Digital Television Terrestrial Broadcasting as claimed in claim 2, each road that it is characterized in that fiber transmission link (2-1) comprise single wavelength light signal in the optical fiber of a plurality of single frequency network signals and enter optical relay (2-6-1) or optical receiver (2-6-3) through the attenuation of transmission path; After wherein the optical relay in light-repeating ship (2-6-1) directly carries out the amplification of luminous power relaying, enter the optical signal repeater transmission of next stage once more.

5. the multichannel mono-frequency network system of a kind of Digital Television Terrestrial Broadcasting as claimed in claim 4, it is characterized in that also being provided with in the described light-repeating ship optical receiver (2-6-3), the single frequency network signal that receiving demodulation goes out a plurality of channels is given the relaying station (3) sub-headend-trunk desk (3-1) or key trunk desk (3-2) separately.

6. the multichannel mono-frequency network system of a kind of Digital Television Terrestrial Broadcasting as claimed in claim 1, it is characterized in that described MTL microwave transmission link (2-2) links to each other by microwave transmitter (1-6-2n), the microwave relay station (2-6-2) in microwave emission transmission link, microwave receiving station (2-6-4), the single frequency network signal that the microwave receiver receiving demodulation among its microwave relay station (2-6-2) and microwave receiving station (2-6-4) goes out a plurality of channels enters the relaying station (3) sub-headend-trunk desk (3-1) or key trunk desk (3-2) separately.

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