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UHF/VHF 470-860MHz DVB-T2 System

DVB-T SFN is mainly used for the transmission within 8 programs, single frequency point, mobile reception. 
The main advantages of Digital TV SFN:
1)  Save frequency resources
2)  Large coverage area
3)  There is no need for subscriber to change channel in mobile reception within the network coverage area.


The core issue of Digital TV SFN 
The core issue of SFN is synchronization. And the synchronization consists of three aspects:
1)  Frequency Synchronizationwhich means that the carrier frequency of all transmitting station should be synchronous.
2)  Time Synchronization
which means that all transmitting station broadcast the same programs at the same time.
3)  Code Element Synchronization, which means that the bit-rate of modulation signal should be synchronous.
The above-mentioned aspects are mainly achieved by GPS clock and SFN adaptor.
At the transmitting side, SFN adaptor deal with the input TS into MIP, inserting time and system control information, and then send into the transmission network. At the receiving end, the corresponding SFN adaptor analyzes MIP, calculating the transmission delay and compensating automatically, and then it can meet the synchronous requirements of transmitting station and SFN.
The Implementation Solution of Digital TV SFN
For the SFN, the system should solve two aspects of problems: first, signal source transmission; second, the design of transmitting station. System synchronization is mainly related to transmission system, so the transmission system should be first considered.


Description of the system main components
(1) Head-end system, the main function is program production, edition, broadcast control, video/audio code, data protocol conversion, data stream multiplexing, SFN adaptation, etc.
(2) Transmission network, transporting the digital TV data stream to the transmitting system, and completing the data stream restoration and synchronization. Usually, the head-end and the transmitting system are not in the same place. In the SFN mode, there are multiple transmitting systems.
(3) Transmitting system, the main task is the input data stream synchronous modulation, frequency conversion, amplification, filtering, and signal synthesis. Then send the signal to the antenna by feeder.
(4) Receiving system, the main task is to convert and demodulate the received high-frequency modulation signal and get digital TV data stream. Then de-multiplex and decode the data stream, combined with corresponding control, to achieve the required function of the subscriber.

DVB-T SFN is mainly used for the transmission within 8 programs, single frequency point, mobile reception.
The main advantages of Digital TV SFN:
1)  Save frequency resources
2)  Large coverage area
3)  There is no need for subscriber to change channel in mobile reception within the network coverage area.

The core issue of Digital TV SFN
The core issue of SFN is synchronization. And the synchronization consists of three aspects:
1)  Frequency Synchronizationwhich means that the carrier frequency of all transmitting station should be synchronous.
2)  Time Synchronization
which means that all transmitting station broadcast the same programs at the same time.
3)  Code Element Synchronization, which means that the bit-rate of modulation signal should be synchronous.
The above-mentioned aspects are mainly achieved by GPS clock and SFN adaptor.
 At the transmitting side, SFN adaptor deal with the input TS into MIP, inserting time and system control information, and then send into the transmission network. At the receiving end, the corresponding SFN adaptor analyzes MIP, calculating the transmission delay and compensating automatically, and then it can meet the synchronous requirements of transmitting station and SFN.
The Implementation Solution of Digital TV SFN
For the SFN, the system should solve two aspects of problems: first, signal source transmission; second, the design of transmitting station. System synchronization is mainly related to transmission system, so the transmission system should be first considered.


The main ways of signal source transmission at present:

1) Adopt SDH trunk network for transmission, which is more suitable for wide range of coverage. The advantage is high transmission quality; the disadvantage is high cost and there may be no present network for building the station in some area.

2) Use TV transmitting station for transmission. To use one channel for transmitting digital TV signal in the coverage center or on the mountain, other transmitting stations receive this signal, and then send out in the form of SFN, after de-modulation and re-modulation. The advantage of this solution is that it can make full use of the favorable resources of broadcast and television with no limit of the terrestrial network. The disadvantages are that it occupies one more TV channel and has limited coverage, just suitable for partial area coverage.

3) Use microwave transmission link for signal source distribution.

In practice, several ways may be mixed used.

The Difference between Digital TV SFN and Analog TV Broadcasting System

Digital TV SFN is a network, not single transmitter. SFN is similar to the cellular network of mobile communication. But they have difference, in SFN, all transmitting stations adopt one transmitting frequency.

1) Most of the previous analog TV adopts high power, broad coverage, and VHF frequency band; while the digital TV SFN adopts low or medium power, multi-distribution, partial coverage and UHF frequency band.

2) As the networking mode varied, different areas adopt different solutions. 

3) At the receiving end, digital TV supports fixed, vehicle and handhold receiving modes, and the picture is clear.

4) The subscriber can receive several TV programs, FM broadcasting programs and data broadcast (such as stock information) in one channel. And each subscriber, as well as each program can be separately charged.  

Digital Terrestrial TV Broadcast Receiving End

Digital Terrestrial TV Broadcast includes fixed reception and mobile reception.  The receiving equipment of Digital Terrestrial TV Mobile System includes: mobile receiving antenna, regulated power supply, delay switch, mobile receiver (DVB-T mobile receiving STB), mobile receiving control software, mobile storage software, display and recording system.

How to require design and quotation:

1.How many TV programs would you like to broadcast?

2.What is the main receiving mode of the subscriber, fixed reception or mobile reception?

3.SFN or MFN?

4.If it is SFN, what kind of transmission mode has been adopted between signal source and each transmitter? SDH network or point to multi-point microwave transmission link? Or to use one channel for transmitting digital TV signal at the highest point in the coverage center, other transmitting stations receive this signal, and then send out in the form of SFN, after de-modulation and re-modulation.

5.What’s the bandwidth of the transmission channel? 6NTSCor 8(PAL)MHz

6.What is the furthest transmission distance?

7.How many frequencies can be used? Please tell us the center frequency of each frequency point.

8.Do you want to encrypt the programs?