Design Of DTMB SFN Adapter

Terrestrial digital TV broadcasting national standards (DTMB, also known as DMB-TH), it combines the Tsinghua-based multi-carrier DMB-T programme, and Shanghai Jiaotong University based on the single-carrier ADTB-T programme. SFN (Single Frequency Network, SFN) Network: SFN transmitter simultaneously with the launch of a band on the same wireless signal that the transmitter frequency radio signal synchronization requirements, time synchronization and symbol simultaneously. In the formation of single frequency network, all between the simultaneous launching of work is to ensure that the SFN correct and effective operation of an important issue, and ensure that the single frequency network synchronization is the product of their corresponding standard adapters.This paper designed DTMB single frequency network adapter, from a global positioning system (Global Positioning System, GPS) receiver to provide precise second pulse (Pulse Per Second, PPS) signal and 10 MHz clock synchronization rate adaptation, in the location of each source programs Second to the MPEG-2 transport stream (Transport Stream, TS) inserted in one second frame initialization packet (Second Frame Initialization Packet, SIP), insert the moment with the GPS receiver to provide the 1 PPS pulse rising edge of alignment, in other locations , DTMB single frequency network adapter from the front of the buffer zone (FIFO), read data stream, if the data provided insufficient number of TS packet, then automatically inserted Single Frequency Network Adapter empty packet to complete the TS-bit-rate adaptation. DTMB single frequency network adapter output TS flow rate and single-frequency transmitter network adapter under the requirements of the mode of loading rate identical to the net and locked from the GPS receiver in the 10 MHz reference clock.In this paper, the DTMB single frequency network adapter technical requirements for detailed analysis, based on the use of FPGA-based SCM and build the DTMB single frequency network adapter design, will be divided into two major component modules: Key board And motherboards in two parts. The keys have a board of the SCM SFN adapter SIP packets of the various parameters, the FPGA device on the motherboard to complete the whole system of SIP package insert, and the program clock rate adapter reference (Program Clock Reference, PCR) correction, and other core functions. The article described in detail DTMB single frequency network adapter set of design options, and developed a prototype of the kind carried out debug verification, the results of its analysis, proved the feasibility of the design and reliability to the corresponding technical indicators .Finally this expansion of the demonstration of the GPS receiver lost lock circumstances, the single frequency network adapter time synchronization of the impact.