This
page is still under construction. This
page is still under construction.Video, Audio sources
compression
datas
multiplexing statistical multiplexing
MPEG-2 transport stream TS
MFN
SFN various transmitters use the same frequency to cover a defined are
all transmitters must transmit exactly the same signal, time, frequency
and content on the carriers
SFN adapter and GPS are necessary to insert and synchronize the time information
SFN means the is no choice to modify the content of the TS for the single transmitters
TS distributing two ways two ASI inputs on the transmitter
Transmitter redundancy
single transmitter option: dual exciter
two transmitters in passive reserve configuration
two transmitters in active reserve: 3dB power reduction if one amplifier fails,
coverage range
n+1 Transmitters n operational transmitters 1 standby transmitter , what
about the priority of the programs if more than one transmitter fails
DVB-T
MFN Multi-Frequency Network
SFN Single-Frequency Network
VHF 7 MHz BW
UHF 8 MHz BW
The Single Frequency Network requires precise time and frequency synchronization of all transmitters
SFN Adapter inserts synchronization marks in the DVB-T transport stream (TS), MIP insertion
delay time control of the transmitter
Insertion of MIP (Mega-Frame Initialization Packet) in the MPEG-2 transport stream is required to synchronize the OFDM modulators to broadcast the same transport stream at the same time. Also, the MIP is used to remotely control the OFDM modulators with respect to transmission mode, ensuring like operation of all modulators.
This SFN adapter receives a 1 pps time reference and a 10 MHz clock reference from a GPS receiver and computes time and control information to build the Megaframe Initialisation Packet (MIP). It inserts this packet into the MPEG2 transport stream and recomputes the PCR information of each programme.
The SFN adapter is also able to insert, in the MIP packet, the definition of all parameters for setting the DVB-T COFDM modes (TPS information + MIP private functions).
The SFN adapter receives the MPEG2 packets as a MPEG2-TS data stream and generates a new MPEG2-TS data stream.
Thanks to its DVB-PI standard ASI interfaces, the DVB-T SFN adapter can be used with any DVB compliant multiplexer and network adapter.
As an option, the V-SFN is able to process two MPEG2 Transport Streams with the required synchronization features for use of hierarchical modes in the SFN network.
All control and monitoring of the SFN adapter is done through RS232 or Ethernet links and using a MS-Windows software running on a PC.
This equipment is packaged in a 1U rack.
modulation scheme
COFDM Coded Orthogonal Frequency Division Multiplex
reception is not influenced by signal reflections and other multi-path signals
data stream splited to various carriers
guard interval
COFDM is an extremely robust modulation technology which provides spectrum efficiency and superior performance in high interference and non-line sight environments.
COFDM modulator generates the digital signal and error-checking codes, output I/Q signals, RF converter, pre-corrector
outputs to feed operating and standby transmitter
ASI input selector for two alternative TS
Bit rate adaptation
PCR restamping
low phase noise
can be configured to handle different modulation types, Guard intervals, Viterbi code rates and output frequencies. Configuration
full remote control of all settings
Updated on 24. Januar 2013.