ITU inter-regional seminar Technical Realisation of Digital TV Transmitter Systems Friedrich Rottensteiner Rohde & Schwarz 7TSP ITU inter-regional seminar 1 DVB-T Transmitter system Technical Realisation of Digital TV Transmitter Systems - MFN / SFN networks - Transition from analog to digital - state of the art transmitter family - redundancy systems 7TSP ITU inter-regional seminar 2 DVB-T transmitter systems Network layout MFN SFN (multi frequency network) (single frequency network) 7TSP ITU inter-regional seminar 3 SFN -network Advantages of the SFN: * Frequency efficiency - the DVB-T system use the SFN: one frequency for several programs (current situation: each program has another frequency ==> MFN: Multi Frequency Network) - the SFN is with the factor of 3 better than the MFN's * Power efficiency - lower transmitter power in the SFN is required because - addition of all signal components from different transmitters and reflection at the receiving antenna - with the lower transmitter output power: lower distortions in neighbor areas - if gaps exists in the coverage (deep valley, tunnels, etc.): these gaps can be filled 7TSP ITU inter-regional seminar 4 SFN-network Disadvantages of the SFN: * the TS is equal at all transmitter sites (no local program can be introduced) * a transmitter which violates the SFN rules is a jammer in the coverage * synchronization (time, frequency, information) is necessary * network monitoring is necessary to control the SFN features 7TSP ITU inter-regional seminar 5 DVB-T transmitter chain SFN MPEG-2 TS RX MPEG-2 SYNC DVB-T Network system modulator TS adapter 10 MHz 1 pps TX MPEG-2 SFN Distribution remultiplexer adapter Network GPS* adapter Network 10 MHz 1 pps RX SYNC DVB-T Network GPS* system modulator adapter MPEG-2 10 MHz 1 pps TS * Could be any common available frequency reference GPS* 7TSP ITU inter-regional seminar 6 DVB-T transmission network (via Satellite) Transmitter n Private NNI TV digital MPEG 2 + DVB-S Transmitter 1 Private NNI 7TSP ITU inter-regional seminar 7 DVB-T transmission network (via Radio Link/dark fiber) 7TSP ITU inter-regional seminar 8 DVB-T transmission network (via ATM/SDH) digital Studio 1 MPEG 2 Private UNI GPS Private NNI 1 pps GPS 1 pps Public UNI Transmitter n NET 1 Private NNI digital Studio 2 MPEG 2 Private UNI B ISDN MIP Network MUX inserter Adapter Public NNI Public NNI digital Studio n MPEG 2 Public UNI Public NNI NET 2 GPS 1 pps Transmitter 1 Private NNI 7TSP ITU inter-regional seminar 9 DVB-T network monitoring 7TSP ITU inter-regional seminar 10 DVB-T networks monitoring program source data rate entire TS program - TS single programs elementary streams protocol- parameters of parameter 1. priority 2. priority 3. priority tables presence repetition rate picture quality DVQL - W DVQL - U TA SA event protocol all unusual events summed up in REPORT program source repeatable measurement measurement-TS sequences for comparable measurements MIP insertion monitoring of PID, synchronisation info, GPS 1pps modulation links modes radio link (HDB3, QPSK) satellite (QPSK) dark fibre ATM over SDH/PDH 7TSP ITU inter-regional seminar 11 DVB-T transmitter monitoring transmitter RF parameters accuracy of frequency output phase noise of LO average level and max. peak level in RF and IF amplitude vs frequency phase vs frequency C/N and intermodulation shoulder distance power efficiency parameters after QPSK/QAM parameters in demodulation 2k/8k mode constellation diagram BER, MER, END TPS signal delay from TS @ transmitter input to antenna 7TSP ITU inter-regional seminar 12 DVB-T Transmitter switch possition: position 1 exciteroutput BER 2*10-4 nach Viterbi @ Noise 1 position 2 DVB-T transmitteroutput BER 2*10-4 nach Viterbi @ Noise 2 TS transfare via END = Noise 2 - Noise 1 radio link exciter satellite RF output fiber ...... DVB-T demodulator BER measurment 1 2 DVB-T transmitter RF output 7TSP ITU inter-regional seminar 13 DVB-T realisation of digital transmitter stations Transition from analog to digital 7TSP ITU inter-regional seminar 14 DVB-T realisation of digital transmitter stations Requirements for the engineering work Definition of the intended coverage area in relation to the existing analog TV Service (area , population, channel, power). Investigation of possible limitation by interference of other services in this area Result: Selection of "free channels" to choose for licensing in terms of frequency and radiated power. 7TSP ITU inter-regional seminar 15 DVB-T realisation of digital transmitter stations Technical planning of the station - Investigation of the existing antenna Result: dependent on the desired coverage area (omnidirectional, sectional, beam) and mechanical (static) situation define modification and antenna gain. - Calculate necessary transmitter power - Space requirement for transmitters 7TSP ITU inter-regional seminar 16 DVB-T realisation of digital transmitter stations Alternativ: transition of the excisting analog transmitter into digital service - Change of encoder module in exciter - bypassing of the sound part (amplifier and v/s diplexer) - introducing of DVB-T band - filter - new equalizing of transmitter 7TSP ITU inter-regional seminar 17 Transmitter DVB-T /Analog(combined) Block Diagram NH/NV7000 7TSP ITU inter-regional seminar 18 Transmitter analog(split) synthesizer amplifier VH602 exciter A inputs VF1 VF2 I I vision ATV digital I / Q RF encoder Q precorrector Q modulator AF1 sound AF2 dB exciter B inputs VF1 integrated power supply VF2 I I ATV digital I / Q AF1 encoder Q precorrector Q modulator AF2 6 x VH602 synthesizer harmonic- 10 kW optional filter vision/sound -4,43- lightning diplexer notch filterr protection 7TSP ITU inter-regional seminar 19 DVB-T transmitter NV7000 Block Diagram 1,3 kW DVB-T Transmitter amplifier VH602 exciter A input ASI HP1 HP2 I I Encoder digital I / Q RF LP1 DVB-T Q precorrector Q Modulator LP2 dB exciter B built-in power supply input ASI HP1 HP2 I I Encoder digital I / Q RF LP1 DVB-T Q precorector Q Modulator LP2 optional 1,3 kW rms harmonics- channel- lightning- filter filter protection optional DVB-T Transmitter NV7130 1,3kWrms 7TSP ITU inter-regional seminar 20 PAL-nonlinearity Black picture Black picture Frequency response in channel bl/wi-amplification 7TSP ITU inter-regional seminar 21 DVB- Transmitter nonlinearity frequencyresponse Constellation Diagramm 64QAM 7TSP ITU inter-regional seminar 22 DVB-T Crest Faktor analog digital Uss / 2 = Us = 6 (ca.) normalised to U rms U clip in Transmitter Urms = 1 7TSP ITU inter-regional seminar 23 DVB-T realisation of digital transmitter stations Example of a radiated signal from a TV station Mixed Operation Analog / Digital PAL in adjacent channels DVB-T DVB-T 10dB/DIV 2MHz/DIV Interference from analog to digital service Interference from digital to analog service 7TSP ITU inter-regional seminar 24 DVB-T realisation of digital transmitter stations Transmitter Output Spectral Mask after the Bandpass Filter Relative Spectral Density (Frequency Response) (dB) +0,5 -4MHz/0,5dB 4MHz/0,5dB 0 -1,0 -3,805MHz/-1,0dB 3,805MHz/-1,0dB -20 UHF Channel N-1 UHF Channel N UHF Channel N+1 -30 -4,3MHz/-36dB 4,3MHz/-36dB Groupdelay Tg=250ns -40 -10,25..-6MHz/-45dB 6...10,25MHz/-45dB -50 Ref. -60 Tg=-250ns -12 -10 -8 -6 -4 -2 F centre 2 4 6 8 10 12 Frequency relative to Multiplex Centre (MHz) 7TSP ITU inter-regional seminar 25 DVB-T realisation of digital transmitter stations 3dB couplers insertion loss / dB narrow band broadband input input 8 cavity filters output frequency / MHz -10 -8 -6 -4 -2 f-center 2 4 6 8 10 MHz 7TSP ITU inter-regional seminar 26 DVB-T realisation of digital transmitter stations 100 90 80 70 60 50 40 30 20 10 Minimum median field strength [dBuV/m] 0 Bitrate [Mbit/s] Tg/Tu = 1/4 FX QPSK FX 16 QAM FX 64 QAM Port A QPSK Port A 16 QAM Port A 64 QAM Port B QPSK Port B 16 QAM Port B 64 QAM 7TSP ITU inter-regional seminar 27 DVB-T realisation of digital transmitter stations 7TSP ITU inter-regional seminar 28 DVB-T realisation of digital transmitter stations Modulation Code Rate DVB-T net data rates Nutzträger 6048 Takt [MHz] 9 1/7 9 1/7 9 1/7 9 1/7 Guard interv.35 1/4 1/8 1/16 1/32 n*T 8192 8192 8192 8192 Tu [us] 30 896 896 896 896 n*T 2048 1024 512 256 d [us] 25 224 112 56 28 n*T 10240 9216 8704 8448 net 20 Tu+d data[us] 1120 1008 952 924 rates 15 Modulation[Mbps] 64 QAM Bit/Träger 6 Code Rate 10 Guard interv.5 1/4 1/8 1/16 1/32 max. Rate [Mbit/s] 2 1/2 4,98 5,53 5,85 1/32 6,03 0 2 2/3 6,64 7,37 7,81 1/16 8,04 1/2 2/3 3/4 2 2 5/6 7/8 3/4 7,46 8,29 8,78 1/8 guard 9,05 interval 2 2 1/2 2 2 2/3 3/4 4 5/6 7/8 1/4 2 5/6 4 4 8,29 1/2 9,22 9,76 10,05 4 4 2/3 3/4 6 5/6 7/8 2 7/8 8,71 9,686 6 10,25 10,56 code rate of inner error protection / 6 6 bits per sub-carrier max. Rate [Mbit/s] 4 1/2 9,95 11,06 11,71 12,06 7TSP ITU inter-regional seminar 29 DVB-T transmitter system The new UHF transmitter family NH/NV7000 for analog and digital TV transmitters - High Power - Innovation and experience for the benefit of the broadcaster 7TSP ITU inter-regional seminar 30 DVB-T transmitter system NH/NV7000 Component Structure and System Family Modulator / Exciter SH700 ATV Splitt Ampl.