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. / SC700 ATV Combined Ampl. / SV700 DVB-T
Control and Monitoring
LDMOS Amplifier Modules 470 - 860 MHz VH602 VH650 500W/200W 2kW/400W
Power Supply integrated in VH602 Power Supply
Liquid Cooling System Air Cooling System
High Power Tx Medium Power Tx ATV: 3,5kW ... 40kW ATV: 250W ... 2kW DVB-T: 800W ... 10kW DVB-T: 100W ... 800W
7TSP ITU inter-regional seminar 31 DVB-T transmitter system
TARGETS for NH/NV7000 Transmitter: Medium Power air cooled Transmitter: High Power liquid cooled l Economical l Compact l State of the art l Modular design l Expandable l Easy to handle
7TSP ITU inter-regional seminar 32 DVB-T transmitter system
Liquid Cooled Transmitter / Amplifier
VH602 LDMOS amplifier
10kW ATV / 2,5 kW DVB-T transmitter into one rack
7TSP ITU inter-regional seminar 33 DVB-T transmitter system Overview NV/NH7000
System configuration for liquid cooling
Exciter DVB-T Filter DVB-T Modulator Analog VH602 Harmonics Modulator and Amplifier incl. PS Combiner Trap Filter
Controlling Heat and Pump System Monitoring Exchanger
7TSP ITU inter-regional seminar 34 NH/NV7000 High Power
NH/NV Power Classes
Number of ATV DVB-T
Amplifier Module Psync Peff (36dB shoulder) (+ Sound Amp. Module for ATV)
2 (+1*) 3,5 kW 800 W
3 (+1*) 5 kW 1,3 kW
4 (+2) 7 kW 1,7 kW
6 (+2) 10 kW 2,5 kW
8 (+2) 13 kW 3,4 kW
12 (+2) 20 kW 5 kW
* optional 2 Further combination: 2*13kW and 2*20kW in active reserve 3*10kW 7TSP ITU inter-regional seminar 35 Redundancy in power
Output Power with Breakdown of Amplifiers:
æ ö2 ç m-n ÷ P = P * ç ÷ ç ÷ out rated ç m ÷ è ø
Pout = real output power Prated = nominal output power m = number of amplifiers n = number of defect amplifiers
for example: m=8, n=1 Þ Pout = 0.766 x Prated
7TSP ITU inter-regional seminar 36 VH602 Amplifier and Power Supply
Cooling Concept Amplifier l Closed loop of liquid through one pipe with continuous identical diameter into the amplifier heat sink (corrosion-less material in stainless steel and aluminium) l Internal blower for transfer of remainder heat to watercooler, thus preventing any hot spot l Transistors mounted directly on top of cooling pipe l DT input / output amplifier < 3°C l Junction temperature < 120°C at 24°C ambient temperature
7TSP ITU inter-regional seminar 37 VH602 Amplifier and Power Supply
VH602 Block Diagram
270W PSYNC 65W PDVB 60W 15W analog 2mW 10W 2kW
440W 0,4mW 2W digital
65W 270W 15W 60W
7TSP ITU inter-regional seminar 38 Liquid Cooling System
Water Cooling System for the transmitter NV6000
M
Heat exchanger
T1 P1 P1
Flexi tubing Drain valve
Safety valve Expansion vessel Ball valve Check valve Pump
M 3-way mixer air-vent valve Flow control monitor
7TSP ITU inter-regional seminar 39 Multistandard Exciter SX700
Power supply
ATV/DVB Encoder
Digital Pre-Corrector
Modulator
Synthesizer CCU
7TSP ITU inter-regional seminar 40 Exciter SH/SC/SV700
Block Diagram
TS HP A / VIDEO 1 DVB-Encoder: ATV/DVB-Precorrector: ATV/DVB-Modulator: - MIP-Decoder - Groupdelay Corrector - analogue I/Q-Modulation TS HP B / - SFN Function - Linear Precorrector for into RF for Video and RF_VIDEO VIDEO 2 - Channel Coding I_VIDEO DVB and I_VIDEO Audio Band III, IV and V TS LP A / and Modulation ATV split and combined - Output Filter for Video and VIDEO_MON Q_VIDEO - D/A-Conversion Q_VIDEO Audio or - Output Amplifier TS LP B I_AUDIO I_AUDIO - RF Checker RF_AUDIO ATV-Encoder: Q_AUDIO Q_AUDIO 1PPS_EXT - digital Video- and Audio processing RF_CHECK RS232 - multi Standard Digital Analogue - optional NICAM or Std M Interface Interface RS232_FLASH module (14 Bit)
CONTROL LOCAL
INT_REF (120MHZ) ATV/DVB-Synthesizer: REF_EXT 1PPS INT - 10 MHz local Ref-PLL - Band III, IV and V RS485 - optional internal GPS- module GPS_ANT
RS232 Central Control Unit Displayunit
RS485 RS232 TTL-Bus Control Bus to to Amplifiers, Switches, par. Interface Blowers, ...
7TSP ITU inter-regional seminar 41 Remote interface
NetLink
7TSP ITU inter-regional seminar 42 Remote interface
Monitoring and Controlling System l User-friendly monitoring software on ROHDE&SCHWARZ TRANSMITTER CONTROL UNIT one large display l Additional PC software (GUI) with very comfortable graphical presentation REMOTE CONTROL Signals Parallel Interface I/O Commands and high level of information (Option)
F1 F2 F3 F4 F5
ESCAPE TAB ENTER BITBUS- RS 485 RS 485 Gateway + + + (BITBUS acc.
com 2 l One interface for the all parameters of - + (Option) to IEC 864-2)
+
the exciter (incl. encoder and RESET RS 232 Modem PSTN RS 232 + + + (Option) (TNPP) com 1 com 3 GPS-receiver in case of DVB-T) com 1 com 4 I / O Web-Server/ Ethernet RS 485 SNMP-Agent (Option) (TCP/IP or SNMP) l Multiple possibilities of remote control GUI (Graphical User Interface)
B B SV700 - Bitbus (RS485) Amplifier A RC RS 232
com 1 A SV700 GS (TNPP) RS 232 (SH700) (TNPP)
com 2 com 1 Amplifier - RS232 with TNPP protocol (SC700) RC -> modem option Encoder Equal. Synth. IQ-Mod.
- NetLink for SNMP interface or CCU : Central Control Unit SV700 : Exciter DVB-T SH700 : Exciter Analog-TV (Split) WEB-based supervision system SC700 : Exciter Analog-TV (Combined) RC : Rack Control - Parallel interface
7TSP ITU inter-regional seminar 43 3. NetLink Unit for Remote Control
Overview on Protocol Types and Layers
Web-Browser HP Openview
Application HTTP SNMP (Layer 7) (Hyper Text Transfer Protocol) (Simple Network Management Protocol)
Transport TCP UDP (Layer 4) (Transport Control Protocol) (User Datagram Protocol)
Network IP (Layer 3) (Internet Protocol)
7TSP ITU inter-regional seminar 44 4. NetLink WEB-Server
WEB-Server Application (Supervision System over TCP/IP)
Transmitter Station Network Control Centre / Mobile Staff
• Ethernet (LAN/WAN) Integrated WEB-server Laptop NetLink from R&S with standard WEB-browser
Internet / Intranet (TCP/IP)
Management system Firewall (Windows, Unix, Linux, Mac) with standard Web-browser
Server Client
7TSP ITU inter-regional seminar 45 5. NetLink SNMP-Agent
SNMP Application
Transmitter Stations Network Control centres
R&S delivery part
NetLink Integrated SNMP agent from R&S
• Ethernet (LAN/WAN) Management platform (e.g. HP openview) and SNMP network manager (software) SNMP Network
SNMP agent Tx from Supplier X
Server NMS SNMP Traps
7TSP (Alarms) ITU inter-regional seminar 46 Transmitter Redundency Systems
7TSP ITU inter-regional seminar 47 Dual drive, single PA stage
band pass 3 port U-link PA filter panel TS OFDM RF out antenna Mod.A Exciter A
TVSS D.L.
TS OFDM Mod.B Exciter B
7TSP ITU inter-regional seminar 48 Dual drive, double PA stage, U-link patching
RF U-link patch panel 3 dB coupler PA A TS absorber OFDM Mod.A Exciter A
band pass filter D.L. RF out antenna
TVSS PA B TS OFDM Mod.B Exciter B
7TSP ITU inter-regional seminar 49 Dual drive, double PA stage, RF relay switch
RF relays automatic switching 3 dB coupler PA A TS absorber OFDM Mod.A Exciter A
band pass filter
D.L. RF out antenna
TVSS PA B TS OFDM Mod.B Exciter B
7TSP ITU inter-regional seminar 50 Passive stand-by
band pass PA A filter TS RF relay OFDM RF out antenna Mod.A Exciter A
TVSS
D.L. PA B TS OFDM Mod.B Exciter B
7TSP ITU inter-regional seminar 51 Passive stand-by with dual drive
band pass PA filter TS OFDM RF out antenna Mod.A Exciter A
TVSS
D.L. PA TS OFDM Mod.B Exciter B
7TSP ITU inter-regional seminar 52 Passive-/active stand-by for half antenna
band pass PA A filter TS RF out UA OFDM Mod.A Exciter A absorber TVSS
D.L.
3 dB coupler
PA B TS RF out LA OFDM Mod.B Exciter B
TVSS
7TSP ITU inter-regional seminar 53 Reserve concepts
N+1 Reserve System
CCU
1 2 n R
ASI crossbar switch
Programm 1 Programm 2 Programm n
DVB-T transmitter n+1
7TSP ITU inter-regional seminar 54 Conclusion
Benefits for the broadcaster
þ Extremely compact design þ Improved technology for exciter, amplifier and cooling system þ Low operational cost þ More flexibility for installation þ More flexibility for remote control þ High commonality of sub-modules for reduced spares inventories þ Easy transition from analogue to digital secures investment
7TSP ITU inter-regional seminar 55 References:
ETS 300 744 Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital Terrestrial television (DVB-T).
ETR 290 Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems.
TR 101 190 Digital Video Broadcasting (DVB); Implementation guidelines for DVB terrestrial services; Transmission aspects. (TR 101 190).
TM 1925 Digital TV Transmitter Performance Specification. (AC106 VALIDATE Del.14)
7TSP ITU inter-regional seminar 56