Technical Realisation of Digital TV Transmitter Systems

Transcription

ITU inter-regional seminar
Friedrich Rottensteiner
Rohde & Schwarz
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DVB-T Transmitter system
- MFN / SFN networks
- Transition from analog to digital
- state of the art transmitter family
- redundancy systems
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DVB-T transmitter systems
Network layout
MFN
(multi frequency network)
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SFN
(single frequency network)
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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 a nd
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
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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
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DVB-T transmitter chain SFN
MPEG-2
TS
RX
Network
adapter
MPEG-2
TS
TX
Network
adapter
MPEG-2
SFN
remultiplexer adapter
10 MHz
Distribution
Network
DVB-T
modulator
1 pps
GPS*
1 pps
10 MHz
GPS*
* Could be any common available frequency reference
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SYNC
system
RX
Network
adapter
MPEG-2
TS
SYNC
system
10 MHz
DVB-T
modulator
1 pps
GPS*
6
DVB-T transmission network (via Satellite)
Transmitter n
Private NNI
TV digital
MPEG 2 + DVB-S
Transmitter 1
Private NNI
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DVB-T transmission network (via Radio Link/dark fiber)
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DVB-T transmission network (via ATM/SDH)
digital Studio 1
MPEG 2
Private UNI
GPS
1 pps
Private NNI
GPS
1 pps
Public UNI
Transmitter n
NET 1
Private NNI
digital Studio 2
MPEG 2
Private UNI
B ISDN
MUX
MIP
inserter
Network
Adapter
Public NNI
Public NNI
digital Studio n
MPEG 2
Public UNI
Public NNI
NET 2
GPS
1 pps
Transmitter 1
Private NNI
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DVB-T network monitoring
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DVB-T networks monitoring
program source
program - TS
data rate
protocolparameter
tables
picture quality
event protocol
program source
measurement-TS
repeatable measurement
sequences for comparable
measurements
MIP insertion
monitoring of
PID, synchronisation info,
GPS 1pps
modulation links
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entire TS
single programs
elementary streams
parameters of
1. priority
2. priority
3. priority
presence
repetition rate
DVQL - W
DVQL - U
TA
SA
all unusual events summed
up in REPORT
modes
radio link (HDB3, QPSK)
satellite (QPSK)
dark fibre
ATM over SDH/PDH
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DVB-T transmitter monitoring
transmitter
output
parameters after
demodulation
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RF parameters
accuracy of frequency
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
QPSK/QAM parameters in
2k/8k mode
constellation diagram
BER, MER, END
TPS
signal delay from TS @
transmitter input to antenna
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
radio link
satellite
fiber ......
END = Noise 2 - Noise 1
exciter
RF output
DVB-T demodulator
BER measurment
1
2
DVB-T transmitter
RF output
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DVB-T realisation of digital transmitter stations
Transition from
analog to digital
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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.
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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
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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
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Transmitter DVB-T /Analog(combined)
Block Diagram NH/NV7000
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Transmitter analog(split)
synthesizer
amplifier VH602
exciter A
inputs
VF1
VF2
I
ATV
encoder
Q
vision
I
digital
precorrector
Q
I/Q
modulator
RF
sound
AF1
AF2
dB
exciter B
inputs
integrated power supply
VF1
VF2
AF1
AF2
I
ATV
encoder
Q
I
digital
precorrector
Q
I/Q
modulator
6 x VH602
synthesizer
optional
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harmonicfilter
10 kW
vision/sound
diplexer
-4,43notch filterr
lightning
protection
19
DVB-T transmitter NV7000
Block Diagram 1,3 kW DVB-T Transmitter
amplifier VH602
exciter A
input ASI
HP1
HP2
LP1
LP2
I
Encoder
DVB-T
Q
Q
I/Q
Modulator
RF
dB
built-in power supply
exciter B
input ASI
HP1
HP2
LP1
LP2
I
digital
precorrector
I
Encoder
DVB-T
Q
I
digital
precorector
Q
I/Q
Modulator
RF
optional
1,3 kW
harmonicsfilter
channelfilter
rms
lightningprotection
optional
DVB-T Transmitter
NV7130 1,3kWrms
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PAL-nonlinearity
Black picture
Black picture
Frequency response
in channel
bl/wi-amplification
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DVB- Transmitter nonlinearity
frequencyresponse
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Constellation Diagramm 64QAM
22
DVB-T Crest Faktor
analog
digital
Uss / 2 = Us = 6 (ca.)normalised to U rms
U clip in Transmitter
Urms = 1
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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
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Transmitter Output Spectral Mask after the Bandpass Filter
Relative Spectral Density
(dB)
+0,5
(Frequency Response)
-4MHz/0,5dB
4MHz/0,5dB
-3,805MHz/-1,0dB
3,805MHz/-1,0dB
0
-1,0
-20
UHF Channel N-1
-30
UHF Channel N
UHF Channel N+1
-4,3MHz/-36dB
4,3MHz/-36dB
Groupdelay
Tg=250ns
-40
-10,25..-6MHz/-45dB
-50
6...10,25MHz/-45dB
Ref.
-60
Tg=-250ns
-12
-10
-8
-6
-4
-2
F centre
2
4
6
8
10
12
Frequency relative to Multiplex Centre (MHz)
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3dB couplers
insertionloss/dB
broadband
input
narrow band
input
8 cavity filters
output
frequency/MHz
-10 -8
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-6
-4
-2 f-center2
4
6
8
10 MHz
26
Minimum median field strength [dBuV/m]
100
90
80
70
60
50
40
30
20
10
0
Bitrate [Mbit/s] Tg/Tu = 1/4
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FX QPSK
FX 16 QAM
FX 64 QAM
Port A QPSK
Port B QPSK
Port A 16 QAM
Port B 16 QAM
Port A 64 QAM
Port B 64 QAM
27
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Modulation
Code Rate
DVB-T net data rates
6048
9 1/7
9 1/7
1/4
1/8
8192
8192
896
896
2048
1024
224
112
10240
9216
1120
1008
Nutzträger
Takt [MHz]
Guard interv.
35
n*T
Tu [us] 30
n*T
25
d [us]
n*T
net
20
Tu+d data
[us]
rates
[Mbps]
9 1/7
1/32
8192
896
256
28
8448
924
15
Modulation
Code Rate 10
64 QAM
Guard interv.5
max. Rate [Mbit/s] 2
0
2
1/2 2 / 3
3/4
2
2 2 2
2
2
5/6
7/8
2
2
1/2
2/3
3/41/2
5/64
7/8
2/3
4
3/4
4
1/4
4,98
6,64
7,46
5/6
7/8
8,29
4
4
8,71
code rate of inner error protection /
bits per sub-carrier
max. Rate [Mbit/s] 4
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9 1/7
1/16
8192
896
512
56
8704
952
1/2
9,95
Bit/Träger
1/8
5,53
7,37
8,29
1/29,22
2/3
6 9,68
6
11,06
6
3/4
5/6
6
6
1/16
1/32
5,85
6,03
1/32
7,81
8,04
1/16
1/8
8,78
guard
9,05
interval
9,76 1/4
10,05
7/8
10,25
10,56
6
11,71
12,06
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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
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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
2kW/400W
VH650 500W/200W
Power Supply integrated in VH602
Power Supply
Liquid Cooling System
Air Cooling System
High Power Tx
ATV: 3,5kW ... 40kW
DVB-T: 800W ... 10kW
7TSP
Medium Power Tx
ATV: 250W ... 2kW
DVB-T: 100W ... 800W
31
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
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Liquid Cooled Transmitter / Amplifier
VH602 LDMOS amplifier
10kW ATV / 2,5 kW DVB-T
transmitter into one rack
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DVB-T transmitter system Overview NV/NH7000
System configuration for liquid cooling
Exciter
DVB-T Filter
Analog
Modulator
VH602
Amplifier incl. PS
Controlling
and
Monitoring
7TSP
Co
m
bin
er
DVB-T
Modulator
Pump System
Harmonics
and
Trap Filter
Heat
Exchanger
34
NH/NV7000 High Power
NH/NV Power Classes
Number of
Amplifier Module
ATV
Psync
DVB-T
Peff (36dB shoulder)
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
(+ Sound Amp. Module
for ATV)
* optional 2
Further combination: 2*13kW and 2*20kW in active reserve
3*10kW
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Redundancy in power
Output Power with Breakdown of Amplifiers:
P
=P
∗
out
rated






m −n 

m 
2
Pout
= real output power
Prated
= nominal output power
m
= number of amplifiers
n
= number of defect amplifiers
for example: m=8, n=1
⇒ P out = 0.766 x P rated
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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
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VH602 Amplifier and Power Supply
VH602 Block Diagram
270W
PSYNC
PDVB
65W
60W
15W
2mW
10W
0,4mW
2W
analog
2kW
440W
digital
65W
270W
15W
60W
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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
M
Flow control monitor
7TSP
Check valve
Pump
3-way mixer
air-vent valve
39
Multistandard Exciter SX700
Power supply
ATV/DVB Encoder
Digital Pre-Corrector
Modulator
Synthesizer
CCU
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Exciter SH/SC/SV700
Block Diagram
TS HP A /
VIDEO 1
TS HP B /
VIDEO 2
TS LP A /
VIDEO_MON
DVB-Encoder:
- MIP-Decoder
- SFN Function
- Channel Coding
and Modulation
RS232
RS232_FLASH
I_VIDEO
Q_VIDEO
- Linear Precorrector for
DVB and
ATV split and combined
- D/A-Conversion
ATV/DVB-Modulator:
- analogue I/Q-Modulation
I_VIDEO
Q_VIDEO
or
TS LP B
1PPS_EXT
ATV/DVB-Precorrector:
- Groupdelay Corrector
ATV-Encoder:
- digital Video- and Audio
processing
- multi Standard
- optional NICAM or Std M
module
I_AUDIO
I_AUDIO
Q_AUDIO
Q_AUDIO
Digital
Interface
(14 Bit)
Analogue
Interface
CONTROL
1PPS INT
Displayunit
RF_AUDIO
RF_CHECK
ATV/DVB-Synthesizer:
- 10 MHz local Ref-PLL
- Band III, IV and V
- optional internal GPSmodule
RS485
REF_EXT
GPS_ANT
Central Control Unit
RS485 RS232
7TSP
RF_VIDEO
LOCAL
INT_REF (120MHZ)
RS232
into RF for Video and
Audio Band III, IV and V
- Output Filter for Video and
Audio
- Output Amplifier
- RF Checker
TTL-Bus
to
par. Interface
Control Bus to
Amplifiers, Switches,
Blowers, ...
41
Remote interface
NetLink
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Remote interface
Monitoring and Controlling System
l User-friendly monitoring software on
one large display
TRANSMITTER CONTROL UNIT
ROHDE&SCHWARZ
l Additional PC software (GUI) with very
comfortable graphical presentation
and high level of information
REMOTE CONTROL
I/O
l One interface for the all parameters of
the exciter (incl. encoder and
GPS-receiver in case of DVB-T)
F2
F3
ESCAPE
F4
F5
TAB
ENTER
+
+
+
-
com 2
F1
+
RS 485
7TSP
Commands
BITBUSGateway
RS 485
(BITBUS acc.
to IEC 864-2)
(Option)
com 3
+
RESET
RS 232
com 1
+
+
com 1
com 4
+
RS 232
PSTN
(TNPP)
Modem
(Option)
I/O
Web-Server/
SNMP-Agent
(Option)
RS 485
Ethernet
(TCP/IP or
SNMP)
GUI
(Graphical User
Interface)
B
(TNPP)
(SC700)
Encoder
CCU :
SV700 :
SH700 :
SC700 :
RC :
Equal.
Synth.
Amplifier
GS
SV700
(SH700)
RC
RS 232
com 1
RS 232
(TNPP)
B
com 1
A
RC
SV700
com 2
l Multiple possibilities of remote control
- Bitbus (RS485)
- RS232 with TNPP protocol
-> modem option
- NetLink for SNMP interface or
WEB-based supervision system
- Parallel interface
Signals
Parallel
Interface
(Option)
A
Amplifier
IQ-Mod.
Central Control Unit
Exciter DVB-T
Exciter Analog-TV (Split)
Exciter Analog-TV (Combined)
Rack Control
43
3. NetLink Unit for Remote Control
Overview on Protocol Types and Layers
Web-Browser
Application
(Layer 7)
Transport
(Layer 4)
Network
(Layer 3)
HP Openview
HTTP
SNMP
(Hyper Text Transfer Protocol)
(Simple Network Management Protocol)
TCP
UDP
(Transport Control Protocol)
(User Datagram Protocol)
IP
(Internet Protocol)
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4. NetLink WEB-Server
WEB-Server Application (Supervision System over TCP/IP)
Transmitter Station
Network
Control Centre / Mobile Staff
• Ethernet (LAN/WAN)
NetLink
Integrated
WEB-server
from R&S
Laptop
with standard WEB-browser
Internet / Intranet
(TCP/IP)
Firewall
Server
7TSP
Management system
(Windows, Unix, Linux, Mac)
with standard Web-browser
Client
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)
SNMP Network
Management platform
(e.g. HP openview)
and SNMP network manager
(software)
SNMP agent
Tx from
Supplier X
Server
7TSP
SNMP Traps
(Alarms)
NMS
46
Transmitter
Redundency Systems
7TSP
47
Dual drive, single PA stage
band pass
filter
PA
TS
OFDM
Mod.A
3 port U-link
panel
antenna
RF out
Exciter A
TVSS
D.L.
TS
7TSP
OFDM
Mod.B
Exciter B
48
Dual drive, double PA stage, U-link patching
RF U-link
patch panel
3 dB coupler
PA A
TS
OFDM
Mod.A
absorber
Exciter A
band pass
filter
D.L.
RF out
antenna
TVSS
PA B
TS
7TSP
OFDM
Mod.B
Exciter B
49
Dual drive, double PA stage, RF relay switch
RF relays
automatic
switching
3 dB coupler
PA A
TS
OFDM
Mod.A
absorber
Exciter A
band pass
filter
D.L.
RF out
antenna
TVSS
PA B
TS
7TSP
OFDM
Mod.B
Exciter B
50
Passive stand-by
band pass
filter
PA A
TS
RF relay
OFDM
Mod.A
RF out
antenna
Exciter A
TVSS
PA B
TS
7TSP
OFDM
Mod.B
D.L.
Exciter B
51
Passive stand-by with dual drive
band pass
filter
PA
TS
OFDM
Mod.A
RF out
antenna
Exciter A
TVSS
PA
TS
7TSP
OFDM
Mod.B
D.L.
Exciter B
52
Passive-/active stand-by for half antenna
band pass
filter
PA A
TS
OFDM
Mod.A
RF out
UA
Exciter A
absorber
TVSS
D.L.
3 dB coupler
PA B
TS
OFDM
Mod.B
LA
RF out
Exciter B
TVSS
7TSP
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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
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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
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
56

Technical Realisation of Digital TV Transmitter Systems

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