1. 1 SHDSL In the Railway Environment

2. SHDSL 2 History Lesson Analogue Leased lines Dedicated lines between sites Lines are costly to maintain (BT will drop this service eventually) Bandwidth 33600 bps maximum, usually 9600bps Typically Master Slave relationship

3. SHDSL 3 Effective data rate; 1200/ number of outstation less pre / post amble time and inter- message gaps approx 50% e.g. 1200 / 10 =120 bps per unit 120bps less 50% = 60 Bits/s! RS-232V.23 V.23 1200bit/s SCADA/Telemetry/HABD multidrop over trackside pilot cables or FTN

4. SHDSL 4 The Requirements Open Standard Technology (COTS) Rail Network Capacity Industrial robustness & reliabilityHigh isolation and EMC requirements

5. SHDSL 5 SHDSL A Way Forward

6. SHDSL 6  SHDSL stands for Symmetric High-Bitrate Digital Subscriber Loop  G.SHDSL was standardised in 2001  Conforms ITU G.991.2  Bi-directional data rates of 192kbit/s to 15.3Mbit/s over a single twisted pair  Upcoming ”Pair bonding” can be used to increase this data rate and provide link resilience What is SHDLS?

7. SHDSL 7 Internationel Standards Why standard?  Get away from proprietary solutions  Increasing Interoperability  Joint development towards the same goal World-Wide  COT’s equipment supply Focus on "spectral compatibility"  Many different technologies have to coexist  The introduction of new technology should not affect (s) the old  New technologies must be designed to minimize the impact on future technologies

8. SHDSL 8 Historical development  POTS (Plain Old Telephone System)  Limited to 4 kHz FTN(3.4kHz)  Analogue Modem 300-33600 bps DSL  Developed in the '80s  Designed to use all the available cable bandwidth In the Beginning POTS Speech band Frequency Rest of the available spectrum unused MHz

9. SHDSL 9 SHDSL Spectrum use SHDSL Spectrum Frequency Mhz 2.5MHz

10. SHDSL 10 SHDSL performance in the rail environment Performance  Advanced modulation techniques  “Spectral shaping”  FEC (Forward Error Correction) provides robust transmission  Error Rate 1000 times better than older Analogue modem, Unicode modulation schemes  Error rates of 10^ -7

11. SHDSL 11 SHDSL in the rail environment Line Protection  TBU (Transient Blocking Unit)  Over Current / Voltage  Indirect Lightning Strikes  Power Induction  Short Circuits  Isolation to other interfaces

12. 12 The success is in the connection setup!

13. SHDSL 13 Negotiation G.994.1 (G.hs) -> Data Mode Purpose: The units will arrive at the best possible link based on current cable-to- noise levels and the configured settings. G. Hs -> (Line Probing) -> G.hs -> Training -> Data Mode

14. SHDSL 14 Negotiation Protocol G.994.1 (G.hs) -> Overview G.hs

15. SHDSL 15 Negotiation G.994.1 (G.hs) Overview G.hs

16. SHDSL 16 Negotiation G.994.1 (G.hs) What are they talking about:  Max / Min Data Rate  Training parameters  Max / Average Latency  Framing parameters  Line Probe  Sync Word  Vendor ID  Power Backoff  Non-standardized information

17. SHDSL 17 Choice of line speed Two Choices to set connection speed Fix Rate i.e. Lock unit to line speed Auto Rate (the DSL chip negotiation) DDW-225/226: fully automatic DDW-120 +: fully automatic (192-5696 kbps), semi-automatic (> 5696 Kbps)

18. SHDSL 18 UTP RS-422/485 Blue Hose Profibus- DP Telephone wire CW1128, CW1308, CW1198 Pilot cables ANY Twisted Pair cable BARBED WIRE !!!!!!!!!!!! Oldest test cable 105 years! @ 2 Mbit/s Longest tested transmission 58km @ 192Kbit/S What types of cables can be used?

19. SHDSL 19 DDW-120+/225&226 Km/Miles

20. SHDSL 20 Topologies

21. SHDSL 21 Twisted Copper Pair Up to 15.3 Mbit/s Transparent Ethernet > 10km Twisted Copper Pair Up to 15.3 Mbit/s Transparent Ethernet >10km On each cable segment Topologies

22. SHDSL 22 DDW-226  Support for legacy RS232 build in Twisted Copper Pair Up to 15.3 Mbit/s Transparent Ethernet > 10km Redundant Ring Legacy Serial Port – DDW-226 Ring Topology Transparent Ethernet > 10km

23. SHDSL 23 Using SHDSL DDW-225/6 Twisted Copper Pair Up to 15.3 Mbit/s Legacy Serial Port – DDW-226 L3 Routing Topology Transparent Ethernet > 10km FTN or FTNe L3 Routing protocol L3 Redundant networkL3 Mesh Topology

24. SHDSL 24 Using SHDSL L2 Diverse Topology FTN or FTNe

25. 25 Thank you for listening