Well put! Would it be appropriate for this to be taken up by UDG? Set up a working party and do the necessary research? DfT funding could justifiably be sought, because it is a National issue. It isn't just data drop out but also latency that is relevant, even with time stamped data. Because data loss affects network control and therefore efficiency it is a real problem and not a theoretical issue. (For sign control etc, providing the system copes with temporary data loss not a worry, but for real time control a real issue.) Over the next few years systems are likely to migrate to a wide range of communication methods, using hybrid solutions for any one system, better that there is an overall consistent and understood approach. Those who have been implementing fibre, radio etc are well versed, as the methodology becomes wide spread there is a potential for inadvertently introducing 'strange' problems. PW -----Original Message----- From: tcug-bounce@xxxxxxxxxxxxx [mailto:tcug-bounce@xxxxxxxxxxxxx] On Behalf Of Morar Jag (ST) Sent: 08 July 2008 10:16 To: tcug@xxxxxxxxxxxxx Subject: [TCUG] Re: Use of fibre-optic, IP addressable UTC For the last decade I have been advocating re-assessment of what we do on encountering communication break-up on IP based UTC communications. The original SCOOT system based on the requirements of MCE0360 specified maximum 15 reply message (MT) errors in an hour before any intervention was required. During the trialling of the original London UTC system back in 1981, we encountered frequent break-up in BT line comms. We therefore applied a heuristic approach to actions that need to be taken with different type of errors that we encounter and developed the rules for UTC intervention. To date we still apply those rules in London. With the advent of many new communications options and also the increased levels of error checking in the Internet Protocols we need to rethink and once again apply the heuristic approach to what we should do when we encounter message errors in modern day wireless IP based UTC communications. -----Original Message----- From: tcug-bounce@xxxxxxxxxxxxx [mailto:tcug-bounce@xxxxxxxxxxxxx] On Behalf Of Welsh, Paul Sent: 08 July 2008 08:20 To: tcug@xxxxxxxxxxxxx Subject: [TCUG] Re: Use of fibre-optic, IP addressable UTC Just as background for those who are not so ancient, the comm's loss isolate was built in in the days when it was hard to keep 300 Baud lines up and reasonably reliable. =3D3D20 BT used average signal strength meters to claim the lines were working (moving coil galvo's no less), failing to understand that we had gone digital - just. =3D3D20 Because of the way intermittent drop out's can cause odd effects on the road so to speak, it is still relevant. PW =3D3D20 -----Original Message----- From: tcug-bounce@xxxxxxxxxxxxx [mailto:tcug-bounce@xxxxxxxxxxxxx] On Behalf Of Douglas Cook Sent: 07 July 2008 15:05 To: 'tcug@xxxxxxxxxxxxx' Subject: [TCUG] Re: Use of fibre-optic, IP addressable UTC The loss of comms for a "few seconds" causes the UTC system to isolate and drop back into local control. This is the problem we have with our comms system. The blue in station has a protocol where any loss of comms for 3 consecutive seconds causes it to isolate that site.=3D3D20 The problem is it seems the wireless comms system we have purchased cannot achieve reliable comms with out these three second drops. Some of our sites currently isolate 10 times during the morning peak which is pretty un workable. I have been told by our comms supplier that the threes seconds drop out are a characteristic of wireless comms and must be accepted! ************************************************** COMPANY PARTICULARS: For particulars of companies within the Amey Group, pl=3D3D ease visit http://www.amey.co.uk/Home/Companyparticulars/tabid/182/Default.=3D3D aspx. Amey plc, Registered Office: The Sherard Building, Edmund Halley Roa=3D3D d, Oxford OX4 4DQ, Registered in England: 4736639 CONFIDENTIALITY NOTICE: This email message and accompanying data are for th=3D3D e sole use of the intended recipient(s) and may contain information that is=3D3D confidential. If you are not the intended recipient, you are notified that=3D3D any use, dissemination, distribution or copying of this message or data is=3D3D prohibited. If you received this email message in error, please notify us =3D3D immediately and erase all copies of this message and attachments. 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