[TCUG] Re: Use of fibre-optic, IP addressable UTC

  • From: "Morar Jag \(ST\)" <Jag.Morar@xxxxxxxxxx>
  • To: <tcug@xxxxxxxxxxxxx>
  • Date: Tue, 8 Jul 2008 10:16:13 +0100

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. =3D20 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. =3D20

Because of the way intermittent drop out's can cause odd effects on the
road so to speak, it is still relevant.

PW

=3D20


-----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.=3D20

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!

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