MARITIMES SCANNING SITE

NOVA SCOTIA DEPARTMENT OF TRANSPORTATION VHF NETWORK
A component of the NSIMRS
Last updated April 2, 2010

© 2010, MARITIMES SCANNING SITE, all rights reserved

HISTORICAL PAGE

This page describes or depicts a service or system that is no longer in operation and is thought to be substantially dismantled except that the repeaters at Hunters Mtn, Salem, Creignish, Savannah and Barr Settlement remain listed in TAFL and licenced to the provincial government.  These few repeaters are now considered to be part of the N.S. Fire Grid.  

This system was a component of the NS Integrated Mobile Radio System, which has largely been replaced by the 800 MHz NS Trunked Mobile Radio System.  The DOT grid is thought to have been substantially shut down in approximately 2001 when operations moved to the NSTMRS.   It may be possible that the actual repeaters are still in place but not operational.   In a few cases thre repeaters are still in operation but not used for DOT purposes.

The indicated dial-up code was used by a unit in one area in order to connect with a distant repeater.   The user brought up the local repeater and dialled the distant one by inputting the dial-up code.  Note that the dial-up code is the site number + 500.  It was possible for DOT users to be connected to the other networks in the system by dialling the operator at Shubie Radio (dial-up code = 0) who would make a manual patch.

Note that most radios as used by non-supervisory personnel did not have the multi-channel or tone-linking capability and instead had something such as Channel 1 for the local repeater and possibly another one or two adjacent repeaters and possibly the DOT simplex frequency.

An accurate description written retrospectively is somewhat complex due to complexities and lack of information. The DOT grid utilized several extra sites, i.e. sites not part of the main IMRS system but on the other hand did not use the Springfield site.   The unusual feature of the DOT system was that in most cases repeaters were arranged into pairs and possibly trios, hard-linked together.  For  example on the chart below Middle Ohio and East Kemptville repeaters were linked so that one input of 149.20 would bring up both repeaters.   When one came up, the other would as well, whether or not the mobile transmitter could hit one or both sites.   The extra sites were later additions to the system and it is not so well known in most cases how they fit into the simulcasting arrangement.   For example, the Savannah site is in the general vicinity of the two sites just mentioned and it is likely that it also was hard-linked with them so that in this case there would be a trio of repeaters coming up simultaneously.   That would also imply that the 150.53 Savannah repeater would also use the 149.20 input of the other two sites, rather than the 149.59 as used for the 150.53 repeater at Shubie.   This detail is however lost with time.

Note that repeaters on 150.605, 150.485 and 150.905 were all stand-alone, i.e. not simulcast with any other repeater.   150.905 was a late addition to the system, introduced in the Halifax region due to the heavy use of the already existing 150.605 repeater.

The pairing or tripling of repeaters also meant that for dial-up purposes in linking the linked repeaters would have the same code.  For example Middle Ohio and E. Kemptville both used 501, with the 502 code not being used at all.  Savannah, if also linked, would also use the 501 code.

Some sites are known to have not been shut down and for some reason still exist and are operational, at least as stand-alone repeaters.   This is a certainty in the case of Barr Settlement on 150.125 which is thought to be used, in theory at least, as a fire department repeater.  Other repeaters at "extra sites" are rumoured to be mostly still in operation for unknown uses.

Tones are not confirmed, except that those in the area of Central Nova Scotia are all thought to have been 82.5. and in the Annapolis Valley and South Shore on 71.9.

DOT Simplex 149.89