Lorain Electronics Great Lakes Automated VHF System
Based on information in a 1982 LEC publication
The Lorain Electronics Great Lakes
Automated VHF System was composed of fourteen remotely controlled
VHF-FM stations (Map)
strategically located to provide ship-to-shore coverage for large
commercial vessels on all but Lake Ontario. While primarily
designed to operate with automatic full duplex radio-telephones capable
of direct dialing land telephones and ships it also operated with
non-automatic push-to-talk equipment.
Normal ranges over open water for large vessels to a shore station were from 40 to 75 miles, for smaller vessels, from 20 to 35 miles.
The fourteen VHF stations were each connected to the national land telephone network via a regular subscriber business line to the nearest telephone central office. This is the circuit over which all telephone calls were made whether directly dialed by the vessel or by the control center operator. LEC furnished the ships with a Great Lakes Marine Telephone Directory (from which this article is derived) which listed the local exchange numbers and the prefixes that could be dialed as local numbers through each station. In addition, each station was connected to the control center at WMI in Lorain, Ohio, by another special leased circuit over which control signals, data information and operator voice communications were made. Leased circuits were very expensive and to make the system economically viable it was necessary to connect three or four of the stations to each of the four leased lines.
At each station a mini computer, or electronic brain, controlled the station functions and temporarily stored call information until released to the master computer at the Lorain control center.
The master computer at Lorain polled each station on each of the four control circuits once every two seconds. The information was in the form of data and only took a fraction of a second to send. The computer sorted the information received into various categories such as incoming manual ship or land calls that signaled the operator, billing information that was to be stored, or various checks on the condition of the station equipment. Portions of the information were displayed on a screen for visual inspection by the operator.
When the control center operator used a control line to talk to a ship through one of the stations, the other stations on that line could not be polled and thus no call alarms, etc., could be sent to the control center until the operator released the line to the computer. For this reason ships may have experienced delays in reaching the control center when making a manual call to one of the other stations on the same control line. Direct dial calls were, not affected and the ships were urged to use that method whenever possible.
Weather broadcasts, storm warnings, hydro-graphic reports, etc., required the use of the control lines and polling could not be done until the broadcast was completed. Weather broadcasts were normally made at scheduled times and customers were cautioned to avoid making calls that overlapped into the broadcast times as they would likely be cut off when the broadcast began.
This system was sold to WJG-Maritel in 198(?), and they closed it in 1990 due to lack of traffic. Some of the stations were then sold to WLC.