At a reception at the Norwegian Embassy on 27th September 1965, a cheque for £400,000 was handed by Colonel Bjørn Rørholt of the Norwegian Joint Signals Administration to Sir Edward Lewis, Chairman of The Decca Group of Companies. The occassion was to mark the establishment of The Decca Navigator System in Norway. Representatives of the Norwegian Joint Signals Administration , Norwegian Fishing and Maritime interests and Kongsberg Våpenfabrik , a company licenced by Decca for the manufacture of receivers was present. The cheque was the first installment on a contract for equipment and services to be provided to the Norwegian Government by The Decca Navigator Company expected to be in excess of £1,000,000. (Decca Company photo)

Decca chains in Scandinavia. (Graphic courtesy Decca Navigator News. Modified by Jerry Proc)

This image depicts the sea coverage provided by the Norweigan chains. (From Decca Navigator News, Spring 1967)

From Decca Navigator News September 1968

The new generation of Decca Navigator automatic transmitters supplied to Norway were designed to operate unmanned with the transmitters of each chain continually monitored and under remote control manned by one person.

Each station was equipped with a Data Logger which scans all critical units at regular intervals and records their serviceability state on punched tape. From this surveillance, comprehensive information about the station's functions are extracted for transmission and display at the control centre.  The control center has a duty engineer in attendance during the day and is connected by an alarm system to the engineer's residence. The primary equipment at the centre is the remote control console into which a continuous a continuous flow of data from the transmitters is fed and displayed.

Command signals from the Centre to the out stations are transmitted by the chain to the chain master station either by direct landline or by radio link. Intervention by the chain engineer in the functioning of a distant slave or master
station is made possible by the remote control system, the purpose of which is to encode commands for transmission to the outlying transmitter stations and decode messages from these stations.

Since an unmanned transmitter station is a relatively complex system require to operate continuously, it is necessary to provide a day to day record of the efficiency of all the major units and critical sub-assemblies. This function is carried out by the Data Logger, one of which is installed at each station and at the control centre as well. The Data Logger has a capability of sending 183 bits of information covering all the vital units of the transmitter and presents the information on standard five hole punched tape which can be rapidly analyzed by an engineer during routine or emergency servicing calls.

At the heart of the remote control station is the remote control and display console which provides the duty engineer with a continuous overall picture of the operating state of the master and slave stations. To enable fault conditions to be dealth with immediately, a number of command functions can be initiated from the console; these include a change over of the duty phase control unit, reset and complete override of the phase control unit automatic selection system, switch off of lane identification signals and switch off of the entire station. To prevent inadvertent or incorrect use, a test transmission must first be made and received back on the coloured light display before the actual command transmission is made by operating a pushbutton beneath the 'lift to operate' push-button flap.

To provide a permanent record of the position-fixing and lane identification readout by the chain, the control centre is equipped with a multi-pen recorder. This 14 channel recorder produces a continuous analogue chart of the red. green and purple patterns in addition to the lane identification transmissions.

A further six channels monitor the pattern torque level thus giving an indication of the loss of any transmission. Two additional channels carry 5 minute and 1 hour time markers.

A Norwegian transmitting station
Bank of five 1.2 kw solid state transmitters. 
Remote control display units Data Logger, Multi-pen recorder and monitor receivers.

David Jones also adds to this caption "The datalogger cabinets on the left side are the chain control system that were part of the 1880 generation of equipment and was used the 8.2f transmitters to send status and control data. During the sequence quiet period, each slave would push out a data string of 8.2f pulses and the master station decoded them for it's status display. Likewise, the chain commander at master could send commands to any slave via 8.2f pulses from the master station. South Africa and Australia used this system, as did the Gulf of Kutch. Although it was intended to allow for fully unmanned sites, I think most stations had some form of local custodian-in-residence to intrusion or possible theft of station components.The 8.2f orange frequency was unused for pattern information, only zone data so the user would not see any loss of information or experience a flag alarm."

Power distribution and battery chargers in transmitting station.
All photos in this table from Decca Navigator News, September 1968

Coverage area of the South Baltic Chain 0A. (From Decca Navigator News, April 1971) 


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