History

The route between Kirk o'Shotts and Aberdeen developed from the earlier BBC TV link between Craigowl - Core Hill and was originally driven by the requirements of Grampian TV. Initially the Post Office had offered faciliies similar to those used by the BBC - "direct pickup" of the Black Hill transmitter at Craigowl and a microwave link to Aberdeen. This was unacceptable to Grampian since it would have resulted in their transmitter carrying the same programmes as neighbouring STV - except for any content produced by Grampian locally. To allow access to programmes made by other ITV companies required access to the ITA vision circuits which were available at Kirk o'Shotts. (There were expected to be areas of overlap between STV and Grampian's transmitter coverage, adding an element of competition and a desire to provide alternative programmes.)

Grampian launched in September 1961, four years after STV and six years after BBC television had reached the region. In part the delay may have been caused by the availability of Post Office "vision circuits" - contract 21877 was awarded to STC in March 1960, for a 4 GHz system and to be ready for service by 1 May 1961. The initial cost was £105,118. The detail of subsequent events is unclear however the "RFS" data was revised to December 1964 and the final price had risen to £116,609 by May 1966. A note records "...the above named work is accepted and taken over [for maintenance by the Post Office?] as from the 11th March 1965". Other notes record "STC is only firm who can do this work" - this may be due to the need to integrate with the existing link from Craigowl northwards.

The extension and upgrade of the route probably included new buildings at existing sites although towers may have been retained at this stage. One new site was required at East Lomond. The station at Kirk o'Shotts was effectively rebuilt in this period, alongside the terminal for the 1951 television link from Manchester and adding a new major route from Carlisle. Some elements of the overall project thus formed part of other plans and it may be some of the delay in completing the work was outside STC's control. In the event the initial link for Grampian relied heavily on temporary outside broadcast equipment and scaffolding towers.

A further contract 23572 was awarded to STC in June 1964 for additional channels at a cost of £42,000. An oddity is contract 23583 for GEC to provide a 2 GHz link between Kirk o'Shotts and Craigowl (£77,614). This may have been associated with contract 300504 in December 1965 for a L6 GHz link between Craigowl and Granite Hill priced at £60,000. STC was awarded contract 300513 in May 1966 for further channels to be added over the entire route (Â27,000).

There little detail of the 1964 to 1966 contracts. Perhaps the differing costs reflect the number of channels being added at different stages and the need for new antennas for 2 GHz and L6 GHz. One possible reason for the short section on 2 GHz is to fit in with the frequency plan in the wider area.

Documents showing planned expenditure in the late 1960s suggest the 2 GHz + L6 GHz link was to be a single two-way channel carrying 960 telephony circuits, plus protection circuit. The 4 GHz links are most likely to have been additional channels for BBC and ITA purposes including BBC2 and conversion to the 625-line colour standard. Documents from the mid-1980s show the BBC had the use of three "vision circuits" northbound - one was used for VHF radio distribution - with the IBA using four northbound and a single southbound circuit. This appears to have been carried across two separate systems, probably still using the bands allocated in the 1960s.

The expansion of offshore oil and gas exploration during the 1970s may have led to additional telephony channels being added. The migration to a digital network in the 1980s led to new links being required for System X "Digital Main Switching Units" at Aberdeen and Inverness. The design required connectivity to all other DMSUs and 11 GHz 140 Mbit/s systems installed at at existing sites were an option used to provide the required connectivity.