Image produced from the Ordnance Survey Get-a-map service. Image
reproduced with kind permission of Ordnance Survey and
Ordnance Survey of Northern Ireland.

Image produced from the Ordnance Survey Get-a-map service. Image
reproduced with kind permission of Ordnance Survey and
Ordnance Survey of Northern Ireland.

The Hyperfix station
The MoD hyperfix chains provided navigation and positioning information to wraships ans submarines of the Royal Navy. The report in Ref. 1 states that the chains were also used by the Royal Netherlands Navy. The chains were complex and featured remote supervision and control from one of two control centres, located in Plymouth and in Scotland, via a telephone/modem link to the master station and from there to the slaves via the data time slot in the Hyperfix transmission itself.

The Bass Point station was enclosed in a high mesh fence topped with barbed wire. The North-Eastern edge had concrete hardstanding for the accommodation and vehicles. The rest of the site was covered with agregate and in the centre of this stood the 10m high tubular antenna, with guys, and at its base a shelter housing the Antenna Tuning Units. The compound is not rectangular but has five sides, with a point at one end. It can be seen in the aerial photograph at Ref. 3; referring to the map above for orientation.

The accomodation consisted of three structures: The main equipment cabin, referred to by the MoD as the Navaid Unit, the Generator Unit housing a Diesel standby generator and a concrete box housing the generator fuel tank. With the exception of the latter, the accomodation consisted of large strong metal containers with double opening doors at one end. The diagram below shows the layout of the site, based on a drawing in Ref. 1.

The site and its equipment
The photographs below were taken when the Cornwall Archaeology Unit visited the site in early 2000 to carry out the recording. The first shows a general view of the site, looking across the compound to the navaid cabin, with the generator cabin behind. The building outside the perimeter fence to the right of the navaid shelter is one of the old RAF Pen Olver buildings.

Photograph ©Cornwall County Council. Used with permission

The next photo shows the ATU shelter. There are two 90516 ATUs, and another unit which is thought to be a 90532 protection unit. The reason for the two 90516's is not clear; it is thought that the site may have been shared between two chains and therefore operated on 4 frequencies. This sort of operation was in order as long as the two chains were synched to one another.

Photograph ©Cornwall County Council. Used with permission

In the Navaid unit was a length of racking that would have held the 90515 receiver/controller and 90512 power amplifier/battery charger unit. There would have been two of these if the site was shared between two chains. Also in the racking would have been lead-acid batteries. Even though the site was generator backed, the microprocessor controlled 90515 would need constant power to ensure proper operation. A telephone was provided for the use of visiting engineers, in addition to the modem connection to the receiver/controller.

Photograph ©Cornwall County Council. Used with permission

The generator was a Hornby-Ackroyd unit contained in its own cabin, along with the electrical switchgear and the generator starting battery. One of the boxes on the left wall will be the automatic changeover gear and the other the starting battery charger. The main fuel tank was outside as is usual practice- it is normal on installations like this to provide enough diesel for the generator to run for several weeks.

Photograph ©Cornwall County Council. Used with permission

Preservation
The National Trust believes that the structures at Bass Point form a unique and nationally important element of our maritime and telecommunications heritage. As a consequence they proposed that, following decommissioning, the site would be left in such a state that a visitor would understand the layout. This meant that the concrete antenna base, guy blocks, aggregate compound and the security fence would be left in situ. The site would be recorded in photographs and these archived.

So was this done? The photographs below were taken in July 2006. That below was taken from the same angle as the first of the views above, only zoomed in a bit more. The navaid unit concrete base is visible (extreme left) and one of the guy blocks, in addition to the Pen Olver building that stood outside the fence. It looks like the fence didn't make it into preservation...

Photograph: Shaun Churchill. Used with permission.

The view looking across the site from approx the north east, the antenna base is in the center of the four guy blocks, and the Navaid unit concrete base is visible to the right. The structure near the top right stands at the end of the access road, and would have been just outside the compound gates. It was presumably part of the RAF radar station.

Photograph: Shaun Churchill. Used with permission.

The photograph below is a close-up view of what remains of the antenna base. The other tube to the right is the cable duct that would have run to the Navaid unit base. It came up inside the ATU shelter.

Photograph: Shaun Churchill. Used with permission.

Further work
Next time I'm in Cornwall I intend to visit County Hall in Truro and get some better quality images of the site prior to decommissioning.

References:
1. "Hyperfix Navigation Site, Bass Point, The Lizard, Cornwall. Archaeological Recording", Report number 2000RO73. Cornwall Archaeological Unit, Cornwall County Council.

2. RAF Pen Olver photos at worldwar2airfields.fotopic.net.

3. Aerial photograph at multimap.com.

Appeal for more info!
Please contact me if you knew where any of the other MoD Hyperfix sites were!