Enter the Labyrinth

The LBA trenches have all been dug and the surveying of the centre pins is complete (the things which mark the cable exit points). The next task is to actually put the cables in, which means dealing with the maze of trenches. Unlike the HBA, the LBA is arranged in a scattered pattern.

(as shown below - click to enlarge the diagram).



This gives the resulting telescope great beam properties. However, it also makes it difficult to install.

Here, Griffin Foster (U.Oxford) and Mayaane Soumagnac (ENS-Lyon, France) start setting up the cables for one of the LBA aerial locations. There is a six-page document describing the procedure, as many of the steps done in this initial phase are critical to subsequent phases of the installation.


"You are in a maze of twisty little trenches, all alike". Here the LBA team are busy placing the LBA cables in place. From left to right: Harry Smith, Griffin Foster, Mayaane Soumagnac, Danny Price and Jack Hickish.


Our equivalent of Ariadne's Thread: countless cable trenching plans, diagrams, lists and tallies are used to keep track of the deployment within the LBA. However the ultimate is this dual-core backpack-computer, with headset, scanning gun, barcoded-trench plan, LBA antenna checking software, text-to-speech synthesiser and rocket launcher! (Okay, okay... maybe not the rocket launcher.)

Home stretch for the HBA cables

After what seems like years to them, the folks at Chilbolton are now reaching the final stages of the HBA cable installation. However, everyone is acutely aware that the LBA (with its labyrinthine trench network) awaits us and time is pressing.

Dave King gathers the strands within the cable grave. This extra-wide trench is used to take up the slack from the fixed length cables.


Richard Armstrong gazes down into the abyss... well, maybe just the last trench where the entry points to the RF-container ducting are. From here, pairs of cables are gathered and passed down for feeding into the ducts.


Well, if Richard was gazing into the abyss, then Chris Caddell is in it! Here, Chris sends the cables through the ducts to the patch panels for final termination.


With the cables patched, it is then time to clear the trenches and gather the cables prior to covering with sand and backfilling. In particular, the trench must be free of any flint which can easily cut into the cable. This is not easy, especially in the final trench where all the cables are present and crowd one another. As this photo shows, the cable crew are obsessed about achieving a perfect job. From left to right: Jack Hickish, Chris Caddell and Kahinde Johnson.

LBA Surveying

With the HBA cable laying mostly done at Chilbolton, work has intensified on the LBA. This means getting all the recently dug trenches re-surveyed ready for the deployment of the cables. The process for doing this involves the surveyor using the theodolite to find the location of the cable exit point. Once the exact position has been determined, the survey staff is removed and a marker peg hammered into the ground.

This photograph was taken through the theodolite. Moments earlier, the top of the survey staff was at the cross-hair. Having established the position, the staff has been removed and Jack Hickish pounds a steel survey peg into the ground to mark off the position.


Danny Price and Remi Paulin return from a morning of survey work.