Cable Testing Revisited

As you may have seen earlier, every cable that we installed was tested before it went into the ground. This was to check that they worked according to the tight electrical specification. Well, now that they are all in place, they have to be tested again to ensure that they are still working.

During the installation process, the cables are exposed and vulnerable. As the backfilling work occurs, it is possible that a tool, rock or other object causes the cables to be crimped, abraded or even cut completely. And, of course, now that the burying has been completed any discovered fault constitutes a major problem.

To test the cables, the same vector network analyser is used. However, instead of testing them individually, they are tested in pairs. A signal is sent from the RF-container patch panel out one cable. At the field end, a small loop back cable is placed to direct the signal out of the first cable back down the second cable. Then at the RF-container, the other end of the vector network analyser is connected to the second cable and the round trip signal degradation is tested.

Harry Smith attaches the loopback to a pair of antenna cables on the HBA. As part of this process, the connectors and cables are visually checked and inspected and afterwards they are re-sealed and secured.


Meanwhile, back in the RF container, Jon Eastment looks at the results of the cable-pair under test.

Sand People

Now that the HBA cables are in place and patched into the RF-container, the HBA cable grave can be filled in.

First a thick layer of protective sand is spread across the cables. The crew work the cables gently to ensure that the sand penetrates between all of them.


Here is the finished sand cover. This protects the cables against flint and other sharp rock as the spoil is back filled into the grave.


With all cables completely covered, the digger moves in to bulk fill with previously excavated material. And that is it! The HBA cables are fully covered and the crew can walk through the area without the risk of falling into the hole or collapsing a trench wall.


There have been many people involved in the laying of the HBA cables, and here are a just a few of them. From left to right: Dave King, Jon Eastment, Mike Willis, Alejo Martinez-Sansigre and Harry Smith. To these few, and everyone else involved in this stage of the project: thanks and well done!

Cable Rivers

The folks at Chilbolton are seriously into cables at the moment! Here's the latest on the cables.

The cables for both the HBA and LBA fields are done in "river" mode. Each antenna has two cables. These go down into the trench and head off in the direction of the RF-container, where the processing will occur. As they pass through the trench, new cables come in from other antennas. Each new "stream" adds to the "river" and the bundle of cables slowly builds up.

This scheme requires care. The cables must be put into the trenches in the correct order and the covering soil cannot be added until the full river has been built up. Managing the bundle of cables as it nears its destination also becomes difficult. The become difficult to handle and must the meticulously checked to ensure that no small stones are caught between the strands.

Here is the start of stream, with a pair of cables (one per polarisation) heading off down the trench.


Half way across the array and already the cable group has become quite substantial. In this section, there are 128 cables in the bundle. Jon Eastment is checking that everything looks OK.