Filling the mausoleum

The cable mausoleum is where the excess cable length is zig-zagged back and forth to use up the extra length between the array and the RF-container. Because of the frozen winter ground it is not possible to directly bury the cables; they must stay free to avoid breakage or stretching. Thus, they are placed on a raised platform (which will be covered later).

Pertti Nissinen and Rauno Oikarainen place some extra cable on the mausoleum table top.

HBA cabling progress — 02-Aug-2011

Today was a very good day on the cable installation. We put out cables to 17 tile antennas. This is a record! We are now getting close to the end and, weather permitting, we should get this stage completed tomorrow. The situation currently looks like this:


In addition to this, there has been some work done on the LBA field, including an initial survey. Although the field work is now done, there is still some work on the data processing, but we hope to have an accurate topographical map of the LBA site available soon.

Cable ends

This is what the end of the cables look like. There are two cables for each antenna. These are for the two polarisations. However, one cable also carries DC-power and the other carries a low-baudrate control signal for controlling the analogue beamformers.


Starting at the lower left, where the end of the cables are, there is a black plastic cap. This is to protect the cables while in storage and also as they are being drawn through the ducts.

Then there is some metal armour. This normally protects the cables at the point where they enter the ground (on a regular LOFAR station). However in the case of KAIRA, our tiles are not directly on the ground, so that doesn't apply. Instead, the armour spans the short gap between the base of the tile and the raised cable duct on the frame. The armour actually slides further down the cable when it is installed. However, during the drawing process it is kept as close to the cable end as possible. Around the armour, there is a black velcro strap. This holds the two cables together while they are being drawn through the ducts and trays. At the end of the armour, there are some black collars, which connect the cable to the tile itself.

The cable itself is black and the first exposed section of it can be seen at the top right

Drawing the cables

With all the duct work completed, the cables can be drawn from the RF-container, through the cable mausoleum, the ducts and trays and finally out to the antenna tiles.

Marko Kauranen assists cables from a tray into a duct.

Stuart Keenan (silhouetted) and Arttu Jutila feed the cable through one of the duct tunnels.

A small section of exposed cable where the tunnel ends
and the ascent duct begins. When complete, the ascent
duct will slide down to completely cover the cables.

HBA cabling progress — 01-Aug-2011

August already?! Actually, the leaves have started turning yellow — we saw the first few some days ago now, and there has been a light dusting of snow on the fells the weekend before last. Today, we pressed on with the cabling and managed to reach the half way point. However, it has been tough going, with the ducts starting to fill up and becoming difficult to manage. But the two small sections of the KAIRA HBA have been cabled.



In addition to the cabling, we've started looking at the LBA field and preparing for an initial survey. We've re-labelled the patch panel in preparation for the RF-installation work. And, we've solved the mystery of the missing sand!

More on all of these stories soon.

Power point presentation

Within the RF-container there is a power switchboard which brings in the electricity supply. Although the power line itself has been brought as far as the site, we have not yet connected it to the RF-container and the container electronics.

However, the next step in this work has now been completed, with the external cable being connected to the switch box inside the container.

In the photograph, Marko Kauranen explains the work that has been done.

From trays to tunnels

One of the challenges that we have found is the accumulate friction of the cable length. For every bend, there is the additional load on the cables. We have found that the original idea of feeding the cables at every point is still insufficient to get the hundred-plus metres through the ducts.

As a result, we have done some rework on the tunnel ducts. The original flex-ducts have been replaced with extended ducts that gently descend to the tunnels. The new pipes installed are extra large, to ensure that they have sufficient strength to withstand any snow loading.

Rauno Oikarainen and Pertti Nissinen measure where
a cut will need to be made in the original cable tray.

Pertti Nissinen removes the surplus section.

Stuart Keenan ties in the new ducting pipe.