When I joined the company, my employer had a microwave system covering most of our then footprint. It was fairly state of the art when it was installed, having 16 2-megabyte “tributaries” which could be used for either E1 30-channel telephone trunks between out PABXs or for 2MBPS data channels (2MBPS was then an acceptable data rate).
The system was costed over 5 years but because of some nifty routing techniques, putting all of our internal calls and data and even some external calls over the microwave, it paid for itself in 8 months in telco cost savings.
Around 10 years later, although the system was still working reliably, it could not support the considerable increase in data rates that we needed so we scrapped it. All our telephony and data was outsourced to telcos by bean-counter managers who didn’t have much understanding of how communications worked.
So our communications department was excited when, about 4 years ago, we started putting in some new microwave links, albeit on a limited scale. The hub of the system was located at Mount Canobolas, a long-extinct volcano which at 1300m high is the highest point west of the main mountain ranges in Australia. There is nothing higher than it to the west until you get to Africa.
The downside is that it gets a lot of ice buildup on the tower in winter and it is actually dangerous to be under the tower as football-sized blocks of ice frequently fall off. We had some problems with our old microwave dishes, which sustained damage even though they were made of thick steel, and in a few instances the protective fiberglass domes were completely destroyed.
One of the dishes from the new system. Note the weather shield has been knocked right off, feed horn bent double, and a nice dent in the top of the dish. The ice shield at top left is for an adjacent dish.
So, when we made the decision to put the new system in, allowance was made in the budget for strong iron ice shields to be installed above the dishes. I was involved in the installation and commissioning of the new system, which went well, and we had 54MBPS Ethernet trunks to play with. But there was no sign of the ice shields. Winter loomed closer and closer.
I spoke to the designer, the project manager, the department manager. “If you don’t get those ice shields up, you might as well chuck the system out!” But I am just a little cog in a big wheel, and no one listened. The ice shields were supposed to be installed by a contractor, and they for some reason didn’t get the work done.
A few weeks into our winter, we had some very cold days. One morning, one of the microwave links was showing a very much reduced signal strength, another was completely down. I rang the council that looked after the site, and they told me that due to unusually thick snow on the mountain, the road was closed, even for four-wheel-drive vehicles. They could not get in themselves.
It wasn’t until four days later that we were able to get to the site, and my workmate took photos that confirmed the dishes were pretty much destroyed. The dishes were severely dented, the flimsy weather shields around them had been knocked off, and one feed horn was bent down at a crazy angle.
We only got the system repaired in the spring, and getting the ice shields installed was completed this time before the dishes were repaired or replaced. Not a high-tech problem or fix, but we were charged another 10% on top of the total system cost.
The system has been reliable since then. And I hope our managers have learned the lesson: protect your assets!
David Ashton is a British-born telecom engineer and self-proclaimed “jack-of-all-trades,” based in New South Wales, Australia.