Put to the test: Workers face severe wind storm with a 4-day-old radio network

— January 6, 2015 — Leave a comment

Just four days after commissioning a Tait DMR Tier 3 system in Canterbury, New Zealand, the region was hit by a huge storm. Electricity Ashburton (EA) Networks Network Manager, Brendon Quinn, tells us how Tait and EA Networks worked together to design and implement the Tait DMR Tier 3 solution and how the storm caused him to rethink his position on trunking.

Put to the Test - Article Cover

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“Back in 2011, we had a single repeater part way up the mountains so coverage, particularly on the eastern seaboard area, was quite poor. In adverse weather conditions, when you need communications the most, it became very poor and we just weren’t able to deliver the kind of service to our customers that we wanted to.

We looked at several options for addressing this. We implemented a voting system but it was confusing for people to use and it wasn’t that successful. So we decided to migrate to digital. We evaluated vendor options and we have a long-standing and trusted relationship with Tait so we chose to work with them.

We initially looked at P25 but when DMR Tier 3 became available we realized that it was a better fit for us. When we have storms and we’re working in other power companies’ areas, the ability for us to communicate with each other is a huge advantage and I believe that DMR is more likely to become a general purpose standard here. P25 also had encryption and security features that we didn’t really need so we made the decision to switch to DMR Tier 3 and started a Beta trial with Tait. Initially, we made the decision to have all users operating on an open channel so that everyone could hear what was happening during day-to-day operations. We knew trunking was an option but we couldn’t quite see the benefits.

EA Networks storm graphicIn September 2013, we were hit by a severe wind storm. To give you an idea of the severity, we had a record 251.9 km/h (157mph) wind gust recorded at the summit of Mt Hutt, our local ski field, and 128km/h (80mph) gusts in town.

During the windstorms, our radio channel utilization was virtually 100% for several hours. The continuous traffic made it challenging to work as efficiently as we needed to.

Following that event, we realized that by splitting radio traffic into multiple channels we could help our people work more effectively during major events. We now run multiple groups, all using the same infrastructure. We have a four channel system – three audio channels plus one control channel so we can have up to three simultaneous conversations on different groups or individual vehicle-to-vehicle conversations. Our operations channel is an open channel so everyone can switch to that to hear what’s going on when they need to.

With the DMR Tier 3 solution, we’re seeing much better coverage. We’ve now put in five repeaters so we have complete coverage across our entire network. Like any digital system it goes and then stops so you don’t get that grey area where people start making assumptions about what has been said. The background noise is gone so you don’t hear hissing and crackling so it’s much clearer.

Sometimes it’s hard to pick who’s talking by the sound of their voice but I think that is partly to do with familiarity of the system. I remember when we switched from 25 kHz channels down to 12 kHz, we had to get used to a slightly different sound and it’s the same with DMR. There is an adjustment period and then it becomes the norm.

Our biggest learning from a user point of view was quite a simple thing. When you trigger the microphone there are a couple of seconds before the channel becomes available. So the biggest adjustment has been getting people to pause for a couple of seconds before speaking. It was a simple thing but that was the biggest learning we had.

As a Beta trial site, we knew that there would be some issues to work through, and some software adjustments were needed, but it has been very good working with Tait. They’ve been very supportive, they’ve responded very quickly. Tait Senior Customer Support Engineer, Glen Whittaker, has been our primary contact and he’s been extremely good on all the technical issues.

I consider that we have a true partnership with Tait. They understand our business, listen to our feedback and we worked together to get the best outcomes possible. As a result, the upgrade to DMR Tier 3 has been accepted pretty well. There was some frustration in the early stages working through the trial but as soon as we worked through that people have embraced the new system.

There are a lot of exciting opportunities that DMR Tier 3 has opened up for us. Now that we’ve had the system in place for six months, we’re seeing the possibilities for how the digital system will alter the way we do business, in a good way. We’re excited about the future and what it holds.”

Tait Senior Customer Support Engineer Glen Whittaker shares his experience:

“The system had only been fully commissioned four days prior to the major windstorm in September 2013. We had installed a listen-only base radio here in Christchurch so we were able to keep a listening watch on the workload of the EA Networks field crews.

To say that they were busy, under very trying weather conditions, is an understatement. We were able to tweak the system from Christchurch to keep a site on-air when it lost mains power, plus made changes to call timers to fit the way the system was being used.

Simply listening to ensure their radio operations were working as expected gave us crucial insight into how busy and life-critical it was in Ashburton over that five to six day period. We have learned as much from EA Networks about the way clients use a radio system as they learned from us about the system’s capability.”


 

Tait Connection - Issue 5 This article is taken from Connection Magazine, Issue 5. Connection is a collection of educational and thought-leading articles focusing on critical communications, wireless and radio technology.

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