Engineers are awesome. I love it when they talk about their area of expertise. They may start a sentence in a regular way and then continue with a flow of terms and abbreviations that mean little to me. They often get quite excited about this too. It’s fascinating.
I also love engineers because they design and make things - such as base stations that serve PMR radios. Here are six reasons why I think base stations are fascinating, and why you should too.
In 1996, when TETRA was still new, the engineer who led our base station development team described the project. “Designing a TETRA base station was technically so difficult,” he said. “There were times when I did not think that we would make it”. He spoke emotionally (for a Finn) and I believe there was the glint of a tear in his eye. “But the team, I admire them, they were so good. When something didn’t work, they always came up with another solution”.
Conquering one challenge after another, this fabulous design team got the world’s first TETRA base station working. Today, base stations are probably performing beyond their wildest dreams back then.
Radio coverage is the area around a base station within which radio users can talk to each other. It’s probably a TETRA network’s most important property.
Here are some common ways to boost coverage (getting rather technical here).
All these methods have their drawbacks though:
The third-generation TETRA base station was launched in 2004, and I still remember the excitement. Three improvements achieved revolutionary results in radio coverage:
Employing six receivers per carrier (not just the two or three typical then) using advanced diversity combining methods made it possible to build a high-gain virtual omni solution.
These improvements meant the base station achieved up to 50% more coverage. To get the same increase with older methods would require an antenna about twice as high. Since then, the radio terminals have also become significantly more sensitive, bringing further coverage improvements.
A typical base station will provide more or less circular (or omnidirectional) radio coverage, which is great for PMR users. Most of their calls are group calls and a circular coverage pattern makes it more likely that more than one group member will be within the area of a single base station. When teams work close to each other, this is almost always true.
This is important because a single base station serving all group call members will make the most efficient use of frequencies.
What if you need to cover an area such as a road, a railroad, or a pipeline? Radio users would need continuous, uninterrupted coverage along such a feature, but not very far away from it. Circular coverage is not the best option for this purpose.
Instead, you need very directional coverage. This is achieved by a base station using two cross-polarized panel antennas set back-to-back, allowing them to handle both transmission and reception in two directions. The base station can then cover a long, narrow area. What’s more, this setup achieves diversity advantages from both sides.
There is also something we call a high-gain fjord solution, which great radio coverage in a long, narrow area in one direction.
So there you have it - six reasons I find PMR base stations fascinating.
Yet you don’t have to be fascinated with base stations to appreciate a larger radio coverage area or a special shape of radio coverage. If you need such a solution, the TB3-series TETRA base stations are your choice. TB3 base stations are the only TETRA base stations that can achieve coverage-maximizing, high-gain, virtual omni configuration. They are also the only ones on the market that can provide directional coverage, too.
And if you still think your users would enjoy better radio coverage if they only had higher-power TETRA radios, think again. Read this blog post for the truth about watts in PMR radios, or you can download the infographic: