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Letters to the Editor: Of Services, Commercial and Non

June 1, 2014  - By
Veripos ground receiver station network.

Veripos ground receiver station network.

In a comment posted to GPS World’s website on Tony Murfin’s recent column, “Hexagon’s Acquisition of Veripos: Why Did This Go Down?”, Craig Roberts of Australia wrote:

Tony, I do take issue with the suggestion that the International GNSS Service (IGS) is somehow inferior and not reliable. I understand that Veripos is a commercial service designed for specific markets, but in central New South Wales (most populous state of Australia) it is 800 kilometers to the nearest base station.

You mention “So Veripos and other commercial providers overcome the weaknesses of IGS by providing a worldwide network that is well maintained — an infrastructure designed for high reliability and availability. Each base station has dual-redundant receiver and communications links.”

The IGS has 400+ base stations. How many does Veripos have? If a station goes down on the IGS there are still 399+ backups.

“There are three processing centers, two active and one on warm standby.”

The IGS has seven processing centers using different algorithms and combined solutions.

“There are seven geostationary satellites with a large degree of coverage overlap.”

OK, IGS is not a real-time service —yet… but some sites are.

How does Veripos handle coordinate dynamics (station velocities)?

Don’t get me wrong, Veripos looks like a very good service for its clients, but please don’t bag the IGS, which I liken to the United Nations of geodesy. Many good people and nations contribute (through their taxes which support infrastructure and personnel) to this service for the benefit of all.

Thanks for putting together this article. It’s good to know more about Veripos, and I hope to try it out soon.

Our survey editor Eric Gakstatter chimed in with this comment:

Good points. Have you used the IGS service yet? I’d like to give it a spin.

Craig Roberts replied:

Not me personally, but one of my students and some researchers have. You can download some open-source software (there are a few options) and try it out. Early days for the RT IGS but results seem encouraging. Still the standard issues with initialization times for RT PPP processing. We are also looking at the LEX message from QZSS which graces our shores thanks to the Japanese. Basically investigating near real-time positioning options for remote locations in the absence of CORS networks and/or mobile phone coverage.

Tony Murfin added:

No IGS bashing from me. IGS is a different tool of a different color. Point of the article is that if you want to run a business requiring PPP performance, you need to use a commercial service. If your application can stand some potential down-time and tolerate longer initiation times — for university and engineering R&D for instance — IGS is perfect. It’s free of charge and accurate and as reliable as you need. Good luck with IGS, it’s a great system!

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