Forum: General Topics
Forums / General Topics / EGNOS / WAAS (??)
| Subject: | EGNOS / WAAS (??) | |
ChrisM 9:36 Location: Phone Model: | Hi Stephen, I've just found out that my GPS thingy supports EGNOS/WAAS... ...once I had discovered what that actually meant, I've got a question for you. First of all, I assume that most of the extra work is done by the GPS thingy, and as far as TMJ is concerned, it will just be getting (in theory) a more accurate fix by the same means as normal. However does TMJ already, or if not, is it POSSIBLE for TMJ to pick up on the fact that the GPS thingy is receiving a signal from one of the geostationary satellites(and therfore I guess, benefiting from the positional corrections) and somehow show this on one or more of the info screens? I ought to say that I'm not especially bothered about this as it seems this system is designed mainly for aviation, and doesn't necessarily work all that well on the ground, but I'm just curious. :) Regards, Chris. | |
Stephen 15:42 Location: Phone Model: | Hi Chris, Must admit I'm not too familiar with EGNOS or WAAS myself, but it looks like WAAS is only active in the US, and EGNOS isn't going to be fully active in Europe for a couple more years, so theres probably not much I need to do... As you suggest, this is all handled by the GPS device anyhow, so TMJ doesn't need to do any particular extra processing. Also, the standard GPS NMEA sentences don't give any info about the WAAS satellites so theres little that TMJ can display about it. I figure this isn't a big deal though...! Cheers, Stephen | |
ChrisM 16:57 Location: Phone Model: | Stephen, Don't worry, I wasn't expecting you to do anything about it! :-) I was just curious as to what(if anything) TMJ 'knew' about EGNOS. From the stuff I read though, I thought EGNOS was pretty much live. It is planned to be certified for use in 'safety of life' applications (by that I assume it means commercial aircraft landing systems etc.) from 2010 but I think it is operational now " EGNOS is now fully deployed and in its pre-operational phase. The system will undergo certification for safety-of-life applications before becoming fully operational. " http://www.esa.int/esaNA/SEMKMQWO4HD_egnos_0.html The EGNOS satellites have got NMEA/PRN Ids http://en.wikipedia.org/wiki/European_Geostationary_Navigation_Overlay_Service So though I'm not sure, it sounds as if they might get reported in the standard NMEA 'Satellite status/position' sentences that you already use for the satellite information screens, though I haven't been able to find anything to conclusively prove that one way or the other... I might record the log from the GPS thingy for a while and see if I can spot anything to do with those satellite numbers being reported. If you're interested (more just for interests sake, rather than for anything to do with TMJ) I'll let you know/email you a copy... It's all interesting stuff. The more I read about GPS technology, the more I'm impressed by how it all works. There's obviously some very clever people working on it! To bring this rather rambling post back to the subject of TMJ, as far as I can see, the only thing you MIGHT want to do with TMJ Mobile at some point, is to have a little marker somewhere on one of the screens to say if EGNOS/WAAS is active or not, and maybe(if it's quantifiable) whether it's likely to be helping or hindering the accuracy. Cheers, Chris One other thing, something I read in passing today(on a forum, so no guarantees of accuracy), mentioned turning GPS features on/off via NMEA messages. Is it possible then, to SEND commands to the GPS thingy, or is it a one way street? | |
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