Today I was finally able to test my Thuraya GmPRS solution. I had already tried it on my trip to Egypt but that was far from perfect due to the fact that the phone has to be in direct line of sight to the satellite at all times. The satellite is roughly at 135° from here (Stuttgart, Germany).
Now I have a "fixed" installation consisting of a Thuraya airplane antenna and a console installed where the (rather useless) dome light used to be. There is a USB charger (disassembled a standard dual USB cigarette lighter adapter) powering the Thuraya XT wifi hotspot. The hotspot in turn connects to the Thuraya XT car holder and also powers/charges the Thuraya XT satphone. I chose to not power the car holder due to the phone taking power from the wifi hotspot. The car holder's power also drives its integrated GPS repeater (it takes the GPS signal from the external GPS antenna that is part of the Thuraya antenna and radiates it from the receiver at the position of the phone's GPS antenna). This GPS repeater creates RF noise and I noticed that the phone is able to get a GPS fix even without the repeater. Even if the phone cannot get a GPS fix, I can just remove it from the cradle, hold it to the window and put it back once it gets a fix. It only needs one fix at startup. I will therefore remove the cable of the car holder altogether.
The wifi hotspot creates a network to which I logon with the iPad. I have an offline web app of a sat phone optimized briefing site (developed based on work done by Peter). It provides one stop shopping for everything relevant and automatically encodes pictures based on a configurable quality level to save bandwidth. Getting a METAR/TAF takes 3-5s, getting a satellite picture about 15-30s. Given the "always on" nature of GmPRS, I don't have to dialup to get data but can keep it running. The wifi hotspot contains a firewall which I have configured to only allow communication with my private briefing server so I don't run the risk of some background apps on the iPad or whatever device I use eating up my bandwidth and money.
In my limited testing I found it to be reliable, fast and sensibly priced. One megabyte costs about $5.50, charged in 10kbyte increments. Speed is up to 60kbit/s. This is orders of magnitudes faster and cheaper than Iridium. This solution greatly enhances my IFR flying.
Here a few pics, the console will be tidied up with shorter/thinner USB cables and a better arrangement.
How happy are you with data transfer rate and reliability of your solution?
The data rate and latency is very good, far better than with any other network. The reliability -- I can't say, need to do more testing. Just last week, GmPRS stopped working on my Thuraya phone and it turned out that it shouldn't have worked in the first place because even though I chose to enable it when I activated my subscription, they never subtracted the 20 Thuraya-Units for GmPRS activation from my account. Now they have done that and it is working again. Their support answers fairly quickly but isn't very competent.
I have yet to test this in IMC and turbulence. Maybe the Thuraya frequencies are affected by moisture.
The German DWD (national weather service) have told me that they are going to provide precipitation radar updates every 3 minutes instead of the current 15 minutes. That is going to make my solution a lot more useful than today.
Maybe the Thuraya frequencies are affected by moisture.
The Thuraya band is really close to the Iridium band so I would be suprised if it did not penetrate cloud.
Their support answers fairly quickly but isn't very competent.
I found that they read internet forums (obviously googling for any mention of their company); once they told me (politely) to remove a comment I posted in Usenet!
Looks good but might want to make it look a little less like an improvised explosive device!
It looks quite decent, bad angle and not the finished install. And it beats the sh*t out of your Iridium datalink 
Ha. Well the Iridium datalink is being sold along with the plane so you have won (I didn't actually realise we were competing). So essentially you have created a wifi hotspot that you use to connect your ipad to download weather etc?
Data costs?
One Thuraya dollar per megabyte, charged in 10kbyte increments. One Thuraya dollar costs about USD 1.10 (cheapest I've found). No ongoing cost really.
Indeed, I use the iPad and my Android phone via wifi to access my private briefing site. The firewall in the wifi router limits communication to my server so background processes in the iPad or whatever other device can't eat my credits or congest the link.
That sounds like a pretty good price.
Achimha, how did you connect the external antenna to the phone, as well as connecting the hotspot?
I have been using an XT for several years, for getting texts of TAFs and METARs. It would be much more useful to get more general weather data off the web. I've found the GMPRS to be very unreliable, but will have another go at it. I gave up on having the cockpit festooned with cables to a laptop, external monitor, knee mousepad etc etc. But the newer touchscreen devices are much more practical, I am trying out Skydemon on a Nexus 7. I have found the XT's antenna really needs to be pointing south-east, which is fine if flying in that general direction, but not when flying north-west.
I look forward to hearing more about this interesting project .......
I am enquiring now about getting a hotspot and external antenna to try out.
Regards
