Thuraya & XT Hotspot - Inflight?

oh sorry, my price is for the V1.
Here the V2: http://m-cramer-satellitenservices.shopgate.com/item/333737
735€

I know I raised this before but what happens with chatty Android or chatty IOS apps, going online quietly in the background?

You can’t disable it under IOS, unless you jailbreak. I spent some time on this a couple of years ago (Justine’s UK data tarriff was 50p/day for any data up to 25MB, which is just a waste of £15/month) and all I found were some IOS hacker forums on which I got the fairly standard semi illiterate one-liner “go away you noob” reception Clearly there are solutions for blocking it all (including the app update notifications which pop up constantly) but they don’t appear to be trivial. And Apple block every jailbreak on every update.

On my win8 Lenovo tablet, dialing out at just 9.6k, any activity like that is very noticeable in that the first minute or so is completely wasted. I suspect this is more due to the huge latency of satellite data (1-3 seconds) rather than any volume of it. I am thinking that perhaps I should just disable everything in the windows firewall, and just enable the few apps which I am consciously using (browser, email). However that may block the dialing app itself and what the hell is the executable for that one called?… also on windows most of the offending stuff can be disabled in Control Panel.

The above will be applicable with the Satsleeve too because it is the client which does the unwanted chatting.

There are Firewall applications for Android, you just limit connectivity to the addresses you are interested in.

I would be in !

Waiting for pireps… !!

Alexandre.

Hello !

Any news from achimba or aeroplus for inflights tests ?

Best regards
Alexandre.

I’ve done some testing of the Thuraya SatSleeve today. Here are my observations:

• The SatSleeve is not directly related to your smartphone, it does not connected with it in the physical sense, there is just a snap in adaptor for the Galaxy S3 and S4 but you do not have to put it in and you can use any other Android or iOS phone. I use it with a Google Nexus 5.
• It has no problem getting a GPS fix in flight (needed for Thuraya). I have turned it on at 150KTAS and it was up and running in less than a minute.
• Using the SatSleeve iOS/Android app, you connect to the SatSleeve via Bluetooth and you can can see the network quality and enable the data service. It is disabled when the phone is turned on. Once you enable it, it creates a wifi that any other device can connect to.
• GmPRS works the same as the Thuraya XT. Once you enable it, it takes about 2-3 minutes until it actually works (don’t know why) and then it transfers data at around 50kbit but with an extremely long latency. I don’t think it is useable with standard web pages. You need specific applications tailored towards sat phone use. I have create such an app for my own purposes.
• Reception is as good/bad as with the Thuraya XT. When I was flying 130° from Stuttgart, it worked fine on the dash because the satellite is over the Somalian coast. When flying back (i.e. 210°), it would not work on the dash but had to be put below the rear window. When flying at 90°, there is no chance to get a fix due to the high wing Cessna. In general, you have to maintain a clear view of the satellite and unless you can guarantee that, the connection will be flaky. I find it impractical to have to position and hold or fix the phone at a specific place in the airplane depending on my course. This means it needs an external antenna which I have but which connecting to the SatSleeve for which I am still trying to figure out the right connector. The SatSleeve does have an external antenna connector but it is not mentioned in the specs or the manual.

The SatSleeve is better than the Thuraya XT because it can create a wifi network directly without the need of a hotspot. As a phone, it is much worse because it has its own (bad) speaker and microphone and only uses your phone as a screen.

I wonder if the long latency was due to the MTU issue.

A lot of websites created on unix servers have an MTU of 1500, and this sometimes doesn’t work with some clients. I know of one website which absolutely never loaded over Thuraya, until I reduced the client device (my Lenovo win8 tablet) MTU to 1450 (actually about 1470 was enough but the performance hit in going to 1450 is less than negligible). Tweaking the MTU on the dial-up connection was a pig as it was possible only with the connection up and running ($1/minute) and by using command line commands.

Obviously MTU “should” negotiate down but you get two problems: (a) the negotiation involves sending UDP packets up and down the link and if the latency is say 3 seconds that is really going to kill the response time (possibly enough to break the protocol); (b) sometimes the negotiation fails completely because something is blocking the MTU negotiation packets.

I had such a case with my business website (hosted on a “proper business ISP”) which was absolutely inaccessible to anybody on a Vodafone UK connection. Well, another website on the same web server worked for accessing small packets (tafs or metars). If the TAF was too long (bad wx) it would never appear The ISP blamed Voda, Voda obviously was useless (call centre script monkeys), and we fixed it by dropping the server’s MTU from 1500 to 1480 or so. I think the problem was between Voda and the ISP but nothing could be done.

There are just too many indications that the default 1500 MTU is responsible for many slow or even totally dead websites.

If I was creating a commercial product for satphone data delivery I would forget TCP/IP and would just do it by streaming loads of UDP packets, mostly in one direction. Send each one twice, in case Most aviation wx data can be done that way. Just like a fax

GmPRS just needs some time to get operational, then it works. Made the same observation on the XT and SatSleeve. That’s not a real issue because you just turn it on once and keep it going. You only get charged for the data, not the time.

UDP doesn’t have any real advantages unless you have losses and you can deal with losses, i.e. you do not need to retransmit. That is not true for most connections. If you need to retransmit, then TCP will do exactly that.

UDP doesn’t have any real advantages unless you have losses and you can deal with losses, i.e. you do not need to retransmit. That is not true for most connections

It is however true for aviation weather charts. And textual data like tafs and metars can be sent wholly in a single packet, so you throw a few of them in just to make sure.

I know I raised this before but what happens with chatty Android or chatty IOS apps, going online quietly in the background?

Can’t you just find ‘background app refresh’ in the Settings menu and turn all of the apps off with one swipe of a button?