Using Iridium Satphone in flight

[SNS3Guppy]

If it is in the aircraft manual, it is sure to be a fixed installation.

In a company manual written by and for our company alone? That's a bit of an assumption, seeing as the manual itself specifically states otherwise.

[IO540]

Perhaps, SNS3, if you knew what you were talking about, you could answer the question instead of changing the subject You and DFC should get married.

Anyway, my loan Thuraya phone (a Hughes one) has just arrived so I am going to have a play (voice and data) and see how it goes.

[Sam Rutherford]

Thanks for all the replies.

FlyingFemme has given the best answer to my question, ie:

Iridium handheld 9505, plus car antenna on 'dash', connected through simple interface (VL1000J comes in at about USD250 but amplifies and cleans sound apparently) works fine.

SNS3, whilst I thank you for your efforts, you have slightly missed the point of my question - unless you are using a handheld unit, with simple direct to headset interface, but I don't think you are??!!

I'm off to choose between USD30 or USD275!

I'll let you know how I get on!

Sam.

[SNS3Guppy]

SNS3, whilst I thank you for your efforts, you have slightly missed the point of my question - unless you are using a handheld unit, with simple direct to headset interface, but I don't think you are??!!

As repeatedly stated, some of them are, some of them aren't. I don't know the model number, and am not in the airplane to look it up. Fortunately, they give us a few days off, every few blue moons and again.

Perhaps, SNS3, if you knew what you were talking about, you could answer the question instead of changing the subject You and DFC should get married.

No subject was changed. You simply provided incorrect information, and are unhappy that more than one poster called you on it.

[BackPacker]

Before everybody starts picking on SNS3, my understanding of his posts is that they use an Iridium handheld satphone, most likely a Motorola 9505A, as well, which has a "mount" (possibly just a holder, maybe with a charger) on the pedestal. Apparently there is a second type of installation as well which hooks into the "com center" (intercom?) in more or less the same way you can hook up your iPod to the intercom in reasonably modern installations?

Furthermore, they apparently have an operations manual (not to be confused with the POH) in which the boss wrote directions for use of the satphone. Possibly along the lines of "no long calls with the significant others, this stuff is EXPENSIVE".

So the way I read his posts, his experience is quite relevant for us. Particularly since they seem to be doing fine at 500 knots plus even without the need for an additional antenna.

Now what I would like to know is what set Bose-X uses, and why he doesn't get his calls through at 130 knots plus. As said, I don't think the Doppler shift resulting from 130 knots airspeed is going to be significant enough, considering that the satellites themselves travel at 15.000 knots, give or take.

The set IO540 has received, based on the Thuraya system, is using a geosynchronous satellite. For starters, this will introduce a half-second delay. But the same system is rumoured to be used by Al Qaida in Afghanistan a lot. I hope customs officals don't know that, otherwise it might be a reason for long delays.

[IO540]

I have a very preliminary report which is.... the set doesn't work at all indoors, behind a patio door with two 6mm non-metallised glass panes.

It would be interesting to see any satellite handheld working with its own antenna inside an airliner but I suppose it's possible.

The advantage of Thuraya - if it works - is that it is a much better deal cost wise than Iridium. In fact it pretty well compares with mobile to mobile phone calls. Thuraya has cherry picked the market by providing just one satellite covering Europe and much of Africa, plus the Middle East.

Thuraya also do a "super SIM" on which you don't get the standard PAYG sat phone ripoff: the confiscation of your outstanding balance at the end of the charging period This is quite relevant to pilots, with the intermittent usage.

I doubt OBL is using his sat phone much these days. The calls are so easily monitored and tracked. The phones have a GPS receiver in them and if somebody spent enough time on the phone, you could drop a GPS guided bomb straight on top of him. The GPS in this phone appears accurate to much better than the length of my patio... The whole system is a GCHQ/NSA dream come true.

[SNS3Guppy]

Furthermore, they apparently have an operations manual (not to be confused with the POH) in which the boss wrote directions for use of the satphone. Possibly along the lines of "no long calls with the significant others, this stuff is EXPENSIVE".

That would be the General Operations Manual. The Aircraft Operations Manual is the aircraft flight manual, or pilot operating handbook, if you will. Each operator has their own, written by the operator...it's the same thing you have in a Cessna 172, but much, much larger and more complex, and this doesn't come from the manufacturer. The material is derived from the manufacturer, but it's an approved document that takes the place of the POH, and comes from my employer. It's proprietary, and includes one full volume on systems, and another on procedures, performance, etc.

All the same,the satphone isn't something we're quizzed or part of any proficiency check. It's more of a convenience that's used in the cockpit. It doesn't get a lot of attention in the manual; they didn't even cite the model number. We also have a little commercial insert from Iridium giving a short rundown on the features of the system and how it works; more of an advertisement than anything.

Sorry I couldn't be of more help there. I hardly use the phone; the flight engineer does most of the calling, and answering.

[BackPacker]

I have a very preliminary report which is.... the set doesn't work at all indoors, behind a patio door with two 6mm non-metallised glass panes.

What side does your patio face?

The Thuraya satellite is in geosynchronous orbit at 44 east (according to Wikipedia), so from the UK this means that it's somewhere in the southeast, approximately 30 degrees above the horizon. I would imagine you have to have a reasonably clear line of vision in that direction to get any reception at all. Particularly since the handheld unit, as far as I can see, does not use a directional antenna.

OTOH, Thuraya claims to have roaming agreements with a lot of GSM providers so if you're in reach of a GSM network (and in Europe, it's rare not to be) your calls will be handled by the GSM network instead of the satellite. But, IO, I assume you know that and deliberately turned that off to test the satellite performance?

The advantage of Thuraya - if it works - is that it is a much better deal cost wise than Iridium.

That does not surprise me all that much. Technically speaking, the Thuraya system is inferior to the Iridium system, especially for voice calls. Latency is far worse with Thuraya than with Iridium and with only one satellite operational, coverage is not truly global.

However, for most applications Thuraya is good enough and with the higher bandwidth available, may be more suitable for data connections anyway. And the roaming agreements with the GSM providers is of course very clever. I have no doubt that Iridium would want to do the same thing nowadays but their handhelds are simply not capable of doing this.

[IO540]

Report #2 - outdoors ground operation

It works brilliant for data - 1.1kbyte/sec data rate and no worse latency than GPRS. It is installed as a 19200 baud generic modem and this data rate is about equiv. to 9600.

I tried it with and without the £25/year Onspeed data compression proxy service which saves a lot of money on GPRS/3G but this test is dial-up with no data volume charge. The data compression should still increase the data rate but I find that Onspeed have taken on so many users that their servers are loaded and there are significant delays which, while still saving the money on data volume billed services such as GPRS or 3G, seem to cancel out on dial-up access.

I used Primex Internet "free" (PAYG) dialup. One can dial their 0845 # from abroad - essential in this case. 0044 845 ...

9600 is easily fast enough for most airborne data requirements, not including dirty movies

Next... vehicle and airborne. The last one will have to wait till Tuesday (no hangar access at weekends).

[flyingfemme]

We started with a UK based account which was quite expensive to use. Now we have a US based pre-paid SIM and minutes cost $1.49. That's cheaper than GSM in a lot of places.

[IO540]

I can well believe it.

Same with plain old GSM and GPRS/3G data - there have been some amazing obscure deals, like South African Vodafone (Vodacom) doing PAYG data at about 10p/MB roaming. Unfortunately they kill the account after ~ 3 months out of the country...

There is an Italian WIND SIM card which does PAYG data at £1/MB roaming, but you have to go to Italy to register it initially.

Tested the sat phone in a car. It is completely useless while moving. A brief obstruction (a few houses) blocking the line of sight and the connection is lost.

[LH2]

I don't think the Doppler shift resulting from 130 knots airspeed is going to be significant enough, considering that the satellites themselves travel at 15.000 knots, give or take

It is, considering that you're talking about centimetre-band frequencies, so unless the unit was specifically designed with high-speed applications in mind, it will in all likelihood never find the signal as it will be outside its scan range.

Tested the sat phone in a car. It is completely useless while moving. A brief obstruction (a few houses) blocking the line of sight and the connection is lost.

That is correct. I have been using Thuraya quite extensively for the last few years and yes, you can't use a handheld from inside a moving vehicle (but at least you don't get done for talking while driving )

Data transfer works fine most of the time if you're happy with 9600. When I first started using the internet it was a 4800 baud telnet job and I thought that was plenty. 9600 bauds while stuck in the back of beyond is the equivalent of fiber optic in London (in fact, it's much better). There is also the SMS feature, which is reliable and at a very reasonable cost (it used to be free up to a certain number of messages).

Cost-wise, as has been said, it compares favorably with using a GSM in roaming mode in many places. Thuraya to Thuraya used to be US$40/min which is cheaper than many standard GSM rates.

So, while most probably not usable in flight (I'm talking about a bare handheld), it is very cost-effective and a pretty reliable solution if travelling within its area of coverage. Certainly much more so than the SW radios we used to use before them (and still carry around, just in case).

[BackPacker]

It is, considering that you're talking about centimetre-band frequencies, so unless the unit was specifically designed with high-speed applications in mind, it will in all likelihood never find the signal as it will be outside its scan range.

LH2, can you expand on this a bit more? With my basic high-school physics it would seem to me that the handheld units and the satellites have to contend with a Doppler shift resulting from speeds between -15K and +15K knots anyway - after all the satellite is moving towards you, or overhead, or moving away from you at (very) approximately that speed. Why is 150 knots extra in either direction going to make a difference?

Also, the Wikipedia article on Iridium specifically talks about frequency bands separated by idle bands to allow for the Doppler shift.

[IO540]

I can now confirm that an old Hughes sat phone, on Thuraya, works fine in the cockpit.

The data rate varies 0.8 to 1.3 kbytes/sec depending on how good the signal is.

A direct line of sight (no in-cockpit obstructions) is essential - possible only if flying a relatively constant heading. So the sat phone will need to be moved about accordingly. It cannot lie down; the antenna must be vertical.

No speed related effects were seen up to 185kt ground speed, on any heading, so doppler shifts (worst case to/from the satellite) don't seem to matter.

This was an old phone, 7100 I think, and I will next try a newer one.

It takes about 45-60 secs to establish a dial-up connection.

Thuraya also block VPN access, which is pretty common on mobile networks; Voda are the only exception I know of. I dare say a VPN on port 80 or 443 (HTTP) would work fine... not that this will bother many pilots since the main use of this would be for simple text only sites for tafs/metars and possibly meteox.com.

The plane was a TB20GT; composite roof. However only the windows were signal transparent.

[wiggy]

Backpacker
I'm confused by the Doppler issue as well. As you say, even with the satphone sationary the signal can be shifted all the way from up 15K's worth ( approaching) through zero ( satellite tangential to the user, either overhead and/or offset laterally) through to minus 15Ks worth as the satellite receeds. I'm standing by for a convincing explanation.

[IO540]

I agree with wiggy, although Thuraya could have potentially presented a different case as it is geostationary. However, there appears to be no issue - certainly at sub turboprop speeds.

[BackPacker]

Thuraya could have potentially presented a different case as it is geostationary.

True. But of course easy to solve by getting onto a heading tangentially to the satellite:

"London Radar, IO540, request heading 045 or heading 225 to eliminate Doppler"

[flaxman]

Originally Posted by IO540

No speed related effects were seen up to 185kt ground speed, on any heading ...

... The plane was a TB20GT

185kt groundspeed in a TB20? I'm impressed.

[IO540]

I tried the obvious headings to test the doppler effect worst case. Could not see anything on either the signal strength or the actual data rate during a large file download (1 meg file).

185kt GS is easy. I've done 210kt once. Vne is 187kt indicated which is easy to reach at say 75% power and in an approx -1000fpm descent, and with some tailwind anything is possible, but this is cheating of course ... 80% power and -500fpm gives ~ 170kt IAS at 5000ft. I am writing up some notes.

[bookworm]

A direct line of sight (no in-cockpit obstructions) is essential - possible only if flying a relatively constant heading. So the sat phone will need to be moved about accordingly. It cannot lie down; the antenna must be vertical.

Can you get an external (to the phone, not the cockpit) antenna to stick on to a side window?