satellite phone [Telecom]

Besides

which is very informative what other webpages or online resources exist to inform me about satphone basics and capabilities? Do they have an IMEI in the main phone and a SIM card as do cellphones? Is it possible for an Iridium or Inmarsat phone to be located on the Earth's surface by triangulation, so say you're in a boat and you want to know where the boat is, can a satphone locate you? What service providers exist for satphone and is there a list of these and their prices anywhere?

Can anyone lend a clue with these questions?

sat phones are _proprietary_ architectures. they work only with the satellite system they are designed to be used on. there are currently only two such sat. systems InmarSAT and Iridium. features and capabilities differ depending on which of those two services you are talking about. Little need for the complexities of an IMEI and SIM in the phone -- they _all_ either talk to one vendor, or they talk to "nobody". Google for INMARSAT and IRIDIUM. you should find the provider pages. Given what the sat provider offers, you should be able to fgure out _WHAT_ the various 'resellers' can provide.`

One of the greatest intelligence community mistakes was bragging how terrorist could be tacked using the satellite phones. Consequently they have stopped using any form of electronic communications. So yes, you can be tracked with a sat phone.

Google for satellite phone.

"Tracked"!, have a look at how many "terrorists" have been blown up in the last few years by honing in on phone handsets' signals.

If you have a major technological power after you, don't use comms technology or you might as well paint a target big enough to be seen from space on your back.

There appear actually to be dozens of different satphone systems in Europe and the Mideast.... Inmarsat and Iridium are the only two ones with worldwide coverage but there are a bunch of other services that cover only limited areas. They may well also use proprietary data formats.

--scott

This might be a good time to learn more about Thuraya, who provide GSM satellite service in Europe, Africa, Asia, and Australia. They have roaming agreements with carriers all over the world, although none in the U.S.

The phones are different from normal GSM phones, but if you put a SIM from a carrier with a roaming agreement into a Thuraya phone, it'll work.

R's, John

Let's suppose I'm a terrorist, which I'm not. I get a Thuraya phone, which operates with two satellites. You can't triangulate with two satellites. How is the NSA going to track down the dangerous terrorist using just two satellites when the phone is connected to only one of them? Does it have to look at transmissions from the Earth's surface, which are directed at a particular satellite? How on earth is American intelligence going to track down these people?

Even with Iridium or Inmarsat which have lots of satellites, how is it possible to track down / triangulate on a satphone when it is in contact with only one satellite and the other satellites don't care about that satphone? You would need to track down the tranmission on the Earth's surface surely?

I can't help thinking we are being sold a dud with the story of tracking down satphones and it isn't actually possible to catch al Qaeda using these methods. It is far more likely that US intel have paid an al Qaeda operative tens of thousands of dollars for betraying his own people and offered him immunity. It's not possible to do technically is it?

Cellphones no problem because those are always on the radar for a thickly forested cellphone tower structure and you can tell from strengths of tranmissions to various towers where the individual cellphone is located.

I am speaking as an amateur and not a radio freak so correct me if I'm wrong.

Don't count on that. You know the positions of the satellites, and that's to locate a point on a known surface (of the earth). It seems to me that would reduce the possible location to two points, which will probably be far enough apart so that the wrong point could be ignored. Come to think of it, if those satellites are moving with respect to the earth, each satellite will observe the call from continually changing points on a line. I'd bet you only need one satellite to do it (and it doesn't have to be Thuraya's).

In any case, what makes you think that those two satellites are the only two receivers that can pick up the signal? Whenever you're running a radio transmitter (which any wireless phone is) you're running a veritable beacon. Don't forget the Chechen insurgent whose satellite phone apparently was used to target a Russian missle. I'm sure that the Americans have other satellites that can pick up the signal, probably the Russians do, maybe the Chinese. And then there's aircraft. And fixed stations with very large antennas. And, closer, trucks.

And, of course, they can use that technology to listen to anybody, not just "terrorists".

Dave

Why do you assume that the 'phone' satellites are the _only_ birds that can listen to the sat-phone transmission?

Do you suppose that spy satellites *can* listen on those frequencies, and that they "just may" have directional facilities?

You'd be surprised at how much 'location' information a single bird can pull from a ground-based signal -- carrier 'doppler shift' analysis can give a surprisingly precise fix, putting the transmitter on a particular line perpendicular to the satellite track, just for one example.

With ground-based systems. Or with military satellite systems that are designed for listening in and locating signal sources intended for others.

Yes.

A lot of it can be done technically, but in the whole, it's generally a lot cheaper and more effective to pay someone off. Unfortunately our Federal friends who answer phones with numbers instead of names have forgotten this and have basically abandoned boring human intelligence programs in favor of flashy signal intelligence. This has come to bite all of us.

That doesn't tell you all that much... it lets you know what cell the user is in, but triangulating the user within the cell still requires additional hardware.

--scott

I believe that other DoD agencies have revealed that the NSA can track satphones. These other agencies behaved in a manner that I would characterize as incredibly stupid. This has pissed the NSA off. Oh well, maybe we'll do better in the next war.

--scott

It is not difficult, but designing building and deploying the equipment won't be cheap. Though if it gets mass produced and deployed widely that would drop the costs well into the commercially viable range.

A big part of making a working sat-phone, or a plain old TDMA CDMA GSM EDGE cellphone is tied to precise timing and time-keeping. Multiple users have to share a single radio channel, to get the system carrying capacities needed. Each phone set has a very accurate internal clock, and even as it is idling without a call in progress it is slaved to a Strata 1 clock through the phone system.

When a call is set up the phone is assigned a specific channel set and timeslot for the call, and it has to transmit the voice translated into data packets in millisecond long bursts several times a second. And it receives the other end of the conversation audio using the same packet-burst method.

If you have two or three receivers (either satellite or ground based) and measure the time delay of how long the signal took getting from the transmitter to each receiver, you can triangulate the transmitter location rather accurately.

Even from one or two receiving sources you can narrow it down to two or three possible locations - then the satellite receiver moves along in it's normal orbit and the logical triangulation cuts the probable locations down to one - the others are either in the middle of an ocean, or moving way too fast to be a stationary person - they can tell the relative speeds from Doppler shift.

That's the exact opposite of GPS - the satellites transmit the calibrated pings, and the receiver times and triangulates from the satellite signals. And a consumer grade GPS can tell you location and elevation down to within feet.

Cost is the reason it hasn't happened widely already. Unless and until the government required that a cellphone be trackable, the cellular companies would not invest in the equipment - they won't incur a cost that isn't recoverable.

Even after phones were required to have GPS chips and triangulation systems were to have been installed (and all the old analog phones without it were to be retired) we still get people lost in the woods that call in - and the 911 PSAP can't tell exactly where they are from those signals. The information gets lost along the chain.

Just had one of those last week in northern California, they told the lost hiker to shut their phone off overnight to conserve the batteries, hunker down for the night, and call the 911 PSAP back in the morning. (And they probably had to send technicians out to the cell sites to extract the info.)

Once they had a latitude and longitude to work with, sending out a helicopter to pick them up was easy.

Yes, but that additional hardware isn't all that difficult to build and deploy at each cell site ahead of time, though it is going to cost a bit.

They use the same method, they already know exactly when the signal was transmitted from the call setup auto-negotiations. They just need to know the time delay for the signal to arrive at each receiver, and it is helpful to know which quadrant antenna it was strongest on, and they can draw a 'distance from receiver' arc on the map.

Two arcs intersecting is a probability location, and if the phone is in a very rural location they might only see one tower well an and a second very faintly if at all. They might have to remotely command the phone to go to full power and look for other receiver hits.

But three or four distance arcs intersecting on the map is a fairly certain location fix. And accuracy of +/- 100 feet is plenty close enough - someone on the ground can sniff out more accuracy than that if needed.

-->--

In "Bruce L. Bergman" writes: [ snip ]

I'd betcha that in a hefty number of those situation the problem is that the "911 surcharge" [a] applied to cell phone customers, which was supposedly designated specifically to upgrade the PSAPs to "enhanced 911", simply went to general gov't coffers.

[a] in quotes because while called a surcharge, it's really most sincerely a ... _tax_... by another name.

Speaking of which, whatever happened to the proposal, post 9/11, to design briefcase sized pseudo cell sites? The idea was that if you suspected people wre trapped in rubble (and had a cellphone), you could walk over there with the briefcase and figure out were to dig.

Similarly, if someone was in a forest or other large area, you could drive by on the roads, or be up in a helicopter, and find them.

Well, the easy was is to listen to the GPS position the phone is reporting back to the control point. During the Great Invasion of Iraq by the Embedded Masses of Press, and ps, also the US Army & USMC; the military confiscated the reporters' Thuraya phones, because allegedly the current position of the incoming attack wave was secret.