Iridium satellite phone query

I have noticed the same from time to time.
I was coming south down the Birdsville Track awhile ago and was speaking to someone in Melbourne and it was as good as my mobile phone.
Other times it can have a small delay.

I just put it down to Sat position relative to me at the time, maybe atmospheric conditions and the possible number of users on the system at the time possibly causing a little congestion???

Still is has never failed to get a Sat Signal within 30 seconds or so of turning on and hold it for as long as I was holding a conversation.
Excellent technology in my book.

I have the 9500 Motorola sat phone and i have the same delay in the outback but over x-mas i was up the high country and run the family in germany and it was crystal clear , same or better then the mobile sometimes.

I have the 9500 and called Perth from between Menzies and Bull Finch and there was no delay and quality was good.

Possibly due to the bandwith of the satellites I noticed over the holidays that the internet slows down a lot. Probably due to all the kids using it. Think of it like a water pipe You can only pour so much down it and its full or the flows slows.
Probably uses packet swirtching which can cause delays like that similar on VOIP phones

Chalk one up for the old useless Globalstar, when... it was working it worked like any normal mobile, no delays, no interfernce it was good no matter where we were, same as when it was on CDMA which is still working but not for much longer.

Cheers

D

Because of the way Iridium works:
Signal goes up to a sat - then hops from sat to sat till it gets around to ground station in the US - then back to who your calling via l_a_n_d_l_i_n_e_s - compression of signal is high as inter-sat bandwidth is limited - more calls on the system = bigger delays. There is always a *little* delay due to sat height and the fact it gets relayed half way round the world :-)

GSTAR - signal goes up to sat and straight back to one of 3 grounds stations in oz then onto the phone network - hence shorter to NIL delay

hope that helps

Permit me (a retired satellite consultant) to offer a few numbers to this discussion.

First, communications signals travel at the speed of light, ie 299,792km/sec. Satellites in the geostationary orbit are 35,786km above sea level, directly above the Equator. A simple calculation suggests that a radio signal takes around 0.24 seconds for the round trip up to the satellite and back to earth. So the latency (delay) in a conversation using a GEO satellite is around one quarter second.

Secondly, Iridium satellites operate at an orbital altitude of 780km; essentially they represent something like a set of mobile phone towers in the sky, with two essential differences. One is that they are moving. The other is that, unlike GEO satellites (and Globalstar satellites), Iridium satellites do not link directly back to earth; instead, they have inter-satellite links allowing the uplinked signal to be "hopped" from satellite to satellite until the it reaches a satellite that can see a ground station. Ignoring the US military station in Hawaii, Iridium has two ground stations, both in the US - in Tempe, Arizona and Leesburg, Virginia. Google Earth indicates that Leesburg is around 15,650km from Sydney, so a signal that started from an Iridium satellite above Sydney would take around 0.1 seconds to get to Leesburg and back to Sydney. That would only be if it came back via terrestrial cable; if the signal came back to Sydney via a GEO satellite, add another 0.24 seconds.

I hope this helps a little.

Bruce M

Who knows Tim.
Ive made and received many calls, some with delay some with out, and always crystal clear, impressive technology.
Dean

I'm not concerned about the delay/latency factor when using the phone. The point I'm getting at is that the lack of delay and clarity of call when making calls within a suburban area indicates that the call is being intercepted and routed through Telstra's terrestrial GSM network.

This would benefit Telstra because they wouldn't be paying Iridium to use their satellites to route your phone call (via the USA), BUT they still charge the customer the satellite call rates!

Is it GStar who advertises that their phones use the GSM network if in range and only uses satellites (and hence satellite call charges) if out of GSM range?
I know Telstra says that the Motorola 9505s can't do that but they would wouldn't they?!
It's beneficial to Telstra to keep this capability quiet and reap the extra money from charging every poor sap who uses the 9505 on their network the satellite rates.

Can anyone prove this either way?

Does anyone who has one of these Motorola 9505A phones with it's own satellite SIM (NOT your GSM SIM) and hooked up via Telstra, experience any form of delay/latency when making a call from within a known GSM /CDMA covered area?

Tim