Thuraya sat phone coverage ?

Big antennas produce bigger signals by narrowing the beam width. For CB antennas this narrowing of the beam is in the vertical direction, not the horizontal direction. If you use that style of antenna you will not get much signal up to the satellite. If you use an antenna that produces a narrow beam upwards then you have to steer it to keep the signal on the satellite..

PeterD

Wayne: antenna theory is amongst the more complicated area of electronics and I regret to tell you that your theory is wrong :(

In addition to the theoretical complexities of antennas the real world comes into play (especially with the high frequencies 200MHz+) and things such as local ground conductivity, mounting location etc. play a major part in the efficiency of the antenna. Modern computing capacity has provided a far greater ability to preform antenna analysis but we're a long way from perfection in this field.

Expert advice is useful but often the best thing is to try it and see if it works :)

Mike Harding

PS. PeterD; any chance of a response to the Amateur Radio/Type Approved thing...?

Wayne, the hand-held Motorola's also come with an external magnetic mount aerial that tends to improve things.
I agree that a car kit will lift the usefulness of sat phones, but I'm not convinced that the service that you use is all that great to start with.
The main thing is that you're happy with it, and that's all that counts :)

Hi John and thanks for you reply. I've re read that thread and got one or two things out of it.
1) They work in at least two places
2) The handsets seem a bit "fragile" for bush use ?
3) At least someone's bought some.
A great pity that there wasn't more info in another follow up.

The aerial question wasn't as silly as it probably looked. At those frequencies bigger isn't always better, as a lot of gain can be packed into the aerial. But unless they have some form of pull out aerial, getting reliable comms with the head and ear in the way, might not be so easy.
It's not quite the same with a terrestrial service, where you can just move a bit.
I stand to be corrected on that one, it's nearly 40 years since I trained on microwave stuff :))

Hi Footy, yep agree with most of that - will be better when more people have tried them all over Oz. If they do work OK though I'm interested, since they'd go much better (encased) in a backpack!

The phones do have a pull-out antenna for satellite use (rather than the rotating type on Motorolas)

Cheers, John

Also this from the SO-2510 manual:

While idle with SAT or communicating with a good quality signal, the antenna need not be pulled out. However, the antenna should be pulled out to receive SAT calls or to start SAT.
While watching the indicator for SAT signal strength, move around to achieve the best connection quality for the mobile phone. SAT communication requires clear space without obstructions. Avoid obstructions such as buildings, trees or mountains. Also, it is important to direct the antenna of the mobile phone towards satellites.

Hmm...I have to admit that I tend to stand still when using my phones, but perhaps thats because I already know the optimal spots to do so.

John R was that 36,000 km above the equator??

Whats the power output on the handset to transmit a signal that far??
And what sort of voice/signal delay would one experience when the words have to travel up and back that sort of distance me wonders??

Iridium Sat's are only 700 km above us.

Hi John, yes 36,000 km above ground, so the signal goes about 75,000 km up and back to the ground station. As the speed of light is 300,000 km/sec, then there would be about a 1/4 sec delay (plus the time to get the signal from the ground station to the phone you are calling). Don't forget though that the Iridium network passes your call from one satellite to another until it gets to one in contact with the ground station, so there can be a significant delay there as well.

The power output is given as max 2 W in satellite mode, which is apparently similar to the max that GSM phones can put out. (this from a FAQ page here).

Cheers, John

Thanks John good info.

You got to admit thats an impressive combination of technology and electronic engineering to achieve those sort of distances with such low power output and such a small antenna

Not an ideal comparison but the old UHF radio in the 4wd has only 5 watts of output and struggles to get 50 km's in ideal conditions.

Thanks Rusty. Interesting info if they're correct.

Thanks for that info RustyHelen, I have done a fair bit of research on these phones as well and hadn't heard about that yet, very interesting. The phones are so new that it is going to be a while before a lot of real out in the field info comes in.
The info that has come in so far from a couple of Forumites hasn't been all that bad up to this point, still watching this space.

Cheers

D

Hmmm ... If you were facing NW, then the antenna (as most people hold phones) would be pointing away from the satellite, exactly opposite the advice in the manual! No wonder you wouldn't want to move around at all. :-)

Do Optus maybe limit use to Australia only? The phone itself will work in over 100 countries (but definitely not US, or anywhere in the Americas).

Perhaps talk to some other sellers, Rusty.

Cheers, John