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[VXL V6]

I change to get the best deals, but I'm kinda forced onto the O2 network, as Voda simply doesn't work here (because they are mongrels, and mounted their 2 masts in the valley), and the EE pair and Three don't work rural.

Nah, My Motorola M8989 Carphone had 3 - 4 Bars outside yours a few weeks back....

Mind you I suppose it's a class II device with a +4db hole mount antenna... Your just not giving that RF a chance!

My telematics can pick up a Voda signal from the road, but struggles from the driveway

The nearest Voda mast is about three quarters of a mile away...

Using the standard GM 'unity gain' (+0db) twig on the roof? Problem I have with that setup is that by the time the signal has traversed a joint two inches from the aerial, a joint at the kick panel and a joint onto the unit itself, there has been quite a signal loss.

I think the saving grace is the power class of the unit.

I would like to know if all 900Mhz supporting cell sites still support the 8W class though, I know infilling for certain areas has been achieved by utilising 1800Mhz channels and dual / multiband phones. Certainly from by experience though, Telematics and GSM carphones still rule when you are off the beaten track, even now, approx 14 years after Motorola and Nokia ditched making the 6090 / M8989 and 2700. Who needs a smartphone to make a voice call!

Maybe a certain Mr Wood could advise?

[sad mode off] lol

[Kevin Wood]

You called? 

You are right to point out that you've got a bit of loss in the connectors and, more importantly, all that RG58 cable between the footwell and the GSM antenna. In comparison to the woefully inefficient antennas on the hand held mobiles that make up the majority these days, you've still got a pretty decent receive setup, though, although receivers have got better in the years since the telematics was developed.

On the transmit side, yes, you have a higher power class but whether it's fully utilised depends on the cell planning in the area. Since 90% of mobiles are handheld, it's likely that the cell sites have been planned based on their output power. (and I'm talking effective radiated power here, so considering their 2W output AND the very lossy patch antenna on the PCB in the phone).

In urban areas, the cell site planning will therefore probably have been quite tight, and bandwidth is pretty scarce at 900 MHz, so co-channel interference with neighbouring cells might be an issue which prevents the network from commanding 8W units to full power.

Also, it's worth remembering that the signal path has to be reciprocal. The base site will have a much better receiver and receive antenna, and will most likely be using diversity, so the uplink path is probably going to be a good few db up on the downlink. A BTS can, of course, use much higher transmit power on the downlink but won't do so if the frequency re-use is a bit critical in the area.

GSM doesn't support layered use of other bands and micro/picocells to infill 900 band coverage that well - it was all a bit of an after-thought.

So, go out into the sticks where the GSM900 cells are turned up to cover the largest area possible and you'll have an advantage, but maybe not in more urban areas.

Unless we know details of how the networks plan cells these days (I don't) it's pure speculation, really, but because 8W mobiles are scarce these days, they won't figure highly in network planning and might end up getting neutered to avoid co-channel interference.

Or, in other words, "it depends".

[VXL V6]

Thanks Kevin.

So, ultimately, 'in the sticks', from a network hardware perspective in the 900Mhz bandwidth, An up to 8W transciever is still the answer then. Appreciate there is a multitude of variables in an urban area.

Incidently, the Motorola M8989 carphone I have supports both 900Mhz and 1800Mhz networks. I'm sure I read somewhere that at 1800Mhz this phone can support up to 5W Tx..... Presumably that was never implemented by the 1800Mhz networks here?

Apologies to the original poster for the thread drift. 

[zirk]

Thanks Kevin.

So, ultimately, 'in the sticks', from a network hardware perspective in the 900Mhz bandwidth, An up to 8W transciever is still the answer then. Appreciate there is a multitude of variables in an urban area.

Incidently, the Motorola M8989 carphone I have supports both 900Mhz and 1800Mhz networks. I'm sure I read somewhere that at 1800Mhz this phone can support up to 5W Tx..... Presumably that was never implemented by the 1800Mhz networks here?

Apologies to the original poster for the thread drift. 

1.2 Watts max at 1800 seems to ring a bell in the back of my brain, although I think it was Country / Region specific, also worth pointing out the original True Global Mobile idea was all based around the 900 GSM Spec. The 1800 PCN plan was originally developed to run Personal Communicators with Value Added Services and Integration within the Home and Office, which never really happened due to the way it was Marketed as just another Mobile Network, so the follow up to that is that 1800 Networks was back boned with Roaming Agreements betwwen Countries before becoming truly Global and soon formed part of the 900 / 1800 World Wide Mobile Bands.

Im surprised the likes of Hutchinson, 121 and T Mobile got away with it tbh, they were issued with Licences to run 1800 PCN Services and then just developed a Portable Mobile Network to compete with the GSM Operators, still there still here to tell the tale.

The one that did fail was Dolphin Telecom, in the late 90's the UK had the first Commercial Nation Wide Digital Tetra Network, but Dolphin in there wisdom decided to Market itself as another Mobile Network to compete with the Big Boys rather than just sell it as what it was designed for, a Secure Digital Push to Talk Service with some decent Data Applications, shame. 

[VXL V6]

Yes, looks like 1W at 1800Mhz according to the Motorola PDF i've found:-

http://www.rivanetworks.com/products/m8989.pdf

Also worth a nose:-

http://www.rfwireless-world.com/Terminology/GSM-MS-Power-Class.html

[Kevin Wood]

GSM1800 was originally spec'ed for 30dbm max (1W) as it was indeed originally only conceived for urban area coverage but they did add power control levels up to 36dbm later on when larger cells were required (INHO because OFCOM started carving up the spectrum with all the finesse and understanding of propagation conditions as a bride cutting a wedding cake, so operators had to make do with whatever band their slice ended up in.)