Bluetooth GPS Receivers (Technical & Buying Advice)

[Guest ricky10]

Hi

I'm currently researching GPS receivers for my SPV M3100.

I thought I'd throw this one to the floor.

My budget is around £40-£50

It would seem the choice of weapon is having a sirfstar III chipset. Any comments on RFMD chipset?

Now I have seen a sirfstar receiver I like at http://www.mobilefun.co.uk/product/10939.htm {OPTION 1}

the other option was the RFMD chipset http://www.kaali.co.uk/index.pl?art=110 {OPTION 2}

My one dilema is that my car has an athermic windscreen (Heat Reflective). I am thinking I might need an external antenna, so option 2 would be the choice as option 1 does not have extenal antenna capabilites.

I do prefer option 1 as it is smaller and the tracking sensitivity is -159dBm or better compared to option 2s -157dBm (which I have read IS a BIG difference!)

So my questions are

1) Chiposet (see above)

2) Has anyone used there device without an external antenna whilst in a car with an athermic windscreen? (What has been the performance? As they say you can put it in your glove box)

3) Option 1, Option 2 or can anyone else recommend otherwise

Thanks

Ricky

[Guest echo3]

I'll be interested to see the answers here.

One more difference is that the RFMD model is 32 channel and the SIRF III is only 20 channel. I'm not sure if this will make a big difference or not - probably depends on where you are going to be using it.

Another to consider is the Holux GPS Slim 240 - which is the size of a packet of chewing gum! handy if you want GPS on foot, or just want it more portable.

Also, some come with a charger that splits the power between your GPS receiver and your PPC (like the one you get with Tom Tom navigator 6), so you can power/charge both at the same time - might come in handy.

e3

[Guest leesmart]

Until recently, the OPTION2 unit was available on eBay with either the SIRF III or RFMD chipset. I have one of each (one for the missus and one for myself) and have done a quick comparison.

The SIRF III may only have 20 channels but both units only appear relay 12 channels to TomTom on my MDA Vario. Either unit seems to pick the best 12 signals and output them via the BT connection. A five minute drive had both units swapping satellite numbers back and forth every few seconds.

I couldn't say that either chipset was better or worse in terms of TTFF or signal strength on the open road as they both pretty much max out. I did find the RFMD unit picked up a lock further inside my house than the SIRF III unit so would suggest it may be more sensitive when driving in a city with tall buildings all around.

As for athermic windscreens affecting the signal reception, a friend of mine gets round this in his BWM X5 by putting his Bluetooth GPS receiver on the parcel shelf in the back...... 10m range on the Bluetooth is more than enough to work at this distance.

The OPTION2 unit also has a mini-USB connection the same as my Vario (and most other WM5 Phone/PDA units made by HTC) so I can easily charge the GPS while running the Vario on battery and vice-versa without needing a second charger/splitter.

Hope this is of some use.

LS

[Guest slimgym]

I have the reflective windscreen on my Peugeot, but there is an area around the mirror which is not treated in this way and I use the tomtom GPS antenna with magnetic mount on the rear of the mirror. Also seen someone who put the receiver under the bonnet within the air intake area. There are vents through the bonnet and he mounted the receiver beneath them, powered from a switched positive supply.

One other tip might be to get one that has a physical power switch rather than a soft one. If you do mount it relatively permanently it can be powered from a switched positive and be on each time you start the car. The tomtom one needs a long press on the power button to turn it on and off and therefore can't be used in this way.

[Guest ricky10]

Some good pointers there.

Thanks for that guys!

I'm still in 2 minds. So I'll wait a few more days and see if there are any further suggestions.

It was interesting to hear that someone who also has an athermic windscreen can get around that "external antenna" issue with the 'blind spot' or underneath the bonnet. I think battery life wouldn't be an issue, as they have 10-13hrs continuous life. I think my phone would probably zap more energy, so I'd utilise the charging that end.

For the above reason, I'd be tempted with the SirfStar III option, due to the higher frequency. I know it is only a difference of 2 dBm but apparently each dB is to the power of 2. So that is quite some difference.

I know they say the more channels the better, but 20 channels should be plenty as it'll probably pick no more than 12, according to research.

The only spanner in the works was the suggestion of the RFMD having a better pick up inside. As you say, round major cities, this could prove a big difference. My job will involve travelling up and down the country, but a lot of my business is in London. So I am in a dilema.

Any more experiences/comparisons for SirfStarIII Vs RFMD?

I would love to hear a few more opinions on the chipset.

Thanks guys for posting, it has been a major help so far.

Ricky

ps

I accidentally misplaced my initial post so I have copied the reply below, in case someone wants to follow that route (apologies for that moderators)

I'd highly recommend the QStarz BT-Q810. Reviewed by Paul on this site, and also got several great reviews elsewhere on the web.

I picked mine up on ebay for £40, next day delivery. I wouldn't want anything else. I'm not sure how it works with one of yer special windscreens (or if my car has one :¬/ ) but I'm sure I read somewhere it can have an external antenna plugged in (80% - don't quote me).