stronger signal = better accuracy?

[Jeevan]

Hi all,

i bought my icn510 and although i love the unit, i am a little disappointed.

firstly, i struggle to get a signal lock-on within my car. before you ask, my 306 doesn't have a heat reflective or heated windscreen. it is normally fine once i have locked on to the satellites. its just getting that initial lock.

also, sometimes i struggle to get a fix when just standing out in the open.

i am interested in purchasing the mmcx antenna. this will hopefully provide me with a stronger signal. Q: will a stronger signal improve accuracy?

sometimes i find that my on-screen position is off the road somewhat? or it instead places me on a nearby road and tries to recalculate my route! is this normal?

[Team225]

Hi, ordered one the other day should be here very soon, mine is tucked any in my audi and again takes time to get a signal and has problems keeping it, will mount it on windscreen and let you know how it goes.

[DavidW]

Theoretically, a good lock on four satellites is enough to provide a 3D position. However, modern GPS receivers, such as that embedded in your iCN, use extra satellites if available to provide an overdetermined position solution.

The Time To First Fix (TTFF) is somewhat dependent on the satellite reception; the poorer the reception, the longer the TTFF. If you haven't used the GPS receiver for a few hours, it will take something like 40-60 seconds (even with perfect reception) to get the first fix if you remain stationary; this is the time taken to get up to date ephemeris data. Do not move until you've got a fix; it's far harder to get a first fix when moving.


As I said, the more satellites you can receive, the more chance there is of a better overdetermined solution - but being placed off-road can also point to map inaccuracies.

I don't use an iCN - but presumably there's some kind of satellite reception indicator. Is it showing good reception? Whilst you may not think your 306 has an athermic windscreen, they are quite common in modern Peugeots.



David

[larkshall]

There is quite good information on satellite reception in the ICN, and shows no of satellites, strength, and whether they are being used for fixes.

The off road scenario is almost certainly due to maps rather than unit accuracy.

TTFF is a bit slow in my mind, when I compare it to the Furuno unit I use afloat, BUT and its a big one, The Furuno is always on standby, has a mast mounted aerial, and rarely has to put up with bridges etc.

I too have ordered an external aerial, though to be fair my incar reception isn't bad. I do find weather seems to affect reception gales hale and heavy rain seem to give the unit a few problems.

regards

David Low

[Jeevan]

cheers for the replies.

i have ordered the mmcx antenna from ebay so it should get here soon.

is this aerial better than the antenna within the icn? or is it just the fact that it is external that means you can get a stronger signal?

also, does anybody know how to wire this in? i have a radio aerial at the front of my roof. i could perhaps place the little box bit there, but i dont know how to get it into my car?

any ideas?

[Tim Buxton]

It will be better in that it should be magnetic so you can mount it on the roof of your car and thereby get a more clear view of the sky. The coax cable will route easily through a doorseal. Just make sure that it doesn't snag on anything like a doorcatch.
_________________
Tim

[Jeevan]

thanks for the swift reply Tim.

so, if i struggle to get a fix out in the open anyway, will this aerial help?

i seem to get a fix from my bedroom window yet, when i stand out the front of my house ... nothing! its really frustrating.

is there any way in improving the TTFF? 8O

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