Weather effects ?

[kmmoore1013]

I was wondering if anyone can tell me whether (no pun intended) weather has an effect on fix time and signal strength.

The reason I ask is that I have put my Ipaq 3970 and Navman3400 (with SmartST 1.91 SP2 software) together for the first time last week, and it was a lovely clear, cloudless night last Friday, so I decided to try it out. Everything went well amd I had 5 locked, green bars in less that 90 seconds, so I was impressed with that.

The next morning, I decided to take it for a test spin in the car, however, the weather had clouded over and was overcast and dull, but dry, and even though I was standing in the exact same position as the previous night, I could not get any green bars after 7 minutes. The most I got was 3 yellows. The unit never even made into the car.

Could this be as simple as the weather affecting the fix time and signal strength ? If so, then living in Scotland, I may as well pack the Navman up and put it away in the cupboard....We get a lot of cloudy days up here

Any thoughts or help would be appreciated.

Cheers,
Kevin.

[Dave]

Hi Kevin, technically, no weather should not dampen GPS signals, all signals are in radio wave form, the only thing that can really affect it is ionosphere problems and solar flares.

However (and this is a big big big however), I have noticed larger drops in signals in huge halestorms and signal has rised again shortly after stopping, but this may be a coincidence as I was travelling, and I may have been receiving multipath errors due to the built up nature of buildings where I was when the halestorm started.

The Navman sleeves, anthing from a 3420 below do have problems receiving fixes, we've had Navman sleeves before, and this was the one main reason why we started this site, because we used to experience the same problems you are experiencing now.

The first thing you want to do is to make sure you have a fix (4 sats) before you commence journey.

The second thing to do is when you have a fix in car, move the iPAQ and sleeve so it is outside the car. If you see a increase in signal, then you may have a UV protected windscreen which will dampen signals and you may need a Re-Radiating antenna.

The other thing with Navman sleeves is sometimes you can get erratic Time To First Fixes. A satellite fix in 97% of cases should occur within 1m30secs. In reality, you should be looking at between 30 and 50 seconds as an average, but Navman sleeves were quite bad in this. It's all due to the chips in the sleeve being too close to the processor on the iPAQ and receiving RF interference causing it to degrade the signal you should be receiving hence causing signal problems.

Navman did resolve this in the 3450 sleeves, firstly by allowing for a plug-in external antenna which you can place on the roof of the car, but also to put a military grade chip (so Navman say) inside the sleeve which appears to cut out this interference.

Another way to speed up the fixes and bring reliability back to normal is to check this thread as some people have found taking an antistatic hard drive bag (silver kind) and folding it up and placing this between the iPAQ and the sleeve can help a lot.

[kmmoore1013]

Thanks for the reply Dave.

I have reads the thread you mentioned, and it sounds very promising. I shall go and see if I have any of those kind of bags. The annoying thing is, I had lots of them about six months ago, but thought I would never need them, and threw them away in a clear-out

That's life Eh !

I'd rather not go down the New Sleeve path just yet, as I have only just bought the 3400, so I shall persevere for the moment and see what effect the anti-static bag has.

Thanks for your help.

Cheers,
Kevin.

[Telboy]

kmmoore1013,

I to had the same problem as you are describing with my 3400 sleeve. I had my unit mounted in a Ford Mondeo with a heated front windscreen and found the sat fix very tempremental. I fitted a re-rad antenna and it made a huge difference.

I've now upgraded to a 3450 sleeve and all I can say is wow!!! There is no comparison between the 3400 and 3450, it's still mounted in the Mondeo and I constantly get a fix of 7 - 8 sats without the external antenna connected!!

The only thing I would say is no two sleeves perform the same, my father in law has exactly the same set up as me, IPAQ 3850 & 3450 sleeve. We carried out a test the other day where we stood next to each other in my back garden to test the performance of our units. I received a 7 sat fix, but he could only manage a 5 sat fix.

If you really don't want to go down the new sleeve route, a re-rad antenna is definately worth a try. The only down side is it requires a power supply.

Keep us informed on your progress as it's threads like these that helped me resolve my initial problems.

[kmmoore1013]

Just to let people out there know that I finally got round to locating an anti-satic bag (the silvered type) and slipped it between my 3400 sleeve and Ipaq 3970. What a difference it made, it is like night and day. Initial fix time is now <60 seconds, and I get a solid 7 sat fix, whereas if I try without the bag, I am lucky to get an initial fix in under 5 minutes, and 2-3 sats is the norm.

I used it in earnest for the first time this evening, and with the anti-static bag, the kit is now "the business". Extremely impressed. Can't wait to try it out on some longer destinations.

If anyone is wondering whether or not to try the anti-static bag thing, my advice is, don't hesitate, you won't look back. This, I am sure, is how the Navman was meant to be.

Thanks to everyone for their advice.

Cheers,
Kevin.

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