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View Full Version : Lilliput LCD + BU303 USB GPS problems



vincentvega
18th July 2006, 10:37 AM
I recently bought a BU303 USB GPS off craig. I have been testing it in my carPC and it has been giving me all sorts of trouble trying to get a lock.

http://www.gpsaustralia.net/forums/showthread.php?t=722

what was really bugging me is i knew there was nothing wrong with the GPS, as craig had been running it in his car for ages.

I did some searching, and it turns out that the lilliput 7" LCDs are known to interfere with the BU303 GPS. I seperated them as much as i could, and still couldnt get a stable lock. I was starting to doubt that it was the LCD as craig ran the exact same screen in his car!

I then found a post that suggested changing the refresh rate. I changed from my usual 75hz to 60hz and whala! I now have a BU303 working perfectly, so much so that i was getting 11 satellite locks last night, and 7 sats parked in my brick/tile garage!!

So if your having problems with the BU303 and you have a lilliput, seperate them and change the refresh rate. I am guessing craig must have been running 60hz all along, as he never had any issues.

festy
18th July 2006, 12:08 PM
hmm interesting... I have an interference problem with my 8" Hami screen, it seems to be emmiting harmonics around ~146MHz - and rendering my 2m VHF radio useless.... I'll try changing the refresh rate, although I've noticed the interference is still there (but weaker) in AV or TV mode too, but still worth a try.

arthurking83
18th July 2006, 05:16 PM
Was it a USB issue??

Maybe the GPS was getting a signal but couldn't send the signal properly down the USB line....
slowing down the refresh rate may have released a small enough amount of bandwidth to let comms with the GPS through??

This is all speculation, as I haven't had any experience with any of the devices you're talking about...

I've had issues with USB bandwidth and VGA ******s and scanners/printers/other devices running concurrently!

Only real way to find out is to run the setup again over a proper USB2 computer system where there won't be any USB bottlenecks by the host/chip!


at least it's working for ya :)

festy
18th July 2006, 06:32 PM
USB on the touch screens is only for the touch input, it's really low bandwidth. The display is via a VGA port.

vincentvega
18th July 2006, 10:20 PM
nothing to do with the USB port mate, the GPS was actually not getting a lock until i turned the screen off. Theres a light on it that flashes once it has a lock... it wasnt flashing ;)

arthurking83
18th July 2006, 10:45 PM
USB on the touch screens is only for the touch input, it's really low bandwidth. The display is via a VGA port.

In that case I'm a nob!...did I mention that I had no experience with these devices :p

I just had trouble with a PIII500 and winXP years back after trying my 'VGA' ******, and some other devices...and the PC kept on BSODing....


:o

vincentvega
19th July 2006, 12:44 PM
In that case I'm a nob!

LOL if you say so mate!! :laughing-

happpyg
21st July 2006, 08:07 PM
I had the same problem & posted that solution on the mp3car forum only to be shot down, however screen on = no lock, off = lock, refresh rate @ 75hz = no lock, 60hz = lock, over and over again, after posting it turns out I was not the only one having this problem & this did fix it. When I put the new xenarc in the problem re-appeard & refresh rate did not fix it, I got around it by folding a piece of household aluminium foil so it was about 8 layers thick and put it in a hard drive anti-static bag, this sits directly underneath the dash mat where the gps reciever sits and viola - no more problems, if anyone else is having the same problems it's worth a go!

the evil twin
22nd July 2006, 08:40 PM
I'm with you Happy and also Arthur....had a horrible bunch of RF interference from a JVC plotter that was affecting GPS lock-on (didn't know it till we fixed it) and two way radio comms.

Crystal clear radio in the vehicle but receiving stations always complained of noisy reception from my Txers.

Heard about similar issues on the web...wrapped the side and back of the display in alfoil....grounded the alfoil.....no more RF issues and the GPS performance improved heaps.

Nicko
6th August 2006, 10:59 AM
You wonder how they pass the US FFC rules, apparently many chart plotters have this problem and having to wrap alfoil around a screen is a bummer This problem is usefull for when we look at screens for the market.