Which is the best OEM GPS board? USB or Serial?

**c5ho** · 02-18-2007, 06:54 PM

Hi everyone, I've been on the board for a couple of months and this is the first time I've posted. I recently started building a CarPC from an old laptop using iGuidance and a Holux GR213 USB GPS receiver.

When I was in a city (Montreal), I found the reception to be really poor so I'm thinking about going the OEM route. I've read most of the threads I could find about this topic and looked at the units on Spark Fun website here:

http://www.sparkfun.com/commerce/cat...php?cPath=4_86

Now I have a couple of questions.

Which OEM unit is currently the best/most sensitive/best value?

Are there other sources to get these than Spark Fun?

Is there a difference in terms of speed or compatibility between the USB and Serial connection units? The laptop I plan to use does not have an serial ports.

Is this the route to go if I want a better GPS?

Thanks in advance for the help!

Cheers!

**2k1Toaster** · 02-18-2007, 07:03 PM

The only thing that really makes a difference, is the chip. The SirfIII set is the best to date. It is what is used in most new systems.

It will be cheaper for you to buy one off ebay than to build one yourself.

This fall we drove from Colorado all the way to Southern Ontario. Then we drove up pretty far. My reception was 100% the entire time.

I use the cheap pharos360 unit that comes with Microsoft Streets and Trips. Very inexpensive and works great in Canada.

**MobiTekLink** · 02-19-2007, 05:28 PM

There's a few threads out there regarding that,,, I use the BU-353 serial with IG 3.
I rather have serial because the plugs make a better connection and the com port stays, as it is physical compared to virtual port in USB. USB vs Serial makes no speed difference, it all goes at 1hz anyway, IR can handle that.

**c5ho** · 02-19-2007, 06:19 PM

I think there may be a misunderstanding. I have tried two mouse type gps receivers such as the Holux GR-213 and the Pharos GPS-500 that came with MS Streets and Trips. Both give me good reception in rural areas but once I'm in more urban areas, I keep losing the satellite signal. Hence, I am planning to go the OEM GPS board route and was wondering which would be best. Any ideas?

**LagunaICE** · 02-19-2007, 07:43 PM

Again brand is not important. It will not make any difference whether you have "mouse style" GPS or OEM GPS board. Just pick any you can come by, but pick the one that is based on SirfIII, as already said. Same for the interface - USB/serial will not make difference. It really depends on what ports you have available. Still most OEM boards is serial. What can really help you in this case is good roof mounted antena with best possible signal gain.

**c5ho** · 02-19-2007, 08:33 PM

I was under the impression that OEM GPS boards by nature have better reception than a mouse style. Is this not the case? If in the case that they are equal, is there a particular reason that when in an urban area, sometimes I don't even get 3 satelites? If it IS simply because I need an external antenna, then I have to get a GPS receiver that would allow me to attach an external antenna, which it seems to me most often are the OEM boards, right?

Thanks again!

**MobiTekLink** · 02-19-2007, 10:49 PM

It's not a matter of reception, its' a matter of signals getting blocked and bounced from satellites on the buildings.
What you need is a Dead reckoning system (DR) this basically compensates the receiver by getting motion signals (speed, direction) to override bad reception.
There are a couple of forums out there, but no one has really been able to make one that is sold. I wish there was, if anyone has more info on this let me know.
Check this link,,,,
Tyco A1029A/B Update...

**c5ho** · 02-20-2007, 12:07 AM

I read on some of the other threads regarding OEM GPS systems that performed better than mouse type ones. Is that because they are equipped with DR systems?

**wi77iam** · 02-20-2007, 07:31 AM

I have one of the SirF III OEM gps modules from Sparkfun. With an external antenna mounted on my roof, I get normally 9+ satellites in all kinds of conditions - trees, buildings, etc. I don't think you can do any better than that. For your laptop, I would pick the usb one since it will get power through the usb cable. You would have to provide separate power for the serial version.

**2k1Toaster** · 02-20-2007, 10:20 AM

I always get 8 satellites even when driving through mountain passes where it is your car in a canyon. Similar to tall buildings I believe. And then you are driving between mountains on either side of you. I use a cheapo USB unit. It has the SirfIII chipset, and that is all that matters. THen if you get an external antenna, it of course will be better, but I have no need for one as of now.