GPS Receiever Placement. Calibrate for accuracy?

**ppgt94** · 09-20-2004, 03:20 PM

I used to have my GPS receiver (BU-303) placed under my front windsheild glass on the dashboard. I recently found out that I get a better signal if I have it placed on the rear deck. The receiever is now at almost the rear end of the car.

Is there a way I can calibrate the placement? Since the GPS receiver is at the rear of the car isn't it now off? I feel like it about 3 meters behind where the actual front of the car is. Is there some setting I can change to displace the tracking a few feet foward with out actually physcially moving the device?

**crosseye** · 09-20-2004, 03:44 PM

My GPS receiver is located in the same place. I am not really bothered by any variation in my actual location as opposed to my location on the map.

I don't think many of the commercial GPS receivers are accurate much lower than a couple meters anyway. The distance from the front windsheild to your back window can't be any more than 2 meters or so. To me, being off by a couple meters is insignificant seeing as vehicles are roughly 4/5 meters in length.

If anything, I'd look in your software preferences or configuration to see if there is a way to adjust an offset. Chances are, there is not a capability for this because you want to adjust the position of the GPS receiver in reference to your car which can point in any direction.

**ppgt94** · 09-20-2004, 07:44 PM

Thanks for your reply Crosseye. I know GPS is not dead-on accurate. I just rather be ahead than behind if I'm going to be off. In the city where it's litterary "turn-by-turn" it's usually saying to "turn" while I'm actually in the turn already. I know I'm just being anal now. Oh well.

**Chairboy** · 09-20-2004, 07:48 PM

Don't count on your GPS being more then 30 feet accurate, so moving it 5 feet will not have a measurable effect on your accuracy. At the speeds a car moves (at 30mph you're going 44 feet per second) it's just not enough of a difference to be noticeable.

**HummDinger** · 09-20-2004, 09:46 PM

The BU-303 is DGPs Compliant which gives it an accuracy of 1-5 meters in good conditions. In other words with 4 or more sats. Easily obtainable. So you can count on accuracy of at least 15 feet aprox. If I was you and you noticed that much of a difference why not move it back and just place it on top of your dash, or on the roof. I recently am considering this with my install. It will give you even better accuracy for it will have a better veiw to the sky and more sats. Place similarily to a XM sat antenna. Run the cord along the inside of the weather stripping of your cars windshield and back in through the fire wall. Use the Magnetic mount on the BU-303 for mounting and if you dont like it, no holes drilled so just move it.
ANyway just one of my recent ideas for the same dilema I have.

**ppgt94** · 09-20-2004, 10:24 PM

I'm now thinking about mounting it inside, under the plastic front bumper.

**DriverDan** · 09-20-2004, 10:28 PM

Originally Posted by ppgt94

Thanks for your reply Crosseye. I know GPS is not dead-on accurate. I just rather be ahead than behind if I'm going to be off. In the city where it's litterary "turn-by-turn" it's usually saying to "turn" while I'm actually in the turn already. I know I'm just being anal now. Oh well.

What software are you using? You should be able to setup the turn warning to display earlier if it's taking too long. The position of the GPS should have no effect.