dbbarron

I have an XGPS160 used with HLT and TA on my iphone.
Aside from the love-hate relationship I have with its bluetooth interface, I'm trying to optimize mounting options for signal strength and accessibility. I prefer to hardwire it and have access (car is 997.2) to the lights and buttons, so that restricts things.

I have secured velcro brand fastenrs to the rear of the GPS unit and secured it near the top of the windshield where its backside has a clear view of the sky.
Thus, I can run a power wire in the headliner and I can see the lights/power button.

I was first worried about it being 'upside down'; however, I seem to get relatively the same update rate and signal strength as an on-dash mounting position.

Can anyone suggest a better mounting scheme and/or comment on the apparent upside-down sensitivity of the antenna?

db

Slakker

Theoretically the built in antenna should be directional. I would think it would need to be right side up, flat, and have a view of the horizons.

I would drive your car in a couple of circles and see how accurately it represents it. Then do the same with it flat on the dash and repeat. If you are only picking up satellites from the direction the GPS antenna is facing (think half an orange with only the peel receiving signal) this should show how this affects accuracy.

dbbarron

One would think; however, I find no material difference flat, right side up, upside down or angled. Guess I'm overthinking this.

Slakker

It all depends on the antenna it has. Radios are like light bulbs. A low or almost 0 gain antenna is like a lamp. The light is spread in all different directions except where the base is. A high gain antenna is like taking that same bulb and putting it in a flashlight that focuses it in a 2" beam at 100'. Receive antenna work the same way.

So the dual most likely has a very low gain antenna, like the lamp, and no shielding on the backside if it works upside down.

dbbarron

I did some more testing. I am assuming the antenna on the XGPS160 is low gain, omnidirectional with no ground plane as I tested positions on the ground both upside down and right side up as well as on a large metal roof of the car also right side up and upside down with no meaningful differences.

I noticed the various signal strength various a bit but in all cases, I had the following stats from HLT:
23 sats in view
15 sats tracked
Update rate 10Hz
Accuracy 7ft.

db

Slakker

Good info. I wouldn't have guessed it.