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650XI takes long to get a lock on position

Bavafa

Well Known Member
My brand new 650XI boots up super fast but it takes way longer to get a lock on GPS position, something between 2-4 minutes. I am being told that this is normal and I was wondering if this is your experience as well.
My last 650 would pick up GPS position nearly instantly so this would be a step in a wrong direction unless it is for specific reason.
 
Yup - sounds about right.

It takes even longer if the almanac is 30+ days old...

Once it does get a lock, how do all the signal strengths look? how many satellites are in view? There should be a minimum of 8 in view at all times...(31 total satellites, 6 orbits, 4+ satellites per orbit...)
 

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Not arguing with the experience of others - if that is what it takes, that is what it takes. But that sounds really long for modern equipment. I have a Garmin Fenix watch that gets a 3D fix in 10-20 seconds. My 12 year old car gets a GPS fix usually in under 10 seconds. 4 minutes for a very modern system really seems like it takes some extra time.
 
Here's an article that explains the reasons TTFF takes time (pun intended)...

https://en.wikipedia.org/wiki/Time_to_first_fix

In a nutshell, the older the almanac the longer the receiver takes to guess where it is...

Your Fenix watch always has a recent time reference, so does your 12 year old car. Take the battery out of both and let them sit for a couple of days, then see how long it takes.
 
I struggled with this issue for a long time with both a Garmin GTN650 and GTN650Xi. I finally discovered that the GPS antenna (non-Garmin, small 1" square) on the G5 was interfering with the WAAS GPS antenna for the GTN. The G5 was on the dash, and the WAAS was behind the slider canopy (5'ish?). I replaced the G5 antenna (non-Garmin) with a Garmin antenna and problem was solved. Lesson learned was that the WAAS antenna is susceptible to interference. It was surprising.

Place the aircraft outside with plenty of sky. Boot up your GTN and go the the systems display that shows the satellite signals. Make sure the canopy skirt is not covering the WAAS antenna. Then, pull the CB or turn off everything else. EVERYTHING! If you get a 3D location quickly (less than 2 minutes), it's a good indication you have another component interfering with the WAAS. Turn on your electronics one at a time and closely watch your satellite signals. When you see signal degradation, you have found your problem.

That all said, I also had a problem with a unit and Garmin had to replace it under warranty. I discovered this by taking it to an avionics shop and having them perform a bench check.

$
 
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