What antenna are you using?  Is your GPS signal coming through the AHRS?

Steve


-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Jeffrey Liegner, MD
Sent: Thursday, May 17, 2007 1:02 PM
To: lml@lancaironline.net
Subject: [LML] Periodic Chelton GPS Failure...Any Ideas?

Here's another Chelton item.

I'll be flying along and will get a "GPS Failure" announcement with loss of
terrain info, plus DR (dead reakoning) counter.  After 1 or 2 minues, the
HITS boxes leave (as expected).  Then in three to five minutes the GPS
signal is restored, and all is well.  In my recent
3.5 hour flight to/from St Louis, it dropped out three times each way.

So I have looked at the antenna mounted under the top of the dash, just
behind the panel, and it is secure and powered correctly.  I have checked
the wiring to the Chelton and all is secure and fine.

The "GPS Failure" can occur whether the dashboard is installed or the GPS
antenna is uncovered, meaning the particle board vinyl is not the
obstruction.

I wonder if the location, behind the top part of the panel, with what seems
like an excellent view of the sky, gets blanked out by the roof edge of the
large front windscreen, reducing the satellites by a couple.  Is there a way
to check the satellites seen by the antenna?

The GX-60 antenna located near by, equally behind the panel looking up
through the same windscreen, does not drop out like this.

It's been doing this off/on since the beginning.  At first I thought I
didn't think too much about it, and then I started to rely on it more and
more, and now I learn from others that this is not a problem with other
installations.

Your ideas?

Jeff Liegner
LIVP (N334P)

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