IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - How long for satellite acquisition?

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How long for satellite acquisition?

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=595
Printed Date: 17 May 2024 at 11:59pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: How long for satellite acquisition?

Posted By: marktrav
Subject: How long for satellite acquisition?
Date Posted: 09 Mar 2015 at 10:02am

I've been giving my 540 a good work out. I've even logged an ILS to 700ft in actual conditions! (Love the audible chime at the FAF!)

So, how long should it take to acquire position after initial startup? It seems to take a LONG time. I'm going to guess it's a little over 60 seconds. I'll remember to time it the next time I'm at the plane.

I know 60 seconds sounds like a short amount of time, but my 430 (non-w) was usually locked pretty quickly. I also can't turn on SV to the Aspen until I get lock, so I'm kind of stuck outside of the hangar waiting for everything to "boot up" for a couple of minutes after I switch on the avionics.

I'm running 10.0.3.

Thanks!

Mark

Replies:

Posted By: MysticCobra
Date Posted: 09 Mar 2015 at 12:10pm

I'm having fun with mine, too--shot an ILS to 350' over the weekend, a new personal record.

My 540 acquires GPS lock almost immediately at startup. The only times I've had GPS lock loss is with the known issue with the initial software release where it can spontaneously lose lock for minutes at a time.

Posted By: AviJake
Date Posted: 09 Mar 2015 at 1:57pm

10.0.3.0 does take a little bit longer (~ 20 seconds) to get position which means the expected time to lock is 60-80 seconds from power on. A lot of older receivers take a long time to get position if they don't have the almanac, but our acquisition time is about the same with or without the almanac.

There is a known issue where the GPS can get locked up on some power cycles in some units. We have a software solution for this coming in Release 10.1.0.0. That would cause a longer acquisition time to include no lock and is only experienced at power up - once lock is achieved, that issue in a non-issue for the rest of the power cycle. If it is experienced, it is resolved by a power cycle during ground ops.

The EGNOS satellites (120 & 126) are expected to be hollow bars. We can use the corrections data from them, but we can't use the range measurement in the solution.

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Steve Jacobson
sjacobson@avidyne.com