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  Garmin GPS 72 WAAS Malfunction and Fix

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Author Topic:   Garmin GPS 72 WAAS Malfunction and Fix
AZdave posted 09-11-2008 12:35 AM ET (US)   Profile for AZdave   Send Email to AZdave  
My Garmin GPS 72 seemed to fail this summer. A few minutes after power-up it would show a vertical line on the display and ignore any input from the control buttons. It could be reset by removing the batteries, but the problem recurred. Tonight I found a troubleshooting site http://www.fixya.com/support/garmin/gps_devices. The problem appears to be caused by a conflict between the WAAS signal and Garmin software. When I disabled WAAS my problem was solved. Garmin offers downloads of software version 2.50 on their site. This is supposed to fix the problem and allow use of WAAS. I thought some of you with handhelds might have the same issue. Dave
jimh posted 09-11-2008 08:57 AM ET (US)     Profile for jimh  Send Email to jimh     
Dave--Thanks for the pointer to that resource. On older GPS receivers there seems to be some problems with WAAS that occurred after the FAA changed the constellation of satellites providing the WAAS data in July 2007.

Scroll down at this news summary page to read about it:

http://www.faa.gov/about/office_org/headquarters_offices/ato/ service_units/techops/navservices/gnss/waas/news/

This change in WAAS satellite location may be related to the problem you saw.

Anjin posted 09-11-2008 05:54 PM ET (US)     Profile for Anjin  Send Email to Anjin     
I have a GPS 72 which I carry as a backup to my console mounted GPS. I have not had to use the 72 for quite a while. After reading this post I decided to test the unit to see if it still worked. After turning it on I could not get any satellites. Then I checked to see if WAAS was enabled. It was disabled. After enabling WAAS the unit quickly acquired satellites and it seems to work fine.

This indicates that there is no conflict between WAAS signals and the Garmin software.

As I understand it the Garmin GPS 72 is not designed to allow software to be downloaded into it. correct? If not how do you download software into this unit?

AZdave posted 09-11-2008 06:26 PM ET (US)     Profile for AZdave  Send Email to AZdave     
If you go to the Garmin site, www.garmin.com and look at downloads and updates, you should find the list of Garmin GPS units and the updates for each. I am not the definitive source since I have not updated mine. It looks like you download to a PC and then connect a serial cable to the four prong connector on the GPS unit. The cable appears to be a high profit item for the manufacturer. There are cables on ebay for a lot less. Dave
Chuck Tribolet posted 09-11-2008 06:30 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Garmin has had a bunch of firmware updates for the 72.
http://www8.garmin.com/support/download_details.jsp?id=227
has info on how to install them.

IIRC, what happened was that some "satellite number" reached
a value that was bigger than the number of bits the firmware
set aside for it. It didn't have to do with relocation of
the birds, but rather a new bird broadcasting something
the firmware couldn't handle.

It's a good idea to keep your GPS receiver up to something
resembling the latest level. If you aren't a nerd like me,
don't install it the day it comes out, but do install it a
month or so later.


Chuck

jimh posted 09-11-2008 08:35 PM ET (US)     Profile for jimh  Send Email to jimh     
Orbital location change of the satellites did cause a problem for WAAS users in the northeastern United States. The WAAS birds were sometimes below the horizon or very low on the horizon for those users.

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