I have a Garmin GPSmap 172c GPS installed and connected to a Raymarine
ST4000 autopilot.

When the GPS is operating properly, it outputs a sequence of NMEA
navigational data every 2 seconds. This NMEA data is used by the
autopilot to steer a course to a waypoint. However, there is a problem
with the Garmin software in that every day at 23:59:59 GMT, it will no
longer transmit the NMEA information reliably. Sometimes the NMEA data
stops entirely and other times it becomes quite erratic and is
transmitted at 8 second, 20 second or some other random interval. When
this happens, the autopilot displays a 'No Data' warning message and
then steers the boat on the last valid course that it received. This
behaviour continues until 00:08:34 GMT at which time the GPS reverts
to the normal 2 second transmission interval.

I also have 2 Icom radios (M502 and M802), both of which are DSC
capable and have a Lat/Lon display. When they no longer receive valid
NMEA position information, the Lat/Lon display flashes, alternating
between the last valid position received and a series of question
marks. This is another indication that the GPS error is occurring.

I've been in contact with Garmin about this problem and sent them NMEA
log files that showed the error occurring. (Software is available that
will display the NMEA data in real time as it is being transmitted.)

After reviewing these log files, Garmin's Technical Support department
acknowledged that it is a problem in their software. The issue was
forwarded to their Software Engineering department in November of 2006
and I was told that a fix would be provided in 2 weeks. When the 2
weeks passed, I was informed that it would be another month and when
that passed, Garmin said that they didn't know when a fix would be
available. I'm still waiting for them to fix the problem.

When the GPS stops transmitting the NMEA navigational information, the
autopilot maintains the last heading that it received. If that heading
happens to be for example, a 30 degree course correction, then the
vessel will be steered off course by 30 degrees until it starts
receiving valid NMEA data again. I think that this represents a
significant hazard and so I cannot rely on the GPS to maintain an
accurate course.

I have notified the U.S. Coast Guard and submitted a 'Consumer Safety
Defect Report' to them. I don't know if they will pursue a recall or
just some kind of advisory but this issue needs to be resolved one way
or another.

The Garmin GPSmap 172c is running the latest firmware version which is
2.60, dated May 9, 2006. On the Garmin download site, the firmware for
the GPSmap 172, GPSmap 178 and GPSmap 178c also have that same date
for their latest updates. I'm trying to find out if this error also
affects these units.

Is anyone else using any of these Garmin GPS units and if you are, do
you get intermittent navigational errors with them?

Very good report, it is a very danger problem because here almost all
sailors is using the autopilots interfaced with garmin Gps. I have
some friends that have reported very similar problems with the GpsMap
276C, maybe could be the same problem. I will ask them to make tests
at that time... If I found something I will report here. I will make
myself this test maybe next week, since it demands the test in the
boat at that time.

Thanks

Pascal



On 11 fev, 13:34, wrote:
I have a Garmin GPSmap 172c GPS installed and connected to a Raymarine
ST4000 autopilot.

When the GPS is operating properly, it outputs a sequence of NMEA
navigational data every 2 seconds. This NMEA data is used by the
autopilot to steer a course to a waypoint. However, there is a problem
with the Garmin software in that every day at 23:59:59 GMT, it will no
longer transmit the NMEA information reliably. Sometimes the NMEA data
stops entirely and other times it becomes quite erratic and is
transmitted at 8 second, 20 second or some other random interval. When
this happens, the autopilot displays a 'No Data' warning message and
then steers the boat on the last valid course that it received. This
behaviour continues until 00:08:34 GMT at which time the GPS reverts
to the normal 2 second transmission interval.

I also have 2 Icom radios (M502 and M802), both of which are DSC
capable and have a Lat/Lon display. When they no longer receive valid
NMEA position information, the Lat/Lon display flashes, alternating
between the last valid position received and a series of question
marks. This is another indication that the GPS error is occurring.

I've been in contact with Garmin about this problem and sent them NMEA
log files that showed the error occurring. (Software is available that
will display the NMEA data in real time as it is being transmitted.)

After reviewing these log files, Garmin's Technical Support department
acknowledged that it is a problem in their software. The issue was
forwarded to their Software Engineering department in November of 2006
and I was told that a fix would be provided in 2 weeks. When the 2
weeks passed, I was informed that it would be another month and when
that passed, Garmin said that they didn't know when a fix would be
available. I'm still waiting for them to fix the problem.

When the GPS stops transmitting the NMEA navigational information, the
autopilot maintains the last heading that it received. If that heading
happens to be for example, a 30 degree course correction, then the
vessel will be steered off course by 30 degrees until it starts
receiving valid NMEA data again. I think that this represents a
significant hazard and so I cannot rely on the GPS to maintain an
accurate course.

I have notified the U.S. Coast Guard and submitted a 'Consumer Safety
Defect Report' to them. I don't know if they will pursue a recall or
just some kind of advisory but this issue needs to be resolved one way
or another.

The Garmin GPSmap 172c is running the latest firmware version which is
2.60, dated May 9, 2006. On the Garmin download site, the firmware for
the GPSmap 172, GPSmap 178 and GPSmap 178c also have that same date
for their latest updates. I'm trying to find out if this error also
affects these units.

Is anyone else using any of these Garmin GPS units and if you are, do
you get intermittent navigational errors with them?

Sorry, I forget to ask: you have noted if the problem is only with not
sending the NMEA messages or the gps is not geting position fix or
satellites as well?

That is, this could be a software problem only, if it is restricted to
the NMEA. But in case it is not geting gps signals or position fix at
that time only, could be that the DoD is making "deny of signal
tests" in this location at that time?

Thanks

Pascal






I have a Garmin GPSmap 172c GPS installed and connected to a Raymarine
ST4000 autopilot.

When the GPS is operating properly, it outputs a sequence of NMEA
navigational data every 2 seconds. This NMEA data is used by the
autopilot to steer a course to a waypoint. However, there is a problem
with the Garmin software in that every day at 23:59:59 GMT, it will no
longer transmit the NMEA information reliably. Sometimes the NMEA data
stops entirely and other times it becomes quite erratic and is
transmitted at 8 second, 20 second or some other random interval. When
this happens, the autopilot displays a 'No Data' warning message and
then steers the boat on the last valid course that it received. This
behaviour continues until 00:08:34 GMT at which time the GPS reverts
to the normal 2 second transmission interval.

I also have 2 Icom radios (M502 and M802), both of which are DSC
capable and have a Lat/Lon display. When they no longer receive valid
NMEA position information, the Lat/Lon display flashes, alternating
between the last valid position received and a series of question
marks. This is another indication that the GPS error is occurring.

I've been in contact with Garmin about this problem and sent them NMEA
log files that showed the error occurring. (Software is available that
will display the NMEA data in real time as it is being transmitted.)

After reviewing these log files, Garmin's Technical Support department
acknowledged that it is a problem in their software. The issue was
forwarded to their Software Engineering department in November of 2006
and I was told that a fix would be provided in 2 weeks. When the 2
weeks passed, I was informed that it would be another month and when
that passed, Garmin said that they didn't know when a fix would be
available. I'm still waiting for them to fix the problem.

When the GPS stops transmitting the NMEA navigational information, the
autopilot maintains the last heading that it received. If that heading
happens to be for example, a 30 degree course correction, then the
vessel will be steered off course by 30 degrees until it starts
receiving valid NMEA data again. I think that this represents a
significant hazard and so I cannot rely on the GPS to maintain an
accurate course.

I have notified the U.S. Coast Guard and submitted a 'Consumer Safety
Defect Report' to them. I don't know if they will pursue a recall or
just some kind of advisory but this issue needs to be resolved one way
or another.

The Garmin GPSmap 172c is running the latest firmware version which is
2.60, dated May 9, 2006. On the Garmin download site, the firmware for
the GPSmap 172, GPSmap 178 and GPSmap 178c also have that same date
for their latest updates. I'm trying to find out if this error also
affects these units.

Is anyone else using any of these Garmin GPS units and if you are, do
you get intermittent navigational errors with them?- Ocultar texto entre aspas -

- Mostrar texto entre aspas -

I also have a Garmin GPS76 handheld unit on board. The last time that
the errror occurred with the Garmin 172c driving the autopilot, I
turned on the handheld unit and it did not have a problem acquiring
the GPS signal. The GPS76 would accurately show my position and
course at the same time as the Garmin 172c was having a problem. This
would indicate that there is no problem with the satellite signal.

In the Garmin 172c, when the error starts to occur, the following two
NMEA sentences are transmitted:

$GPRMC,235959,V,,,,,,,,,,N
$GPRMB,V,,,,,,,,,,,,,N

The first field of the $GPRMC sentence contains the time and the
second field is a 'V'. The 'V' indicates a navigational receiver
warning and none of the following fields exist except for the 'N' at
the end. This 'N' means that the data is not valid.

In the $GPRMB sentence, the same indication occurs.

If you are using a Mac computer, download A HREF="http://
www.gpsnavx.com/downloads/GPSUtility.dmg"GPSUtility/A to display
the NMEA information.

On 11 Feb 2007 08:34:03 -0800, wrote:

I have a Garmin GPSmap 172c GPS installed and connected to a Raymarine
ST4000 autopilot.

When the GPS is operating properly, it outputs a sequence of NMEA
navigational data every 2 seconds. This NMEA data is used by the
autopilot to steer a course to a waypoint. However, there is a problem
with the Garmin software in that every day at 23:59:59 GMT, it will no
longer transmit the NMEA information reliably. Sometimes the NMEA data
stops entirely and other times it becomes quite erratic and is
transmitted at 8 second, 20 second or some other random interval. When
this happens, the autopilot displays a 'No Data' warning message and
then steers the boat on the last valid course that it received. This
behaviour continues until 00:08:34 GMT at which time the GPS reverts
to the normal 2 second transmission interval.

Do you have WAAS corrections enabled? If so, you might try turning
WAAS off to see if that affects the problem.

Here, the WAAS satellites are very low on the horizon, and when they
hide behind a hill, my GPSMap/Sounder 168 spends so much time and
effort trying to get the WAAS correction data that it ignores, and
therefore "buggers up" the NMEA data output. For me, this problem
depends on my location, and it is hard to explain how time-of-day
could affect WAAS reception, but it may be possible.



--
Peter Bennett, VE7CEI Vancouver BC, Canada
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

It's not due to WAAS because the error occurs both when WAAS is on and
when WAAS is off.

During normal operation, NMEA transmissions occur every 2 seconds.
For those who are familiar with software programming, the interesting
thing is that the error begins at 23:59:59 GMT and normal
transmissions resume at 00:08:34. The time interval of 8 minutes and
32 seconds just happens to be 512 seconds.

Garmin has already acknowledged that it is a software problem in their
product. What we don't know is how many other Garmin GPS models have
this problem. Considering the amount of time that Garmin has taken
thus far and no fix has been posted, the error may be quite widespread
in their product line. They have a new series of Marine GPS units
that are coming out soon and maybe they are quite concerned if this
defect affects those as well.

I agree with this. I am worrying if the problem is shown in the
Map276C. Some of the new "land" units have SIRF gps engines, in place
of our traditional "legacy gps Garmin receivers", and could not have
the problem. If the problem is with the legacy gps software, it
could affect many (if not all) marine models like mine 276C.

Sounds to me like the problem is in the "back end" of the software, and
would be independent of the "front end" (ie, which receiver).


"Pascal" wrote in message oups.com...

I agree with this. I am worrying if the problem is shown in the
Map276C. Some of the new "land" units have SIRF gps engines, in place
of our traditional "legacy gps Garmin receivers", and could not have
the problem. If the problem is with the legacy gps software, it
could affect many (if not all) marine models like mine 276C.

I Chuck

I understand that you are saying that the problem is with the
"application software" and not with the firmware of the gps engine" ?
In this case, the problem could be restricted to the 172C and not
spread to others models using the same "legacy engine"?

Thanks

Pascal





On 15 fev, 17:57, "Chuck Tribolet" wrote:
Sounds to me like the problem is in the "back end" of the software, and
would be independent of the "front end" (ie, which receiver).

Ok, I have just made a test with my 276C for about 10 minutes in the
time interval of 23:56 - 00:04 GMT (-3 here) and it do not showed any
problem with the position or satellites. I could not make the NMEA
test because my serial cable is hardwired in the boat, pheraps I can
do it this weekend.




n 15 fev, 20:38, "Pascal" wrote:
I Chuck

I understand that you are saying that the problem is with the
"application software" and not with the firmware of the gps engine" ?
In this case, the problem could be restricted to the 172C and not
spread to others models using the same "legacy engine"?

Thanks

Pascal

On 15 fev, 17:57, "Chuck Tribolet" wrote:



Sounds to me like the problem is in the "back end" of the software, and
would be independent of the "front end" (ie, which receiver).- Ocultar texto entre aspas -

- Mostrar texto entre aspas -