[aprssig] impressions of the Garmin 276c

Wes Johnston aprs at kd4rdb.com
Thu Feb 16 12:14:29 EST 2006

I've just bought a garmin 276c for use with the D700 radio.  It has a
nice large'ish color screen... not as physically as big as my gps162
screen, but the pixel density is much higher (480px x 320px).  When
stations come in from the D700, they are plotted without having to
redraw the map like the gps162 which could take 2 or 5 seconds after
each station was plotted.  My solution with the 162 was to limit the
number of miles I would allow the d700 to monitor so that the d700
wouldn't publish stations to the GPS so often and that reduces the
frequency of the screen refreshes. 

The unit has two serial ports AND usb.  The usb is a standard mini A
type connector that is probably used on your digital camera.  I loaded
32megs of maps into a memory cart in about 60 seconds.  Although the
unit has two serial ports, only one can be in a given mode at a time. 
Both cannot be in NMEA mode at the same time.  Doing so will cause one
of them to shut off.  So running a laptop on port 2 and d700 on port 1
is out of the question.  However, you can run garmin transfer mode wth
the laptop and NMEA with the d700.  Also,  reading and writing maps over
USB does not cause the nmea output to cease on the serial port.  In the
end, you can run NMEA mode on one serial port, and garmin mode on the
other serial port OR garmin mode over the USB.  The power/data plug on
the back of the unit has in/out for two serial ports, power, alarm, and
two wires to a speaker - 9 pins in all.  Although it looks like the 4/5
pin round garmin plug we're accustomed to seeing with 4 pins around the
outside circumference, it is a little smaller and not compatible.  Last
night I made the cable supplied with the GPS into a "hydra" with power
pole, 1/8" speaker jack, and two de-9 serial ports.

The unit does point to point, turn by turn directions.  If I miss a
turn, it will recalculate a route within 10 seconds.  I have not
listened to the speech synthesizer yet. I also will test if the route
calculation (and auto recalculation) respects changes to the destination
position just like the missed turn function does.  For example, when I
am watching another station's car and plot a turn by turn route to him,
and his station's position changes will it auto recalc a new route?  The
route calc sometimes comes up with strange answers because 1)it doesn't
know about newer roads in the area, 2)it doesn't know the correct speed
limits and tends to prefer routes with faster speed limits even though a
parallel road has the same speed limit and no stop lights... but in the
end, it's all just due to the fact that maps are not up to date.

Now for the bad.  I watched kc4pl-9 drive to work this morning.  By
default, new waypoints that come in from the d700 are plotted with a
square gray dot.  I altered his icon in the GPS to be a car.  The next
position I recieved from him, the GPS created ANOTHER kc4pl-9 icon with
a car symbol, but this time with a " 1" appended to the end.  So I now
have "kc4pl-9" and kc4pl-9 1" on my screen.  Subsiquent updates to
kc4pl-9 were applied to the waypoint "kc4pl-9 1" without problem.  Now,
my other tracker kd4rdb-15 was also edited to be a car and it did the
same thing of appending the 1 on the end of the name, but this time, it
truncated the SSID, then added the " 1" to the end.... so I now have two
kd4rdb-15 trackers on my screen... kd4rdb-15 and "kd4rdb-1 1".  This
only is a problem when you alter the waypoint icon.  I'm sure some
programmer at garmin spend hours figuring out how to keep incoming
$GPWPL sentences from overwriting waypoints that had been edited by the
gps operator, but it's a PITA with the d700.  I will have to leave all
my aprs icons as the default grey square.  That is a shame because this
gps allows 64 icons in it's library of >200 to be edited and customized. 

Also, I've tricked out my 276c by customizing the startup "splash"
screen by replacing garmin's screen with the APRS globe logo.... just
neat fluff.

Another thing that dawned on me today on the way to work... the RINO
series GPS units are the only ones I know of that will keep a bread
crumb trail for moving waypoints.  Every other GPS I know of will simply
move the waypoin to a new location whereas the rino will show you a
trail....   I'll have to see if this trail feature works with all
waypoints or just those it knows as other RINO contacts.  This has the
potential to be really neat for use with the d700.


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