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Sam Guccione wrote:
<blockquote cite="mid:NMECIJHMPCBDFBDKIPJNOEBMCEAA.gucci1@mchsi.com" type="cite">
<pre wrap="">After a long lapse I am trying to get my THD7A setup with a GPS. However,
something doesnt seem to be working. I am using a Garmin ETREX set to NMEA
output. I can see the GPS sentences when I plug it into the serial port on
my laptop. I connected the ETREX to a cable with a subminiature plug then
into the GPS jack on the THD7A. I expected to see the POS have the GPS lat
and long but all I get are all zeros. Manual does not say much of anything
about the GPS port. Anyone have suggestion on what I could try to get it
working. What am I missing? Something stupid?
Sam K3BY
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</pre>
</blockquote>
<font face="Arial"><br>
<br>
Are you using a 2 or 3 conductor cable? You need a full-three-wire
serial cable. <br>
<br>
The Etrex, like many battery-powered gadgets conserves battery power by
shutting down it's serial port when nothing is connected. (The DC-DC
power converter required to produce the negative half of a true RS-232
signal is one of largest power consumers in low-power battery
gadgets.) <br>
<br>
These devices don't power up the outgoing side of the serial port until
they see a NON-ZERO voltage coming into the receive side of their port,
indicating that the GPS has actually been connected to another device.
When the GPS is connected to a PC with a full bidirectional
three-wire cable, the quiescent state of the PC's outgoing serial port
is -8VDC which is sensed by the GPS data in. This makes the the GPS
serial TXD wake up and start talking. <br>
<br>
The TH-D7 leaves the outgoing side (TXD) of it's serial port resting at
+8VDC when it is not talking, but the GPS won't see this if you use a
simple two-wire RXD-only connection. <br>
<br>
<br>
<br>
--<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: 14400 [Think bottom of the 2M band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.com">http://wa8lmf.com</a> --OR-- <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
NEW! World Digipeater Map<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/APRSmaps">http://wa8lmf.net/APRSmaps</a><br>
<br>
JavAPRS Filter Port 14580 Guide <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs/JAVaprsFilters.htm">http://wa8lmf.net/aprs/JAVaprsFilters.htm</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/DigiPaths">http://wa8lmf.net/DigiPaths</a> <br>
<br>
Updated "Rev H" APRS <a class="moz-txt-link-freetext" href="http://wa8lmf.net/aprs">http://wa8lmf.net/aprs</a><br>
Symbols Set for UI-View, <br>
UIpoint and APRSplus:<br>
<br>
<br>
<br>
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