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<a class="moz-txt-link-abbreviated" href="mailto:swdrumm@gmail.com">swdrumm@gmail.com</a> wrote:
<blockquote cite="mid2cb253d40703041521m2be983f0x7591d06856928446@mail.gmail.com" type="cite">I need some advice on building a multi-mode APRS tracker.
<br>
<br>
The attached schematic illustrates what I'm trying to do.
In case the list manager strips attachments, it shows that I want to
build a beacon-style tracker that will
simultaneously feed the GPS position and APRS network traffic to a
laptop PC. The GPS data would be used for onboard vehicle navigation
and the APRS feed is to monitor the location of other stations. <br>
<br>
I'm using a dedicated radio (Yaesu FT-1500) for this
purpose. The FT-1500 has a 6-pin DIN port on the back specifically for
TNC communications.
<br>
<br>
My original design concept was to attach a Byonics <a href="http://www.byonics.com/tinytrak/tt3plus.php" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">TinyTrak3+</a>
to the microphone connector of the radio for the beacon. An RS-232 <a href="http://www.sfcable.com/store/d920-yy.html" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
splitter</a> would send the <a href="http://www.deluoelectronics.com/customer/product.php?productid=99" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">GPS</a>
data to the TinyTrak and to the laptop simultaneously. An Elcom USB <a href="http://www.elcom.gr/" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">MicroTNT</a> in
KISS / listen mode attached to the radio's data port would send all of
the APRS data to the laptop. Will this work?<br>
<br>
Alternatively, I just read a writeup about the <a href="http://www.paccomm.com/" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
PacComm</a> dual-port PicoPacket...<span style="font-weight: bold;"></span><br>
<br>
</blockquote>
<br>
<br>
1) DON'T put up line art (like your schematic) as JPGs!! JPG is
only intended for continuous-tone images; i.e. photos. It applies image
compression by looking for gradual gradients of brightness and color
from groups of adjacent pixels. When applied line art images like your
block diagram that jump from 100% white to 100% black in a single
pixel, you get the kind of squirmy, fuzzy compression artifacts that
are showing in your diagram. For any kind of non-continuous-tone
images such as maps, schematic diagrams, architectural diagrams, line
art, etc, that use a limited palette of colors, the proper
web-friendly formats are either GIF or PNG. <br>
<br>
<br>
2) What you are striving for is not a "multimode tracker" but a
full-function APRS station that happens to be mobile. The
commonly-accepted usage of the term "Tracker" is for a dumb (or should
I actually say deaf") transmit-only mobile that spews out posits
periodically and can't receive anything.<br>
<br>
<br>
<br>
3) The "GPS splitter" linked in your original post is nothing
really. It's just three DB-9/DE-9 series connectors wired in
parallel. There are no active electronics inside. The critical issue
is whether only ONE of the connectors has it's TX data line
connected. Since RS-232 outputs are low impedance and RS-232 inputs
are relatively high impedance, it is no problem to have one output
(the GPS) feeding two or more inputs (the Tiny Track and a PC) in
parallel. You just don't want twoRS-232 OUTPUTs wired in parallel.<br>
<br>
<br>
<br>
4) By far the simplest and tidiest way to do this is with a Kenwood
D700 or TH-D7 which will do all of this automatically. You connect the
GPS receiver to a dedicated GPS port on the Kenwood and then connect
the radio's main serial port to the PC. When these radios are
operated in standalone (i.e. without a PC) "APRS" mode, they send
posits from the GPS , and SEND and RECEIVE data (messages, bulletins,
posits) and display them on it's control head screen. <br>
<br>
When the Kenwoods are placed in "TNC" mode, they automatically forward
GPS data from the dedicated GPS port out the main serial port, along
with off-air receive data from the TNC. APRS-specific programs on
the PC like UIview, APRSplus or APRSpoint generate maps showing both
other stations posits from off-air reception, and your OWN position
from your local GPS. Additionally, UIview can optionally forward
the received GPS data out a virtual (simulated) 2nd serial port for use
by an external "civilian" mapping program like Streets & Trips or
Delorme Street Atlas at the same time!<br>
<br>
<br>
<br>
3) Either the PacCom or a Kantronics KPC3+ can create the same effect
for a non-Kenwood radio, i.e. the GPS pass-through function that can
share a single serial port connection to the PC for both TNC RX and GPS
data, or act as a standalone dumb tracker. (Both devices have the
dedicated GPS port with pass-though to the main serial port.) In
standalone mode, they are really dumb in that they transmit raw
uncompressed NMEA strings as they come out out of the GPS, instead of
the highly compressed Mic-E packets of the Kenwoods. (The
100-character-plus raw NMEA strings take much more air time to
transmit, and are significantly less likely to be received successfully
than the much shorter compressed Mic-E packets.)<br>
<br>
The Elcom MicroTNC plug can also do this. The difference is that while
it accepts a serial GPS connection like the others, the main connection
to the PC is via USB. This is an advantage on today's "legacy-free"
laptops that lack serial ports (saves you having to screw around with
USB-to-serial cable "dongles"). It also reduces the mobile
installation power cable rat's nest since the USB TNC can draw it's
operating power from the laptop it is plugged into instead of needing a
separate DC connection or wall wart.<br>
<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! TNC Test CD<br>
<a class="moz-txt-link-freetext" href="http://wa8lmf.net/TNCtest">http://wa8lmf.net/TNCtest</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 G" 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>
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