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Setting up an APRS 'dumb' (transmit only) tracker
with a PacComm TINY2 TNCThe TINY2 is a TNC2 clone. APRS software often has a preconfigured option for the TNC2 format which saves time. Unfortunately the Tiny2 broke with TNC2 compatibility when it reached ROM version 5.
If you don't need to receive APRS packets, then version 5 TINY-2 TNC has an APRS stand alone mode that provides both digipeater functions, as well as allowing your mobile station to beacon position packets.
The TINY2 doesn't need much setting up for packet generally, and once it works on packet the same settings will work on APRS.
The degree of modulation of the signal generated needs to tailored to the audio circuits of the transmitter being used.
The TINY2 manual explains how to set the do this - if you lack measuring equipment for deviation then a trick is to keep turning up the TINY2 modulation until just don't hear a further increase on a second receiver- and then back it off slightly. The audio from the TX/RX has to be fairly quiet for effective communication with the TINY2. This is a matter of trial and error as the volume control isn't usually calibrated.
| TINY2 Settings (As applied to both Mark I and Mark II - v5 firmware is available
for either) You must refer to the manual for the many and varied TINY2 settings, but some are worth mentioning here as they diverge from earlier ROM versions and TNC2 clone compatibility. MYCALLWhat suffix do you use? Fixed stations tend not to have a -number at the end, although in earlier APRS systems dumb trackers gave information about what type of icon mapping programs were to use. There are exceptions in the UK (and no real rules), but -7 tends to mean Kenwood mobile (i.e. able to receive messages) and -9 means dumb tracker. You see all sorts of suffix however, since in most cases a status text is transmitted with the postion packet.. ALIAS - The TINY2 will now support multiple aliases. This is useful - because people can either digipeat through you as RELAY or your callsign. Chosing a special name for your station doesn't do any harm, but it makes identifying you more difficult if distant people are seeing your station name in a path list. MYA RELAY is a minimum setting for APRS. If every station is a RELAY then mobiles are more likely to be able to hit the network whenever they can hear an APRS station. MY1 WIDE is only useful if you are in a good location. DIGI 7 is a powerful digipeater option that prevents your station digipeating the same packet twice (even from different Aliases) it substitutes your callsign into the packet path so folk can see the route it has taken. Which adds to interest. The TINY2 has a GPS mode - which is detailed below. The TINY2 is connected to a PC running either a terminal program, or APRS package. The mobile set-up.
In the car I ran a mobile APRS station and RELAY digipeater. This was
based around a small 5/8 whip magnetically mounted to the roof of the car, feeding an ALINCO DJ580e handheld that in turn is powered at 10v to reduce the demands on its voltage regulators (I had one blow up on me once) and runs about three watts on 144.800MHz.The Alinco took a 1.5mm two core jack microphone feed, and a 2.5mm stereo jack audio out. This feeds the TINY2 (mark II) again through a 5PIN DIN. In the car, the TINY2 settings are as above, using GPS mode. The TNC is connected via its 9PIN serial port to a GARMIN GPS12. This is a basic 12channel GPS that stores routes, tracks and waypoints and plots them on a plain LCD display. I do not connect the TNC output to the GPS as it wouldn't understand it. However, the Kenwood THD7 will communicate with a GPS and sends to the GPS the position of stations heard - so they appear on the GPS screen. (and fill up your waypoint memory!) Another thing that works well, is plugging a laptop into the TNC and running UI-VIEW on it. When you do that you cannot have the GPS connected at the same time - I only have one serial port free on the laptop. DILEMMA! What I wanted was to have the laptop connected AND have GPS data update my location? The final problem was that I liked to connect the GPS to a Psion Series 3a palmtop running mapping software so that my precise location is available on a map for my son to look at (and it works, he stopped asked 'are we there yet') To do this, I rather crudely split the GPS data and sent it to the TNC, to update the LTEXT position string, whilst also sending it to either the laptop, the Psion series 3a or indeed the Kenwood THD7. Enter the 'chewey-looking' null modem connector[top of page] . Chewy Null Modem
Click here for the chewey NULL MODEM page (use BACK to return). TINY2 GPS MODETiny2 GPS mode. The version 5 TINY2 firmware (as did version 3) supports GPS mode. The command is GPS ON This disables ordinary commands from now on, and the TNC instead scans data coming into its serial port, looking for anything that matches with the string in the memory called GPSTEXT.The default setting is for GPSTEXT $GPGGA If the NMEA format strings that the GPS produces contain this piece of text, the entire string following is copied to LTEXT and is beaconed at an interval determined by the memory called LOCation. So LOC E 30 will beacon the GPS string captured every five minutes to the path determined by LPATH. LPATH is the same as the PATH command but only applies in GPS mode. The Beacon text, and UNproto settings will continue in GPS mode- this can be used for station information, or just disabled. Where LOC works just like the Beacon command, LPATH is like UNproto, and LTEXT is like BTEXT (except the content is determined by the GPS as mentioned. Download a TXT file of my TINY2 version5 settings here.. (As an aside the PacComm200 v5 settings I notice are listed here) :http://www.theworks.com/~wa6ylb/tnc200.txt [top of page] |
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