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Re: [Raspberry_Pi_4-Ham_RADIO] APRS and the Pi

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  • Ray Wells
    Kristoff, I used the beacon command extensively back when I ran a multi-port node and BBS and I ve now managed to get old enough to have forgotten about it
    Message 1 of 27 , Jul 19, 2013
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      Kristoff,

      I used the beacon command extensively back when I ran a multi-port node and BBS and I've now managed to get old enough to have forgotten about it <grin>

      Ray vk2tv

      On 20/07/13 06:07, Kristoff Bonne wrote:
       

      Hi Ray, Marco, Erik,


      Actually, I have been experimenting with this yesterday-evening (but it was already past midnight, to late to still post a follow up on this message).

      It actually turns out there trick to do this using one of the basic tools of the ax25-tools package: beacon.

      As the name implies, it's a tool to broadcast AX.25 "beacon" messages, but it turns out that these are nothing else then just regular "UI" AX.25 packets; which is exactly the same as used by APRS.

      This is the CLI command to do this:
      beacon -c ON1ARF -d 'APZ001 via WIDE1-1' -l -s aprs ";ON4OS    *182215z5117.04N/00253.53E-UBA-OST vrijdag 20-24u, zondag 10-12u"

      -c = source call, -d = destination call
      -l = only transmit one single "beacon" message
      -s = ax.25 port (as found in /etc/ax25/axports)

      This works together with the soundmodem and kissattach. The hardware is a simple audio-dongle, 2 caps to provide some kind of seperation and a FM trx in VOX mode.

      I'm currently testing this on my pandaboard but I see no reason that it should not run in a pi too.





      73
      kristoff - ON1ARF



      On 18-07-13 22:58, Kristoff Bonne wrote:
       

      Hi,



      On 15-07-13 23:55, kb9mwr wrote:
       

      A software approach to DTMF decoding could be done with a the multimon-ng software package.


      Actually, I have been looking for a quick and easy way to generate APRS message. I use APRS via the internet to "broadcast" some information about events in out local radio-club (ON4OS).

      However, it would be nice (and more "ham" like) to actually broadcast this via a radio. As I am pretty close to the local APRS digipeater, I guess all that is needed is a device that generates a AFSK stream, one of these cheap chinese HTs and a a little bit of interfacing.


      I know that using a pi for this is probably really "overkill" and that this can probably also be done using an arduino (a nice exercise in DDS :-)) but a unix device would be a nice "quick hack" to get something in the air.


      I know there are programs like xastir, aprsd and othters, but I am looking for something to just generate a APRS packet and pipe it out to the audio-port.


      73
      kristoff - ON1ARF



    • Ray Wells
      Kristoff, There s some great command line tools (sed, head, tail, etc) available to extract just the information fields you need from those beacons and pipe
      Message 2 of 27 , Jul 19, 2013
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        Kristoff,

        There's some great command line tools (sed, head, tail, etc) available to extract just the information fields you need from those beacons and pipe the result through festival.

        Your project has given me an idea. I have a script that's a combination of shell commands and Perl that downloads the html weather page from the local airport as a text file, with lynx. I then use egrep, head, sed and cut to extract the fields I want from the first line (latest data) of wx data. Perl handles the mathematics to convert metric data to the aprs format. The various data is then assembled into an aprs wx beacon format for sending to xastir or dixprs for broadcast. Some of that data would be suitable for broadcasting on a voice channel, along the lines you mention. Mmmm, just what I need, another project <grin>

        Ray vk2tv



        On 20/07/13 06:31, Kristoff Bonne wrote:
         

        Hi Ray,



        What I had in mind was to generate APRS messages using some tool; but your message did get me thinking. As you mention festival (a text-to-speech tool), why not use a Pi to create a sort of bridge between APRS and normal FM radio?


        Using a radio (or the 20 dollar "RTL" DAB/DVB-T stick) we can monitor the local APRS frequencies and decode it with multimon-ng.


        Then, use certain information as received in APRS to trigger the broadcast of a spoken message in FM (on a local FM frequency or on the local repeater).

        A possible application would be to monitor the information from a local WX-station and send out a "warning: low-temperature alert, possible ice on roads" warning if needed.

        Another idea is something I noticed yesterday when looking at the log-files of all APRS messages I received:
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 00:44:48
        DX de    ON0ABT>430512.5  ON0BT-10     110 dg frm    ON0ABT            81km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 01:04:48
        DX de    ON0ABT>430512.5  ON0BT-10     110 dg frm    ON0ABT            81km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 01:24:48
        DX de    ON0ABT>430512.5  ON0BT-10     110 dg frm    ON0ABT            81km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 01:27:11
        DX de    ON0ABT>430512.5  PI1RWK       033 dg frm    ON0ABT           123km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 01:47:17
        DX de    ON0ABT>430512.5  PI1RWK       033 dg frm    ON0ABT           123km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 02:27:15
        DX de    ON0ABT>430512.5  PI1RWK       033 dg frm    ON0ABT           123km
        aprs: fm ON0ABT to DX via WIDE2-2 ctl UIv pid=F0(Text) len 76 02:39:08
        
        

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