What is APRS2SOTA and how do I use it?

APRS2SOTA is a gateway between the APRS system and SOTA (SOTAwatch)

The gateway accepts suitably formatted messages from approved users of the APRS network and posts Spots on the SOTAwatch system.

The APRS2SOTA gateway accepts only messages as detailed in the APRS Protocol Specification (V1.0.1 Chap 14) 'MESSAGES BULLETINS AND ANNOUNCEMENTS'.

Information Required

Each APRS message requires:

Optional Information

APRS messages may also contain:

The system is not case sensitive so you may use mixed case for any of the parameters.

The preferred order of parameters is:

<Ass/Ref> <Freq> <Mode> [callsign] [comment]

However the following are also valid:

<Ass/Ref> <callsign> <Freq> <Mode> [comment]
<callsign> <Mode> <Freq> <Ass/Ref> [comment]
<Mode> <Freq> <callsign> <Ass/Ref> [comment]

As can be seen above, whilst the system will accept most parameters in any sequence any optional callsign should be given before any comment.

The 'comment' should NOT contain something that looks like another callsign with a prefix or suffix (as the wrong callsign may be spotted).

Any characters defined as 'separating' paramaters (below) that are contained in the comment may be replaced by spaces during processing.

When given the units for a frequency MUST be included without any spaces or other characters (i.e: 7031.2k, 10111.5kz, 144.320mh, 10368.120MHz etc).

Separating Parameters

Parameters may be separated by any of the following:

'   "   `   ^   #   @   %   ,   :   ;   <   >   |   (or a space)


An example APRS message when sent over AX25 may look like:

G0LGS-2>APRS,WIDE2-1*::SOTA     :ON/ON-010 144.320 SSB ON/G0LGS/P Calling now{003


G0LGS-9>APRS,WIDE2-1*::APRS2SOTA:G/CE-001;144.320;SSB Need 2 more{0A3

(i.e. a message sent to 'SOTA' or 'APRS2SOTA').

The system accepts any SSID on the originators callsign.

The system does NOT accept APRS 'position comments' , 'location' reports or simple AX25 Beacons.

How to send a suitable message

Details on how to send a APRS message vary a little between radio's, a search on YouTube or Google (i.e. 'aprs vx-8r message') should find examples for your radio - just remember that the destination for your message is 'SOTA' or 'APRS2SOTA' (no SSID is required - set the SSID to 0 if your radio requires one).

Prefix, Callsign and Association matching

The APRS2SOTA system accepts UK calls with any regional variation (G,GW,GM; M,MU,MW; 2E,2W,2M etc) and handles putting in the correct regional callsign variation to match the given Summit reference.

The system originally added /P to all callsigns (unless some other suffix was given) however this feature has been disabled (following user requests).

For non-UK operators in the UK and any operators in another Country it will try to add the Country Prefix (i.e. ON/G0LGS or MW/F6ENO etc) when necessary (unless another one is given with the APRS info).

The code for callsign/summit matching is complex and may not always work exactly as users expect, this means spots may appear on SOTAwatch with different pre-fixes to those actually being used by an activator (work on this part of the gateway code is ongoing as anomalies arise and are notified to me).

Spot de-duplication.

The gateway should not re-post an identical spot if received within 10 minutes of the previous spot.

APRS Ack's and Gateway Messages

The gateway will attempt to send APRS Ack's and attempt to respond via APRS with information informing the APRS user of successful, failed, duplicate spots etc.

Access to the APRS2SOTA Gateway

If you would like to use the APRS2SOTA gateway then contact me via email so that I can add you to the list of authorised users - I will need your Name and Callsign - You will get an email back when I have processed your request.

Other Commands

The following commands may be useful (when a bi-directional i-Gate is available):

The ? character may also be used in place of / at the start of the above commands

Further commands may be possible and changes may be made to those above


Filtering of certain callsigns

I have been requested by the SOTA Management Team to prevent spots using certain callsigns from being posted on SOTAwatch, so in accordance with their wishes the system will NOT permit certain callsigns to post spots (or have spots posted for them) - you may get an error message if you attempt to post a spot for any such blocked callsign.

Stewart Wilkinson G0LGS
(Last update: 07-Sep-2019)