The APRS2SOTA User Guide

APRS2SOTA is a gateway between the Amateur Radio APRS system and SOTAwatch

The gateway accepts suitably formatted messages from pre-approved users of the APRS network and posts SOTA 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' sent to SOTA or APRS2SOTA

Information Required

Each APRS message (which must be addressed to 'SOTA' or 'APRS2SOTA') requires:

Other operating modes may be accepted by APRS2SOTA, but will be converted to one of those above (the supported modes are subject to change from time to time)

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, however 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).

Anything sent in the APRS Message that does not look like a Mode, Frequency, Callsign or Summit Reference will be treated as part of the comment sent to SotaWatch.

Messages that appear to be returns of messages sent by APRS2SOTA to users may be ignored (such messages typically start with 'Spotted:', 'Dupe:', 'Error:', 'Sorry:' or similar).

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

NA6MG-7>APU25N,TCPIP*,qAC,T2GREECE::APRS2SOTA:w6/ct-071%na6mg%7063%cw%CQ CQ{a1b

The system accepts any SSID on the originators callsign.

A few people have seen APRS 'rej' messages sent to them after sending a message to SOTA. This does NOT seem stop the messages getting to my server, these 'rej' messages are NOT being sent by the APRS2SOTA system (it never sends rej messsages), I am currently (12 June 2021) trying to ascertain the true source of these messages, using APRS2SOTA as the destination for your messages does not currently appear to be subject to this minor annoyance.

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 (except when any callsign is provided in the APRS data).

When operators are activating in another DXCC it will try to auto add a suitable DXCC Prefix (i.e. ON/G0LGS or MW/F6ENO etc) when it thinks this is necessary (unless another one is given with the APRS info).

The code for DXCC / Summit matching is complex and may not always work exactly as expected, this means spots may appear on SOTAwatch with different pre-fixes to those actually being used by an activator. (Please advise me if you notice any errors).

Note: No Assocation matching will be applied when the APRS message includes a callsign - if you want a DXCC Prefix or any Suffix, you must send the full callsign required.

Callsign Suffixes

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

If you want a spot with a /P or other suffix you MUST send the full callsign required (That is Call/Suffix or Prefix/Call/Suffix) as part of the APRS Data.

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. Note:Your email MUST be written in English, I may ignore emails that are not in English and emails where I am unable to verify the Callsign (either on QRZ or on the SOTA Reflector).

Other Commands

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

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

The - character may be used in place of / in all commands that take additional paramters

The 'spots', 'alerts', 'last' and 'mylast' commands will accept an additional param '/full' that will include any 'comment' that was posted with the related spot or alert (i.e. /spots/full/5 or /spots/5/full)

There is a 3 minute window during which the system will Silently ignore Duplicate commands (Since 09-Nov-2019)

Further commands may be possible and changes may be made to those above - this page will be updated as any changes are made.


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: 05-Feb-2022)