APRS2SOTA User Guide

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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.

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, the SOTA Reflector or some other web resource).

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 '-' and '?' characters may be used in place of / in all commands that take additional parameters

The parameter '/full' will show any 'comment' that was posted with the related spot or alert (i.e. /spots/full/5 or /spots/5/full)

The parameter '/ref' will show Summit details (Summit Name, Height and Points) for the related spot or alert (i.e. /spots/ref/5 or /alerts/5/ref) (Since: 22 Oct 2022)

The parameter '/name' for the spot command adds the Acitivators Name (if found in SotaAPI data) (Since: 27 Nov 2022)

The parameter '/by' for the spot command shows the Spotters Callsign (or System Name) (Since: 27 Nov 2022)

The parameter '/[band]' for the spot command allows you to filter spots by band, any one of '160m,80m,60m,40m,30m,20m,17m,15m,12m,10m,6m,4m,2m,70cm,23cm,hf,vhf' are permitted (i.e. /spots/10m or /spots/vhf etc) (Since: 25 Nov 2022)

The parameter '/[mode]' for the spot command allows you to filter spots by mode, any one of 'am,cw,data,dv,fm,ssb' (i.e. /spots/full/5/cw or /spots/5/cw/ref etc) (Since: 25 Nov 2022)

You can use any/all of the options shown for each command above in any order (i.e. /spots/5/name/ref/full/10m/ssb/by or /alerts/5/ref/full)

There is a 3 minute window during which the system will silently ignore duplicate commands.

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


Filtering/Blocking 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 disallowed callsign.

Access Limits

There is a limit to how many requests can be made to the server (currently 5 in any 5 minute period), this has been introduced to prevent flooding of the APRS radio network (which as far as I know has occured on just one occassion in April 2024), the server will simply ignore (apart from sending any requested Ack) any message or request it recieves from the same callign for a further 5 minutes.

Stewart Wilkinson G0LGS
(Last update: Sun 19th May 2024)