“Amateur Radio Spotting Systems” was the title of MM0FMF Andy Sinclair’s Presidential Address to the LRS on 14th November 2012. This is a summary of his talk which included systems used in his favourite operating activity – SOTA - Summits On The Air.

Andy Sinclair MM0FMF giving his LRS Presidential Address 2012

Since the first DX station was worked, amateurs have been advising each other where there is DX on the air. Eventually this developed into formal “spotting“ systems. The first was the “Packet Cluster” using digital packet technology on the 2m band. Among its advantages was the ability to filter the spots by band, mode etc, but its disadvantages included end user delivery, the use of dedicated frequencies - leading to “packet wars”, and the need to purchase the software. Nevertheless packet clusters lasted quite a long time and their use only declined when free software became available for other systems, particularly those using IRC / Internet. 

 

Internet distribution solves all packet issues at one fell swoop - anyone and everyone can be a cluster, and better service resulted in better spotting. Internet distribution allows niche spotting systems such as:

                                    ON4KST (aka KST): VHF & up (live example shown)

                                    SOTAwatch (& clones)

                                    -         allows to alert when & where they will be on the air

                                    -         allows DX to be spotted

                                    RSS – everyone can show spots

 “Self-spotting” is considered to be very bad “form” when contesting, but it is very useful for SOTA. It does require mobile Internet / SMS access, which can be a problem. Don’t believe the cell-phone coverage maps! Access from hills can be patchy due to multiple connections; often you can see a good signal strength but cannot connect, thus this mode is of limited value.

SMS often gets through when voice and data calls fail, but requires special software. Andy provided a live demo using SOTAwatch2 on 40m. Your reporter got quite excited when he noticed several spots for W2RDX, the club callsign of his previous club, the Rochester DX Association in Rochester NY.

Example of a SOTAwatch2 display

APRS – the Automatic Position Reporting System – provides APRS SOTA Spotting using the same principle as SMS but allowing messages to travel the APRS network (and therefore it doesn’t work in Scotland)!

Automatic SOTA spotting leverages CW Skimmer and the Reverse Beacon Network. It is a computer data mode in which a band of spectrum is monitored and all well-formed CW is decoded automatically.

Many stations worldwide are monitoring and feeding a central database whose data is available to all. If you combine SOTAwatch alerts, RBN and some logic and you get live spots! Andy did another live demo and his spot came up within a few seconds.

What system do you use when you must spot at all costs? – the Iridium satellite network SBD Modem. This employs SMS via satellite with 20s latency worldwide. Andy demonstrated a (very small) Iridium SBD9602 satellite modem. It has serial data signals and some antenna sockets. The circuit board takes one SBD modem and adds a USB interface, a power supply and a patch antenna. The uplink and downlink frequencies are 1616-1626.5MHz.

The Iridium SBD9602 satellite modem

 

The credit-card-sized circuit board takes one SBD modem and adds a USB interface, a power supply and a patch antenna.