A DX cluster is a global federated network of telnet nodes where amateur operators report ("spot") interesting contacts they have made or heard. A spot looks like:
DX de K1ABC: 14025.0 W7XYZ CQ DX 1422Z
That single line carries: the spotter's callsign (K1ABC), the frequency (14025.0 kHz, 20m CW), the DX station being spotted (W7XYZ), free-text comment ("CQ DX"), and the time in UTC (1422Z = 14:22 UTC).
Spots propagate from the originating node out across the entire cluster network in seconds, so when one operator reports hearing a rare DX station, the rest of the world finds out almost immediately.
operator tells you a band is open to a region, even if you weren't hearing anything yourself.
minutes, 20m is wide open to EU right now. The cluster is the empirical evidence behind the [[hf-propagation]] indices.
rarely-activated DXCC, the cluster lights up with spots and you know exactly where to tune.
others can work them.
Spotting is the act of typing into a cluster client: "I just heard or worked this station, here are the details." Most modern logging programs spot automatically when you complete a QSO. Manual spots get used when you hear something interesting that you want to share.
There are unwritten norms:
and considered poor form on most clusters).
ruining their day by triggering a pile-up).
for a while).
The Reverse Beacon Network (RBN, reversebeacon.net) is a separate parallel system where automated CW + digital decoders at fixed sites listen for any callsign that calls CQ and post a spot automatically. RBN spots include signal-to-noise ratio, so they're useful for evaluating propagation paths and your own antenna.
Most cluster software now ingests both human and RBN spots in the same feed.
The /dx page on this site polls the DXSummit cluster every 30 seconds and shows the most recent spots. Filters by band and mode help you narrow down to "what's open on 20m right now" or "who's on 6m FT8 right now."
Each DX callsign in the table is a link to the [[callsign-lookup]] on this site, so you can see who they are (across the US, Japan, Canada, Germany, Finland, Australia corpus) without leaving the page.
/dx tool on this site.feed for our /dx page.
similar data shape.
automated decoder side.
spotting norms.