Reverse Beacon Network
| Reverse Beacon Network | |
|---|---|
| Abbreviation | RBN |
| What it is | A worldwide network of automatic receivers that report which stations they hear |
| Website | reversebeacon.net |
| Started | 2008 |
| How it works | |
| Receiving stations | Volunteer-run "skimmers": a receiver, usually an SDR, and decoding software |
| Key software | CW Skimmer, by Alex Shovkoplyas VE3NEA |
| Modes spotted | CW and RTTY; more recently FT8 and FT4 |
| Reports | Call sign, frequency, mode, signal-to-noise ratio, CW speed, time |
The Reverse Beacon Network (RBN) is a worldwide network of automated receiving stations that listen to the amateur bands and report every station they hear calling CQ. An ordinary beacon is a transmitter that anyone can listen for; the RBN turns that idea around, with fixed receivers listening for everyone else. Its reports, called spots, appear within seconds on the network's website and on DX clusters, so any ham can call CQ and find out at once where the signal is being heard and how strong it is. The network was started in 2008 by volunteers led by Pete Smith, N4ZR, and Felipe Ceglia, PY1NB, and its receiving stations are run by individual hams and clubs around the world.
How it works
Each RBN receiving station is called a skimmer. It is usually a software-defined radio connected to a good antenna and a computer running decoding software. The key program is CW Skimmer, written by Alex Shovkoplyas, VE3NEA, which can decode dozens of Morse code signals at once across an entire band segment, picking out call signs from each. Companion programs do the same for RTTY, and the network has more recently added the FT8 and FT4 digital modes.
When a skimmer decodes a station sending CQ, or TEST in a contest, it sends a spot to the RBN's central servers. Each spot gives:
- the call sign heard and the call sign of the skimmer that heard it;
- the frequency and mode;
- the signal-to-noise ratio in decibels, a measure of how far the signal stood above the noise at that receiver;
- for CW, the sending speed in words per minute;
- the time in UTC.
Skimmers spot only stations that are calling, not those answering, which keeps the feed manageable. Software screens out many miscopied call signs, but some busted spots still get through, especially for weak or unusual calls.
Testing your signal
The RBN's most popular use is as an instant, impartial signal report. Call CQ on CW for a minute or two, then search for your own call sign on the RBN website. The results show which skimmers heard you, how far away they are and how strong you were at each, often on a map.
This makes the network a practical tool for comparing antennas or power levels. Call CQ on one antenna, switch to another and call again, and compare the reports from the same skimmers a few minutes apart. Because each skimmer has its own antenna and its own noise level, numbers from different skimmers can't be compared directly; the useful comparison is the same receiver, at nearly the same time. One test is only a snapshot, since propagation changes from minute to minute, so repeat it several times before drawing conclusions.
Other uses
- Propagation checking. Watching spots of other stations shows which bands are open to which parts of the world right now, often before a human notices the change.
- Finding activity. DXers and contesters use RBN spots, usually through a DX cluster or logging program, to find stations as soon as they start calling. In contests, using these spots generally places an operator in an "assisted" category.
- Research. The RBN keeps an archive of its spots, which hams use to study propagation, the solar cycle and station performance over long periods.
Similar networks cover other modes. PSK Reporter collects automatic reception reports from FT8 and other digital-mode software, and WSPR is a mode designed entirely around reporting where signals are heard.
Hosting a skimmer
Anyone with a suitable receiver, a quiet location and a reliable internet connection can contribute a skimmer. Wideband software-defined receivers can cover several bands at once. New skimmers are especially welcome in parts of the world with few receivers, where a single station can fill a large gap in the map.