Be patient, the software is being upgraded, data may be wrong! Reload the page with CTRL -r to use the latest version!
NEW: you can now hide bad SDRs by double clicking on circles: the circle will disappear. On the next reload of the page you'll see it blacked out and by double-clicking again you'll reactivate it.
Please don't ask for scores to classify SDRs, a single number cannot convey how well a receiver/antenna is working: maybe the best reception quality predictor is how widely the SNR oscillates during the day and of course by a low level background noise!
Black circles represent receivers that did not reply to the last measuring request.
The idea originally started to improve upon linkfanel's (Pierre Ynard) original SNR map. Each SNR value is computed by estimating the background and peak levels within the received waterfall. This SNR estimation may be skewed by local, non-uniform, noise. For instance, a series of noise peaks is not easily distinguishable from the 9/10-kHz separated MW stations. Such noise is produced by many routers and cheap switching power supplies.
The quad band concept emerged from the observation that many SDR, though excellent on LF and MW, show a terrible decrease of performance on higher frequencies towards 28MHz.
Another issue that this page tries to address is the low updating frequency of the previous SNR map.