Re: Web Noise Plots

Rob Robinett

There are two noise level measurement techniques reported by wsprdaemon:

In Red is the RMS noise level for the whole WSPR band taken from the 0-1 seconds and 110-120 seconds of each 2 minute WSPR cycle when all transmitters are supposed to be quiet.  However this measurement can be disturbed by the presence of an RF carrier (e.g. CW station) which persists through those measurement windows.

In Blus is a FFT noise level which is derived from the quietest 4 Hz channels of the WSPR band.  This measurement looks at the whole 2 minutes of the WSPR cycle, so it averages the noise over a much longer period but may be perturbed by transient noise events like thunderstorms.

In general the FFT measurements seem more useful and frequently show slightly lower noise levels, but we chart them both.

Gywn and Clint have written about this noise subject and you can find links to their documents at

The noise level measurement database we are building seems to be unique in the radio research world and we have started some efforts to exploit it for new insights into the ionosphere.

On Wed, Oct 13, 2021 at 12:18 PM KD2OM <steve@...> wrote:
Why do the colors of the lines change? The lines from my three receivers change, it seems to vary based on the noise level.

Steve KD2OM

Rob Robinett
mobile: +1 650 218 8896

Join to automatically receive all group messages.