WSPR transmission gaps enable adaptive noise cancellation

The gap of about 9 s between the ends of WSPR transmissions and the start of the next enables noise level estimates within the 1400-1600Hz audio band that can be used with a passive software-controlled switched delay-line, attenuator and combiner system to provide very useful noise cancellation.

An outline of the approach together with examples of the noise cancellation achieved at G3ZIL on 40m using a pair of inverted V dipoles with their apexes at just 5m is provided in the following pdf.

Given the prevalence of noise on our HF bands this approach may be of interest to others.

Gwyn G3ZIL