Patterns in Received Noise: Methods, Observations and Questions (ePoster)

TitlePatterns in Received Noise: Methods, Observations and Questions (ePoster)
Publication TypeConference Paper
Year of Publication2020
AuthorsGriffiths, G, Robinett, R, Elmore, G, Turner, C, Bunch, T, Benischek, D
Conference NameHamSCI Workshop 2020
Date Published03/2020
Conference LocationScranton, PA

There are valid concerns that local noise, often as common mode, is an increasing problem for radio amateurs. By adding two noise measurement algorithms to a robust Weak Signal Propagation Reporter (WSPR) processing and reporting package ‐ wsprdaemon ‐ we now have the capability to record and share noise level measurements from over twenty amateur stations. With locations from Maui to Moscow, and ranging from very quiet rural Northern California, Utah, and Austria to more typical suburban noise environments we have observed a multitude of patterns in received noise on the LF to HF bands (136 kHz to 28 MHz). These patterns show clearly where and when the local noise floor becomes a limiting factor. More intriguingly, we have observed coherent fluctuations in the noise over periods of hours at a pair stations 1000 km apart. Now with observations from a 'diamond' of four stations we can look in more detail at the timing of these coherent fluctuations. With over six months of observations every two minutes from several stations we can show systematic seasonal variations in the daily noise patterns. We think we understand the root causes of some of the features, such as the local noon minimum and the post‐sunset maximum in late spring and summer. However, we have yet to reach a satisfactory understanding for some patterns, including a transition to a daytime noise maximum in autumn. The challenging task of calibration to a field strength in free space will not be ignored, but for this presentation it will be set aside as we concentrate on patterns and not absolute noise levels. This presentation will outline the noise measurement methods, show examples of noise patterns from several stations, introduce the on‐line database and its Grafana interface that delegates will be able to explore, and we will seek comments, insights and suggestions as to causes for the patterns and next steps for this collaborative effort.

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