TY - Generic T1 - Contrasting effects of the 3-5 November 2021 geomagnetic storm on reception in Colorado of WSPR transmissions from North-Eastern North America with those from Australia T2 - HamSCI Workshop 2022 Y1 - 2022 A1 - Gwyn Griffiths A1 - Glenn Elmore AB -

Solar wind particles from three M-class flares hit the Earth's magnetic field around 19:30 UTC on 3 November 2021. The planetary geomagnetic disturbance index (Kp) peaked at 7 that evening and the following morning. At the USGS Boulder Geomagnetic Observatory, Colorado the vertical magnetic field anomaly was below -40 nT between 07:38 UTC and 12:56 UTC on 4 November, dipping briefly to -75 nT. These dramatic space weather events are examined using WSPR spots at N6GN, near Fort Collins, Colorado. Between 10:30 UTC and 11:00 UTC the 7 MHz WSPR spot count showed a ~90% drop compared with previous days at that time interval. Second, the median distance for remaining spots increased to 7089 km from ~2500 km of previous days. Furthermore, the noise level dropped about 4 dB. At that time of day the noise at N6GN's remote receiver is limited by propagated-in noise rather than local or receiver noise. Central to the observed spot count decrease and median distance increase was a 98% reduction in spots received from grid FN, North Eastern North America: down to 5 spots from a typical 245 on other days in the same interval. But what caused that precipitous drop? We look at signal levels of individual transmissions to try and understand whether received signal levels dropped below the noise or whether Doppler flutter spread the signals beyond the bandwidth of the WSPR decoder. We also seek to understand the increase in spots from Australia compared with previous days. During the storm itself, signal levels from Australia were unchanged; it was not until the following day that levels and the number of spots decreased. We caution and investigate that the very narrow band transmissions may not be decoded more due to spectral distortion and spreading rather than the more usual lack of signal to noise ratio. This analysis provides a valuable use case for WSPR transmissions, reporting via wsprnet.org, augmented with noise estimates and on-line access via the WsprDaemon database with quick-look Grafana and animated Octave visualizations.

JF - HamSCI Workshop 2022 PB - HamSCI CY - Huntsville, AL ER - TY - CONF T1 - Patterns in Received Noise: Methods, Observations and Questions (ePoster) T2 - HamSCI Workshop 2020 Y1 - 2020 A1 - Gwyn Griffiths A1 - Rob Robinett A1 - Glenn Elmore A1 - Clint Turner A1 - Tom Bunch A1 - Dennis Benischek AB -

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.

JF - HamSCI Workshop 2020 PB - HamSCI CY - Scranton, PA ER -