The Science and Technology Museum has issued a notice to the General Public that its facilities are closed until further notice, presumably due to the COVID-19 virus containment situation. As all facilities are closed, this includes the OVMRC meeting room, therefore the March OVMRC meeting is cancelled by authority relayed to me by Norm, VE3LC, Club Vice-President. We will continue to monitor the situation with hopes that we can resume with the next scheduled meeting in April.
Now that we’ve gone through the December solstice and are approaching
the March equinox. I figure it’s about time to update what’s happening
with the 80 metre band noise trends. The solar flux remains quite low
and constant, essentially unchanged from a nominal value of 70 since
July 2019. Despite this, the band does open up quite well in the
evening and there’s a lot of DX to be had on FT8.
the 24 hour noise floor snapshots, I now have a set from October 2019
to March 2020 – roughly 6 months covering a period about 2 weeks after
the 2019 equinox to 3 weeks before the next equinox. I’ve combined the
charts into a mp4 movie with each month’s record pausing for 10
seconds. If you have a decent mp4 media player (such as VLC) you can
pause in the transition regions to examine more closely how things
change from month to month.
frankly, I was encouraged to see the change in the diurnal noise floor
between October/19 and January/20, but things don’t seem to be changing
as quickly as I thought between January and March. Maybe there’s a lag
and an effect associated with the solar analemma that I haven’t
considered yet. Anyway, here’s the movie for your pleasure.
Hello all. I’ve made another measurement of the observed noise level in the 80 metre band as a follow-up to the measurement done in early October and do see some expected changes. Here’s the plot:
It should be immediately obvious that the noise trend during daylight hours is less saturated at the -110 dBm. level than it was in the October record, which is consistent with the premise that the lower sun angle will cause less D Layer ionisation. Yet, there are a couple more observations I take from this measurement when compared to that of October:
1 – The night time noise mean level is lower than October. Could it be that the lower sun angle is also causing less F Layer ionisation, thus there being less “visible” area being refracted back to the observer?
2 – The day time saturation level of -110 dBm. is essentially unchanged from that observed in October. I’m not sure about why this is, other than this level being the result of my antenna+coax noise temperature. I re-checked the instrumentation noise level, i.e. that of only the digitiser with antenna disconnected, and it sits at around -117 dBm., as it was in October, so it would seem that there’s at least enough separation between the noise floor of the measurement set and the coax+antenna+sky.
So there it is. I’ll continue with these measurements once a month until the summer of 2020 and perhaps combine all the monthly jpegs into a movie to have a more dynamic view of how things change throughout the year.