While its no big surprise, noise has dominated the Summer thus far but a few bright spots were observed during this session that might signal a little hope. First, Merv, K9FD/KH6 / WH2XCR, was reported by Eden, ZF1EJ, several times. This path was relatively common during the Winter but can be quite difficult from KH6 as Merv has pointed out.
Second, Ken, K5DNL / WG2XXM, was reported twice near sunrise by David, VK2DDI:
Ken noted high noise levels from storms in Kansas most of the night, resulting in his only decoding two WSPR stations but he was decoded by seventeen unique stations including twenty spots from Merv, the best at -23 dB S/N.
Activity across the US as a whole seemed a bit down but there were pockets of sizeable activity, like in the Pacific Northwest. Several stations like John, WA3ETD / WG2XKA, are in the midst of station maintenance. John is rebuilding his ATU after his yard guy recently cracked the tub while mowing.
Phil, VE3CIQ, reports that he decoded WH2XGP and WH2XNG on WSPR2 and was decoded by VE2PEP, WE2XGR/3, WG2XJM, WH2XZO, WI2XFI and WI2XHK.
Neil, W0YSE/7 / WG2XSV, had a good night in the very packed Pacific Northwest:
Geomagnetic activity was very quiet with only a slightly South-pointing Bz and very calm solar wind velocities, averaging 325 km/s. Most DST values appear to have recovered and are on the increase:
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-African, trans-Atlantic, or trans-Equitorial paths.
Laurence, KL7L / WE2XPQ, reported WG2XSV, WH2XCR, and WH2XGP during this session:
Merv, K9FD/KH6 / WH2XCR, had a nice night with the previous reported decodes by ZF1EJ. Other paths were “situation normal” including the path to VK which appears to have been healthy:
Jim, W5EST, presents, “HOW INTERPRET SNR PEAKS AND VALLEYS ON MF/LF?”:
“Nighttime WSPR SNR (signal-to-noise ratio) variations are a continually familiar feature of MF/LF reception. On 630m early last November I sorted SNRs in order of the SNR values for each of many USA one-hop paths on low/no storm nights. The middle half of each sorted 630m SNR list regardless of path regularly encompassed a range about 7-9 dB.
Can we go beyond these merely statistical observations and physically interpret what these SNR peaks and valleys on one-hop paths actually might mean? Provided one keeps an open mind to alternative ideas going forward, I do think that something more interpretive can indeed be said.
I’m talking about propagation on nights when the band noise is relatively steady so that SNR is a proxy for signal strength. Right or wrong, some possible interpretations might include those listed. You can probably think of other physical ideas about the ionosphere. A, B, C, D are different concepts, I think. Concept A is subdivided by suffix letters.
A1) Reflective ionospheric contours slowly change their position and curvature. Consequently, separate places in the ionosphere may reflect the RF signal, causing multipath. Varying levels of self-interference by multipath signal rays arriving with different phases occur in the receive antenna, so SNR varies.
A2) Reflective ionospheric contours slowly change their position and curvature. Single path RF signal ray encounters a reflective ionospheric contour that slowly changes its shape and reflects more or less of the RF signal to the receiving antenna.
B1) Reflective ionospheric contours slowly change their absorption and reflectivity. Single path ray encounters a reflective ionosphere that slowly changes in its level of absorption or reflectivity and reflects more or less of the RF signal to the receiving antenna.
C1) Reflective ionospheric contours form a fairly stable, but a very gently puckered terrain that’s stable over even a few hours. The ionosphere moves en masse relative to the Earth’s surface beneath it. An RF signal ray encounters contours that move past its path midpoint, causing its SNR to vary at the receiver.
D1) A combination of two or more of the above interpretations.
In this discussion, I’m concentrating on the ionosphere as it presents itself to RF signal. I’m leaving aside topics about how geophysical and astrophysical processes might cause ionospheric contours to change their position, curvature, reflectivity/absorptivity, etc, and/or be caused to move en masse.
Caveats underlie this discussion:
–What makes a peak or valley in a sequence of SNRs strongly depends on the amount and duration of SNR variation by which you define it. So it’s important for me to state how I determine whether there is a peak or a valley in a set of data. If the data varies quite rapidly, even the idea of peak or valley may be meaningless. 2200m SNR sequences are more likely to display gradual and deliberate descents and rises than the SNR variations one is likely to see on 630m.
–Depending on each WSPR TX station’s transmit percentage TxPct, some SNR peaks and valleys may be missed when receiving that station.
–The ionosphere’s same contours even at the same place may “look” different to MF/LF RF signal rays arriving at different angles because of different TX distances from RX.
–The MF/LF RF signal is probably refracted to execute one or more arc-shaped paths in the ionosphere. So some volume of relevant ionosphere may be involved and not just a mirror-like “point” of reflection at a particular of contour of electron concentration. Also, a possibility of reflection from different regions at significantly different altitudes in the ionosphere is ignored.
–One probably needs different approaches than for nighttime as above compared to ways one would go about explaining what’s happening in the hour before and after sunrise, and before and after sunset SS, not to mention the daytime regime as well. Terminator-induced waves and plumes or upwellings of electron concentration might all be involved around SR.
–The duration of SNR peaks and valleys matters. Long SNR plateaus and extended SNR troughs may show up in the SNR sequences instead of clean peaks and dips. Sometimes decodes are entirely absent. These nighttime occurrences also should be interpreted.
In another blog post I’ll offer some more nighttime analysis and/or interpretation. In the meantime, let us know your ideas about these or other interpretive possibilities and caveats for nighttime propagation. If you have an article or book section that you’ve found helpful on this topic, tell us so we can blog it. Thanks and have a good summer!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!