Recent storms that have plagued the central US have moved East, giving a operating reprieve, albeit a short one, to a few of us. This storm system may have created a natural laboratory for investigating the impact of terrestrial weather conditions on RF at 472 kHz. Merv, K9FD/KH6 / WH2XCR, has long reported behavior on 160-meters that changes in-step with weather systems moving across the Pacific. In fact, Merv can almost set his clock by the openings he has observed! Note that these observations are not related to increased QRN levels. Because of limited observations on land, it has been theorized that salt water is in some way a major contributor to this effect. Investigations continue but similar behavior has been observed by Merv on 630-meters. Last night Phil, VE3CIQ, observed interesting WSPR decode behavior that seemed to following the line of thunderstorms.
While the data is far from conclusive due to a lack of homogeneity in station activity, particularly in the eastern coastal areas, these are certainly valid observations. As Phil points out, the opening forms a line between his station and mine, with many points in between. I’ve always felt there was something to this phenomenon and it certainly bares further observation and study.
Geomagnetic conditions remain quiet. Solar wind velocities have been consistently in the low category, below 400 km/s. The Bz has been tending slightly to the south, however, during the session.
Phil, VE3CIQ, was listening overnight with the HI-Z vertical and provided the following additional comments for the session:
Mike, AI8Z / WD2XSH/12, was active with a CW beacon around 474.5 kHz this morning with a great signal (S7) here in Texas around 1030z. Mike has set up the beacon in conjunction with the Rocky Mountain convention this weekend where he is speaking and performing a 630-meter demo.
Ken, K5DNL / WG2XXM, reports that he decoded three WSPR stations through low QRN and was decoded by 22 unique stations during the session including 23 decodes by WH2XCR at 6000km.
Neil, W0YSE/7 / WG2XSV, reports perhaps a slight improvement with the return of two-way reports with WH2XCR.
Neil also reported that Dick, W7WKR / WD2XSH/26, was active, receiving reports from WH2XGP. Its nice to have Dick active again.
Ron, NI7J / WH2XND, provided this interesting link on peak, RMS, and PEP measurements that some might find useful.
Regional and continental WSPR breakdowns follow:
There were no WSPR reports from the trans-Atlantic or trans-African paths during this session. UA0SNV was present but no reports were found in the WSPRnet database.
Eden, ZF1EJ, decoded three stations in the central US.
Laurence, KL7L / WE2XPQ, shared two-way reports with WH2XCR and additionally decoded WH2XGP and WG2XXM.
Status quo rules the session in Hawaii as Merv, K9FD/KH6 / WH2XCR, continues to experience very consistent performance from one session to the next. Two-way reports continue with Roger, VK4YB, who reports that the opening to KH6 was later than usual but yielding single digit S/N reports after the opening started. Reports continued right up to sunrise in KH6.
Jim, W5EST, digs deeper in this discussion entitled, “PART II: 630M LONG PATH PROPAGATION: HOW?”:
“Let’s consider some 630m spring 2016 peak SNRs in the WSPR database from April 5 to date on various paths in mid-2000km and longer, and do propagation interpretation. If an appealing interpretation doesn’t explain how SNR would be strong enough to reach the actual peak SNR, then some other interpretation may be needed. If two different interpretations both do explain the peak SNRs, perhaps they should be distinguished or combined.
Today’s illustration shows computed SNR curves applying antenna elevation pattern (inset), inverse square distance, and per-hop loss over salt water. Among the curves, see “All F Hops” in blue. For reference, “All E Hops” in red here repeats the May 10 curve in this blog. “E-hops & 1 Gnd Refl” in green imposes 6dB additional loss for a single ground reflection among E-multihops.
Data points “x” mark the illustration for comparison with the SNR curves (per Notes). Colored ovals indicate various path categories, like “N.Am.-N.Am.”, transatlantic “TA”, etc.
Each colored oval assigns its color to both its station notes and the computed curve that most nearly satisfactorily interprets the data in that oval. Capitalized station letters indicate TX. Lower case station letters signify RX. Double arrows signify data for both directions between same two stations.
By way of interpretation, TA paths and VK-JA likely involve multihop E, in my opinion. Using the green curve to adjust the red multihop E for ground surface reflection helps make sense of points ranging from 3300-7500km like XGP-xzo, XCR-zf1ej, and XJM/XZO-xcr.
By contrast, N.Am.-VK peak SNRs seem more nearly related to F-multihop propagation (blue). See the lower right end of the blue curve.
However, it’s difficult to reconcile the supposed E-hops in N.Am. with the idea of F-reflection on every hop to VK. Both SE Australia and western N.Am. lie in temperate latitudes.
Moreover, several XCR HI-VK SNRs exceed even the computed F-multihop SNR by about 5-7dB. Other issues show up as departures from the computed curves as well.
Let’s dig into some of these more difficult issues in a further blog post! If you have ideas to offer, let us know. GL.
NOTES: Superimposed on the model SNR curves, peak SNR data points “X” represent path performances. The peak SNRs are adjusted for TX power so that weaker-power station SNRs are adjusted up. No adjustment was attempted for unknown variabilities such as method of estimating WSPR power, different RX antenna performances, and unknown headings of directional RX antennas.
Peak dB WSPR SNR since April 5 to May 11 was obtained by taking the median of the top five SNRs adjusted for TX power for each given path, or simply the median of whatever fewer such SNRs were available.
It could be objected 1) It’s too late in the season to take peak SNRs. 2) The data surely would have too much error to be worth comparing with the computed curves. 3) Different paths can’t be compared, they are too different in their ionospheric and surface reflection characteristics. 4) The dB corrections for power are too severe since reduced power often doesn’t much make much difference to signal strength.
I’ve proceeded with the study because errors can offset each other generally and also can be reduced somewhat by taking the median of top 5 SNRs per path. I’ve corrected for lateness in the season adjusting and referring all the computed SNRs to 10w XGP peak SNR at 1007km into WW6D in California at this time of the season.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!