Happy Summer Solstice! The days start getting shorter tomorrow. I can’t wait!
This was another ‘pretty good’ session at my station in spite of only hearing three stations. The noise level was low for the most part so it really was luck of the draw. The geomagnetic field seems to be a little more stable as the Bz has moved North and the solar wind velocities have decreased to moderate levels near 450 km/s. I suspect the coronal hole is no long as geoeffective as it was a few days ago.
This morning’s CW session was a mess. My original GW3UEP VFO that drives a pair of GW3UEP waveform – shaped amps saw massive frequency instability, literally “warbling”, and seems to have lost some regulation and power filtering OR the power supply that I am using to power it is sick. I will investigate later today but I had a hot spare available, built into an Altoids tin, and the signal it strong and stable. As much as I like this new VFO and the smoothness of the tuning capacitor, I do hope to get the original unit working well again. I have a lot of hours on the air with that driver.
John, VE7BDQ, reports that his WSPR was decoded by WE2XPQ, WH2XCR, N6RY, VA5LF, VA7JX, VE7SL, WH2XGP, VE7CNF, and WG2XSV. He also reports that he decoded WG2XIQ, WH2XCR, WG2XXM, WG2XSV, VE7SL, VE7CNF, VA7JX, and WH2XGP.
Phil, VE3CIQ, reports very strong storm QRN that sounded like an “old 78 record” near his QTH in Ontario.
John, W1TAG/WE2XGR/3, posted a write up on his website about the loop that he is currently using on 630-meters.
David, W4CLJ, was a new receive station from Florida but was reporting a variation on the old 600-meter WSPR frequency. I sent him an email with updated frequency information and received a reply indicating that he had fixed the problem. Perhaps WH2XZO will be QRV tonight to help in this testing.
Ken, K5DNL / WG2XXM, reported that he decoded three WSPR stations and was decoded by 21 unique stations through a night of QRN.
Steve, VE7SL, reports a better session than the previous, decoding nine WSPR stations and being decoded by nine unique stations.
Neil, W0YSE/7 / WG2XSV, had one of his strongest sessions in quite some time and provided the following statistics and comments:
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic, trans-African, or trans-Equitorial paths.
In the Caribbean, Eden, ZF1EJ, reported WG2XXM and WG2XIQ:
Laurence, KL7L / WE2XPQ, had a relatively good session for the first day of Summer. He reports that the new antenna is within about one dB of his original antenna’s field strength at a distance of one mile after adding additional top loading. Laurence also indicates that at midnight it is still very light outside:
Merv, K9FD/KH6 / WH2XCR, heard quite a few stations during this session, as activity in the Pacific Northwest spiked. The path to Australia may have been down slightly from the previous session but two-way reports were still managed with VK4YB. Don’t get me wrong, it was still a very good session to VK. The most recent benchmark, however, has been reception reports of Merv’s signal by three stations that have never provided reports for him in the past so that sets the bar pretty high going forward:
Jim, W5EST, presents a discussion entitled, “ANNUAL BULLS-EYE DIAGRAM SHOWS VK – N.Am. SEASONALITY”:
“Imagine two transmitters of equal power represented by the same TX Power Circle in the illustration. Think of one 630m transmitter TX0 from N. America transmitting to a receiver RX1 situated somewhere in the middle of the southwesterly path to Australia VK. Then think of a transmitter TX1 at that middle station transmitting the rest of the way to a receiving station RX2 in VK.
Draw two dB difference arrows colored red and orange from the TX power circle to each of two curves of peak SNR shown also in red and orange. The arrows represent these quantities:
PTX – SNRTX0-RX1 and PTX – SNRTX1-RX2
Add the two arrow lengths to get within an additive constant of path loss from N. America to VK:
(PTX – SNRTX0-RX1) + (PTX – SNRTX1-RX2) = 2[ PTX – (SNRTX0-RX1 + SNRTX1-RX2)/2]
Next, do an illustrative maneuver by graphing only the quantity inside the brackets. That maneuver leads to the purple SNR curve that’s the average of the red and orange SNR curves. The SNR from N. America to VK would actually very likely be less than SNRs for either of the half-paths, of course. But it’s the annual behavior we are after. Fortunately, the graphical shape of the variation in annual records of daily peak SNR behavior inherently cancels out the irrelevant additive dB constant.
For two half-paths on a path between similar latitudes in just one geographic hemisphere, the red and orange curves would probably be rather similar. But when both the Northern and Southern Hemispheres together encompass a long path, the red and orange half-path curves become significantly different and displaced on the bulls-eye diagram.
That way, the orange curve for Southern Hemisphere bulges at the top to represent good 630m conditions in Southern Hemisphere winter for paths there. The red curve for Northern Hemisphere bulges at the bottom because 630m conditions are generally better in Northern Hemisphere winter for paths there, which corresponds to Southern Hemisphere summer. The curves would jaggedly vary and be broken up somewhat by storms, of course.
The average of the orange curve and the red curve is the purple oval SNR curve, which instead bulges in the weeks around the Fall and Spring Equinox in either hemisphere. The purple curve illustrates why we have been expecting a fall mini-season, a hiatus in winter, a spring mini-season, and a hiatus in summer. This last 2015-2016 630m season, we indeed had two N.America-VK mini-seasons each bracketing an equinox.
So far, so good. Now recall that the previous season 2014-2015 had no N.America-VK mini-season bracketing the March equinox. And now in June, 2016, within days before the June 20 equinox, both WG2XXM and WG2XIQ have been successfully received in SE Australia by VK2DDI, and XXM was received by VK2XGJ as well. To reflect on what that means for the half-path diagram, and 630m, let’s do some Q &A.
Q1: Is the concept of a N.Am.-VK “season” valid in first place? Doesn’t XXM-vk2ddi/xgj -22dB on June 16 mess up a seasonal curve-with-variation concept?
A1: If sudden, large, random variations were the norm all year long, the idea of a “season” would indeed be meaningless. However, the clustering of N.Am.-VK successes around one or both equinoxes does indicate seasonality some years. I think the XXM/XIQ-VK successes around S. Hemisphere winter solstice these last couple of days may signal a possibly favorable trend from last season to the upcoming 2016-2017 630m season.
Q2: What about the fact that one or more N.Am.-VK multihop modes have different skip distances and may skip over the middle station (such as WH2XCR in Hawaii)? There aren’t really two half-paths to analyze this way.
A2: Yes, to work this through more rigorously, the path loss summing approach would be done multihop mode by mode because the geographic points of reflection are different for each of them. However, the oppositely bulging red and orange curve concept would apply to each of the multihop modes individually. If the SNR bulge of the orange curve in S. Hemisphere winter now is enough to convey XXM/XIQ signals into VK when averaged with N. Hemisphere summer conditions, then we can hope for a similar bulge of the hemispheric red SNR curve in N. Hemisphere winter after a favorable fall season.
Q3: Where does sunrise SR enhancement fit into this picture?
A3: SR enhancement, when it occurs, is “nature’s fuel injection system” for your 630m antenna and SNR. At the long distances XXM faces, for instance, favorable path propagation is important and SR enhancement beneficially contributes as well. Eastward thunderstorms may also get desirably blanked out by the blanket of D-layer absorption that the sun puts in place before SR on the eastward side of the terminator.
XXM-VK decodes all happened pre-fall equinox and post-spring equinox in the 2015-16 season according to my records. That further suggests the importance of the sunrise heading establishing a favorable terminator orientation perpendicular to the launch direction within about 10°-25° of being perfectly perpendicular. Such sunrise headings in the Northern Hemisphere only occur pre-fall equinox and post-spring equinox.
Q4: Will the N.Am.-VK opportunity time window get significantly longer as we go into August and September?
A4: No, there’s very little such window lengthening for stations around Dallas, for instance. But the N.Am.-VK window does lengthen in N.Am. PNW due to that region’s much higher latitude north than Sydney’s latitude south. N.Am-VK opportunity time window mostly migrates in time in the lower continental US rather than getting dramatically longer and shorter with seasons as it would for a same-Hemisphere long path. The center of the N.Am-VK opportunity time window migrates on the 24-hour clock, like windshield wipers back and forth one cycle per year, or like wagging your finger.
See some US-to-VK2 time windows for different dates tabulated below.”
TABLE: VK2 – WA/TX TIME WINDOWS (Sydney SS to Dallas / Seattle SR)
DATE START(z) END(z) DURATION(hr) CENTER(z) REMARKS
June 20 0654 1120 / 1211 4:26 / 5:17 0907 / 0933 Wtr/Smr Solstice
Aug. 15 0726 1151 / 1306 4:25 / 5:40 0938 /1016 Mini-season “starts”
Sept 20 0750 1214 / 1354 4:24 / 6:04 1002 / 1052 Spring/Fall Equinox
Oct. 15 0809 1232 / 1429 4:23 / 6:20 1021 / 1119 Mini-season “ends”
Dec. 20 0905 1325 / 1555 4:20 / 6:50 1115 / 1230 Smr/Wtr Solstice
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!