This session was a bit odd. The first look at the numbers suggests the session might have had poor propagation but really it was the conditions that were poor due to storm noise and propagation as perfectly fine, particularly in the West. Notable was the odd-ball path to VK from Oklahoma just days before the start of Summer. Ken, K5DNL / WG2XXM, was reported at VK2DDI and VK2XGJ:
Some of these levels suggest a JT9 QSO might be possible. That’s encouraging.
It was very noisy here and I noted early that it was impossible to null the noise with directional antennas although I was able to split the difference and find the point where the noise was less prolific. Around 0700z I switched back to an omnidirectional receive antenna so I would not alienate any of the active stations. The noise continued to be high but it wasn’t as bad as it had been.
Geomagnetic conditions continue to be somewhat unsettled as solar wind velocities are currently above 500 km/s and during many reporting periods yesterday the levels were at or near 600 km/s. The Bz is currently pointing to the North and the K-index has returned to quiet levels for the moment. It was reported yesterday that a geoeffective coronal hole was the main cause for this most recent activity.
Phil, VE3CIQ, reports that he decoded VE3EFF, WG2XKA, WG2XXM and WH2XZO on WSPR and was decoded by WA3TTS/2 and WG2XKA during the session and notes that the session seemed weird.
Roger, VK4YB, reports that a station in ZL2 answered his CW CQ but the station faded before the QSO could occur. Roger notes that VK3HP also heard this station.
VA5LF was reported to be active again during this session and Toby, VE3CNF, notes that this was his first time to be reported by this station on 630-meters.
Larry, W7IUV / WH2XGP, reports that he decoded five WSPR stations and was decoded by 18 unique stations. Larry’s receive antenna was the East-pointing Flag, but he reports that he still didn’t hear any stations on the East coast and he feel conditions in the Pacific Northwest were not very good overnight.
Steve, VE7SL, reports that he decoded seven WSPR stations and was decoded by ten unique stations. He notes that the path was closed beyond the Midwest and that VA5LF received him 45 times, many of which were single digits S/N reports.
John, WA3ETD / WG2XKA, was QRV with no surprises over night and offers these details:
Neil, W0YSE/7 / WG2XSV, had a strong session from Vancouver, Washington with better reports from the western side of the Cascades:
Neil also received JT9 from VE7BDQ during the overnight period:
Lots of daytime JT9 activity occurred in the northwestern and northeastern US / southern Canada yesterday. Stations in British Columbia were beaconing with reports by stations in the Pacific Northwest and VE3CIQ in Ontario was performing a few beacon tests with WG2XKA in Vermont in the late afternoon / early evening.
Rik, ON7YD / OR7T, posted the following on the RSGB “Blacksheep” reflector regarding 472.org:
The 472kHz.org website is online since 3 months, having over 13000 visits.
55 hams active on 630 meter registered and entered their station data (see http://www.472khz.org/pages/
on-the-air/who-is-who.php). This is a good portion of all hams active on this band (but the more the better).
On this occasion I would like to thank all who participated by entering their station data or giving suggestions to improve the site.
In particular a big thank you to Alan, G3NYK, for his great article on propagation (http://www.472khz.org/pages/
I would also invite everybody to have a look at the table of countries that have access to 630 meter (http://www.472khz.org/pages/
about-472-khz/countries.php). You will probably note the many blank fields in the table (power, bandwidth, modes …). If you have any information that can fill these blank fields please let me know (reply to this message or email@example.com). Same if you see any information that is not correct or complete.
Please also have a look at the link page (http://www.472khz.org/pages/
and-more/useful-links.php), maybe you know some interesting sites that are not yet included.
Any suggestions about additional topics for the site are also welcome.
I have received a few mail from hams that were reluctant to register for privacy (spam) reasons.
I can assure that privacy of the registered users is most important to me:
– Only your callsign, first name and QTH (city) are obligatory listed in the “Who is who”
– Unless you agree to have tour e-mail address listed it will be only used for registering and in case you lost (forgot) your password.
– Even if you agree to have your e-mail address listed it will be shown as a picture (without link) in order to be save from e-mail harvesting robots.
73, Rik ON7YD – OR7T”
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic, Caribbean, trans-Equitorial or trans-African paths. ZS1JEN and PU3VRW/SWL were present during the session but no reports have been filed at this time.
Laurence, KL7L / WE2XPQ, operated in a receive-only capacity once again during this session:
Merv, K9FD/KH6 / WH2XCR, shared reports with a number of stations during this session both in North America and Australia John Simon, VK2XGJ, reported extremely quiet band conditions during this session, where he operated with the Kenwood R5000 and mini whip “#1”:
Today Jim, W5EST, presents “POLARIZATION DIVERSITY: COULD IT BENEFIT 630M RECEPTION?”:
“Today’s Appendix and illustration lay out the reasons that I think either Faraday rotation of polarization or multipath self-interference are responsible on 630m for a lot of the SNR variability we see even on a favorable quiet reception night during the best of the 630m season. I’m not sure we can do much about 630m multipath, if that’s the culprit. But if Faraday rotation is a significant contributor to SNR variability, then we’d want to get very shrewd about the subject of polarization.
What does this mean for hams and other experimenters? I think it means that we may well consider whether an experimental receiving antenna system at someone’s 630m station could be arranged to adequately receive 630m horizontal polarization as well as vertical polarization. A horizontal loop or dipole positioned as high up as possible over imperfect ground could be a candidate antenna.
The SNR would probably be significantly different for the horizontal vs. vertical polarization. We could discern whether the SNR variations of the two polarizations are correlated or not, however. If the SNR of horizontal polarization increases when the SNR of vertical polarization decreases, that would be a clear sign of predominant Faraday rotation as distinguished from multipath.
A horizontal loop would be omnidirectional at all headings, while a vertical loop is bidirectional with nulls. For a given signal, SNR would probably be less in the horizontal loop due to omnidirectional reception of noise. Stray capacitance to ground would contribute vertically polarized pickup and deliver it mostly into the common mode that could be mostly rejected by careful construction.
A receiving dipole, by contrast, would receive zenith noise like a vertical loop does, and has a bidirectional azimuthal pattern like a vertical loop. A 630m horizontal reception dipole might be constructed like two E-probes back to back. If such a horizontal dipole and its preamp were oriented perpendicular to the plane of a vertical loop and situated high and far enough away from the loop to avoid interaction and detuning, it could be rotated in tandem with the vertical loop.
The $64 question is whether a double E-probe 630m reception dipole would deliver a bidirectional azimuthal pattern for the horizontal polarization (subject to some horizontally polarized zenith noise pickup in both the dipole and the vertical loop antenna). I suspect the stray capacitances to ground from the dipole ends would make it act like a low-sensitivity vertical loop instead and would receive mostly vertically polarized noise and overwhelm horizontally polarized signal from the desired direction.
If the double E-probe dipole arrangement were effective, then would noise cancellation would be effective as between the two antennas to reduce zenith noise? The dipole would pick up zenith noises perpendicularly polarized to the zenith noises received by the vertical loop,. That means such cancellation opportunity would probably be modest at most, I think.
What do you think? Neither antenna would work? Already tried? Better wisdom? Worth a shot? Tell us your experience!
APPENDIX: Middle 50% of decodes, SIQ (SNR Interquartile Difference):
A first picture imagines that nighttime 630m SNR variability arises from Faraday rotation causing the polarization arriving at the 630m RX antenna to vary. Faraday rotation of an RF signal can occur when the signal wave encounters a magnetic field in a plasma–like the geomagnetic field (GMF) in some layer or region of the ionosphere. Faraday rotation of a vertically polarized signal as originated from a TX vertical probably delivers any and all polarizations to the RX antenna sooner or later in a reception night. But how to recover the energy from both polarizations and employ them for improved reception?
If the receiving antenna is sensitive only to vertically polarized 630m waves, as to such waves incoming at low elevation angles, then the received electric field amplitude in the vertical direction is proportional to sin(A). (A is the angle of rotation or orientation of the field relative to the horizon around the heading of the arriving signal as its axis.)
Suppose Faraday rotation at 630m makes all the arriving-signal’s polarization angles equally likely, which means the middle 50% of signals occupy a 45°-wide range of angles A centered on A=45°. That range extends from 22.5° to 67.5°. The dB calculation involves 10log10 of power, and power is proportional to the square of the electric field strength that varies as sinA. So the middle 50% of signals occupy a dB range
SIQpolzn = 10log10[(sin67.5°/sin22.5°)2] = 7.655 dB
This theoretical 7.655dB value falls squarely in the middle of observed variabilities of single hop paths across the USA November, 2015. See illustration of USA paths shown at Ham-Com.
If, instead, the polarization were unchanging, and wave amplitudes from 0.0 minimum to 1.0 maximum are instead all equally likely due to granularity in the ionosphere, then the middle 50% of amplitudes would range from 0.25 to 0.75 and
SIQgranul = 10log10[(0.75/0.25)2] = 9.542 dB (high end of observed variabilities Nov. 2015.)
If, in a third picture or concept, the amplitude variations are due to multipath self-interference, then I would imagine a mixture of amplitude and phase variations due to varying amplitudes and phases on two or more paths perhaps involving reflections/refractions at points only a few wavelengths apart. The resulting SIQmultipath would probably be at least the above 7.655dB and probably considerably more.
A fourth picture would include rise of SNR during the evening and fall of SNR before sunrise due to changes in absorption along the path. This undoubtedly contributes somewhat to the observed overnight SIQs. However, deep nighttime SNR variations are substantial enough to require additional explanation as above.
Fifth, I have omitted to discuss band noise variations that surely contribute to SNR variations. The nights in question were reasonably quiet nights and the dB contribution from band noise variation was probably small.
I conclude that one of these sources of signal variation predominated in early Nov. 2015 because the observed variability SIQ was 6-8dB, no more than any one of the first three main source possibilities would predict. If these sources of variation were equal contributors and at least somewhat uncorrelated, then the variability SIQ would be larger than any of the estimated values, which is inconsistent with observed variabilities Nov. 2015.
(The sources probably are indeed uncorrelated because I picture ionospheric spatial granularity to arise from local mass flows in their larger geophysical context, while Faraday rotation would vary signal polarization mostly by timewise changes in geomagnetic field strength and electron concentration. Multipath would depend on features of the path in multiple places at altitude as well as the separation distance(s) between those multiple places–which likewise does not correlate fully with the other proposed sources of variation. In these cases I focus only on the place (or places) in the ionosphere where the signal wave is reflected/refracted. In the middle of the night on single-hop, such place or places would most likely be near the path midpoint at altitude.)
So, what sources of variation are predominant? I speculate that the deep nighttime 630m-relevant ionosphere is probably relatively stable physically because there’s not much to disturb it. The terminator is far away. The earth shields it from solar wind, so whatever disturbance may reach it would be indirect. So it’s probably relatively free from turbulence and resulting granularity. I ignore TIDs (temporary ionospheric disturbances, deep subsonic acoustic waves).
Instead, electron mobility means ionospheric currents can affect GMF intensity locally at altitude. Also, multipath would easily occur due to slight variations in electron density contours. Consequently, I surmise that either Faraday rotation or multipath or both are the important contributors on the short time scales over which SNR variability plainly occurs on 630m.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!