The details for March 4, 2016 can be viewed here.
This session was generally quiet as far as lightning and terrestrial weather was concerned but around 0300z my noise floor increased and signals seemed to become erratic while a number of domestic reports increased significantly. There were a few active storms in Mexico but most of the noise was an elevated noise floor and not indicative of lightning strikes. I’ve seen this happen before during periods of disturbed ionospheric and geomagnetic conditions.
Geomagnetic conditions spiked to storm levels again during the evening. The Bz is currently pointing to the North but there has been quite a bit of variability and solar wind velocities are averaging near 610 km/s. DST values continue at negative levels, varying in step with the Kp spikes.
Trans-Atlantic openings were greatly diminished during this session although WD2XSH/17 managed a significant haul of WSPR reports. Report details can be viewed here.
WD2XSH/17 -> DK7FC/P, DL4RAJ, DL4RAJ/2, EA5ZL, EA7HPM, EB8ARZ, F1AFJ, F59706, F5WK, F6GEX, G0LUJ, G3WCB, G3XKR, G4KPX, G8LCO, ON5TA, ON7ZO/P, OR7T, PA0O, PA0RDT, PA7EY, SV8RV/1
Doug, K4LY / WH2XZO, reported a strong night of transcontinental openings and provided these comments:
“The 14 unique decodes included Hawaii and three extreme northwest CN grid stations. I used the west northwest favoring amplified delta antenna all night. With low QRN here, I was hearing well in that direction. The 49 decodes of XZO included two VE7s, but none of the nearby CN grids or Hawaii.”
Paul, N1BUG, reported no QRN at his station but he indicates that propagation took a hit from the geomagnetic disturbance. He decoded eleven WSPR stations including WH2XGP on the high latitude transcontinental path from Maine although Paul indicates that the path was weak and decodes were few. He also indicates that he had no trans-Atlantic reports.
Al, K2BLA / WI2XBV, reported that it was a good session but not spectacular in Florida. He provided reports for ten WSPR stations including WH2XCR on a path that was not reciprocated and he received reports from 35 unique stations.
Ken, K5DNL / WG2XXM, reported that he decoded thirteen WSPR stations and was decoded by 64 unique stations including two-way reports with WH2XCR.
Mike, WA3TTS, reported, “The cold weather into the Mid-Atlantic region brought favorable propagation with it on 630m overnight.” He provided the following statistics and comments:
Trans-Pacific openings to Asia hit seasonal highs for WH2XXP. Amazingly it was just one year ago that WE2XPQ hit a bonanza with reports from seven JA stations. Late Winter and early Spring in the northern hemisphere seem to be the best propagation to JA from North America. Report details, excluding KL7 and KH6, can be viewed here.
Roger, VK4YB, reported, “Heavy static in the early evening, a little less later. Not good for receiving but propagation was good. JA path is back. 630m/160m tests with VE6XH continue, 160m 6 spots best -19, 630m 9 spots best -24. Similar reports from Don, VE6JY, 160m 4 spots best -24, 630m 3 spots best -26.” Roger received reports from 7L1RLL4, CF7MM, JA1NQI, JH1INM, JH3XCU, TNUKJPM, VE6JY, VE6XH, VE7SL, W7IUV, and WI2XJQ. He provided reports for WH2XGP and WH2XXP.
Grant, VK3HP, received first time reports from JH3XCU.
Rick, W7RNB / WI2XJQ, reported a strong night with reports for VK4YB this morning. Rick provided reports for eight WSPR stations and was reported by 27 unique stations. His unique report details can be viewed here.
Ward, K7PO / WH2XXP, received reports from 76 unique stations and hit the jackpot with nine unique JA stations reporting his signal during the ~1200z-1300z, including 7L1RLL4, JA1NQI, JA3PKG, JA3TVF, JE1JDL, JH1INM, JH3XCU, JR1IZM, and TNUKJPM. Ward also received reports from VK4YB and ZL2AFP.
Larry, W7IUV / WH2XGP, provided reports for eleven WSPR stations and was reported by 58 unique stations including VK4YB, VK2XGJ, and ZL2ZFP. As W7IUV, Larry provided reports for eight unique stations.
Ron, WA4JNX, in Alabama reports that he has a Heathkit HD-1420 receive converter that will be on consignment shortly at HRO in Salem, New Hampshire. Ron indicates that it was well built and has recently been recapped and the case has been repainted. He is asking $60 which is a very good price given how much they tend to go for on Ebay (well on $100!). The unit will arrive today but anyone wanting to reserve it before it shows up on the website can call HRO at 800-444-0047 and reserve the unit.
The evening session produced a few early reports from WH2XZO that ceased shortly after full darkness arrived in South Carolina. UPDATE: Doug indicates that he was NDB DXing around the same time that reports ceased. Openings during the early evening were somewhat slow to develop but by 0300z a flurry of single digit reports including harmonics from around North America began to stack up so I transitioned to CW for a bit. Ron, WA4JNX submitted a report from Alabama, indicating that I was RST 579. The East / West paths were very healthy from my station while openings to higher latitudes were less predictable. WSPR openings overnight suggest good domestic conditions from Texas but no trans-Atlantic or trans-Pacific reports were registered. My WSPR transmission report details can be viewed here and my WSPR reception report details can be viewed here.
Activity during the evening was very high, with 140 MF WSPR stations observed on the WSPRnet activity page at 0215z.
Regional and continental WSPR breakdowns follow:
Eden, ZF1EJ, reported that he would be in a “receive-only” conditions this weekend as his station is active in the ARRL DX phone contest. He provided reports for four WSPR stations.
Laurence, KL7L / WE2XPQ, spent time receiving during this session but indicates that transmit antennas would need some work due to damage. Laurence provided reports for VK4YB and WH2XCR and indicates that aurora in his area is quite active. Report details can be viewed here.
Merv, K9FD/KH6 / WH2XCR, shared two-way reports with VK4YB and received reports from VK2XGJ, ZL1BPU, 7L1RLL4, JA1NQI, JE1JDL, JH3XCU, and JR1IZM. Coverage of North America was very good although eastern two-way reports were lacking during the session. Merv was heard by a number of East coast stations, however. His DX report details can be viewed here.
Jim, W5EST, presents, “XSH/17-g8huh PRE-SUNSET 630M TA GIVES CLUE TO ASCENT ELEVATION ANGLE”:
“It’s a bit rare when the timing of a single WSPR decode can tell us much more than that a signal got through at the time. On March 1, what a treat then when Dave XSH/17 transatlantic (TA) transmitted from Massachusetts to Tom G8HUH in Somerset, England. Tom decoded Dave 18 minutes before Dave’s local sunset. FB!
We ordinarily can’t independently determine the maximum elevation angle at which a 630m RF signal might be leaving a TX antenna on its way to a particular distant station’s receiver– except by presuming a number N of hops and the dividing the path distance by N. We got a break March 1, when the absorbent daytime D-region jutted out like an overhanging shelf NE from Dave’s QTH as shown in today‘s 1st illustration.
About 413km away (Endnote 1*), near or beyond the terminator, the D-region’s vanishing shelf admitted just enough signal for XSH/17 to deliver -28 dB SNR at G8HUH. This tells us that the XSH/17 ascending elevation angle to reach G8HUH was at most 8.3°. That angle would constrain the signal ray to go 413km out over the Atlantic Ocean no more steeply than would ascend 60km (arctan 60/413 = 8.3°). Otherwise, Dave’s signal would have been absorbed in the sunlit late afternoon D-region.
Because the XSH/17 signal successfully reached England when its signal rays were all less than 8.3°, it seems unlikely that any rays fanning up from the XSH/17 antenna pattern at higher angles later after dark would have significantly contributed to the signal strength later in the evening when the D-region even more fully ceased absorbency. This supports the idea of a ray-reflection picture as shown, rather than propagation according to a diffraction pattern from the ionosphere.
Consider the appended SNR sequence after that first decode. SNR goes from threshold around -30 dB and after about an hour gets up to -20 dB before ending 2326z in middle of night at G8HUH in England. Since the database shows G3XKR was still receiving XSH/17 transmissions for hours beyond that time, apparently G8HUH stopped all receptions or uploads at 2330z as indicated by numerous regional decodes at 2330z and none at the G8HUH RX thereafter.
Interpretation: I lean toward a great circle 3E-hop picture of the propagation as shown by three black hops arrowing in the 1st illustration and as directionally illustrated (bold red) in the geometric 2nd illustration. The E-region most likely was reflective to ascending 630m RF, especially around sundown over the NW Atlantic, when E-region ionization would have not diminished too much. It’s possible that a mode transition to 2F-hop occurred later to deliver SNRs up to -20 dB, but natural post-sunset decline in D-region absorption seems as good an explanation for the SNR increase as a hypothetical change from E-mode to F-mode propagation within so soon as an hour. After G8HUH decodes of XSH/17 ended 2326z, G3XKR receptions continued the rest of that night and varied high and low, peaking -18dB at G3XKR. That SNR variation is mostly due, I believe, to the way the WSPR2 decoder handles 630m QSB.
Could lateral skew propagation have been at work, so that XSH/17 signal might have ascended more nearly eastward, as shown in thin dashed red, 2nd illustration? That direction would allow for a little more decline in D-region absorption and/or a somewhat greater range of elevation angles since the terminator would be at its closest to XSH/17 and such a ray would enjoy more darkness. The lateral skew idea is reasonable and possible, but there’s no reason compelling that more complicated idea and I’ll presume 3E-hop great circle prop (bold red).
Reasonable minds can differ on interpretations, and feel free to offer your thoughts. This is challenging stuff!
I think the 2F-hop picture (Endnote 2**) is a less probable interpretation (black dashed arrows, 1st illustration) than 3E-hop because the first March 1 decode occurred so very soon after the terminator passed by the XSH/17 signal ray. Therefore, it seems unlikely that the E-region critical frequency would have fallen low enough soon enough to allow 475 KHz RF to pass through it, to ascend to the F-region on the first hop. Perhaps the E-region might have become transmissive on first hop descent and 2nd hop ascent and descent, but would not the E-region on first hop ascent not far from the terminator have blocked a first F-hop? (Contrast the May 14, 2016, blog where some F-hop prop may have been involved over equatorial Pacific Ocean. http://njdtechnologies.net/051416/ )
Can ducting explain this early decode? See a duct propagation concept using brown dashed arrows. Imagine a possible hole in the E-region some distance from XSH/17 followed by internal reflections between the E and F regions the rest of the way across the Atlantic until another hole would permit the signal to reach G8HUH. Since G3XKR received XSH/17 all night, the E-region duct holes would have presumably lasted all night.
I hesitate to adopt an E/F ducting explanation of XSH/17-g8huh March 1 for several reasons. First, if the E-region were tenuous enough so an E-region hole would admit RF on the first hop ascent phase, would not the entire rest of the e- region have become at least that tenuous so far into the eastward night and thereby would have defeated ducting in favor of 2F-hop? Second, if the E-region topside were reflective enough to support ducting all the way across the Atlantic, why wouldn’t the E-region underside be reflective enough to prevent a hole from forming as of 2214z near the westward terminator? Third, wouldn’t a ducted signal be no stronger than a 3E-hop mode since the illustrated number of upper and lower reflections in an E/F duct is the same as the number of E-region sky reflections and surface reflections. Indeed, wouldn’t the two salt water surface reflections in 3E-hop mode be likely to impose less reflection loss than two duct reflections would lose on the E-region topside? 73 & GL with 630m TA!”
SEQUENCE OF SNRs: XSH/17-g8huh
2017-03-01 23:26 WD2XSH/17 0.475647 -20 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 23:20 WD2XSH/17 0.475647 -22 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 23:14 WD2XSH/17 0.475647 -20 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:58 WD2XSH/17 0.475647 -23 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:38 WD2XSH/17 0.475648 -25 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:36 WD2XSH/17 0.475648 -31 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:34 WD2XSH/17 0.475648 -25 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:32 WD2XSH/17 0.475648 -26 0 FN42pb 5 G8HUH IO81mg 5081 54 XSH/17 SS 2232z. 261 W
2017-03-01 22:16 WD2XSH/17 0.475648 -30 0 FN42pb 5 G8HUH IO81mg 5081 54
2017-03-01 22:14 WD2XSH/17 0.475648 -28 0 FN42pb 5 G8HUH IO81mg 5081 54 18 min pre-SS. = 371.9 km
* Endnote 1: See geometrical 2nd Illustration.
The average speed V of the terminator along East-West distance d from WSPR database is
d =V Δt
Eastward speed V of Earth’s surface in km/hr at a given latitude L is found by multiplying cos L times the equatorial speed, which is Earth’s circumference 40K km divided by 24 hours. So:
V = ~1670 km/hr cos L
XSH/17 position: 42.1 N, 70.7 W, and cos(42.1) = 0.742. Terminator speed near XSH/17:
V = 6371 x 2π x 0.742 / 24 hr = 1239.3 km/hr = 20.66 km/min.
Kilometer distance X along TX/RX path to XSH/17’s signal ray entering the D-region is proportional to the 18 minute duration Δt prior to Dave’s sunset multiplied the eastgoing speed V of the Earth’s surface beneath that great circle divided by abs(sin H + cos H ctn σ).
X~= (1670 cos L) Δt (hr) / abs(sin H + cos H ctn σ)
The trig denominator accounts for the great circle path headingH from WSPR database in degrees clockwise from North and the date-specific sunset heading in degrees σ (sigma) likewise clockwise from North. Look up the sunset heading σ for your westward station and date using a web site such as: https://www.timeanddate.com/sun/ . Sunset heading at XSH/17 3/1/17: 261°.
(Absolute value abs() means to ignore the sign of any negative result.) Compare Nov. 30 blog for a similar formula used for a 630m sunrise topic. http://njdtechnologies.net/?s=113016 .
** Endnote 2: Estimate the minimum hop distance by extrapolating to a 100km high E-layer from 60km high D-layer based on the distance from XSH/17 to the D-layer. https://en.wikipedia.org/wiki/Ionosphere
3E-Hop distance >= 1376km
= (2x100km E-layer/60km D-layer)*371.9km/(sin54 + cos54 ctn 261).
First hop distance > 1376km is 5081/3 = 1694km, at 3E-hop mode or 2540km at 2F-hop mode.
If F-layer altitude is about 180km at night, then
2F-Hop distance >= 2540km
= ~ 2477km = (2x180km F-layer/60km D-layer)*371.9km/(sin 54 + cos 54 ctn 261).
F-hop distance and angle are barely consistent with 2F-hop, providing the F-layer was as low as 180km. I think this calculation casts further uncertainty about the idea that F-hops were involved.
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).