The band was open in spite of noisy conditions from a large storm system currently moving across the southeastern US. The band was well represented with a few very long distance reports on trans-Atlantic and trans-Pacific paths. Low power daytime openings are beginning to be reported on a regular basis and I had a chance, overnight encounter with a nemesis that I vowed never to put on the air again that provided startling results. The period between the Thanksgiving holiday and the New Year has historically offered some of the best propagation of the season in the northern hemisphere. This season is no exception and amazingly we are less than a week into this year’s “sweet spot”.
The geomagnetic field has returned to quiet levels. The Bz continues to point slightly to the South but solar wind velocities have decreased to low levels, averaging 350 km/s. DST values are stable and nominal.
The trans-Atlantic path presented some interesting and exciting long-haul openings with WH2XXP being reported at DJ0ABR for the first time. Additionally, WG2XXM was reported by F1AFJ and coming from Europe, G3KEV was reported by WD2XSH/17. As I mentioned a week or so ago, I find the intermittence of these openings very interesting. Why didn’t stations in the northeastern region of North America experience similar results? What mechanisms are in place to allow the longer openings sometimes but not others. It’s fascinating. These trans-Atlantic report details can be viewed here.
Ken, K5DNL / WG2XXM, adds that he was decoded by 56 unique stations including previously reported F1AFJ, and also WE2XPQ and WH2XCR.
Doug, K4LY / WH2XZO reported an early QRT due to weather, which will continue later today. Due to the QRN in his region, he reports that he only decoded four stations. Doug also added that the nighttime noise at PY2GN was not any better than during the day. He indicates that William will try moving the antenna to a different location and may contact his electrical utility for help.
Rick, W7RNB / WI2XJQ, reports that the session seemed down, receiving decodes from 25 unique stations and he provided reports for nine WSPR stations. Rick’s unique report detail can be viewed here.
Al, K2BLA / WI2XBV, reports very high storm noise this morning. By comparison, WG2XXM was S8 but QRN was S9.
Similarly, Ken, SWL-EN61, located in Indiana, reported 60 dB+ peaks on noise during the evening. Expectations for the session were low.
Neil, W0YSE/7 / WG2XSV, reported good daytime openings with reports from VA7BBG at a distance of 710 miles. Neil believes that this may be his longest daytime report but its definitely his longest in recent memory.
Neil reported a tough evening and overnight with WSPR decodes to the East likely due to QRN. He provided these comments and statistics:
“This session I was not heard east of SE Minnesota, but Laurence in AK decoded me twice. I am still amazed at the number of times Merv in HI copies me every night. I got 24 decodes from him this session with a best of -14.
I heard these 4 on 630m wspr: WG2XXM, WH2XCR, WH2XXP, WI2XJQ…and on 2200m JT9, John, VE7BDQ came thru many times. John and Ron, WH2XND, both came thru on wspr many times as well. No luck printing Laurence’s DFCW on 2200m but there is a small trace right on his frequency around 10:45 PM (0645Z).”
Trans-Pacific report details for this session are aggregated here.
Ward, K7PO / WH2XXP, experienced a remarkable night, with first time WSPR decodes by DJ0ABR as previously reported. Ward covered a tremendous amount of ground, with additional reports from JA1NQI-2, VK4YB, and VK2XGJ. These types of achievements are good for what we do. Congrats Ward!
Roger, VK4YB, experienced a very good night on the path to JA from Queensland, perhaps one of his best yet. While storms in the area continues to impede receiving a bit, Roger received reports from JA1NQI-2, JA1PKG, JA3TVF, JE1JDL, JH1INM, JH3XCU, VA7JX, VE7BDQ, and VK7TW.
David, G0MRF, provided a very nice assessment of his new, and recently modified for 630-meters, Icom-7300. Those measurements and comments are posted on the instructional page of this website and can be viewed here. Thanks to David for providing this information.
I got in late last night and was pretty “ragged out” but I felt like working on a project to decompress rather than just turning on WSPR and going to bed. I missed the evening CW session but wasn’t in the right frame of mind to operate. I also didn’t want to get bogged down in a multi-day project, just something to clear my head. Sitting in a box for the last two years that was destined for trash was my Ultimate-3 which saw an abrupt end due to an unidentified failure. I decided to spend a few minutes troubleshooting. I originally thought the problem was only a power supply failure but after repairing that for another project, it was obvious that the U3 continued to struggle. My U3 is probably more hacked than most U3’s. I had pulled the low pass filter for use in my Altoids tin transmitter so that was going to need to be addressed. It seems all three FET’s were dead and I only had one replacement so I pulled the old ones and installed the only spare that I had on hand. Probing the unfiltered and unmatched output into 50 ohm with the scope, I was observing about 2.1 volts RMS but since there was no matching and the signal was not a sine wave, I don’t think that applying ohms law to find power provides an accurate picture. Either way, I was likely making less the 100 mW at 12-volts PA voltage. Whether it was 50 mW or 150 mW was immaterial. There wasn’t much there – that was clear. I routed a makeshift “twisted pair to BNC connector” and found an unused coax jumper to my W1VD low pass filter that was currently connected to the output of the combiner. Powering up with the auxiliary fixed 12-volt and 5-volt outputs on one of my variable power supplies, the U3 appeared to be working. GPS synced relatively quickly and I was seeing a clean waveform on the scopematch. I found that the match was tenuous enough that it was causing the signal to drop out intermittently when operating into the antenna in spite of being in a matching conditions. I found that I could stabilize this by detuning the antenna just a bit. I was registering no base current on the meter but I was receiving near detection limit reports from stations around North America. It was a bit surprising given amount of noise and such low TPO which translated to even lower ERP. I don’t know how low the ERP actually is but its probably in the 10-30 mW range as a best case. I received reports into Canada, Hawaii, Cayman and many points in between. My WSPR transmission reports can be viewed here.
I almost threw out the U3 when cleaning up a few months ago and I’m glad that I didn’t. This was just the project that I needed on what was otherwise an out-of-control day. I need to do more projects like this in the future as it really seems to have rejuvenated me. I won’t run the U3 every night and it does have it’s deficiencies which have been handled in later releases but there is a place for this unit in my station. It will likely continue to sit in the floor, with clip leads and bailing wire holding it together but I suspect it will be on the air again very soon.
Regional and continental WSPR breakdowns follow:
Eden, ZF1EJ, was behind a wall of noise due to the storms in the southeastern US but he managed to provide reports to VE3CIQ, WD2XSH/15, WG2XIQ, WG2XXM, WH2XXP, and WH2XZO. How he managed to hear my QRPP signal is a “head scratcher”. Report details for these stations can be viewed here.
Laurence, KL7L / WE2XPQ, provided a few pictures (click to enlarge) of the portable receiver system that he uses to monitor his signal from the office. He reports remarkable stability after about 20-minutes of warm up from the Tecsun PL-600 portable receiver. I tried something similar with my Sangean and could never get the frequency to settle down so this is a nice accomplishment.
Laurence, had a good night, sharing two-way reports with VK4YB and WH2XCR and receiving reports from 7L1RLL4, JE1JDL, JH1INM, and JH3XCU. Report details for these stations can be viewed here. UPDATE: JA reports continue on the approach to sunrise and a few “late” decodes from this session are included in this addendum to the report detail.
Merv, K9FD/KH6 / WH2XCR, did well in the western portions of North America, Japan, and Oceania. East of the Mississippi River was experiencing strong storms, impeding receptions significantly. Merv received DX reports from 7L1RLL4, JA1NQI-2, JA1PKG, JA3TVF, JE1JDL, JH1INM, JH3XCU, VK2XGJ and ZL2BCG and two-way reports with VK4YB. Those report details can be viewed here.
Jim, W5EST, presents “630M SUNRISE, 630M SUNSET: PART II”:
“Yesterday’s blog outlined D-region absorption “time constants” of charging at sunrise and less rapid discharging of the D-region after sunset. Sunrise and sunset “bumps” provide intervals of considerable SNR, and sunrise enhancement can bring DX dividends. Today let’s discuss the elastic timescale of seasonality around sunrise and sunset, and what it means for us.
First of all, the mental assignments we think of as “pre-sunrise” and “post-sunrise” depend on the eastward or westward end of the path you take as your reference. As sunrise speeds its way along the great circle joining TX and RX, their 630m SNR dynamics is “pre-sunrise” as far as the westward station is concerned and “post-sunrise” from the perspective of the eastward station.
Perhaps it’s more helpful to imagine ourselves looking down from space at the path and the terminator moving along it. We keep track of times on a UTC clock as 630m magic happens. Three possible path-specific propagation regimes emerge: 1) An initial pre-sunrise period of time before the terminator passes above the eastward station. 2) An intermediate sunrise regime when the terminator is intersecting and moving along the TX-RX great circle. 3) A subsequent post-sunrise period of time after the terminator passes overhead the westward station. A pre-sunset regime, intermediate sunset regime and post-sunset regime can be similarly pictured.
The sun’s density of solar radiation into a given ionospheric region increases with the elevation angle of the sun relative to the horizon. Suppose we say that the initial pre-sunrise regime is the interval when the sun is within 12° elevation below the horizon at eastward station, and that the subsequent post-sunrise regime is the interval when the sun is within 12° elevation above the horizon at westward station. The arbitrary 12° below the horizon marks both the times when nautical dawn begins and nautical twilight ends. https://www.timeanddate.com/astronomy/different-types-twilight.html
As we currently approach northern hemisphere winter solstice, the sun’s daytime arc gets less wide and days shorten as it tilts lower and more southerly in the sky. In the tropics, the sun’s approximately 12-hour daily arc migrates somewhat southward in noontime position high overhead. In the southern hemisphere right now the days approach summertime’s longest day as the sun’s path widens and its daily arc tilts higher in the northern sky.
The pre-sunrise regime can provide daytime absorption to block storm noise east of the terminator and that way increase SNR on paths that remain in the 630m nighttime. The pre-sunrise regime may also feature pre-sunrise propagation enhancements even in storm free conditions. The post-sunset regime temporarily can use westward daytime absorption to block storm noise west of the terminator and help you access eastward 630m paths. Sunrise and sunset “bumps” can briefly yield signals. We don’t know much about why they happen, nor how to predict them even a few minutes ahead.
The intermediate sunrise regime particularly interests me because the terminator rapidly increases the absorption of the D-region as the terminator progresses along the signal path. The absorption might individually block one-by-one whatever signal ray or rays connect TX and RX and that way reveal their existence and pattern. Let me discuss this regime a bit more.
In duration, the intermediate sunrise regime lasts longer in fall and winter and is shorter in spring and summer. Its duration will depend on geographic latitude. The time scales of whatever might be its 630m propagation effects will presumably get spread out or compressed due to the that seasonality. The sharpness of definition of the 630m propagation effects will probably be fuzzier or clearer at different times of year too.
Find the intermediate sunrise regime duration Δt from sunrise times at each end of your choice of 630m path on a selected date. To do this, consult a web site such as https://www.timeanddate.com/sun (Enter a city location and get information for current date and month. Scroll down halfway to enter some other month.) You also can see entries indicating when nautical dawn begins and nautical twilight ends.
The average velocity* of the terminator along the path distance D from WSPR database is
vavg = D / Δt.
Let’s see some 630m SNRs at this time of day in another blog post!”
*ENDNOTE: You can get some deeper insight by doing the algebra for duration of intermediate sunrise regime on one-hop paths in mid-latitudes like those of southern Canada, the USA’s lower-48, and Australia. Eastward speed 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. Miami FL is 25°N., ~1470km/hr. Vancouver BC is 49°N., ~1130 km/hr.
Duration Δt of the intermediate sunrise regime is proportional to the kilometer distance D of TX/RX path divided by the eastgoing speed v of the Earth’s surface beneath that great circle. An approximate correction factor abs(sin H + cos H ctn σ) accounts for the path heading H from WSPR database in degrees clockwise from North and the date-specific sunrise heading in degrees σ (sigma) likewise clockwise from North. Calculate Earth’s speed v for a point near the middle of the path. Look up the sunrise heading σ for your choice of path midpoint and date using a web site such as: https://www.timeanddate.com/sun/ .
Δt (hr) ~= abs(sin H + cos H ctn σ) D/(1670 cos L)
(Absolute value abs() means to ignore the sign of a negative result.) Using calculus, one finds that the maximum duration happens when ctn H = ctn σ when sunrise heading aligns with path heading. If the path has an E/W heading H=90°, then cos H =0 and the time Δt is independent of season. Another special case happens when the terminator is parallel to the path, meaning σ=H+90°. Then the intermediate sunrise regime vanishes because the sun simultaneously rises everywhere along the path at once, i.e., the correction factor itself becomes zero.
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).