The details for April 12, 2016 can be viewed here.
While no where near perfect, it was a much quieter night here in North Texas. A few evening storms to the East seemed to fizzle relatively quickly leaving average propagation around North America. VK4YB reported low QRN in Queensland but little propagation early in the session so it was a mixed bag.
Geomagnetic conditions reached unsettled conditions and continued through much of the session at elevated-quiet levels. The Bz continues to point slightly to the South and solar wind velocities are generally unchanged, averaging near 435 km/s. DST values reached the low point during the evening session but those values have generally leveled-off and returned to near the center line.
Joe, DF2JP, reported recently that changes to his antenna system to improve performance at LF have impacted his tuning range on MF, requiring Joe to add series capacitance to the system. Joe notes that the addition has allowed him to resonate his system again on 472 kHz but the impedance matching has reached a limit near 30 Ohms. He will have additional adjustments to find the 50 Ohm point but these changes are a significant improvement and provide him with an operating position solution to his duel band tuning problem.
Roelof, PA0RDT, reported VO1NA’s CW beacon on 477.7 kHz. He offered these comments that were posted on the RSGB-LF reflector:
“Propagation was a bit better and I had aural copy in a 20 Hz bandwidth. There was no pre-dawn enhancement on your signal, whilst NDB QY-263, Sydney, CAN NS showed a very pronounced peak just before my sunrise. Those are the wonders of propagation. It is rare to find two nights in a row that are the same!”
Trans-Atlantic openings were once again depressed with a single low-latitude report registered during the session. Report details can be viewed here.
EA5DOM -> WA9WTK
Paul, N1BUG / WI2XTC, reported low QRN that continued to decrease through the evening. He provided reports for ten WSPR stations including new station WI2XUF located in North Carolina.
Al, K2BLA / WI2XBV, reported moderate QRN, decoding eight WSPR stations and receiving reports from 32 unique. Al also shared two-way reports with WH2XCR and reports for “four stations at or very near 4000 km.”
Doug, K4LY / WH2XZO, reported a power outage after 0322 EDT this morning. He provided reports for ten WSPR stations and he received reports for 44 unique stations. Doug has been QRT for ten days after antenna damage from recent storms.
Rick, W7RNB / WI2XJQ, reported heavy rains in the Seattle area which coincided with good transcontinental openings to the Eastern US. He provided reports for eight WSPR stations and he was reported by 29 unique stations. Rick’s unique report details can be viewed here.
David, N1DAY / WI2XUF, went on his maiden voyage overnight and experienced pretty good success. He provided the following comments and statistics:
“Last night I was feeling like a little kid telling the XYL “I did it!”. My first night of transmitting on 630M yielded 14 spots and 9 stations heard. In addition to testing my homebrewed transverter that I copied from an August 20th, 2014 post, I was testing my SDRPlay/SDRUno combination to see if it would receive 630M WSPR signals. The SDRPlay did OK, but my ICOM 7200 did better in the reception department. On the transverter, I was thrilled that it worked and was not generating a lot of harmonics as a result of power filtering issues. From my guitar amplifier building days, I remembered that additional electrolytics at the power in stages is always a good thing, and I had already modified the transverter in that manner. The nice thing about the SDRUno software is that even with RF muting during transmit, I could view my signal during transmit in real time to watch for power-related harmonics. At present, with an additional low pass filter in place, my rig is putting out 8 watts, and with an antenna efficiency of 8.3% courtesy of my Lowes bucket inductor (better than home depot because it is blue), I am estimating about 320 mW of radiation from my antenna. Next order of business is to build G0MRF’s amplifier that is now sitting on my bench and to modify my transverter to eliminate the MOSFET to get appropriate drive power into the amplifier. I think Ernie – Wi2XQU, who got me interested in 630M in the first place, and I spent as much time texting one another last night on our progress as I did transmitting hi hi. We have 2 presentations to local clubs on our activities as the 630M ‘Cellar Dwellers’ in the next couple of weeks, so having some actual success on transmitting has come just in time. I am also relieved that my transmissions yielded very little signal drift last night… that is one less thing to worry about at this point.”
Dave, N4DB, reported a two-tone signal around 475 kHz this morning. Its not unheard of for someone to utilize PSK-31 but at this time there have been no other reports. Dave provided reports for eleven WSPR stations.
Mike, WA3TTS, reported “Better than I expected with the weather moving through the area…. ” He provided the follow statistics for his best session DX:
Ron, NI7J / WH2XND, provided reports for eleven WSPR stations while listening with his modified multi-turn K9AY loop pointed towards to Northeast.
Trans-Pacific report details, excluding KL7 and KH6, can be viewed here.
Roger, VK4YB, reported “low QRN, average DX propagation, good VK- VK propagation. VE6XH stats: 160m 3 spots ,best -4, 630m 16 spots, best -19.” He received reports from JA3TVF, JH1INM, VE6XH, VE7SL, W7IUV, and WH2XGP. He provided reports for WH2XXP, WG2XXM and WH2XCR.
John, VK2XGJ, reported very quiet conditions, allowing WH2XXP to be received very early at 0748z.
Ken, K5DNL / WG2XXM, reported that he provided reports for twelve WPSR stations and he received reports from 63 unique stations including VK4YB. He shared two-way reports with WH2XCR.
Ward, K7PO / WH2XXP, received reports from 63 unique stations includingVK4YB, VK2XGJ, and VK3GJZ.
Larry, W7IUV / WH2XGP, provided reports for thirteen WSPR stations including VK4YB and he was reported by 31 unique stations. As W7IUV, Larry provided reports for nine WSPR stations including VK4YB. Larry also indicates that inclement weather in his area resulted in a transmitter shutdown during the evening.
Propagation was “OK” for this session. Domestic openings were reasonable and noise was not overwhelming compared to recent sessions. Two-way reports with WH2XCR was my session highlight. My transmission report details can be viewed here and my reception report details can be viewed here.
Regional and continental WSPR breakdowns follow:
Eden, ZF1EJ, provided reports for nine WSPR stations and he was reported by thirty unique stations. He shared two-way reports with WH2XCR.
Laurence, KL7L / WE2XPQ, reported that he had to tap the coil on the Marconi for spring weather conditions but depressed propagation made it a really tough session, Alaska. He was heard by a number of stations in the West including WH2XCR on KH6. There were no reception reports from Laurence in the WSPRnet database.
Merv, K9FD/KH6 / WH2XCR, provided reports for WE2XPQ and he shared two-way reports with VK4YB and ZF1EJ. Merv received reports from 7L1RLL4, JA1NQI/1, JH3XCU, and VK2XGJ. The eastern areas of North America was once again well represented and included reports from WA3TTS, W9MDO and two-way reports shared with WI2XBV. Merv provided reports for WI2XRM. DX report details can be viewed here.
Jim, W5EST, presents, “INTERPRETING 600 KHz MICROFREQUENCY DEPARTURES AS DOPPLER AT SUNRISE”:
“Some groceries you can enjoy as soon as you bring them home, like fresh fruit. Prepared dishes await mixing the right ingredients and using the oven before you can pull the results out and appreciate them. MF radio information comes both ways. So today let’s do some batch-mixing and hot-oven work!
Consider, for instance, what appear to be sunrise-coincident milliHertz frequency departures in 3/27-29 screenshots of a 600 kHz BCB carrier at 219 km. (Endnote 1*) Suppose each frequency departure is a sky wave return around sunrise of a TX MF RF ray that has departed in frequency somewhat from its ground wave frequency.
Today’s first illustration shows how I read off frequency departure data minute-by -minute from the 3/28 screenshot by magnifying it and advancing dashed-red measure lines. The positive frequency departure, by frequency difference between measure lines, tells us the path length is shortening and how fast.
I interpret the onset of the frequency departure as Doppler shift (Endnote 2**) due to westward moving tilt or slant of the E-region around sunrise. The frequency departure commences as soon as the E-region slant reaches a position somewhere overhead that can establish a vertical skew angle that supports reflection to the receiver. from that position The departure diminishes until it disappears–which was about 24 minutes later on March 28.
The actual slanted geometry of the E-region may be complex and by its surface complexity randomly may give a reflection opportunity for multiple rays. Arriving at RX, that could markedly increase signal strength and give a sunrise enhancement. I started with thesimplest mapping method I could construct by picturing 630m E-region reflection as if from a mirror-like smooth curved reflecting contour surface of the E-region. Then, at any moment, reflection only occurs where the angle of RF ray incidence equals the angle of RF ray reflection and both angles lie in the plane defined by the TX, the RX, and a line perpendicular to the particular E-region reflection point at that moment. I ignore the actual surface complexity for this purpose.
The second illustration (upper graph) shows a profile of the 600 KHz E-region effective reflecting contour that I worked out by the mapping method. As the tilt’s width moved westward and the RF reflection point descended in altitude, the curvature at each point of reflection became more nearly horizontal. You can see the tilt angle getting less as you look from left to right in the illustration.
My mapping method (Endnote 3***) starts with an arbitrary point in the sky at a presumed 110 km nighttimeE-region contour altitude and somewhere east of the mid-path. Then I used a spreadsheet loaded with frequency departure measurements from thefirst illustration to compute the necessary tilt for reflection to the RX, to follow the tilt downward while progressively shortening the path length due to those frequency departure measurements, and to re-compute the tilt at the continually changing position coordinates of the reflection point all the while.
Some wag could say “If you aren’t confused, you haven’t gotten very acquainted with the subject.” For me, that’s quite true in this case of MF at sunrise. The curved, downward bulging shape calculated for the E-region on 3/28 near here extended about 500 km eastward and ~36 km downward to daytime altitude. The second illustration’s lower graph re-dimensions the upper graph to show that bulging shape better. Meanwhile, the sunrise-related reflection commenced at a place roughly 40km east from midpath with 34° and 55° ray elevation angles on this very short 219 km path from Memphis to Little Rock.
That way, a vertically skewed reflection started perhaps 40km east of midpath and caused a varying microfrequency departure curve. The reflection point slowly worked its way back to midpath and to 42° ray angles by migrating westward 1-2 km/minute over 24 minutes. Meanwhile, at my latitude the sun’s illumination was moving westward across the ionosphere at high speed 22.75 km/minute, 850 mph. The E-region assumedly maintained one bulging shape continually while the profile shape and sunrise-induced E-region dynamics producing that shape moved swiftly westward. Dizzying!
Keep in mind that the sunrise-affected E-region contour that reflects a 500m wavelength on a 219 km path probably won’t be the same contour that reflects the RF on a longer path or on a different wavelength such as 630m. Other paths at other frequencies would yield other frequency departure curves from our receiving equipment.
On this 219 km short path, the sunrise-related changing RF sky path may not have been an enhancement in the sense of substantial signal strength increase. If the shape of the E-layer bulges downward as shown from a starting point 40km east of midpath, the westward motion of that bulge would soon have obscured and extinguished the usual midpath nighttime hop reflection. The 40 km number on 3/28 is credible because the initial frequency departure would have been far greater (Endnote 2**) if the starting point were instead farther east directly overhead the eastward station, for instance.
The results puzzle me for several reasons. First, the early onset of the frequency departure occurred about 13 minutes before sunrise time 3/28 at the reflection point 40 km east of midpath. (The white dashed vertical lines on first illustration indicate the timing). Perhaps the 22.75 km/minute, 850 mph, supersonic terminator motion acts like an ionospheric “shovel.” Does the terminator’s front as it moves westward against the E-region continually produce a bow shock somewhat to its west in the E-region? Even if it does, 295 km west seems doubtful, 13 min. x 22.75 km/minute.
https://en.wikipedia.org/wiki/Terminator_(solar) ; https://en.wikipedia.org/wiki/Bow_shock_(aerodynamics) (blunt bullet photo) ; https://en.wikipedia.org/wiki/Shock_wave (scroll halfway to detonation photo).
Second, the computed profile shape: One could just as well expect the calculated profile curvature in the E-region to be curved like part of a dish antenna or like a parabolic mirror focused on the eastward station. That way, at least a few RF rays from TX would converge at RX and enhance the signal strength. But the second illustration is curved the opposite way.
Third, faint-intensity frequency departure traces additionally appear here and there in the screenshots all three days. I leave these weaker signal traces unexplained.
To explain the strong frequency departure traces, should the model have imagined tilted E-region profiles that bring at least two RF rays to their destination? If the simple model strategy I did adopt is right, the results are intriguing. Even if the results instead motivate us to seek a better approach, I think it’s encouraging that MF reception information within our reach now or in the foreseeable future might promote amateur science investigation of the MF ionosphere. TU & GL!
*ENDNOTE 1: Similar frequency departures showed up around sunrise on three consecutive days 3/27, 28, 29. http://njdtechnologies.net/032817/ (3/27 screenshot)
http://njdtechnologies.net/032817/ (3/28 screenshot), http://njdtechnologies.net/040317/ (3/29 screenshot). However, the BCB TX and SDR RX risk introducing artifacts, see: http://njdtechnologies.net/040317/ . If the screenshots do show artifact, today’s blog at least offers a possible analysis method to use when well equipped stations may gather more reliable data someday.
**ENDNOTE 2: At 600 KHz 500m, frequency f=0.600 x 106 Hz. Terminator westward velocity v at 35°N latitude based on rotation of earth circumference in a day compared to speed of light c leads to maximum Doppler Δf = (v/c)f = v/λ = 0.600 x 106 Hz [(40×103km cos35°) /86.4 x103 sec)]/(3×105km/sec) = 0.758 Hz = 758 mHz. Terminator velocity v was 22.75 km/ minute. Doppler is reduced by the ratio of horizontal distance between midpath and actual sunrise E-region reflection point divided by ~100km E-region height. That ratio may be 0.3 or less. ARGO QRSS600 mode can resolve 20-200 mHz departures.
***ENDNOTE 3: Let TX-RX ground distance be D and sky wave path length be L. L = L1 + L2, the sum of the sky wave ray line lengths based on horizontal distance D/2 + X from TX to E-region at altitude Y and then horizontal distance D/2 – X from E-region to RX. L1 = SQRT[(D/2+X)2+ Y2] , and L2 = SQRT[(D/2-X)2+ Y2] .
Now assume whatever sunrise E-region profile Y(X1) is time-independent. As time passes after onset of frequency departure f(t) of 1st illustration, a profile position X=X1-vt moves westward as viewed on the ground even though it corresponds to a same given spot X1 on the time-independent profile.
Profile tilt angle T is clockwise from horizontal at profile point (X1,Y), see its formula and graph at http://njdtechnologies.net/040417/ .
A small altitude change ΔY = – ΔX1 tan T. The ground position change affects ΔX1 = ΔX+vΔt, so ΔY = – (ΔX+vΔt) tan T and vΔt = 22.75km at my latitude 35°N.
Path length change (km) in 60 seconds is ΔL(t) = – 60 λ f(t) / 106 where λ is wavelength in meters and f(t) is evolving frequency departure in milliHertz from the first illustration. (At 600 KHz, every 10 mHz of frequency departure corresponds to 0.3 km of path length change each minute.) Each row in the spreadsheet stands for a minute of time t. The process hunts in each row for ΔX(t) based on the frequency departure in the corresponding minute of time to reduce an error epsilon ε to less than 0.0001 km:
ε = 60 λ f(t) / 106 + SQRT[(D/2+(X+ΔX))2 + (Y+ΔY)2] – SQRT[(D/2+X)2+ Y2]
+ SQRT[(D/2-(X+ΔX))2 + (Y+ΔY)2] – SQRT[(D/2-X)2+ Y2]
where ΔY = – (ΔX+vΔt) tan T.
I performed the hunt manually since it wasn’t apparent how to automate it on the spreadsheet. The Excel spreadsheet auto-updated all other numbers and error ε based on my choice of three-decimals ΔX. Then I line graphed the final Y(X1) for the 2nd illustration. (Copy of spreadsheet is available on request.)
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).