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Current Operating Frequency and Mode



Much improved propagation as geomagnetic storming conditions decrease allowing DH5RAE -> K4RCG, N4DB, K3RWR/3 and VK4YB -> WA3TTS plus others; W5EST presents, ‘Does 630m nighttime ionosphere show contour surface variation?’

– Posted in: 630 Meter Daily Reports, 630 Meters

The details for April 25, 2016 can be viewed here.

Reports suggest that North American QRN was significantly improved over recent sessions.  It was somewhat noisier in Oceania, however, but good propagation supported a number of long haul openings that have been impacted in some capacity over the previous few session.

11-hour North American lightning summary


Geomagnetic conditions continue to trend to quieter levels although the Bz continues to point to the South for persistent periods and solar wind has largely persisted above 600 km/s but has recently decreased to an average of 570 km/s.  DST values have improved, at least on paper, but persist at negative levels.




Joe, K9MRI / WI2XUL, inquired about JT9 or CW QSO’s during the evening.  Neil, W0YSE/7, helped Joe with details of accessing his remote receiver via join.me and WA3TTS may have also been listening for calls.  WG2XKA also reported that he would listen for Joe and call him on JT9 if heard.   I wish I had been active during this session.

Trans-Atlantic reports returned during this session for a German station after several day’s hiatus, allowing at least one receiving station to provide an all-time best distant report for his station.  Report details can be viewed here.

DH5RAE -> K4RCG, N4DB (station best), K3RWR/3

Ken, K5DNL / WG2XXM, reported that he decoded four WSPR stations and he was decoded by 41 unique stations including WH2XCR as his best DX at -4 dB S/N at a distance of 6007 km.

Neil, W0YSE/7 / WG2XSV, reported that he decoded seven WSPR stations and he was decoded by seventeen unique stations.

Dave, N4DB, reported that he decoded eight WSPR stations including first time DX reports and all-time station best report of DH5RAE.

Jim, W5EST, submitted these comments regarding the opening between WA3TTS and VK4YB:

“VK4YB-wa3tts singleton -26 at 19 min pre-SR 14986 km if g.c. Tx/Rx hdgs 59/~270. tts SR hdg 72, not far 20 deg off alignmt rx hdg”

Regarding the opening between N4DB and DH5RAE, Jim noted,

“Virginia had fb nite: dh5rae singletons 0322z middle nite TA midpath each n4db -27, k4rcg -26, k3rwr -27, k3rwr/3 -25. “

Trans-pacific report details, excluding KL7 and KH6, can be viewed here.

Hideo, JH3XCU, posted links to two tables showing VK -> total JA DX  and VK -> JA peak S/N for the session.

Roger, VK4YB, reported, “QRN was lowish at the start of the session but slowly increased to moderate. Ken, WG2XXM was not in the log and there were only 2 spots of Larry WH2XGP. While Ward, WH2XXP only eached -18, which is modest by his standards. So the only joy was on the transmit side. There were widespread and prolific reports.  The icing on the cake being a -26 S/N from Mike, WA3TTS. There were reports from other stations that I think also may be first timers for me.”  Roger received reports from 7L1RLL4, JA3TVF, JR1IZM, K6RRR, KR6LA, N6RY, VE6XH, VE7BDQ, VE7SL, W7IUV, WA3TTS, WE2XPQ, WH2XCR, WG2XSV, and WI2XBQ.  Jim, W5EST, wonders “VK4YB-k6rrr, n6ry, kr6la, new vk 630m decodes?”

Ward, K7PO / WH2XXP, received reports from 49 unique stations including  VK4YB, VK2XGJ, ZL2AFP, and ZL2BCG.

WH2XXP session WSPR activity (courtesy NI7J)


Larry, W7IUV / WH2XGP, provided reports for six WSPR stations and was reported by 34 unique stations including VK4YB, ZL2AFP, and ZL2BCG.  As W7IUV, Larry provided reports for seven WSPR stations including VK4YB and he notes that while using the western receive antenna, he “…decoded Roger 20 times, best -18, and last at 1234Z abt 20 mins b4 sunrise 12.”

WH2XGP session WSPR activity (courtesy NI7J)


Mike, WA3TTS, provided reports for eight WSPR stations including VK4YB.  Mike notes, “Really strange no XCR decodes along with VK4YB overnight.”  Mike posted these extensive comments on the LOWFER reflector:

“John & All:  Rather astonishing decode this morning on my NW EWE antenna which is my lowest background noise direction pointed at 300 degrees, VK4YB at -26 1006 UTC.  Bearing to VK4YB is 270 degrees, so there is only 1/2~1 dB difference versus middle of main lobe on the EWE cadio pattern.

No WH2XCR decodes overnight which seems strange, so perhaps a different propagation mode or reflection angles and iono height. I was thinking I might have a chance of an XCR decode overnight with the lower QRN and post geomag quiet conditions.
But only VK4YB and XGP for best overnight DX….
Last week I did change over to a new pair of antenna matching transformers on my other NE/SW EWE which is more or less orthogonal..  I had a pair of larger type 75 core binocular transformers on the NE/SW antenna which had low loss (1dB range) at 10 kHz.   Anyway, I had been concerned about system imbalance and the potential effect on common-mode noise ingress,  so I went back to the same transformer design used in the NW/SE EWE antenna which I decoded VK4YB on overnight.
That transformer design is a set of 4 BN73-202s glued together end to end which are 3T/10T.  The back-to-back insertion loss was very low and was difficult to measure with high accuracy at the time (2013).  A the time I only had a Wavetek signal generator and CA-91 RF voltmeter and back-to-back transformer insertion loss was around .1dB for the pair as far as I could tell.  I will have to make some measurements with my HP3586c over the weekend and make a better determination of the insertion loss on the 4-core BN73-202 transformers.  I also want to IMD test those transformers as well, but that takes a bit more effort….
Once I have some solid and recent data, I will elaborate more on the antenna transformers if there is interest.  That was the only recent change to the antenna system here. There is a chance my common mode noise situation improved slightly, or there may be no change at all. It’s to early to say.   The VK4YB decode could be just a fluke of propagation and local weather  and not anything I did on this end of the communication link hardware…”


Roger, VE7VV, posted sage advice on the topic of radials on the 600-meter research groups email reflector in response to a question and his response can be viewed here.

Regional and continental WSPR breakdowns follow:

North American 24-hour WSPR activity


European 24-hour WSPR activity


Japanese 24-hour WSPR activity


Australian 24-hour WSPR activity


Eden, ZF1EJ, provided reports for four stations and he was reported by 24 unique stations including VE7SL in British Columbia and two-way reports with WH2XCR.

ZF1EJ 24-hour WSPR activity


Laurence, KL7L / WE2XPQ, reported that high latitude propagation was “still poor overall but water paths still there (thank you Salt Water).”  Laurence indicates that he was not transmitting last night but he provided reports for a few stations in the western US.  He also provided reports for VK4YB and WH2XCR on salt water paths.  Those report details can be viewed here.

WE2XPQ 24-hour WSPR activity


Merv, K9FD/KH6 / WH2XCR, received late reports from ZL which has been atypical on the approach to sunrise.  He also received VK4YB after ZL reports ended, which is a much more common event.  Merv shared two-way reports with VK4YB and ZF1EJ and provided reports for VK5FQ.  The path to JA is cut off once again but he received reports from WE2XPQ, VK2XGJ, ZL2AFP and ZL2BCG.  Report details can be viewed here.

WH2XCR 24-hour WSPR activity



“‘Probably yes,’ I’d say. Indeed, the 630m nighttime ionosphere is probably less smooth some places and some times than at others. Microfrequency departures on the scale of as much as 60 mHz (+/-.06 Hz) provide the evidence. (Endnote 1*)  As a general matter, moreover, it’s unlikely that natural structures on this scale would be perfectly smooth.

Recently, this blog pictorially oval-outlined some of these microfrequency departures. http://njdtechnologies.net/042117/  (Pics 1 and 2).  The article discussed 1-Ehop and 2-Ehop nighttime reflection concepts

The larger departures in frequency are probably caused by double hop encounters with the contour surface variations of the reflecting E-region on this very short path. The reason is straightforward.  Double hop propagation encounters the ionosphere in two places. At least sometimes the two places where double hop reflections occur are both increasing in altitude at the same time or decreasing in altitude at the same time. Then the rate of change of double hop path length is maximum, and indeed about 2.5 times the rate of change of one-hop path length (Endnote 2**) due to mid-path reflection of one-hop on the short 219 km receiving path tested.

Microfrequency departures in Hertz are proportional to the rate of signal path length change per second, divided by the wavelength.  If double hop is responsible for 60 mHz frequency departure, than single hop encounters with the same varying contour surface would generate only about 24 mHz at most.  One can see some nighttime broadening in frequency relative to the line imagery for daytime ground wave.  I attribute such slight nighttime broadening in frequency, as a general matter, to single hop encountering the ionosphere. But beyond that, it’s hard to take measurements on such broadening, while one can do so with the microfrequency departures that I attribute to double hop.

3-Ehop propagation would provide even more micro frequency departure if it were not for the additional ground surface reflection losses that make three-hop propagation even more difficult to observe than double hop.

There’s a reason I put such emphasis on the example 219 km path on 600 KHz between Memphis in Little Rock, despite the fact this blog serves readers worldwide who are interested in continental and even intercontinental paths on 475 KHz.  I presume the ionosphere is nearly the same ionosphere regardless of path length in regional and continental-size mid-latitudes. Even so, the microfrequency departure on a lengthier path is likely smaller and weaker to observe than on a much shorter path. For instance, double hop microfrequency departure is about 3.6 times as much on that 219 km path compared to a 2000 km path and about 4 times as much as 1-hop in the paths comparison. (Endnote 3***)

Can we say whether the microfrequency departures reveal motions in the ionosphere relative to the ground surface far below?  Perhaps the ionosphere’s varying 630m contour surface gets moved horizontally by winds. That way, places of reflection in the ionosphere would move, especially up or down, then the RF signal path length would change at a given rate that would lead to a microfrequency departure. Perhaps the contour surfaces get moved instead, or in addition, by updrafts and downdrafts. Perhaps pulses or waves of compression and rarefaction occasionally move through the nighttime E- region here. If so, such waves would move at the E-region’s speed of sound. Somehow the ionosphere’s 630m-reflective contour is moving at single hop and double hop points of reflection.  Beyond that, the subject must await another day or another person to address.  TU and GL!”

*ENDNOTE 1: For nighttime microfrequency departures at 600KHz (λ=500m) see screenshots: http://njdtechnologies.net/032817-2/    (3/27 screenshots)

http://njdtechnologies.net/033017/  (3/28 screenshots), http://njdtechnologies.net/040317/ (3/29 screenshot).  In such tests beware in case BCB TX and SDR RX create artifacts, see: http://njdtechnologies.net/040317/ .

**ENDNOTE 2:  To figure the ratio Δf2 / Δf1  of maximum microfrequency departure for 2-hop to that for 1-hop, first recognize that microfrequency departure Δf in Hz is:

     Δf (Hz) = (1/λ)(dL/dY)(dY/dt) 60sec/minute

meaning the calculus derivative of path length in wavelengths with respect to altitude Y, then multiplied by the rate of change of altitude Y with respect to time in minutes.

So the ratio of microfrequency departure for hop mode m=2 to that for m=1 is equal to a ratio of derivatives of mode-specific path lengths with respect to altitude Y:

          Δf2 / Δf1  = (dL2 /dY) / (dL1/dY)

Omit dY/dt  because sooner or later in the night, I presume the 1-hop reflection will encounter a maximum E-region contour altitude rate of change dY/dt that’s nearly the same as the 2-hop reflections do. In the ratio, dY/dt then cancels out.

Now let’s get the mode-specific path lengths. For maximum 2-hop overall path length rate of change I assume reflection points at equal altitude Y, say 110 km. Length L for hops mode m and total ground distance D = 219 km on spherical Earth with radius RE = 6371 km is:

Lm = 2m SQRT{[Y+ RE(1-cos(D/(2mRE))]2 + [RE sin(D/(2mRE))]2}

     Derivative dL/dY of path length turns out to be:

dL/dY = 2m sine of ray elevation angle to horiz. at altitude =

       2m/SQRT{1 + [RE sin(D/(2mRE))]2/[Y+ RE(1-cos(D/(2mRE))]2 },

or,  2m/SQRT{ 1 +  (D/2m)2/[Y+ (D/2m)2/2RE]2 }

    The ratio Δf2 / Δf1  = (2×2 /SQRT(…)2) / (2×1 /SQRT(…)1).

The ratio is 2 with an adjustment factor value after plugging in all numbers for Y, D and RE that yields about 2.5, from:

=  [2×2 / sqrt(1+ 552/(110+ 0.24)2 ] /[2×1 / sqrt(1+ 109 2/(110+ 0.93)2 ]

 = (4 / 1.12) / (2 / 1.40) = 2.5 times more freq departure.

***ENDNOTE 3: Now go through Endnote 2 except take a ratio of microfrequency departures with mode m=2 in each instance but path distance D being 219 and 2000 km in the same formula for comparison.

  Δf2(D=219km)  / Δf2(D=2000 km)

       =  (dL /dY) [m=2, D=219] / (dL/dY) [m=2, D=2000]

 =  [2×2 / sqrt(1+ 552/(110+ 0.24)2 ] /[2×2 / sqrt(1+ 5002/(110+ 19.6)2 ]

 = (4 / 1.12) / (4 / 3.99) = 3.6 times more freq departure.

We can expect only 17 mHz frequency departures on a 2000 km, 2-Ehop.  Meanwhile, for one-hop

      Δf1(D=219km)  / Δf1(D=2000 km)

=  [2×1 / sqrt(1+ 1092/(110+ 0.93)2 ] /[2×1 / sqrt(1+ 10002/(110+ 78.5)2 ]

= (2 / 1.40) / (2 / 5.4) = 3.9 times more freq departure or about 6mHz on the 2000km 1-Ehop path.  So the 2000 km path is not very useful for distinguishing 2-hop from 1-hop nor for assessing ionospheric contour variations with current or soon-foreseeable equipment.

Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).