Last night the central US and Midwest was inundated with raucous storm QRN from a storm system that really didn’t look that impressive at the time. I could not find an adequate null until well after bedtime and by then the intensity of the system began to diminish for the night. Stations on the East and West coasts may not have had much awareness of this QRN source based on reports.
Propagation was great, however, at least domestically, and there were a number of new stations listening during the session, including W1GJM, NM5SW, and VE3046SWL. In spite of the noise, there were quite a few active stations over night.
Geomagnetic conditions have been quiet to unsettled through the session with a Bz that is pointing slightly to the South. Solar wind velocities have decreased below 500 km/s in the last few reporting periods. DST values are trending to less negative values at this time:
Phil, VE3CIQ, reports “…better conditions here, was heard by ZF1EJ first time in months. Best decode was WH2XXP at -7, followed by WG2XIQ at -12.”
Doug, K4LY / WH2XZO, had some big reports overnight and provided these comments:
“Less QRN and better conditions here in the southeast despite the hurricane churning south of us. The +4 SNR from ZF1EJ was tops for the season; the VE6JY decode maybe the first ever, the seven decodes from Hawaii a seasonal high, WG2XIQ peaked seasonal high of +2, and conditions to VE2 and New England good, too. Totals were 8 heard, but only 21 copying XZO, so activity was down a bit from recently.”
Roger, VK4YB, reported a “pre-code 3” but later revised to “code 5”, and reporting “Noise is low but condx are fairly flat.Most reports in the mid to high twenties and no sign of spotlighting. Very similar to last night but down a little…I will put the North West beam on and see if there is any path to JA.”
“Tx 6*ve6jy (-24) 9*wh2xgp (-21) 11*w7iuv (-20) 6*ve7bdq (-21) 10*ve7sl (-25) 3*wd2xsh/20 (-24) 2*kl7l (-26) 3*we2xpq (-27) 33*wh2xcr (-3) 2*ja1pkg (-28) 1*ja1nqi-1 (-26)
Rx 14*wh2xgp (-21) 21*wh2xxp (-16) 22* wh2xcr (-13)”
Roger added, “Looking back one year: Oct 5 2015. was “Best day of year so far” 143 TA spots. Very different this year.” I am convinced this is the result of so much activity in Europe. We are literally victims of MF WSPR’s success as so many stations stack up on the same frequencies and operate high transmit cycles. It was suggested that North America operate WSPR below 475.700 kHz and Europe operate WSPR above 475.700 kHz. Where does that leave VK or JA? Success has its consequences.
Ward, K7PO / WH2XXP, was decoded by 44 unique stations including four VK’s:
Larry, W7IUV / WH2XGP, is operating with two receivers and two receive antennas once again. Larry was decoded by VK4YB and WG2XGJ and decoded VK4YB using the omni receive antenna. Under W7IUV he also decoded VK4YB on the western BOG:
Rick, W7RNB / WI2XJQ, reports that rain continues in his area but he is enjoying the new remote tuning ability. He adds that propagation seemed either the same or a bit worse and that wet trees to the East don’t help. He decoded seven WSPR stations and was decoded by sixteen unique stations. He was also decoded here this morning.
Larry, W7IUV / WH2XGP, reported that Joe Taylor recently posted some important reminder information about signal-to-noise and how that relates to reported values in the “JT modes” on the Yahoo WSJTGROUP. The excerpt is included below:
“Perhaps this is a good time to remind everyone that estimates of signal-to-noise ratios for very weak signals *always* have an associated (if unexpressed) uncertainty. When S/N is quoted in dB, this can have important consequences.
In a stochastic (noise-like) process, experimentally measured values will be scattered around the unknown “true” value; some will be pretty accurate, some too high, and some too low.
Suppose a signal’s true S/N (in the detection bandwidth) is equal to 1.0. In a series of measurements of that signal, some of the estimated (“measured”) values will be close to 1; some will be higher, maybe as high as 2 (or even more), and some will be as low as 0 (or even less). These are *linear* values of S/N: estimated ratios of signal power to noise power.
When the S/N is expressed in dB — a logarithmic scale — you quickly see the problem. A perfectly plausible estimated S/N=0.1 means that in dB, S/N_dB = -10 dB. At S/N=0 we get “minus infinity dB”.
Some people think it’s a big deal when they see a JT65 decode displayed with an estimated S/N_dB of, say, “-30 dB”. This is nothing more than a statistical fluctuation of noise and an illustration of the nature of logarithms. — 73, Joe, K1JT”
I recently made an inquiry to Hideo, JH3XCU, about the licensing status of JD1 on 630-meters as I developed a list of DXCC entities with access to 630-meters. The discussion migrated to the licensing process in Japan and he indicated that while there were a number of steps, the process is not insurmountable. In fact he provided the following list of stations that are currently permitted to transmit on 630-meters:
Its my hope that we will hear more of these stations in the near future. Hideo included a link to his Japanese-language website dedicated to MF in Japan: http://6212.teacup.com/472khz/bbs.
Jochen, DF1VB, reported that he was offering access via join.me to his receiver during the session. It was fascinating to see the operating perspective from Europe. His join.me portal, at least for this session, was accessible here.
This weekend maritime radio KPH will return to air under its original frequencies after a recent arrangement with the KPH license holder. In 2014 I copied them on 426 kHz during the Summer “Night of Nights” so I am excited to see an MF operation at what is hopefully a quieter time of year. The ARRL presents the story here and the Marine Radio Historical Society has specific details about the operation here.
As I reported earlier, it was a very noisy, miserable session to be an MF operator in Texas overnight. I took a hands-off approach again during the evening and overnight and ran WSPR. Listening improved by morning and my CW session was relatively quiet. My CW sked was somewhat fragmented as the other station had to troubleshoot a connection problem in real time so there was a lot of “what about now… ok what about now” during this one. It was a more conversational interaction than normal, however. I returned to WSPR at 1100z. My transmission reports for the session can be viewed here and my receive reports can be viewed here.
There will be no North American map breakdown of WSPR activity for this session due to two stations that absolutely made a mess of the dataset due to poor band selection and HF data pollution of the MF map. Better luck tomorrow? I hope so.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-African path.
Eden, ZF1EJ, had an absolutely fantastic session, with multiple reports from stations across North America, including VE3CIQ who reported earlier that he had not made it to Cayman since the Spring, and WH2XCR, who is on an awkward path. All of this in spite of a hurricane in the Caribbean / Atlantic region:
Laurence, KL7L / WE2XPQ, had a very similar session to the previous and absorption is not much improved. HF continues to be dead and only the path to VK4YB is fair:
Merv, K9FD/KH6 / WH2XCR, also had a very similar session to the previous, with plentiful VK and JA reports in addition to a strong showing along the West coast and receptions of stations in the eastern US:
Jim, W5EST, gets down to the numbers with this discussion, entitled “MAGNETIC LOOPS: ANTENNA AREAS AND DB COMPARISONS”
“Today’s TABLE compares various electrically small loop shapes. All entries assume the mag loop plane is vertical and has same wire size and number of turn(s). The comparisons provide fractional values F of loop area versus a circular loop. “dB Down(V2)” logarithmically compares the areas-squared for high-impedance preamps that respond to voltage.
Table column “dB Down(V2/Rmetal)” logarithmically compares the areas-squared adjusted for metal resistance when impedance matching the metal resistance to a 50Ω receiver. Rmetal varies in proportion to circumference of the loop shape.
The comparisons of various loop shapes are all sized allow the same circular loop to circumscribe them. The diameter of that circle coincides with a diagonal of loop shapes other than the triangles.
Comparisons, of course, depend on what you compare to. Doubling a square to make a 1:2 rectangle twice as wide as the square is worth +6dB, for instance. You also get +6dB by scaling up all sides of whatever shape by just 40%.
SNR may or may not improve with more loop output. If the example square loop’s output was already well above RX system noise, then widening the square may give 6dB more signal, but not 6dB more SNR.
Suppose you make a large triangular loop by suspending much of its wire from a high tree branch and complete it with a horizontal return. Even though the triangle shape is many dB down in the TABLE, its signal pickup may nevertheless approach or even exceed that of a small circular loop having diameter less than half the horizontal length of the triangle. (Resistively terminated loops like K9AY are not covered here, however.)
You get the same loop area regardless of orientation in its vertical plane. Orienting a square to make a diamond may give some advantage as simple perhaps as keeping birds from perching on it. Orienting a rectangle with the long sides up may fit a horizontal space at your QTH more conveniently than a loop with long sides horizontal.
In the TABLE the area fractions F and dB Down compare each loop shape to a circular loop. To compare dB of a second shape with a noncircular first shape, take F2/F1 to get the fraction and find dB as the dB difference (dB2 – dB1 ). For instance, using a center pole to give the loop some support at top and bottom converts a square to a hexagon, which gives a net benefit about +2dB (-1.6 –(-3.7)) in signal strength.
Comparative results may vary between different shaped actual loops due to differing average heights, cable distances and circuits between shack and antenna. Stray capacitances inherent to the loop geometry and to differing proximities to foliage, utility cables, and metal structures may affect comparisons as well.
TABLE: LOOP AREAS AND DECIBELS COMPARED TO CIRCULAR LOOP
Loop Type Area Fraction F dB Down(V2) rc rc(dB) dB Down(V2/Rmetal)
Octagon 0.90 -0.9 1.03 +0.1 -0.8
Hexagon 0.83 -1.6 1.05 +0.2 -1.4
Square 0.65 -3.7 1.11 +0.5 -3.2
Rectangle 3:4 0.61 -4.3 1.12 +0.5 -3.8
Rectangle 2:3 0.58 -4.6 1.13 +0.5 -4.1
Rectangle 1:2 0.51 -5.8 1.17 +0.7 -5.1
Triangle 1:1:1 0.41 -7.7 1.21 +0.8 -6.9
Rectangle 1:3 0.38 -8.4 1.24 +0.9 -7.5
Triangle 1,.7,.7 0.33 -9.7 1.31 +1.2 -8.5
Notes: For regular polygons with n sides, the area fraction F = (n/2π)sin(2π/n). For a rectangle with sides a and b, F = (4/π)/(a/b + b/a); and a diamond with diagonals a and b has half that fraction. “dB Down(V2)” is 10log10 F2 = 20log10F because antenna voltage is proportional to loop area and power is proportional to voltage squared.
A further factor rc (circumference of circle divided by circumference of loop shape) somewhat offsets dB by adding 10log10 rc to obtain a total “dB Down(V2/Rmetal)”. For the regular polygons rc = (π/n) / sin(π/n). For a rectangle with sides a and b, circumference ratio is
rc = (π/(2(1+(b/a)))√(1+(b/a)2). For a diamond with diagonals a < b, rc = (π/2)/√(1+(a/b)2).
For a triangle with side ratios 1:a:b, with both a, b< 0.71, then rc = π/(1+a+b).“
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).