This session seemed like it was not quite as good as the previous although the band opened early here in Texas with reports of W5OR / WD2XSH/15 in Little Rock, Arkansas. Terrestrial weather systems had subsided significantly compared to the previous session except for a small, active storm in southern Missouri and a large cluster of storms generating almost constant lightning in Virginia. Reports were generally consistent with necessary signal levels for JT9 QSO’s but many of the better equipped receiving stations were very close to the storms in Virginia so while propagation may have actually been good, the noise may have masked that fact. I also reported the inability to null some stations during the early portion of the session, typically indicative of somewhat disturbed conditions.
Geomagnetic conditions were reported as quiet and the Bz was pointing solidly to the North but the solar wind velocity was in excess of 600 km/s during much of the session.
Rick, W7RNB / WI2XJQ, near Seattle, Washington receive his grant yesterday and began testing his station by running a CW beacon on 473.9 kHz. Steve, VE7SL, located 86 miles away reported that Rick was S9 and provided the following recording from the afternoon:
Toby, VE7CNF, reported intermittent receptions of Rick’s signal and Neil, W0YSE/7 / WG2XSV, reports a signal in ARGO while monitoring in QRSS3. It seems like the signal below belongs to Rick, at a distance of 145 miles from Neil:
Max, IK0VVE, operated QRSS10 on 476.176 kHz during the session. No reports have been filed at this time.
Phil, VE3CIQ, reports that he decoded WG2XKA, WG2XXM and WH2XGP operating WSPR and was decoded by SWL/K9, VE2PEP, W8RUT, WA3TTS/2, WG2XJM, WG2XKA, and WH2XZO during the session.
Steve, VE7SL, reports a bad night for the East / West path, decoding six WSPR stations and being decoded by seven unique stations.
Larry, W7IUV / WH2XGP, decoded eight WSPR stations and was decoded by seventeen unique stations. Larry notes that the recent data has been very confusing.
Ken, K5DNL / WG2XXM, reports that he decoded three WSPR stations and was decoded by 24 unique stations including six Canadian stations.
John, VK2XGJ, reports that he would be monitoring JT9 in parallel with WSPR during this session since many stations in North America have been operating JT9 in beacon mode during the overnight period. John reports that he was using the Icom R71a with Mini-whip “#2” while WSPR was decoded by the Kenwood R5000 and Mini-whip “#1”.
Neil, W0YSE/7 / WG2XSV, reports the following raw JT9 statistics for John, VE7BDQ:
Neil also noted that he decoded the following WSPR stations: VE7BDQ, VE7CNF, VE7SL, WG2XIQ, WG2XXM and WH2XGP. He also was decoded by VA5LF, VE7BDQ, VE7KPB, VE7SL and WH2XGP.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic, trans-African, or trans-Equitorial paths during this session.
In the Caribbean, Eden, ZF1EJ, returned with reports for WG2XXM and WG2XIQ:
Laurence, KL7L / WE2XPQ, reports that he was operating JT9 through the session as he continues to shake-down the new transmit system.
On the surface, Merv, K9FD/KH6 / WH2XCR, had what looked like a typical session. Spot counts and S/N levels were down, however, compared to the previous session. Most of the reports with Australia were from earlier in the session although a few were recorded as sunrise approached KH6:
Jim, W5EST, presents, “STORM NOISE AND POWER CIRCLES ON THE SNR BULLSEYE DIAGRAM”:
“Today’s discussion shows how an SNR bulls-eye diagram is augmented to show additional concepts.
On a 24-hour bulls-eye diagram in the accompanying illustration, let’s consider relative path losses on a hypothetical stormy night in late September into AC0ZL in Colorado from 1 watt WG2XKA in Vermont and 5 watt WG2XXM in Oklahoma.
First of all, the jagged inner blue SNR line and inner red SNR line respectively follow the course of WSPR SNRs (or half-hour median SNRs if you prefer) being hypothetically decoded at AC0ZL (CO) from WG2XKA (VT) and WG2XXM (OK) on the stormy night.
Since the SNRs that “would have been” without any storms are unmeasurable for that night, one can rough-in SNRs on the same path for another night that was storm free. Propagation conditions can vary from night to night, and this diagram is mainly conceptual and illustrative. In between the stormy and storm-free SNR curves, I have shaded the deleterious SNR effects of the storms.
Next, what about relative path losses into the same antenna? First, draw what I call a power circle for the dBm of each transmitting station—30dBm “radius” for XKA and 37dBm “radius” for XXM. As long as each TX power and TX antenna gain on its TX-to-RX path stay the same, they are independent of time and simply establish circular curves that follow the 24 hour clock. If a station’s transmitter power is changed or turned off or the TX antenna pattern is switched to another heading, then the power circle for that station becomes stepwise segmented–it begins to look like pizza wedges instead of a circle.
The radius of a power circle need not be to scale. But when multiple power circles are entered, it’s convenient to make their radius difference in dB be to same scale as SNR differences between the SNR reference circles farther in toward the graph center. Accordingly, the power circles for XXM and XKA are shown with the radii of those power circles 7dB apart, to same scale for comparison with the 10dB differences of successive SNR reference circles -40 -30 -20 -10 0.
Second, I draw radial arrows in red and blue to have respective lengths that time-dependently indicate a loss-related quantity. The radial arrows take you from the red 30 dBm and blue 37 dBm EIRP transmit levels down to their corresponding inner red and blue WSPR SNRs reported by the antenna/receiver/decoder system at AC0ZL as the curves hypothetically progress through the stormy night.
For WG2XXM, the hypothetical blue SNR curve shows some decodes along the XXM-AC0ZL path during the early and late daytime as well. The early and late daytime segments of such SNR curve of the daytime decodes, to the extent they occurred, are then connected by a conceptual blue joining line below the WSPR decode threshold and going from -30dB SNR down to nearly -40dB and back to -30dB during the daytime. Someday, perhaps the actual deep diving daytime SNRs on 630m can be measured accurately.
For these approximate pictorial purposes, I ignore differences between XKA’s and XXM’s transmitting antenna azimuth patterns and whatever receiving antenna azimuth pattern differential exists at the AC0ZL receiving antenna between the headings at which XKA and XXM lie.
Purists would rightly throw up their hands at the imprecision of this approach. Understand that path loss is not the difference between TX dBm and WSPR SNR. There’s at least an additive constant that would be needed to account for the antenna gains and to convert EIRP dBm to a form that’s commensurable with WSPR SNR. But at least one is able to do some back-of-envelope visual thinking with a graphical tool of this type.
The difference between the radial arrow lengths is what eliminates the additive constant and takes account of the difference between XKA and XXM TX power to provide some picture of comparative behavior of the 630m paths themselves (XKA-ac0zl and XXM-ac0zl) as time elapses during the 630m night. Then by hand, or with an app, one would plot that progressively varying arrow-length difference to compare the path performances through the night going into the RX destination.
Earlier this year, I posted some formulas for propagation potential difference (Jan. 31-Feb. 1, this blog) and a ratio-of-number of decodes method K4LY offered. You may have still other methods and web sites you use to represent and even dynamically visualize what goes on with 630m. Tell us about your favorites. Improve on these techniques and let’s blog your methods. TU and GL!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!