I thought the evening was very quiet as I tuned the band from Texas but this morning has brought significantly higher noise levels from storms in the upper Midwest. As I write this and call CQ on 474.5 kHz I just can’t wait for sunrise in that area of the country!
Propagation was good, at least here in Texas, and receiving, particularly of stations in northern areas that have recently been impacted by the poor geomagnetic conditions, was the best its been in over a week. Part of that may be the fact that many of the stations in the Pacific Northwest and British Columbia that were recently effected by heavy weather are now back on the air.
Geomagnetic conditions had been quiet through much of the day yesterday but a surge in the late afternoon brought storm levels again with solar wind velocities peaking over 700 km/s. The Bz has been variable but is currently pointing to the South and the storm conditions have decreased to unsettled levels but solarham is reporting that G2 storm levels are possible for the next 24-hours. While decreases in DST values have been observed, at least at this point the mid and lower latitudes seem to be mostly unaffected by this most recent activity. I expect this is not the case at high latitudes, however. Reports from WE2XPQ may be more interesting than normal today:
WD2XSH/17 was fortunate to catch G8HUH and DK7FC during the evening, following the return of the storm conditions:
Doug, K4LY / WH2XZO, reports “…Pretty noisy for lightning so far away. And conditions returned to fairly disturbed. Heard 8 and heard by 26…”
Ken, K5DNL / WG2XXM, reports that he was decoded by 44 unique stations including three VK stations. Ken adds, “158 decodes fm VE6JY best -3 @ 2378 km.”
Steve, VE7SL, reports ten decodes for Roger,VK4YB, down to -20 dB S/N but a WiFi problem prevented those from being reports in the WSPRnet database. Five additional reports were uploaded this morning, detailed below. Steve also indicates that it was too noisy for DX CW.
Roger, VK4YB, issued a “code-5” for the session at 1050z. He reports that the storms that were expected to cause significant QRN in Queensland had already passed and were not creating many problems for his operating. He received first time reports from W0AY and WH2XNV. Roger’s statistics follow:
“Rx 21*wg2xxm (-20) 41*wh2xxp (-15) 5*ve7bdq (-21) 33*wh2xcr (-15)
Tx 1*ve6jy (-28) 1*wh2xnv (-22) 1*w0ay (-30) 2*va7mm (-29)15*ve7bdq (-22) 3*wi2xjq (-28) 15*ve7sl (-26) 40*wh2xcr (-9) 8*jh1inm (-23) 3*ja3tvf (-26) 4*zl2bcg (-17) 1*va7bbg (-26)”
Ward, K7PO / WH2XXP, reports that he was decoded by 53 unique stations including six VK’s and ZL1BCG. Ward adds that no JA’s were reported in Arizona today:
Phil, VK3ELV, received more reports from stations in JA late in the previous session and added ZL2BCG to the list with early reports during this session:
Neil, W0YSE/7 / WG2XSV, is back on the air and had a good session at QRP levels. He provided the following statistics and comments:
Rick, W7RNB / WI2XJQ, reports that weather is returning to normal again and damage to antennas have been repaired so he was back on the air overnight. He decoded VK4YB five times over night (previously reported) and indicates that it was a quieter night than the previous. He decoded seven WSPR stations and was decoded by sixteen unique stations:
John, VK2XGJ, reports that WH2XCR and WH2XXP were both reported prior to his local sunset at 0812z:
John also decoded VE7BDQ five times during this session. John indicates that he first decoded VE7BDQ last August:
This morning’s CW activity from my station did not yield any additional reports or QSO’s. My CW skeds will resume tomorrow once the other stations that I QSO each day returns from travelling later today. My WSPR transmission reports can be found here and my WSPR reception reports can be found here.
At 0200z I observed 90 MF WSPR stations on the WSPRnet activity page. While there was at least one instance of a band error contaminating the North American dataset, its my belief that there were over 100 MF WSPR stations reported later in the evening as I visually filter the WSPR maps for the reporting period.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-African path. Stefan, DK7FC, reports that FR5ZX is returning to reunion after a stay in France with a large amount of hardware in hopes to improve his performance on MF and he should be active once again in the near future.
Eden, ZF1EJ, received a nice assortment of stations across North America in addition to a report for WH2XCR in KH6:
Laurence, KL7L / WE2XPQ, reports continued high winds with freezing temperatures during this session. He continues to operate in a “receive only” capacity but reports that he lost power around 1000z:
Merv, K9FD/KH6 / WH2XCR, found his way out of the slump from the previous session, with numerous reports from the Caribbean, North America, Australia, and Japan. He was approaching CW-levels here this morning in the 0900z-hour but QRN was increasing from storms in the upper Midwest. Merv decoded WH2XZO in South Carolina and received reports as far East as WG2XJM and WA3TTS in Pennsylvania and ZF1EJ on Cayman.
Jim, W5EST, presents “NOISE CANCELLING: GETTING THE LAST BIT OF NOISE OUT!”:
“Generally a noise canceller varies each of the noise phase and noise amplitude approximately linearly to effectively achieve a subtraction from noise accompanying the signal. Local noise cancellation is discussed at: http://njdtechnologies.net/052816/
Unfortunately, a noise antenna may not often deliver an exact scaled replica of the noise that needs to be canceled from your primary RX antenna. Even if the noise antenna and a noise canceler circuit may null the vast majority of the local noise power content from the primary RX antenna, a small residue of noise power is likely to remain.
SNR(dB) responds logarithmically to the declining noise. In percentages, as shown in Figure 1, that means if all the noise in the main antenna were theoretically cancelable, then canceling 90% and leaving just 10% of the noise power gives you 10dB SNR improvement.
Canceling 9% more to leave 1% of the original noise power yields another 10dB SNR. Local noise cancellation, say 25dB more or less, is very beneficial, but it may be about all your noise canceler employing a noise antenna can deliver. (In the SNR improvement process, some unavoidable moderate cancellation of the signal itself by the noise canceller may also occur. So this discussion is approximate.)
If you could just eliminate as little as 0.9% more noise power, you could get still another 10dB SNR! At some point, you are tantalized like a dog chasing its tail! Any amount of effort you expend on repositioning and improving the noise antenna to eliminate some more noise power simply fails to employ some other scintilla of noise power that before had been included in the nulling process.
When this point is reached, the noise antenna is delivering sufficient noise power for cancellation purposes, but the noise antenna’s noise is not sufficiently correlated with the noise in the primary RX antenna. If it were perfectly correlated, the noise waveforms could be phased and scaled to perfectly cancel out the noise from the primary RX antenna using the noise antenna.
The only ways to entirely get rid of local QRN seem to be: Stop it at its source or locate the main RX antenna sufficiently far from the QRN source to avoid it. If you can’t do any more than you already have done on either of those QRN projects, then what? You can still do plenty of useful 630m work and have lots of fun—indeed, a few dB of 630m nighttime band noise may show up after sundown and cover up some of your uncanceled local QRN. But beyond your reach may remain the weaker stations on cross-continent paths and the stronger stations on the most advanced long-paths.
That’s the bad news. Fortunately, some local QRN sources may do you a favor and turn themselves off at night. Also, WSPR and JT9 are digital modes. Even if SNR is not as favorable as you’d like, digimodes do decode a station at those times its SNR rises above the decode threshold.
Moreover, the 630m band provides a level of noise power in the signal bandwidth arriving from and with the same azimuth, elevation and polarization as the signal. Even in the absence of local noise, most receiving antennas unavoidably receive 630m sky wave noise from a substantial fraction of the sky.
Suppose you can cancel local noise power to about one tenth of the 630m band noise power relative to signal level, which may concurrently decline somewhat as you cancel noise. At that point, you don’t need to cancel further because the SNR is as high as it can be for that particular signal. Figure 2 shows how some example noise power cancellation percentages work in that situation. You can see the process reaching a point of diminishing returns.
If your local noise power is so strong and intractable that you just can’t cancel the local noise down below the sky wave 630m band noise, then you face the tantalizing conundrum described in this post. GL!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).