This evening was characterized by more storms in the central US (and off of the Florida Atlantic coast!) either keeping some stations (myself included) off air or increasing the noise floor to uncomfortable levels. Additionally, quiet geomagnetic conditions would make one think that propagation should have been good or at least better than it was but it seems there was not enough spark to really get things going. As Steve, VE7SL, relates, “I think TP path thrives in a little solar wind kick”. And for that matter both trans-Atlantic and trans-Pacific openings seem to have their own specific levels and requirements for openings to develop which may be divergent for the other. Hopefully the solar minimum will bring enough energy for openings to develop but not enough to suppress them.
Geomagnetic conditions were quiet with a Bz that is pointing to the South but very low solar wind velocities that are averaging 390 km/s. DST values are approaching nominal values but continue at negative levels.
There was a discussion between Phil, VE3CIQ, and John, WA3ETD / WG2XKA, on the ON4KST chat/logger that seemed to suggest that VE3IQB was transmitting for the first time during this session. I was thinking that he had been transmitting in the past be he is not listed on the North American operators list (yet) and I have no record over the previous year of him being reported:
Roger, VK4YB, reported a very low noise floor but indicated that propagation was poor with only one decode of WH2XXP and WH2XGP by 1100z. He issued a “code 2” for the session. The trans-Pacific path did yield a few reports for Roger and others, however, including a late opening to JA. Roger indicates that “Several of those spots were off the side of my North East beam. First time that has happened”:
“Rx 3*wh2xgp (-24) 17*wh2xxp (-10) 22*wh2xcr (-17)
Tx 4*w7iuv (-26) 2*wh2xgp (-26) 2*ve7sl (-29) 1*wd2xsh/20 (-26) 1*wi2xbq (-29) 28*wh2xcr (-1) 10*jh1inm/1 (-19)”
Steve, VE7SL, reported this morning “Very odd condx TP … almost nil from Roger but 91 spots of Merv right down to -4. Not a peep from the east.”
Joe, NU6O / WI2XBQ, decoded Roger in addition to receiving reports from VK2XGJ. He adds that the path to the East in North America was down:
Larry, W7IUV / WH2XGP, felt like band conditions and propagation were down for the session but he is unclear whether that is due to high noise and reduced activity. He was decoded by 33 unique stations “including VK4YB, VK2XGJ, and several east siders but overall number of spots way down.” He adds that he operated two receivers during the session, each pointing West with different antennas. W7IUV was the other call sign used. Both arrangements decoded the same seven stations, including VK4YB, at near identical S/N level:
Ward, K7PO / WH2XXP, again received reports from fifty unique stations including five VK stations:
JH1INM/1 reported VK4YB, VK5FQ, and VK3ELV this morning:
Hideo, JH3XCU, reported VK3ELV and VK5ABN this morning:
Phil, VK3ELV, received reports from both receivers at 7L1RLL:
Rick, W7RNB / WI2XJQ, reports more rain but he decoded six and was decoded by eighteen unique stations:
Doug. K4LY / WH2XZO, was planning on testing a flag receive antenna versus the receive loop but there were not enough signals so I suspect that this test will be bumped to future sessions.
Two new stations were observed during this session: WA5ETV and KD4ADC. Welcome aboard. We continue to have a stations in the southeastern US that is having problems with band transitions and contaminating the WSPR dataset with HF reports. Hopefully that problem will be resolved shortly.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic or trans-African paths.
Eden, ZF1EJ, reports that he decoded WH2XCR at 1130z but the report did not post to the WSPRnet database. He additionally decoded stations in the southern US:
Laurence, KL7L / WE2XPQ, reported during the evening that he was beginning to hear a few stations on 30-meters, a first for several days. By morning, it seems obvious that absorption was very high, so high, in fact, that there was no QRN at all. Laurence adds, “After a long event its like a huge storage Cap up there with high R leakage – on 137 it can take weeks for recovery especially over the pole (Iono pse prove me wrong !)”. Remarkably a few stations did make it in and Laurence made it out on a few occasions. The “diode effect” differences between WE2XPQ and WH2XCR are interesting:
Merv, K9FD/KH6 / WH2XCR, did not see JA reports during this session but a healthy number of VK and West coast of North American reports. KU4XR in Tennessee decoded Merv and WH2XZO in South Carolina was decoded so the eastern path was open at lower latitudes. Merv also shared two-way reports with three different VK stations during this session, which is a relatively rare occurrence:
Jim, W5EST, presents, “ARE YOU RECEIVING 630M BAND NOISE, REALLY?”:
“To receive 630m well, your RX antenna needs to provide adequate signal-to-noise ratio SNR for the mode at hand. That’s relative to antenna’s received band-noise power confined as nearly as possible to the compass heading from which the signal arrives.
To obtain best SNR, how much more than the level of receiving system noise should the 630m band noise be? By “receiving system noise,” I mean the local QRN and receiver’s internal noise combined. In answer, I’d say the rms 630m band noise should exceed 3x (three times) the rms receiving system noise.*
How does one tell if the “>3x” criterion is met? That’s more difficult! One answer would tell us to put, in place of the antenna, a resistor (or some RL or RC circuit equal to antenna impedance) at the far end of the incoming transmission line. If the noise level drops about 10dB or more, or about 1½ S units,** then the criterion is met. The criterion is not met, then ensuring the transmission line has its shield securely grounded near the antenna may reduce local noise pickup sufficiently.
Unfortunately, that method is not foolproof. Why? Because the antenna itself may be picking up local QRN as well as 630m band noise. Local QRN sources may couple noisy displacement currents via the antenna’s own stray capacitances. The antenna cooperating with the transmission line may deliver common mode noise that reaches the 630m receiver. Noisy local magnetic fields may also deliver some local noise regardless.
Local QRN often has a different noise texture than 630m noise. AC wiring, motors, fluorescent lights, PC display monitors, TVs—they each have their noise “signature.” Local QRN may also vary in level and character by time of day, enabling you to better track it down. If it’s intermod from a local AM station, you can vaguely make out voice patterns or music in the mess.
What can you do after you have eliminated or mitigated local QRN sources that are within your control? Before the 630m RX antenna is put up, select a best feasible location by walking the property to find a low-noise spot with a handheld AM band radio set at high volume at the bottom end (~530 KHz) of the band.
Now established in a low-noise spot, an RX vertical or E-probe may work quite satisfactorily for you. If not, a magnetic loop antenna judiciously located there outdoors instead may beneficially shunt noisy electric fields. A loop has pattern nulls that can reject even some band noise too. Putting the antenna high up or low down near the ground—either way may help at your place. Stay safe in the process, of course. Consider lightning exposure as well when site-planning your antennas.
OK, you’ve done all that and the “>3x” criterion is still not met. Some people revise the antenna design and increase the length of the antenna or change the number of loop turns or loop diameter. They add a preamp outdoors ($$), or they remove it. As a last resort, a noise canceller may help. For that, you set up a small noise antenna near enough to the QRN source(s) and then at least partially cancel the local noise from the RX antenna with noise from the noise antenna by adjusting the noise canceller.
Like mountain climbing, things get ever more challenging as you approach the 630m SNR summit. For long-path 630m success that’s the place to be. If we haven’t blogged your most effective techniques or linked a blog post to your web site on this topic, let us know. GL on 630m!
*Suppose rms band noise developed by the antenna exceeds by at least 3x the receiving system noise that is uncorrelated with it. Then total noise power is 32 + 12 = 10 compared to the band noise power 32=9. 10log10(10/9) = 0.46dB. SNR will be diminished by receiving system noise by only 0.46dB, which is probably acceptable.
** On a receiver S-meter with 1 S-unit = 6dB, the noise level with antenna connected will appear to increase by 10log10(32 / 12) = 9.5 dB, which is about 1½ S units, over prior noise when an equivalent dummy impedance was substituted.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).