Activity was low during this session as only a few stations, mostly in the Pacific Northwest and British Columbia, were able to transmit through the entire session. The South and East were plagued with numerous short-lived storms overnight. One could make a full time job out of unhooking and hooking up coax during weather patterns like this. We will get through it.
The transcontinental path was open once again as WE2XGR/3 reported WH2XGP. This is a good sign as we have seen a few consecutive nights of this path opening in spite of unsettled geomagnetic conditions, which were observed during a single reporting period overnight. Protons are elevated and the Bz was variable. Solar wind velocity is elevated but continues at low levels below 400 km/s. The DST experienced a peak prior to a decrease during this event that led to unsettled conditions:
Phil, VE3CIQ, decoded VE3EFF on WSPR and was decoded by VE2PEP, WE2XGR/3 and WI2XFI.
Roger, VK4YB, notes “Very low noise -86dBm here in VK land. Lots of weak signals not normally seen. Can’t be poor propagation because spots have already been exchanged with WH2XCR.” Roger also had the following comments about signals not decoded but seen on the very quiet night:
“Hi John,Take a look at this screen capture.See the carrier at 475.685. It wanders around between 685 and 695.Tonight it was below Larry’s frequency.I was expecting his signal just above it.I only saw it once at 12:00. I knew it was him straight away.I went in the other room to check my second computer.Just to confirm he was transmitting in that period.He was, of course. I knew that.I was hoping for a peak after his sunrise but no luck.My next target would have been VE7SL.If the low noise continues, there may be some North American spots soon.73Roger, VK4YB”
Neil, W0YSE/7 / WG2XSV, experienced a much improved session and provided these comment and statistics:
Steve, VE7SL, reports that he decoded four WSPR stations and was decoded by six unique stations, including eight two-way decodes with WH2XCR. Steve adds that it was “Nice to see AL7RF in Reno listening.”
Larry, W7IUV / WH2XGP, reports poor conditions, decoding only three WSPR stations and being decoded by eight unique stations.
Ken, SWL/EN61, from Indiana, reports that he was “shut out” overnight with no stations decoded.
John, K5VGM, of Hockley, Texas near Houston was granted WI2XLJ. Similarly, Brian, WA1ZMS, was granted WI2XLQ, as he filed for his own grant outside of the ARRL’s 600-meter research group.
Regional and continental WSPR breakdown:
There were no reports from the Caribbean, trans-Atlantic, trans-African, or trans-Equatorial paths.
Laurence, KL7L / WE2XPQ, reports an OK session and its beginning to look more like Autumn in Alaska:
Merv, K9FD/KH6 / WH2XCR, took advantage of quieter conditions, sharing two-way reports with VK3ELV and VK4YB. VK2XGJ and VK2DDI also reported Merv in addition to stations along the West coast of North America and Alaska:
Jim, W5EST, presents “PART 4: THEORY JUNGLE SAFARI IN E & F LAYERS”:
“Below the gyrofrequency (~1.5MHz), , the Appleton-Hartree (AHL) formula surrounds us with a mathematical jungle! 630m is a perfect band for this “safari” because the Appleton-Hartree formula has lots of special cases that could possibly apply on 630m. To dig deeper, the illustration visually represents my spreadsheet results from Appleton-Hartree specifically for 630m to reveal how those special cases work there. Think of that graph depicting a weird tropical plant deep in the jungle!
475KHz is not low enough frequency to regularly propagate via D-layer by day as 2200m probably does. Both 630m and 2200m probably use the E-layer at night but show noticeably different behaviors. 475KHz is far below HF, where many journal articles and web pages assume their discussion and then go apply AHL at HF. 475KHz stands at a crossroads of physical processes that affect propagation in less-predictable ways. What happens to the E-layer at night as regards 630m propagation and polarization? And in what seasons, at what latitudes, on what paths? 630m is a frequency venue that begs for experimentation!
The strategy of the illustration holds operating frequency constant at 475.5KHz and sees how a lossless GMF-permeated ionized region varies in refractive index-squared (n2) as plasma frequency goes up with altitude from 125KHz to 475KHz.
The E-layer confronts the RF signal wave with not one but two refractive index values n. They split the RF power into the O and X waves. The computed refractive index-squared values are that way, squared already, because that’s what Appleton-Hartree gives us. For X-waves (left), n2 is greater than 1.0, unlike HF. For O-waves (at right), n2 is less than 1.0, like HF. (On HF, the n2 values would be different and both under 1.0.)
Plasma frequency rises with the square root of free electron concentration. In turn, free electron concentration generally increases with height or meters of penetration by an ascending RF ray into an ionized region such as E-region. In short, the graph illustration on the vertical axis shows a proxy for height up into the ionized layer. Horizontally, the colored curves fan outward to indicate horizontal axis values of n2 corresponding to each plasma frequency. (Don’t confuse this graph with a ray trace in the E-region, even though O-wave curves do suggestively curve concave right.)
The n2 curves are paired and colored the same in each pair—X-wave at left and O-wave at right. The colors signify particular values of angle A between the signal ray and the GMF (geomagnetic field).
Total reflection of NVIS 630m RF waves occurs when n2=0. Refractive index in AHL apparently vanishes for both X-wave and O-wave at the same reflection height corresponding to sufficient electron concentration to make plasma frequency 475KHz. If the E-region nowhere has sufficient ionization make n2=0, then NVIS waves propagate to the F-region, where they are more likely to be reflected.
I do not know whether long path 630m ever actually reaches the F-region, or whether long path 630m does reach the F-region in some geographic places like the equator, or in some seasons of the year. E-mail us if you have information about this question.
Numerical angle legends for the color curves (navy, red, green, purple, blue, brown, gray) offer 0° 30° 45° 60° 70° 80° 90° as a shorthand for the full 0° to 360° set of angle possibilities. Read angles as +/-0° +/-30° +/-45° +/-60° +/-70° +/-80° +/-90° and add 180° to any of them to cover all other angle possibilities. (The reason you can do this is that AHL squares all cosines and sines in the formula.)
Can today’s graph help us understand 630m propagation better? What can it tell us about Faraday rotation? What does it imply for reflection of O-waves and X-waves? I have some ideas, but these topics need to wait for further study and another blog post. GL and keep up your 630m efforts!
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!