I have a general question to better understand analysis of SSB ( RX Pass Band) signals displayed as waterfall, mainly on RX of night time/evening low bands (80m/40m) propagation.
(Sorry up to now no waterfall screenshots available yet. Anomality is only sometimes occurring, but not very short lived. Waterfall: The horizontal axis is frequency , the vertical axis is time and the brightness corresponds to signal amplitude received via any propagation mode (Skywave/NVIS/Groundwave, or mixtures) Modulation/ splatter become visible. The propagation effect I try to understand does not always occur. It is a "specially (modulated) signal pattern" , a vertical waterfall signal fine structure with periodic signal amplitude (brightness) minima and maxima lines. These lines are sometimes in SSB just straight down vertically with ca. 300 to ca. 400 Hz intervals (6 periods) . Digital signals seem to have more lines in RX Pass Band on the waterfall. Sometimes in the RX Pass Band these minima/maxima (QSB) lines are shifted right ( QRG >) Or at later observation times also may be left shifted (QRG<). I can rule out EMI of broad/narrow band nature. It must be due to propagation of the very observed signal Sometimes signature appears as " distributed cloud islands" in the vertical SSB PB waterfall band I observe for TX SSB Mode (e.g., 2.7kHz BW) in the RX waterfall display : 1. About 6 Periodic, straight vertical lines (periodic signal amplitude minima, which are darker), --normal propagation 2. About 6 Periodic, right shifted ( staring low f to higher f) vertical lines (signal amplitude minima) , --special propagation mode? 3. About 6 Periodic right shifted ( staring high f to lower f) vertical lines (signal amplitude minima) , -- special propagation mode? 4. The angle to the vertical axis seems to change often over time. Probably according to HF Condx/Propagation? 5. It seems to be independent of TX LSB or USB mode. 6. Digital signals have often more vertical lines 7. The angle to the vertical axis seems to change often over time, according to HF Condx/Propagation. 8. I have observed this effect also on day on 80m night time on a KIWI SDR only 12km away in hilly HB9 ( combination of NVIS/ groundwave?) Questions: 1. Is this an indication of Multi-Path Reception? May be with different propagation modes at that time over certain distances possible? 2. Is this therefore, e.g., based on delay times (phase/arrival time differences) of reflections from different ionospheric layers ( e.g. f1, f2 etc.) ? 3. Is this based on quasi simultaneous occurrences of skywave, NVIS and may be even groundwave mode ? Any comments or reporting of similar observations are greatly appreciated. PS: I observed this " shift effect" also sometimes for OTH-Radar (real or faked, yes some are faked, see my qrz.com under DQRM) signals recently on 40m, in EU late afternoon , night time here. Tnx, Cu, vy 73 de Andy HB9CVQ, DK2VQ, AK4IG <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
