Paul, With each piece of data (your NAA/WH2XBA 3-day amplitude below) this becomes more interesting. Summarizing some previous discussion and thoughts: NAA amplitude and phase are stable and repeatab
"Antenna current is essentially constant during the transmission with negligible tuning adjustments" "Some little shift of phase and amplitude of the modes involved, altering the interference pattern
Alan, Good point regarding a possible additive process that could disproportionately affect a small signal; and I agree with all of your points regarding phase, and add that the repeatability of NAA
Paul, Thank you for the data and analysis. The WH2XBA/1 and WH2XBA/1 - NAA phase and amplitude plots are fascinating. Thanks to you and Bob for providing this valuable information (and great SNR!). T
Bob, Some information below on the effects of above-freezing and below-freezing temperatures on various VLF losses, including (a) ground-wave losses, (b) near-field ground effects losses and (c) skyw
Markus, I found a typo: At 30kHz, ground-wave loss in non-frozen soil of poor conductivity (10^-4 mhos/m) might be 20dB greater (20dB more loss) than in non-frozen soil of fairly good conductivity (1
Clemens, Not necessarily; two possibilities come immediately to mind: trapped surface wave and a change in the modal interference pattern (from phase changes due to ice and/or frozen soil, a change i
Markus, Thank you for the feedback. I have a feeling that with discussion, the group might make particularly quick progress on electrically short VLF antennas for long-range paths. It’s an area
Dumb question but just in case: was the quick phase change of 120 degrees corrected prior to integration? Jim AA5BW I think the propagation at 29.5 has changed, even though NAA looks normal at 24kHz.
Yes Markus, By some calculations, Bob’s signal is close* to being detectable 24/7 at Todmorden and often during daylight at your QTH, for the next two weeks or so. A 24-hour opportunity in Apri
Markus, I’m glad that you suggested a 2-hour time slot (if it works for Bob). Based on your NAA spectrogram (attached), the window that you’re shooting for may be a multimode interference
Bob, Rob Moore at the University of Florida has a wide network of VLF receivers in continuous operation. He would like to look for your signal tonight. I told him you'd be on 29499.0, is that correct
Markus, This is a welcome sight. Thanks to you and Bob. Was this detection made approximately ten minutes before Bob switched off? 73, Jim AA5BW From: [email protected] [mailto:owner
Bob and Markus, Thanks, this seems consistent with the shape of the late-night/early-morning amplitude characteristic in the LWPC simulation (for 43N, 75W to Todmorden) that Paul sent to the group on
Laurence, Very interesting plots. An eyeball-average of day signal strength compared to and eyeball-average of night signal strength seems like ~ +11dB (day to night) for the 12Mm NWC path, and ~ +8d
Your data seems generally consistent with Bob's intended switch-on time: in an early message he said he was switching off to go to dinner, and *intended* to switch back on at 2330. Jim I don't know t
Paul, Great data as always. I don't know the to-from polarity of your phase measurement; but: the slope of phase change and the slope inflection point at 04:30 look generally consistent with what the
Paul, Thanks for great data and analysis. Comment 1: based on a best-guess loose extrapolation from Davies (Ionospheric Radio) pp 382-383, the phase slope and total phase shift shown in your measurem
! Bob, how accurate is your frequency calibration? Jim AA5BW There is a strong signal received Todmorden UK 53.7N,2.07W at 29499.000 +/- 0.01 Hz. Begins around 00:30 UT +/- 15 mins and continues. Ver
