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 peak, which might be shifted (an hour or so?) for a Penn Yan path; and I don’t know which direction in time the window would shift. Paul is doing so many things that I hate to mention this, but I wonder if LWPC would show the interference peak near 1500 UT; and if so, which direction in time the peak would shift for the Penn Yan path. I seem to remember that Paul provided an online interface to LWPC, I’ll see if I can find it. 73, Jim AA5BW how about a straight carrier on 29.499, from 14 to 16 UT? The narrow grabbers will be on even if I have to be away. Results may depend on the qrn situation here (aka Eu weather). Sent: Friday, March 07, 2014 10:29 PM Subject: RE: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial Freq...
Markus;
With you home [not at work] tomorrow lets try around that 1500. I left the signal on two nights ago till 1200 but after 0800 signal was gone till 2400 next night.
What mode and what time you want signal? Bob
From: [email protected]
To: [email protected]
Date: Fri, 7 Mar 2014 21:45:19 +0100
Subject: Re: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial Freq... I would think that the main difference between Todmorden and Nuernberg is that I'm into the sunrise dip an hour earlier. And my noise background is higher, so I tend to completely lose a weak signal which Paul would still receive well. Anyway looking at the attached NAA plot I'm sort of perplexed by the strong propagation during the day. If Bob decided to transmit sometime around 15 UT, there's a good chance we'd pick it up. Sent: Friday, March 07, 2014 8:57 PM Subject: RE: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial Freq... 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 March 1, 2014: a smooth, fast transition (and particularly with minimal multimode peak/null effects). It’s interesting to note this characteristic (for this month, frequency and path), but more interesting to note consistency of Paul’s LWPC result with last-night’s data. I don’t think that the difference in paths from Bob’s location to Todmorden and to Markus’ location should make much difference in the shape of the late-night/early-morning amplitude characteristic, but I could be wrong. In another example of rough agreement between VLF models and test results in this group’s efforts (for roughly similar paths and times of year): the shape and magnitude of the phase characteristic measured by Paul (for 43N, 75W to Todmorden) overnight March 1st/2nd was consistent with a published model (Chilton 1964, based on empirical data) for a path of roughly similar land distance and water distance. The diurnal phase characteristic for paths of this length and orientation (43N, 75W to Todmorden) varies considerably month by month, so it was most interesting to see the close correspondence between Paul’s March 1st/2nd measurements and Chilton’s 1964 results for a different but analogous transatlantic path in early March. 73, Jim AA5BW Markus;
I closed at 0820 as I saw the signal went away at about 0700 on the Markus grabber. Had to be up early so couldn't stay on longer. Will stay on longer tonite-Bob
From: [email protected]
To: [email protected]
Date: Fri, 7 Mar 2014 11:37:49 +0100
Subject: Re: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial Freq... I dont really know when Bob switched off... On my grabber, the signal dropped sharply around 6 UT, thus the correlation peak was probably based on the first half of the sequence which ended 6:52. But on Paul's spectrogram http://abelian.org/vlf/sg29499.shtml the carrier stayed visible until after 8 UT. Sent: Friday, March 07, 2014 9:28 AM Subject: RE: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial Freq... 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 Just one detection here, but that makes it worth the effort: 2014-03-07 06:52:02 WH1XBA 6448km 29499.000Hz 1mHz -52.9dBOp 100% 15.3dB Out of the last four nights, this was the one with the highest noise. The carrier was visible since about 0:30, but the detection occured only in the morning when the noise went down before the signal did. Unlike Paul in Todmorden, I don't have a steerable pair of loops, so only the blanker to combat the statics. Bob, thanks for this signal! |
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