I’ll second Mike’s motion of fascinating, including Bob’s perspective on relative SNR between captures by Hartmut, Henny and Mike.
On long-term average one might expect a path loss of a dB or so between QTHs of Mike and Henny (for a signal originating from Bob’s QTH), and a path loss of 3 dB or so between QTHs of Mike and Hartmut (for a signal originating from Bob’s QTH). I eyeballed SNRs from 3 nights’ captures between October 13th and last night, and on two of those nights, relative SNRs between the RX QTHs are not inconsistent with the above (give or take a few dB, and with some indication of a system SNR advantage at Mike’s RX). But last night, if my subjective reading of the grabber plots is in the ballpark, max and average SNR at Mike’s RX may have been up to 10dB above max and average SNR at QTHs of Hartmut and Henny. In other words, the differences (a-b, b-c, c-a, see following) between the overnight average SNRs (for periods of readability) at QTHs of (a) Mike, (b) Henny and (c) Hartmut may have varied by perhaps as much as (5dB?) over 3 nights’ captures between October 13th and last night; and the difference between the overnight max SNRs (for a few characters) at QTHs of Mike, Henny and Hartmut may have varied by perhaps as much as (7dB?) over 3 nights’ captures between October 13th and last night.
For this T/A path distance, modal reinforcement/cancellation shouldn’t be huge, but I wonder:
a) Could it be a contributor to the above?
b) Could cross-polarized RX antennas help to even things out over distance and time in this case?
I use loop RX antennas in my AZ QTH as cultural noise in the desert is not a big problem; and these are easy to cross-polarize. Are loop RX antennas not used for cultural noise reasons in most of the RX equipment in this group?
Regards,
Jim
AA5BW
Mike;
Fabulous captures-I don't know of anyone operating higher up the band only below me as there are Loran artifacts higher up-Dex on 74.5485 and John at 74.5478 or .5475
Being weekend tomorrow I hope there will be late activity tonight and I will be on until at least 0600.
Can you give me little info on your RX equipment and what antenna are you using [active or passive]? Bob
From: [email protected]
To: [email protected]
Date: Fri, 18 Oct 2013 09:38:05 -0400
Subject: RE: LF: 74.5495 QRSS 60 2300 till 0500+
Mike;
I shut down at 0500 as I didn't see even a trace on Hatmut's grabber! You have some great captures and will let it run tonight till after 0600. It is strange that the skywave only makes it so far and some nights just stops short of Germany.
If you are up early shoot me an e mail if you want it to run longer than 0600. G4WGT's grabber is not sensitive enough to show anything so I only have Hartmut's grabber to go by-Bob
> From: [email protected]
> To: [email protected]
> Date: Fri, 18 Oct 2013 10:12:06 +0100
> Subject: Re: LF: 74.5495 QRSS 60 2300 till 0500+
>
> A good night! Bob on 74.5495kHz appeared at 0130 and traces included
> a clear 'R' were seen until 0215. Then very good signals between 0245
> and 0500 when the transmitter appeared to have been turned off.
> During this period, there is very good 'O' copy of "4 XRS4 XRS4 X".
>
> There are traces (possibly DFCW) on 74.5465kHz around 0145. Was this
> an amateur signal?
>
> Also traces on 74.5485kz between 0550 and 0630.
>
> See the attached pictures. Fascinating stuff.
>
> Mike, G3XDV
>
> > WG2XRS/4 WNY [XRS4] with /5 and maybe /3 will be on unless more
> > lightning-only more rain predicted-Bob
>
>
