This is a good example of what I meant by “scatter” being a (confusing) garbage
term! The kind of scatter that Jerry describes is tropospheric and is quite
different from ionospheric backscatter. There are all sorts of weird and
wonderful reflections usable at VHF and above, including rain scatter, aircraft
scatter and – who knows – maybe turbine blade scatter! However, tropospheric
forward scatter is always present on 10m. The range is considerably lower than
at VHF and the propagation mode is often misidentified as “ground-wave”. If
you hear a beacon in the 50-100 mile range at times when ionospheric
propagation is not possible then the mode is most likely to be tropospheric
forward scatter.
Steve ‘AEV
From: hfbeacons-bounce@xxxxxxxxxxxxx <hfbeacons-bounce@xxxxxxxxxxxxx> On Behalf
Of ac5jm @ aol . com ("ac5jm")
Sent: 05 January 2024 17:53
To: hfbeacons@xxxxxxxxxxxxx
Subject: [HFbeacons] Re: VE3IIM/B 28296.7
Keith,
Yeah, right after I sent that email I did a Google search and found a mountain
of scholarly articles on backscatter. It is basically how radar works.
However I have so far found very little on backscatter phenomenon for
wavelengths around 10 meters. I found where snow is mentioned as not being
very reflective for weather radar but that is at C-band frequencies. Non Line
Of Sight (NLOS) propagation is always caused by something. I think this is a
very interesting subject. We are expecting snow on Monday-Tuesday. It's not
very common here but if it is very heavy, which happens once every few years,
I'll be listening for my beacon that is 80 miles to the west of my home QTH. I
have never heard it at this distance, however I have heard it at 50 miles while
mobile moving toward the beacon in a rather deep valley with wind turbines at
the top of the overlooking ridge. My theory is that the turbine blades which
stick up in the air about 400' and move at high velocity may be reflecting or
refracting the 28 MHz signal down into the valley.
73,
Jerry AC5JM
On Friday, January 5, 2024 at 10:00:55 AM CST, William Hibbert
<wkhibbert@xxxxxxxxx <mailto:wkhibbert@xxxxxxxxx> > wrote:
Jerry:
The textbook definition of backscatter is that the signal, after skipping to a
DX location, has a portion if the signal reflect back to the ionosphere on a
reciprocal basis. This returned signals path is broadened thru scattering off
the reflective "surface" and ends up being detected across a wider area on the
return. I gathered this from conversations with the Old Timers back in the
1960's when I first got on the air, and discussions with the Radioman on my
ship in the Navy.
I.may be wrong, this is anecdotal information rather than something learned
from a textbook (I am a retired Pipefitters, not an Electronics Tech), but it
has worked for me over 5-plus decades. YMMV, but I am sticking with what I have
observed...
73, Keith, WB2VUO
On Fri, Jan 5, 2024, 10:38 ac5jm @ aol . com <dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
What is back-scatter? What would cause the signal to suddenly scatter and then
not scatter? Does the "back" part of the phrase "back-scatter" just refer to
the shorter skip zone? Or is back-scatter actually diffraction off of
atmospheric particles? Is back-scatter caused by the same mechanism as
tropo-scatter that affects UHF frequencies? Is it possible that the shorter
wavelengths of UHF that "Scatter" off of humidity is the same phenomenon as 10m
wavelengths scattering off of snow flakes?
-Jerry, AC5JM
On Friday, January 5, 2024 at 08:35:27 AM CST, William Hibbert
<wkhibbert@xxxxxxxxx <mailto:wkhibbert@xxxxxxxxx> > wrote:
Hi Ian, Keith here in the semi-snowy Buffalo area. The lake effect only dumped
a couple inches of snow over some narrow bands. 95% of the city didn't see a
thing.
As for the scatter signals... Well, it's sort of a trained ear from working
scatter on 6 meters for 50 years. The scatter signal actually arrives on
various paths and the slight differences in the timing give the signal a watery
sound, that's about the best way I can describe it. Lots of QSB on scatter
signals, too. I have found the higher bands, like 2 meters and 70 cm, forward
scatter is less common but there are scatter characteristics on tropo signals.
It's not unusual to see an FT8 signal widen to 250 - 300 hz, and CW signals
almost get an auroral flutter.
II have been working weak signals on 10 meters and up since 1966. I guess it's
a acquired ability? I have heard it described as developing a Scatter Ear, hi!
I have VA3KAH in here steady at a 419 this morning. EU and AF are very strong,
so I am assuming backscatter from the DX paths. I wish that I still had my
beams, I could verify the backscatter direction, but stuck with a Cobweb on
horizontal and a 5/8-wave vertical to choose from.
Have fun in FL and CU further down the log!
73, Keith, WB2VUO
Amherst, NY: Grid FN02ox
Cell: 716.481.8840 (Voice or Text)
On Wed, Jan 3, 2024 at 6:20 PM Ian Baines <va3kah@xxxxxxxxx
<mailto:va3kah@xxxxxxxxx> > wrote:
Thanks for the honourable mention KEITH. Sorry to hear about the lake effect
snow.
I’m down in Florida and I copied my own beacon this morning. It seems that we
are having regular E skip north-south
How do you know that it is scatter? I only ask because I’m never certain what
the propagation is when somebody reports hearing the beacon.
73
Ian
VA3KAH
On Jan 3, 2024, at 11:57 AM, William Hibbert <wkhibbert@xxxxxxxxx
<mailto:wkhibbert@xxxxxxxxx> > wrote:
Hi. Keith, WB2VUO at the home station for a change. My quiet mobile spot is
getting hammered with lake effect snow, so I listened for VE3IIM/b ffom home. I
can copy the beacon here near Buffalo on scatter, runnjng from 419 to 539 with
QSB. I copy tge signal on all 3 of my 10 meter antennas, a ground-mounted
Hustler 4BTV, an iMax 2000 5/8-wave vertical up 12 feet and a Cobweb up 30
feet. The signal sounds great considering it's making it here on scatter.
I am also hearing VA3KAH/b, also on scatter. Not surprising as the paths are
similar!
73, Keith, WB2VUO in Amherst, NY
Grid: FN02ox
On Wed, Jan 3, 2024, 11:28 ac5jm @ aol . com <dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
Weird. I found you on RBN. DF2CK heard you less than 2 hours ago- VE3IIM/b.
-Jerry
On Wednesday, January 3, 2024 at 07:45:21 AM CST, Tim Smith
<dmarc-noreply@xxxxxxxxxxxxx <mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
..No Jerry, no changes here. It is quite amazing that my beacon can be so
strong at many different locations, but nothing is showing up on the RBN. The
CW is clean, proper spacing etc.
Tim..
On Wednesday, January 3, 2024 at 08:26:50 a.m. EST, ac5jm
<dmarc-noreply@xxxxxxxxxxxxx <mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
Perhaps you discovered something affecting propagation from your locality? Is
there a new structure or overhead wires near by causing multi path reflections
or blocking the signal? Or has your ERP dropped for some reason? Has your
antenna changed orientation? Also there are more KiWi receivers than RBN
skimmers I think. Just random ideas.
Jerry, AC5JM
Sent from my iPhone
On Jan 2, 2024, at 6:52 PM, Tim Smith <dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
..Thanks Bob. I get the search for "/B", etc. What I am wondering is why I am
heard on so many kiwi receivers, but not many on the RBN. I checked a friend's
beacon (VE3RIP/B 28119.4) and Larry has many hits today. If you look on the RBN
at my hits today, there is a period of no activity at all. But..I was hearing
myself on all these on line receivers at those times..Odd..
Tim..
On Tuesday, January 2, 2024 at 07:46:03 p.m. EST, Bob Coomler
<w7swltucson@xxxxxxxxx <mailto:w7swltucson@xxxxxxxxx> > wrote:
Tim, It sounds like a similar situation I recently had when changing
equipment. If you ask RBN for VE3IIM it will look for that. If you ask it for
VE3IIM/B, it will look for that. It won't do soft/fuzzy searches. I just did
a quick RBN search using VE3IIM/B and you are being well heard from Hawaii to
Germany!
73,
Bob W7SWL
On Tue, Jan 2, 2024 at 3:59 PM Tim Smith <dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx> > wrote:
I have a question regarding the RBN. Today (Jan2) I have very few hits on the
RBN. I understand propagation, so I don't believe that really is the concern. I
have listened on the KIWI receivers all around the world, and my beacon is
being heard, but does not show up on the RBN.
Anyone have an idea about this?
Thanks..
Tim
VE3IIM
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