Topband: Effect of trees- tree appreciation

[Guy Olinger K2AV]

It's very handy to have a close-by RBN node that can hear us on 160 in
the daytime.  This allows us to evaluate our signal independent of
night-time variations in propagation.  Note that the figure is signal
to noise, not signal strength.  So sometimes we will have a varying
signal to noise report, even if the signal is steady, particularly at
night, due to the varying level of noise.

Once one gets used to the RBN concept, it's easy to pick out "quiet
nights", and do other things to extract meaningful evaluation from RBN
numbers.

RBN will watch a signal over an entire contest, document the
propagation modes changing and compare antennas from the same region,
particularly on a quiet evening.

To see one stellar example of this, go to
http://www.reversebeacon.net/analysis/   Enter 02/19/2011 as the date.
Click on the Europe bar.  When the station selection expands, click on
S50ARX. Enter NY4A, W3LPL, and K3LR under stations.  Look at the 40
meter spots.  On the right side of the graph for the zulu day,
Saturday evening was for propagation one of those wide open very
"smooth" propagation evenings analogous to reflections off a lake on a
windless day.

In particular, starting around 19Z or so, see how NY4A's strength goes
through three jumps up to a plateau.  You can see that LPL and LR
climb them as well.  These plateaus follow the propagation changing
modes (numbers of hops and angle) as the band opens into the evening.
Note that the NY4A 5 element long quad (at 84 feet center height, over
179 feet of catenary) engages all three modes cleanly and fully as
they open, without any fading. If the path to EU from NY4A is cleanly
open, the path must be open from LPL and LR distances.  By common
expectation LPL and LR should have a propagation advantage over NY4A.
LPL and LR both have excellent stacked 3 or 4 element 40m yagi's. But
note how as the fourth mode is engaged, both LR and LPL fall off
because they are not cleanly engaging the mode, most likely because
the increasing elevation angle is starting into a notch in the yagi
vertical pattern.  Also note that NY4A carries the best signal for
most of the 24 hours. This is an evaluation of the NY4A 40 EU quad vs.
known excellent installations that is hard to argue with. Can't be
done like this without RBN.

73, Guy

On Sat, Aug 10, 2013 at 10:14 PM, Bill Tippett <btippett at alum.mit.edu> wrote:
>
> "
>
> On Sat, Aug 10, 2013 at 7:47 PM, <chacuff at cableone.net> wrote:
> >
> > I haven’t used the RBN.  Guess I need to figure out how so as to quantify the performance of what I have up.
> >
> > Is there a tutorial on the site?
>
>
> I don't think so but go to "DX spots", then "spots analysis tool".
> Then select a date (e.g. 02/16/2013 for the ARRL DX), a continent
> (e.g. Europe) and a prolific RBN (e.g. DR1A) and add your call in the
> box at the bottom.  You can then add a competitor's call and see how
> your signal strength compared over the 24 hours.  You could also have
> a buddy call CQ simultaneously on a different frequency and compare at
> different RBN locations.
>
> If you want to check your own strength, Mike's advice will work.  You
> can also test different antennas yourself by calling CQ on even
> minutes with one antenna and odd minutes with another.  Then search
> RBN for your call and note the signal strengths at even and odd minute
> spots by RBNs.
>
> If you play around on the site you'll get the hang of it.
>
> 73,  Bill  W4ZV
> _________________
> Topband Reflector