Sorry for being away so long. I came down with something this week shortly
after the experiment between John (KB1FPM) and I. John, I hope that viruses
can't
travel by radio waves 8-).
I have been reading all of the comments and would like to thank you
for your suggestions.
Clearly, pactor/PSK-31 communications should
be considered in these instances. It was interesting to note that
they were using 20 watt radioes....
I have talked with John about this and I certainly think that tremendous
advantage could be
had by using PSK31 based upon some contacts I have made over the last few
months.
I must have missed that assertion that low power was in the 400 watt
range - that could be more of the peculiar military viewpoint - kind
of like the viewpoint that if one asprin will make my headache go
away, a whole bottle will do so much more quickly....
I have read about other experiments with much lower power that implies that
almost 100 percent copy
might be likely with NVIS to NVIS type antennas. Part of this is because the
noise floor
is lowered because you are not getting all kinds of QRM/QRN from sources far
far away. Because the
noise floor is lower a lower power signal has a much greater chance of
getting through.
But I recall one article where he discussed the advantages of NVIS
but from mostly from a military perspective. For example, Feilder
asserted that radiodetermination of a station using NVIS is much more
difficult because of the near-vertical take-off of the transmitted
signal producing an omni-directional signal. Additionally, I am sure
he also mentioned that this characteristic is compounded by the use
of low power, in the 10 to 20 watt range, HF radioes. Looks like I
will have to re-read the book (for the fifth time!).
I have read this also and makes perfect sense. It also says if I remember
correctly that the DF-ing
station cannot be within hearing range of the ground wave or else the
advantage is lost.
- the author(s) suggest that the best antenna for NVIS may
in fact be ye goode olde dipole (or , if the angle is not
too great, an inverted Vee) at low fractions to the ground,
possibly with a reflector below at a measured distance.
I think this point is made in several publication and by several people. I
haven't seen
anything with respect to this antenna that makes me think that it is wrong.
Yes, I think that was the message that I had picked up. Indeed, go
to the University of Hawaii Amateur Radio Club site and take a look
at their recommendations with respect to using a three-wire reflector
underneath the dipole.
I have seen this and it looks interesting also but would be difficult to put
up in the woods on a camping trip in the
woods of New England.
I tried a similar though simpler setup with a center fed dipole and a
reflector underneath. I consider that there
may have been several things wrong with my test though and intend to do it
again.
I have a few ideas to try and perhaps you and I and maybe others in this
part of the world can experiment on 40 and 80 metres over the
summer. I did a quick check with Mapblast, and I see we are not
quite 500 mile away via roads, so we are closer, I am sure, as the
crow flies. I don't know if I can get anything up for this Saturday,
but I sure would like to try. So let's keep in touch via e-mail.
I can't do anything on Saturday because of my son's birthday party but am
definitely game.
You are about 271 miles from me N1XTK and about 296 miles from John
(KB1FPM).
Have you any interest in trying to maintain a pactor link? I don't
have any means of undertaking a portable/mobile PSK-31, and I am
couldn't afford the Kantronics box!
I can't do Pactor but all you need to do PSK31 is a computer and a sound
card and transceiver.
I and I think John would be very interested in an experiment with PSK 31 at
some
time.
Also, it make me very happy to see the kind of response this has generated.
72,
Keith
N1XTK
