Readers may find this article of interest:


VHF Marine Radio Communication

http://continuouswave.com/whaler/reference/VHF.html

In article ,
James Hebert wrote:

http://continuouswave.com/whaler/reference/VHF.html

I find your math to be very good, but your conclusions don't track
very well with REAL World experience.

Bruce in alaska
--
add a 2 before @

Would you care to be more specific?


"Bruce in Alaska" wrote in message ...
In article ,
James Hebert wrote:

http://continuouswave.com/whaler/reference/VHF.html

I find your math to be very good, but your conclusions don't track
very well with REAL World experience.

Bruce in alaska
--
add a 2 before @

On Sun, 9 Jan 2005 07:47:25 -0800, "Chuck Tribolet"
wrote:

Would you care to be more specific?


"Bruce in Alaska" wrote in message ...
In article ,
James Hebert wrote:

http://continuouswave.com/whaler/reference/VHF.html

I find your math to be very good, but your conclusions don't track
very well with REAL World experience.


off the top of my head, looking at the article, i think there's an
error. he says EACH antenna needs to be 12.4 feet above the surface,
but i think the SUM of the antenna heights needs to be this...IOW each
antenna needs to be 6.2 feet high.

---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field

In article , (Bob) wrote:

On Sun, 9 Jan 2005 07:47:25 -0800, "Chuck Tribolet"
wrote:

Would you care to be more specific?


"Bruce in Alaska" wrote in message
...
In article ,
James Hebert wrote:

http://continuouswave.com/whaler/reference/VHF.html

I find your math to be very good, but your conclusions don't track
very well with REAL World experience.


off the top of my head, looking at the article, i think there's an
error. he says EACH antenna needs to be 12.4 feet above the surface,
but i think the SUM of the antenna heights needs to be this...IOW each
antenna needs to be 6.2 feet high.

---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field

If two vessels are ten miles apart, they will each
need antennas 12.4 feet high in order for their
radio horizons to be in view (line-of-sight) of
each other.

The case presented shows how much margin there
is in a typical circuit. There are many poor
radio installations aboard recreational vessels
which can barely talk to the marina office
from its dock own gas dock, but this does
not constitute a negation of laws of physics.

On Sun, 09 Jan 2005 23:52:46 -0500, James Hebert
wrote:

In article , (Bob) wrote:


off the top of my head, looking at the article, i think there's an
error. he says EACH antenna needs to be 12.4 feet above the surface,
but i think the SUM of the antenna heights needs to be this...IOW each
antenna needs to be 6.2 feet high.

---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field

If two vessels are ten miles apart, they will each
need antennas 12.4 feet high in order for their
radio horizons to be in view (line-of-sight) of
each other.

why is that? the equation sez 12.4 feet for antenna height. does that
mean 1 antenna could be on the ground and the other at 12.4 feet?
---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field

In article ,
James Hebert wrote:

If two vessels are ten miles apart, they will each
need antennas 12.4 feet high in order for their
radio horizons to be in view (line-of-sight) of
each other.

The case presented shows how much margin there
is in a typical circuit. There are many poor
radio installations aboard recreational vessels
which can barely talk to the marina office
from its dock own gas dock, but this does
not constitute a negation of laws of physics.

this is where the Practical and empirical evidence shows that
the math isn't showing what really is hapopeneing.

I have two 1 watt Vhf handhelds, with rubber antennas.
I can talk 16 miles over water with these two radios.
Both myself and my wife are less than 6.5 ft tall.
We are both standing at sealevel. (water lapping at our feet)
Now how does you MATH explain this empirical DATA?

Do my handhelds have receive sensitivity lower than atmospheric
noise? Maybe the Laws of Physics cease to apply north of 58 degrees?
Since this is a perfectly viable Path 24/7 and we have used it
daily for the last 15 years, what is your explanation?

Me who actually does know the answer.........

In article ,
James Hebert wrote:

Readers may find this article of interest:


VHF Marine Radio Communication

http://continuouswave.com/whaler/reference/VHF.html

There seems to be some confusion regarding the
calculation for radio horizon. I am afraid I did
not collect anecdotal reports from anonymous USENET
contributors, but instead relied on other sources.

Cf.: definition of radio horizon:

http://amsglossary.allenpress.com/gl...radio-horizon1

"James Hebert" wrote
VHF Marine Radio Communication

http://continuouswave.com/whaler/reference/VHF.html

There seems to be some confusion regarding the
calculation for radio horizon. I am afraid I did
not collect anecdotal reports from anonymous USENET
contributors, but instead relied on other sources.

Cf.: definition of radio horizon:

http://amsglossary.allenpress.com/gl...radio-horizon1

James, don't confuse 1w-rubber-duck man (anonymous "me" contributor) with
logic. Heck, after reading his story, I may pull down my antenna and replace
it with a rubber-duck. After all, I only get 20-25 miles reliable range to
surface craft from a 60' amsl antenna w/25w! This might have something to do
with small craft's antenna rocking through an arc of 60 degrees at the
entrance to the Chesapeake Bay!

Tropospheric Ducting is a real problem with VHF-Marine. While Bruce has some
interesting stories to tell about making use of that up North, we normally
find it a real hindrance to good communications in the mid-Atlantic. Having
five or more CG Groups trying to answer the same mayday, and hearing traffic
from a hundred or more miles up and down the coast is not a good thing for
vhf-marine radio.

see http://home.cogeco.ca/~dxinfo/tropo.html for ducting forecasts

Jack Painter
Virginia Beach, Virginia

On Wed, 12 Jan 2005 01:43:12 -0500, "Jack Painter"
wrote:



Tropospheric Ducting is a real problem with VHF-Marine.

yes, as a ham i once talked from allentown, PA to n. carolina on VHF
FM in the ham bands.

While Bruce has some
interesting stories to tell about making use of that up North, we normally
find it a real hindrance to good communications in the mid-Atlantic. Having
five or more CG Groups trying to answer the same mayday,

yes, we CG radio operators try to avoid that situation but it's
sometimes inevitable. what's even worse is that we sometimes don't
respond to a mayday, assuming it's in some other CG AOR.


---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field