[Lowfer] MF Multipath Propagation

Sun, 18 Jan 2004 20:40:56 -0600

I would think that an ionized 'cloud' in the atmosphere could move so fast.
Look at e-skip and how fast it can be there and not as the ionized 'cloud'
moves about which changes the point where your signal drops back to earth.
Communicate using e-skip on a band long enough and you see how the cloud
moves and lets you communicate to other states but the previous contacts
have long faded away.

If I have the explanation correct, an ionized cloud is not a cloud, as we
would look at it but groups of ionized particles, which we refer to as a
cloud. Am I right on this explanation?

What about backscattered signals? Multi-path certainly has delays, but of
how much may be determined on the atmospheric conditions at that specific
frequency at that specific time.

Mike>WE0H

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Dexter McIntyre W4DEX
Sent: Sunday, January 18, 2004 7:37 PM
To: [email protected]
Subject: Re: [Lowfer] MF Multipath Propagation

Eric KD5UWL wrote:

> On Sun, 18 Jan 2004, Eric KD5UWL wrote:
>
> > Fascinating.  Dale Rice, I believe, saw this effect on my UWL HiFER
signal
> > back in the late summer or so...

Yes I remember seeing that Eric.  My guess is there are two different paths
the
signal takes to the receiver.  The Doppler shifted signal has to come from a
moving median.  This median would need to move at a speed of 16 km/hr at
13.555
MHz to produce a 0.2 Hz shift.  But to produce the same 0.2 Hz shift at 1705
kHz
the median movement would have to be 127 km/hr and 190 km/hr for 0.3 Hz!

Neat Doppler calculator at:

http://www.ualberta.ca/~norris/navigation/DopplerShift.html

Dex