This has me very intrigued.
Do you know of any software that could project an arc 800-1000KM from my
QTH? That way, I can look for a station that would theoretically, be in the
target area to experiment with.
Thanks,
Paul Rollinson, KE1LI
Rollinson Associates
860-928-5147
860-928-3844 Fax
860-208-8814 Cell/Text
Paulrollinson@sbcglobal.net
Representing Component Part
Manufacturers for over 35 years
-----Original Message-----
From: VHFcontesting [mailto:vhfcontesting-bounces@contesting.com] On Behalf
Of Keith Morehouse
Sent: Monday, October 24, 2016 3:38 PM
To: vhfcontesting@contesting.com
Subject: Re: [VHFcontesting] Ionosphere Scatter
There is a considerable amount of path loss, so, in theory, all the "good
things" you would want for long-haul troposcatter (or sporadic-E) are
useful for ionoscatter. High ERP, low angle take-off and low environmental
noise. Research says scattering occurs around 80-90 KM up, so more-or-less
the same ionospheric height as some sporadic-E. Because there is refraction
in the ionosphere, there will be a minimum distance for Ionoscatter of
approx 800-1000 KM ("skip zone"), with a maximum distance based on your
ability to get a signal into that 80-90 KM high sweet spot (just like Es).
Distances shorter then 800-1000 KM can be covered (somewhat unreliably) with
troposcatter. Studies show there is a diurnal
(daily) variation in ionoscatter signal strength of around 10 dB, with
minimum attenuation (maximum signal strength) occurring at mid-path noon.
Note that path attenuation increases rapidly as frequency increases. The
optimum traffic frequency (FOT) for ionoscatter was calculated many years
ago as 50-60 MHz, taking into account path loss vs typical band noise
levels. At low and mid-band frequencies, path loss increases about 5 dB for
every 10 MHz upward change of frequency. This is why ionoscatter at
144 MHz is much more difficult.
Jay W9RM
DM58 CO
Keith J Morehouse
Managing Partner
Calmesa Partners G.P.
Olathe, CO
On Mon, Oct 24, 2016 at 11:32 AM, Mark Spencer <mark@alignedsolutions.com>
wrote:
> Hi this is interesting. From a practical perspective I'd be curious in
> knowing if there is much difference in what needed to be successful
> using long haul tropo scatter versus iono scatter on 50 MHz ?
>
> Presumably bigger antennas, higher power levels and a clear view of
> the horizon will all be useful ?
>
> The comments about the K index and time of day for iono scatter are of
> particular interest to me.
>
> 73
> Mark S
> VE7AFZ
>
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