Message-ID: <000301bf1f72$bf132920$d34c8cd4@dave>
From: "Dave Sergeant" <sergeantd@compuserve.com>
To: rsgb_lf_group@blacksheep.org
References: <0.d7aacac3.2544fd92@aol.com>
Subject: LF: Re: Re: Technical details of CFH (137kHz)
Date: Mon, 25 Oct 1999 18:45:25 +0100
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>From Dave G3YMC

David G0MRF wrote:

<Some rambling......
<If the ERP from the VE on 137 is  20% of 10kW, that equals about 2kW ERP.
<I can't remember what the best signal to noise is on the signal.  Would 10dB 
<be about right?

CFH when it was on earlier this year was consistently much stronger than this, over s9 for most of the night (at least when I listened) and would be some 25-30dB above noise level. 
However before we get too exicted you must include a term for relative antenna gain.  I assume very few European amateurs have access to a 600ft mast with an extensive ground system.  We must assume an antenna efficiency of 1% at best, and although this just means more power to achieve the 1W erp I suspect the big mast will radiate just a bit better...

<The problem for the very slow data rates used by Andy and Peter would be 
<changes in propagation during the transmission.
<How long is the signal audible at reasonable signal levels each night?

CFH was a consistent strong signal during the night (2200-0700z in winter) so there would be plenty of time!

Note that CFH is on the east coast of VE.  The path down to Andre and the other USA operators is very considerably further and we should not draw too many conclusions about a possible path down there.

Cheers Dave G3YMC
sergeantd@compuserve.com
http://ourworld.compuserve.com/homepages/sergeantd