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Message-ID: <7665659012654DCE89B4DD1FC8228550@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
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In-Reply-To: <003301c9759e$c21f3f00$0301a8c0@mal769a60aa920>
Date: Tue, 13 Jan 2009 18:37:00 -0000
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Subject: LF: Re: Antenna Diversity
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Dear Mal, LF Group,

That is an interesting experiment - It would be interesting to know how far 
apart the loops are to result in different fading patterns.

I would be very wary in interpreting the results from two totally different 
types of receiver - The SLM has essentially a fixed gain, while I see the 
IC-746 has a DSP "back end" with complex AGC loops acting on both analogue 
and digital parts. I guess the AGC in the IC746 is never totally disabled in 
order to prevent overloading of the A/D converter. So that may explain why 
loop "B" has a more constant apparent output level. One check would be to 
swap over the antennas between receivers, and see what difference that made. 
I suppose it would not be too difficult to have, say, a relay that switched 
the same RX input between the two antennas, perhaps every 10 or 20s or so, 
with an attenuator pad to get the signal levels roughly equal. That way , 
the comparison could be made with a single receiver.

Cheers, Jim Moritz
73 de M0BMU

----- Original Message ----- 
From: "mal hamilton" <g3kevmal@talktalk.net>
To: "rsgb" <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, January 13, 2009 4:48 PM
Subject: LF: Antenna Diversity


LF/MF
I am experimenting at present with antenna (space diversity) using two 
loops...