[time-nuts] Active LORAN antenna
phk at phk.freebsd.dk
Fri Aug 26 21:16:06 UTC 2011
In message <4E580972.6080103 at pacific.net>, Brooke Clarke writes:
>It looks like the noise floor is maybe 10 dB higher than the AMRAD
>or 30 dB higher than the McKay Dymec active antenna.
If you are basing that claim on the SA plot in my blog-post, you
instantly win the "inappropriate apple-oranges comparison price of
First there is nothing even remotely close to a natural noise-floor
in the LW broadcast band in the middle of a city here in Denmark,
there is far too much EMI from switchmodes etc etc.
Second, there is a significant impedance mismatch between the antenna
and my SA in that plot. I backhaul the signal over a balanced
twinax cable (78Z I belive) and crank it up for the LORAN-C receiver
in the matching balun, so the feed impedance is way higher than 50Z
Mind you, I don't dispute that you may be right, I just don't think
you have data to back up your claim...
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
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FreeBSD committer | BSD since 4.3-tahoe
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