Hello to all and especially, Don, K4KYV who still owes me a carrier meter
needle for my R390A after we had our last AM QSO on 1.885...
I have followed this thread just a bit and thought I'd throw in my $.02
When I was with what is now Northrup-Grumman, we built several receiver
sites that employed diversity reception. Most of this was accomplished by
employing Frequency Diversity, that is to transmit the same data on several
widely different but propegationally related frequencies. The If signals were
routed to "voters" which selected the receiver with the best path/lowest error
rate.
There is also sideband diversity, transmitting a dual sideband signal on a
single frequency but with no or supressed carrier. You receive on 2 receivers,
1 on upper sideband and the other on lower. Both were phase locked and in
our case, the reference oscillators were served by an external Cesium
standard. This is replicable in the FT-1000(D).
The next two can easily apply to Topband reception:
Space Diversity. This method employs 2 receivers on the same frequency
being fed with seperate antennas spaced more than 1 wavelength (as related
to the listening frequency) from each other. Both can be horizontally
polarized or both vertically polarized.
An interesting variant is to use the Space Diversity configuration above but
compose the antenna array of 1 vertically polarized antenna and the second
with a horizontally polarized antenna. This final example has been used here
on AM on shortwave broadcast DX in the 120M band has amazing results in
combatting fading.
Both are replicable with the FT-1000D.
I think this season, I'll re-rig my space diversity arrangement using antennas
of different polarity and feed a pair of R390A's, which have built in
voters, with
the array. Would work great. And for my next trick, I'll keep them both on
the same frequency..... actually, that might not be too difficult...
----------------------------------
Chuck Rippel, WA4HHG
Westview Farms
FM-16uq
reply to: wa4hhg@r390a.com
------------------------------------
|