Bruce,
You certainly have difficult circumstances. The usual suggestions are to get
rid of (or reduce) the external interference. I understand that you can not.
Two thoughts come to mind:
1. Use digital HF communications, rather than voice. If the noise floor is as
broad and as high as what you say, S/N ratios will be very poor and even good
DSP may not be able to handle the problem. I'd suggest seeing if someone in
the group has a state-of-the-art rig you could borrow to see if DSP can solve
the problem in voice mode. If not, then using a compatible digital mode might
work, but the stations at the other end of the circuit would also need to run
the selected mode(s). The idea is that required bandwidth for some of the
current digital (non-voice) modes is narrow enough to produce usable S/Ns,
which is the key to communicating. Some ARES ops in Iowa are currently
experimenting with this approach on 75m.
2. Consider a remote base operation if your op center location is relatively
free of RFI on 2m and above. Use VHF or UHF from your operating location in
the high noise HF district and handle voice communications via a remote base
that can (hopefully) be tuned to whatever HF band and frequency you need. This
approach at least has the advantage of not requiring the station at the other
end of the circuit to have non-voice data capability. You need only have an
assured line-of-sight path from your operation center to the remote base site.
I believe that there are several rigs on the market capable of this duty, one
of them being Kenwood TS-2000. I have made several 10m contacts with West
Coast hams using a '2000 up in the hills or mountains and the op being in his
car or walking with a VHF/UHF HT somewhere and running the '2000 as a remote
base. It seems to work well.
Let us know what you decide to try and how it works (or not). Best wishes.
73, Dale
WA9ENA
EC for Jones County, IA
-----Original Message-----
>From: wa3afs@nycap.rr.com
>Sent: Feb 20, 2014 12:05 PM
>To: rfi@contesting.com
>Subject: [RFI] DSP for a noisy environment
>
>I am the Regional SKYWARN Coordinator for the NWS, Albany NY which serves 4
>states, 19
>counties. Mountains prevent much access via UHF/VHF and we want to be able to
>communicate without IRLP, etc if there is something major. Also HF access to
>other NWS
>stations would be nice.
>
>At this point, HF (80 and 40 meters) is totally unusable due to RF hash likely
>generated by
>plasma monitors, computers, miscellaneous weather equipment, and nearby
>'stuff' from the
>Nanolabs that are in the same building and surrounding buildings. (Can't
>change the
>environment)
>
>We presently have an older Ten-Tec that has no DSP and are now searching for
>something
>better.
>
>Any suggestions for a modern rig that is:
>* Probably less than about $2000 or so (I have no idea how much funding we
>will have...it
> may even be less)
>* Easy to use by operators that may have little or no experience with HF rigs
>* Great DSP to cut through the hash
>* Built-in antenna tuner would be nice, but we do have a small LDG tuner
>already. Antenna
> is an off-center fed dipole.
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