[RFI] DSP for a noisy environment
wa3afs at nycap.rr.com
wa3afs at nycap.rr.com
Fri Feb 21 20:30:18 EST 2014
Thanks Dale (and others),
Yes, we have considered attacking the problem from several aspects. Due to governement
security concerns, we have no internet access either (no computers, unless we bring our own
and then there is NO wifi either).
We did try a KX3 and its DSP was quite an improvement. That is why I am looking to see
what rigs may work well in this environment and the budget of the NWS who have agreed to
'look into' andd possibly fund this effort. I do find the K3 and KX3 a little daunting when it
comes to finding something in the menus. Want a well designed rig that considered the
human in front of the knobs.
The NWS is located on the 3rd floor of a nano research facility (multiple buildings) on the
campus of the U of Albany. We have no access to the ground for a NVIS antenna. We do
have an off center fed dipole (and UHF/VVHF antenna) on the roof which does work well (if
only we could 'hear'). Those driving on interstate 90 in Albany may have noticed the weird
(almost boat-shaped) building just south of interstate 90.
Hopefully a modern rig could easily interface with a laptop (which we would have to provide)
and psk would then become a possibility.
Staffing multiple locations (remote base, etc) is problematic as any 'big' event will take up our
skilled operators (Hurricane Sandy had our SEC, DEC, down at shelters almost 100 miles
south of here.) There are not a lot of skilled operators around here once we staff the county
EOCs, the Red Cross, the state EOC, NWS, and any local shelters. At least we do have
good relationships between the counties.
So far I have seen some 'votes' for the Kenwood 590S, the Kenwood 2000. I love my ICOM
7600 but I am sure the cost would not fly.
On 21 Feb 2014 at 0:00, Dale wrote:
> 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
> EC for Jones County, IA
> -----Original Message-----
> >From: wa3afs at nycap.rr.com
> >Sent: Feb 20, 2014 12:05 PM
> >To: rfi at 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
> >We presently have an older Ten-Tec that has no DSP and are now searching for something
> >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.
> >RFI mailing list
> >RFI at contesting.com
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