At 03:08 PM 8/31/2009, you wrote: >I definitely agree with John on this one. Digital, by and large, is a >big yawn, if all we're doing with it is the same things we've done >before. > >Where it gets interesting in digital is in techniques like WSJT, which >aren't nearly fast enough for speech (without being ridiculously broad- >banded), but make contacts possible well down into S/N ratios that the >human ear can't even "copy".
Well, one of the things we lack here is blanket coverage of repeaters. It only takes a few hours drive from here in the big smoke to find places devoid of repeater coverage. Traditionally, HF fills this gap, but then you're isolated from the international networks and have to rely on the vagaries of HF propagation. Even domestically, this can prove a challenge, with the Travellers Net requiring several relays to achieve national coverage, and even then, results can sometimes be marginal. "short range" (i.e. up to 500 miles) HF links that can manage acceptable audio, consistent signalling and a control channel could be interesting in this environment (Anyone want a gateway with a 300 or 500 mile radius to mobiles? ;) ). Benefits: 1. Travellers in rural areas can still access their favourite networks (analog, possibly digital if transcoding can be done without totally screwing up the speech at this extreme compression). 2. The Travellers Net (or a parallel net) could have a semi-permanent presence on a conference bridge somewhere, instead of being an hour or so each day. If the formal net was held this way, it would take less NCS stations to hold it together, and could be run from an urban area (i.e. from a PC or VHF/UHF frequency). Of course, in the event of the system going toes up, good old HF SSB is still available as a fallback. 3. It would be an easier way to link regional (with good S/N between them) with urban stations (lousy HF S/N) for EMCOMM applications. I have achieved this with SSB, but it is a bit of a pain, and haven't resolved the issue of controlling the links. ;) Down here, urban areas are as noisy as anywhere else, but once you get out of town, the noise floor is often so low, I have to check if my front end hasn't died! ;) 20m goes from S2 - S3 noise to what would be equivalent to a few S points below the 0 stop on the meter (signals that don't move the meter sound LOUD out there). Don't write of HF DV yet. Sure, it's not my choice if I want to chase a bit of DV and push the boundaries, but I do see a place for it, once it's been refined a bit. Getting that bit rate as low as possible is going to be vital. 73 de VK3JED / VK3IRL http://vkradio.com
