I agree with you about not having the perfect locations for microwave frequencies. We have some nice sites on mountains and some not-so-nice sites with trees. So I was originally excited to read about the UDR56K.
*BUT* I, for one, am really disappointed that the UDR56K is also a linux machine. I think they screwed the pooch on that (although I understand about 300 pre-orders would disagree with me). Why do I say this? Because I already have a linux machine running JNOS (and a bunch of other stuff). I was excited about the prospect of switching our current backbone from 1200 to 56K. I was hoping to just plug it into another serial port on my existing linux machine. But it has no serial ports for my other TNCs/radios. (and adding multiple usb-serial adapters and a powered usb hub is just trouble waiting to happen). And I'm betting it doesn't have the horsepower that my existing linux system does, which runs an amprnet gateway, mail gateway, lots of iptables rules, spam and virus checking, etc., plus some automated network testing stuff. Whatever processor it does have, will be aging along the processor aging curve (speed doubles every 18 months) and to upgrade, you would throw out the radio, too - a bit of the baby and bathwater approach. In fact, forget about upgrades. If anything fails -- radio, modem, linux system memory, linux system storage -- I've got to replace the whole thing. All things fail at some point. So this just seems strange to me.
I wish they had just made the radio/modem and provided a serial port so I could connect it to whatever machine I want. I would have bought one for each of our machines, plus a spare (7). But I don't know what to do with what they built - namely a fast modem and radio hard-wired to a very limited, non-expandable linux platform. But again, I guess I'm in the minority because I understand they have about 300 pre-orders.
Oh well. Michael N6MEF
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We don't all have mountaintop microwave sites....
We have homes and ham stations in compromise locations with city lots, restricted antennas and big RF absorbing trees... 25W of 440 MHz will probably get through where less power at higher frequencies won't. The UDR56K is a good compromise real world solution that is probably the last best hope for AMPR data...