Here's what I think should be the stock reply about the MD380:
*The MD380 is interesting, and Codec2 can be ported to it, but it would
fall short of providing the full benefits of Codec2. Codec2 is capable of
substantially narrower bandwidth for the same voice quality, and with the
narrower bandwidth come greater clear voice range or greater battery
savings (pick one) and at least five channels in the space a wider
bandwidth HT uses for one. To do this, you need a modulator and demodulator
that work efficiently at narrower bandwidth, and greater frequency
stability.*
Being able to lock on a base station that indicates a higher-precision
oscillator may be helpful for mobiles. Even a high-precision crystal can
drift the width of one of our narrow channels at 440 MHz.
I don't think we need finely variable frequencies for anything but
satellites. For terrestrial use, we just need narrower channels and a way
to make our frequency precise. But internally, our synthesizers provide
more fine adjustment of frequency than channelized systems would generally
use.
Bruce
On Mon, Feb 1, 2016 at 2:01 PM, Steve <[email protected]> wrote:
> I think the most important design aspects for VHF voice is continuous
> tuning.
>
> You don't want channelized CB operation. In HF we usually stare at our
> panoramic displays and put the pipper on the signal. We may scoot our
> signal right next to some other guy. Maybe in the future, we will have
> a modem that can decode two signals at a time (a la PSK31) :-)
>
> The FDM modem is neat, in that it can track any slow drift. This drift
> is almost insignificant at HF, but noticeable at VHF. As the radio
> warms and cools, it goes up and down in frequency. Adding temperature
> stabilization at the LO costs money, and heck, if the modem can adjust
> fast enough, who cares what the exact frequency is.
>
> Back in the 90's when I ran a couple of D4-10 radios from Kantronics,
> they were basically worthless, as the two LO's would drift at
> different rates. The radios were simplified direct FM, with a data
> slicer. No way to modify them, except disconnect 90% of the radio.
>
> I think the SM2000 would be a lot of fun, even without spending a lot
> of money on frequency stability. Well, I mean, it couldn't drift by
> 10's of kilohertz, but even if it did, we could turn the dial a tad as
> we listened.
>
>
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