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. ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
