Dear group, I have used the search tools in the list archives to try to find the discussion about choice of modem. I wonder why FreeDV is using a modem with quadrature signals rather than a pure FSK system similar to RTTY and MFSK or Thor.
(1) With a pure FSK system (one carrier on continuously, varying frequency) I think one can use class C amplifiers. This would be a selling point for DV. The need for amplifier linearity is a product of the SSB era, but it need not be part of the DV era. (2) Ionospheric multi-path is notoriously hard on PSK systems since the phase gets scrambled more severely than does the amplitude or the frequency. This is why PSK31 communication often has a high error rate in spite of seemingly good conditions. Could someone point me to the white paper or email thread that treats these issues? Thanks, Oliver W6ODJ ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
