So, in a nutshell, we are modifying an FM RTX by removing the analogue audio shaping and letting the AMBE chip do all the work each way.
To be honest, SZM's boxes sound totally different on analogue FM than the Icom ones. It sounds more like a TRBO carrier than a D-Star one from experiance. I will try and get some waveforms of both for comaparison next time I'm up that way. Thanks for the write up Bob, hopefully that will clear up some of the 'myth's' for some. 73 de Neil. G7EBY. --- In [email protected], "Bob K0NR (email list)" <l...@...> wrote: > > Woodrick, Ed wrote: > > Saying D-STAR IS plain FM is even worse than calling PM, FM. There's a > > difference, a very big difference. FM=Frequency Modulation. D-STAR <> > > Frequency Modulated, no way, no how. > > > > Can a FM transmitter send a GMSK signal? Well, a FM transmitter can be > > modified to do so, but then it really isn't an FM transmitter anymore. > > Normal FM transmitters often have all sorts of audio shaping to optimize > > transmission. > > > <snip> > > I wrote an article for CQ VHF magazine (Winter 2009 issue) that > describes how GMSK works in D-STAR, without going too deep into the details. > I put a pdf version of it out on my web site, if anyone is > interested in reading it. > > > http://www.k0nr.com/Files/CQ%20VHF%20Article%20on%20D-STAR%20modulation.pdf > > 73, Bob > > Bob Witte K0NR > b...@... >
