[hpsdr] Is DRM the only free Digital AM waveform?

[Chris Albertson]

DRM is "AM"?   No, I think it uses OFDM where every
carrier is modulated with QAM

I really think this is the way to go forward with ham
digital modes.  I wouldn't mind working on this.  The
ARRL has proposed a new digital mode that is free
and Open Source to replace some of the closed  modes
and I think is looking at OFDM.

One thing ham radio CAN do that DRM can't is use a
"back channel" that sends error statistics back to the
transmitter from the receiving end.  With this data
the transmitter can redistributed power between
the carriers and even "tune" the inter-symbol timing.
(opening a hole around QRM, so to speak)
I really think with this kind of tuning you can do very
close to the Shannon Limit.

DRM's bandwidth is to wide to be used on ham HF bands.
I think you can do this on UHF.   But there was an effort
called "ham DREAM" or something like that where they
modified DRM to get it down to under 3Khz bandwidth.

"DREAM" is an Open Source implementation of the full
DRM standard.

But "Narrow DRM" is already been done.  I ran across
this the other day
http://www.linuxinsider.com/story/56710.html

Even the full DRM is still narrow enough that a sound
card would work.  So only simple SDR hardware is
needed

I'd like to try things like "TCP/IP over ham-DRM"  this
ham-DRM could work like or replace AX25




--- Tim Schoenfelder <hpsdr at timschoenfelder.com> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> > A couple of us were discussing receiving and probably even
> transmitting
> Digital AM signals with HPSDR or equivalent.  We are looking for a
> good
> quality open source/free digital AM protocol that we could implement.
> However, the other person mentioned that he wasn't sure if any of the
> waveforms/protocols were free.  He thought that we'd have to license
> any
> that we wanted to use for transmitting.
> 
> I found the following that appears to be free, however, I'm curious
> if
> anyone else in the list has researched this area and/or has any
> opinion on
> this topic:
> http://en.wikipedia.org/wiki/Digital_Radio_Mondiale
> 
> -- 
> Tim Schoenfelder
> http://timschoenfelder.com
> > _______________________________________________
> HPSDR Discussion List
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Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Office: 310-336-5189  Christopher.J.Albertson at aero.org


 
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