Re: [Discuss-gnuradio] DV Dongle - AMBE USB Device

[Jeff Brower]

Jared-

> speex is nice.  I've used it as well as the AMBE2000/2020.  I wasn't in love 
> with
> the AMBE.  We ended up doing lots of hacking to make the DVSI AMBE 2000/2020 
> pair
> of DSPs work in our application.  Specs were light and idiosyncrasies were
> numerous.

What was the lowest bitrate you used with Speex?  My understanding is that 
Speex's
PESQ scores are below 3 for anything below 3000 bps.

-Jeff

> > Date: Wed, 19 Mar 2008 09:02:46 -0700
> > From: address@hidden
> > To: address@hidden
> > Subject: Re: [Discuss-gnuradio] DV Dongle - AMBE USB Device
> > CC: address@hidden
> >
> > On Wed, Mar 19, 2008 at 07:02:08AM -0600, Jeff Brower wrote:
> > > Rick-
> > >
> > > > > I am also thinking of writing a APCO P25 Voice to AMBE2000 frame 
> > > > > converter
> and see
> > > > > if the device can decode P25 as well. This may be a general IMBE and
> > > > > AMBE codec.
> > > > >
> > > >
> > > > I hope so. I looked at this a while back. What concerned me most was the
> > > > AMBE2000/2020 documentation seemed to omit P25 style IMBE compatibility.
> > > > Compare the docs to another DVSI product - the VC55 - to see what I 
> > > > mean.
> > >
> > > If you're looking at low bitrate codecs for GNU radio, why use a hardware
> (dongle)
> > > dependent solution? You might look at MELPe, which provides 600, 1200, 
> > > and 2400
> bps,
> > > and can be implemented as a software solution. MELPe is a US/NATO standard
> (STANAG
> > > 4591). Common applications are HF radio and L band satellite apps where
> bandwidth is
> > > very limited.
> > >
> > > -Jeff
> >
> > Unless something has changed, MELP is also encumbered. How about a
> > free codec, such as speex? http://www.speex.org/
> >
> > Eric