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

[Eric A. Cottrell]

Gregory Maxwell wrote:
> On Mon, Mar 24, 2008 at 11:24 AM, Jeff Brower <address@hidden> wrote:
> [snip]
>   
> >  > Using a AMBE or other codec chip is part of the hardware versus software
> >  > decision.  We want to do everything in software but there are
> >  > limitations.
> >     
> [snip]
>   
> >  Agree.  In the open source voice community, many times I see people try to 
> > cram something into software, even though
> >  they know it's would barely fit or likely would not.  In some of the more 
> > flagrant cases I've seen, after spending
> >  great time and effort, the end result is poor voice quality (usually due to 
> > increased latency), unstable system that
> >  crashes or hangs easily, and code that is dependent on server characteristics. 
> >  They're so determined to avoid a
> >  hardware solution they end up with no solution.
> >     
>
> You guys do realize that the 'hardware' AMBE solutions are just
> software running on a TI DSP, don't you?
>   
Hello,

That is what I meant by "peeking in the black box". :)
> Unlike filters or RF mixers wisely implemented in the analog domain
> for reasons of physics, dynamic range, and component availability AMBE
> is available only on chips in order to protect the ability of some to
> profit at the expense of freedom and flexibility for users of the
> technology.  (I'm making no argument here about the ethics of limiting
> people's freedom in order to maximize profit, only pointing out the
> irrefutable fact it is being done. Being that this is *GNU*Radio
> perhaps I should be, however).
>
>   
Well, after being part of a weird process where my employer had to sign 
a NDA and get an account to access one small area of a company's  site 
to look at one datasheet for a hardware chip my employer was 
considering, I think DVSI is reasonable in providing AMBE2000 
documentation freely on their website even if it is marked 
confidential.  Hardware companies should be in the business of providing 
hardware.  Some companies feel that hiding how to interface to the 
hardware gives them a competitive advantage and it seems some companies 
go to extremes.

I thought about the issues of including IMBE support in GNU Radio but 
did not think it would spark a lively discussion.  I consider the other 
long-term GNURadio developers like EB to have a better handle on these 
issues.  I just use and write GNURadio code as my hobby of learning 
about and building SDR.  I think it is neat that when I have an interest 
in some digital mode I can code a receiver and learn some DSP 
techniques.  So if it is decided not to include IMBE support in GNURadio 
then I will still likely write it for my own private use.

On another note, I found some example ASCP source code for the RF Space 
SDR-14 that I can modify to use with the DV Dongle.  I got off on the 
wrong foot on DV Dongle list but I got a surprise tonight of the 
AMBETest application  posted to the web site.  This is a good start but 
I may still need to write some of my own code.
http://www.moetronix.com/files/ambetest103.zip

If I modify the SDR-14 files to work on the DV Dongle and get a  C++ API 
for my experiments then I plan to feed that back to the DV Dongle 
project.  They need some example files if they expect software 
developers to use it for other modes.

73 Eric