[hpsdr] DttSP (was Blackfin)

[Philip Covington]

On 7/11/07, Frank Brickle <brickle at pobox.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
>
> On 7/11/07, Lyle Johnson <kk7p at wavecable.com> wrote:
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> > > One can't help thinking a Mac Mini would make a very nice SDR host.
> >
> > or a PS3... :-)
>
> Only with Ozy/Janus! You guys have made it a possibility for the first time.
> There's basically no other way to get high-quality audio into the PS3 except
> for the HPSDR hardware. No FireWire, and there are no adequate USB2 sound
> interfaces, period. HPSDR is it.
>
> 73
> Frank
> AB2KT

Speaking of interfaces...

My QS1R project prototype uses USB2.0 and I have just now respun QS1R
into QS1RT VERB
<http://pcovington.blogspot.com/2007/07/qs1rt-verb-pcb.html>

QS1RT VERB has USB 2.0 and 2.5 Gbps fiber/copper serial interfaces.
The other end of the 2.5 Gbps fiber/copper link will be a PCI and PCI
Express board in the PC.   Obviously neither looks like a sound card
to the PC (although they could be made to do so).

The VERB has a TI CODEC which provides mic in/audio out on the board,
but there are times (like with the earlier QS1R prototype or AOJ) when
the audio out is more convenient to the sound card in the PC.
PowerSDR uses portaudio and DttSP on Linux uses jack for handling the
sound card input/output.   In PowerSDR (not sure about DttSP on Linux)
the demodulated audio output is at the same rate as the audio sample
rate in (for example 96 kHz in and out).   In the AOJ and QS1R(T)
cases the audio in is not through portaudio or jack so it seems a
waste of bandwidth to run the demodulated audio out at 196 - 98 - 48
kHz.  Is there provision for lowering the demodulated audio output
rate from DttSP to something like 8 or 16 kHz?

73 Phil N8VB