[hpsdr] Dumb question - HPSDR sound card

[J.D. Bakker]

>SPDIF on most inexpensive sound cards is one-way - outbound (D/A).  The
>wrong way.

True, however there are a few PCI sound cards out there with an extra 
bracket offering optical I/O. I have one such card, a noname board 
based on (I believe) the CMI8768. Most cheap CMI87xx boards have 
(pads for) a pin header with the relevant signals (which may or may 
not be too much hacking for prospective users).

This looks like mine:

http://www.trust.com/products/product.aspx?artnr=12950

Street price is around EUR25 (~US$33). The brand name 'Trust' appears 
to only be marketed in Europe; I'm sure US-versions exist.

>                                 Notebook/laptop support is nonexistant
>without another interface to the computer, exactly what I am trying to
>avoid.

Sorry, I see I missed the 'Especially laptops'-point in your original message.

>What rates does SPDIF suppor these days?  192kHz & 24-bit sampling?  I think
>so, but most of my hardware is 32/4.1/48k and 16-bit.

S/PDIF and AES/EBU run up to 24/192 these days; I regularly use 24/96 
for audio recordings.

>I still use SPDIF for DATminidisc, and other pro audio applications, but I
>don't think it's what I want for SDR.

Is that mostly because of your 'on a laptop'-requirement ?

Like I said, my main reason to go for S/PDIF is that it offers a 
cheap sound card compatible interface for existing SDR apps *with 
zero driver-writing effort*, while being able to use an optical link 
to separate the codec from the (noisy) PC. My experience with USB 
audio at rates other than 16/44k1 is that it is very fragile when 
faced with different PC/laptop chipsets, and FireWire performs well 
but is rather expensive.

Does anyone else feel such a 'remote sound card' would be useful for 
SDR ? I don't mind designing one, but if it's just for me I'd rather 
modify my existing design (a 24/96 board for a portable multitrack 
audio recorder, based on the CS5381).

JDB.
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