RE: [Discuss-gnuradio] SDR 1000 progress

[John Ackermann N8UR]

--On Thursday, May 08, 2003 10:17:46 -0700 "Ettus, Matt" 
<address@hidden> wrote:

> > Oh, one question, Matt -- on the wiki you note to use the
> > LINE OUT rather
> > than SPEAKER OUT on the soundcard.  All of the cards in my
> > collection have
> > only a single output, usually labeled as SPEAKER OUT.  What
> > to do in that
> > circumstance?  (And a follow-on question -- what about
> > laptops like my
> > current work machine, a Dell Latitude C640 that has only two
> > sound card
> > I/Os -- mic/line in, and headphones out?)
>
>
> Ok.  I haven't bothered running the windows software, and Gerald doesn't
> mention it, so I'm not sure if he's using one soundcard or two.  The
> problem is that, assuming you are doing voice communications, or that you
> want to HEAR what is received, there is a conflict in using one sound
> card.  The radio needs to use one stereo input and one stereo output
> to/from the computer.  You would also need a microphone connection and a
> speaker connection for your voice and listening.
>
> I had always assumed Gerald used 2 sound cards, but since he never
> mentions that, I'm assuming that instead he uses one soundcard, with the
> SDR-1000 on the line in/out and a mic/speaker on the mic/speaker
> connections.  This means you have to have the soundcard mixer controlled
> automatically.  It also means you need a soundcard with all 4 of those
> connections.
> Unfortunately, most soundcards don't have all 4 of those connections.  It
> also makes the software a little more difficult.
>
> I am using a 2 soundcard setup, which is easy on a desktop machine.  On a
> laptop, I think you'd be forced to use a USB or PCMCIA second sound card.
> Thankfully, having 2 soundcards is no problem for Linux.
>
> What setup have you been using under the windows software?

Gerald uses one soundcard, but does audio switching on the board and in the 
soundcard mixer to change the mapping between RX and TX.  If I understand 
correctly, it works like this:

1.  In RX mode, the soundcard mixer is set to use line in for the IF, and 
in the radio the line out/speaker out (whichever you have) signal is routed 
to the speakers.  The soundcard output is mapped to use wave out, and 
disable line in (otherwise, the speakers output the raw IF signal, which is 
interesting but not what we're looking for).

2.  In TX mode, the soundcard mixer is set to use mic in, the mic plugs 
into the mic jack on the radio and is routed to the mic in connector on the 
soundboard, and line out/speaker out is used to deliver the IF to the 
radio.  The speaker is out of the system at that point.  The soundcardmixer 
is switched to send wav out to the line out/speaker out jack.

So, Gerald is using switching both on the board and in the soundcard mixer 
to use a single card for both RX and TX functions.  It's clearly a 
half-duplex system.

73,
John