On Tue, 27 Nov 2007 12:36:29 -0800, Joe Analssandrini wrote:

I was unaware that one could still buy old operating system discs new.
Do you know of places one can buy them? And can one buy a very
inexpensive (new) notebook computer with no operating system installed
so that one could install an older operating system if desired?

Do any of these SDRs operate with Linux?


Yes, the SDR-1000, SDR-5000, SDR-14 and SDR-IQ are all supported by
Linrad.

http://www.nitehawk.com/sm5bsz/linuxdsp/linrad.htm

Anything that outputs I/Q audio will able to be used with Linrad in fact,
eg the Softrock.

Leif also produces his own hardware for Linrad, specialising in EME and
very weak signal.



I'm still not keen on an SDR (I like a "real" radio on which I can put
my hands, though I have no problems with radios with menu-driven
operating systems) mostly because, at the present time, I do not feel
these SDRs are good value for money. Some of these cost much more than
the computer to which they will be attached and which supplies most of
the processing power! The "guts" inside these SDRs do not, in my
opinion, justify their relatively high prices. But I'm sure that you and
many others here will disagree with me.

Perhaps one of these days someone is going to design an open-source
"radio program" which will do everything these current SDR models do
and, if history is any guide, he/she will put it out on the internet for
free. Maybe you'd just have to buy a USB-compatible connector for an
antenna.

Linrad is open-source.


Am I dreaming too much?


A little - you can't just connect an antenna to a USB port or the like -
you either need something to downconvert the RF to audio frequencies so it
can be sampled by your sound card (like the SDR-1000/5000/Softrock), in
which case you can see a band segment equal to the sampling rate of your
soundcard, or instead sample the whole band with an A-D convertor. The
latter approach is used by the SDR-14/IQ/Perseus.

The advantage of the latter system is that you can have a Panadaptor
covering as much of the HF spectrum as you like. The disadvantage is that
when you want to select a particular "band" to listen to, you need a
digital downconvertor to get rid of the extraneous data (so you don't
exceed the bandwidth of your USB port.) The DDCs tend to be quite
expensive - eg in the case of the Perseus they use Altera FPGAs, which are
not cheap by any means and require very specialised knowledge to program.

However, since SDR is rapidly becoming "de facto" in commercial situations
(especially mobile phones) there will be more and more devices and ICs
coming onto the market, which will keep driving prices down.

Cheers

Alex