Actually, in addition to the flex-radio mentioned elsewhere, you can
buy a receiver built on just such an architecture today -- the Winradio
G303i (www.winradio.com) is an internal PCI card receiver (VERY well
shielded) that uses the sound-card for the final I.F. I have one and
it is an absolute blast to play with. There is a published interface
for writing your own demodulators, or you can run the radio "bare" and
use soundcard software to do you demodulation separately.
The only thing I wish it had was a pseudo-sound-card interface that would
allow the output of the built-in demodulator to interface to another
software package without leaving the digital domain. But it doesn't
stop one from writing their own...
For those familiar with WinRadio products, this is by far, head and shoulders
better than anything they've done before.
(Not affiliated, satisfied customer, etc, etc...)
Eric
At 07:27 PM 11/28/2003 -0500, you wrote:
Instead of assuming a dedicated microprocessor embedded within the
radio, consider an architecture in which the software runs on your PC,
which is connected to purchased (or home-brewed) external hardware via a
Firewire (IEEE-1394) connection. The external hardware is the minimum we
need to convert between RF and digitized data (I and Q): bandpass
filters, RX and TX RF amplifiers, an A/D, a D/A, a synthesizer, and
mixers.
With the exception of a QRO TX RF amplifier, the only "expensive" parts
of this system -- the firewire interface, the A/D, the D/A, and the
synthesizer -- can be inexpensively implemented with high-volume parts
from the consumer PC, digital imaging, and/or telecom worlds. You'll
already own the PC.
Much of the differentiation between competitive products will thus be
software that runs on your PC. Hams will of course be free to develop
such software themselves, either from scratch, or on frameworks that
provide basic capabilities with support for customization and
experimentation.
My prediction: within 3 years, you'll be able to purchase a QRP
transceiver in the above configuration for under $200.
--
Eric F. Richards
efricha@dimensional.com
"The weird part is that I can feel productive even when I'm doomed."
- Dilbert
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