[comp.sys.next] DSP and FAX

rlin@cs.ubc.ca (Robert Lin) (08/25/90)

I considered using the DSP to emulate a fax modem, when I designed the
Mirage Fax for NeXT. But in the end I decided against it, for a number
of reasons:

1. The DSP may be used by someone else; Digital Eyes, Digital Ears,
   many other possibile candidates;

2. It's horribly complicated to try implementing the T.30 protocol in
   software;

3. You need specific approval from the phone company, to plug a piece
   of equipment into the phone jack. It would complicate product release
   date;

4. It's a formidabble piece of software to write, especially given the
   sketchy knowledge I have of the DSP;

5. The RS/6000s do not have any DSPs, and I want to make sure IBM RIOS
   machines are supported.


So I ended up using RS-232 controlled fax modems in the end. There are
still problems with this approach, but they are at least solvable problems.
One problem still is fax modems raise the cost of the final package.
Obviously a DSP fax modem would have the best price tag: nearly free.
But I think for $895 ($795 to developers and academics), including the
fax modem hardware, which also comes with 2400 bps Hayes compat. modem,
the price is actually quite reasonable.

-Robert Lin <rlin@cs.ubc.ca>