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[kelly@pleiku.netcom.com]

>From kelly Mon May 03 06:24:09 0700 1993 remote from pleiku
To: toad.com!cypherpunks
Subject: 
Date: Mon, 03 May 1993 06:24:09 -0700
From: "Stop the Big Brother CHip" <pleiku!kelly>
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I thought this my be interesting to those designing encrypted phones...
    cheers
    kelly 

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From: kelly (Kelly Goen)
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To: junem, kelly, phil
Subject: quaderno Speech capabilities
Status: R

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From: duck@nuustak.csir.co.za (Paul Ducklin)
Newsgroups: comp.sys.palmtops
Subject: Re: Quaderno speech hardware
Date: 22 Apr 1993 10:01:03 +0200
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Thus spake mg@cs.princeton.edu (Michael Golan):

  [stuff about the Quaderno's sound digitising capability]

>Can the mic/speaker be accessed from software to produce 8-12bit digital
>sound? If so, and assuming a 9600bps modem is available (is it?), the
>machine is an excellent candidate for a truly secure phone

The speech DSP hardware is quite fancy -- you can download your own
vocoder program, if you have the right DSP code development tools, to
implement things like DTMF-recognition. Or you can select one of the
built-in vocoders, which provide various levels of compression. The
speech program which comes with the Quaderno is just a TSR which hooks
to the speech hardware, and which writes digitised sound to a file.

No reason why you couldn't write your own speech program which grabs 
digitsed blocks from the DSP [you can give the BIOS the address of a 
routine to be called when the DSP is ready to deliver] and stuffs them
wheresoever you desire -- such as into the serial port. On the other
end, you have a DSP "play" program -- once again, you can give the
system the address of a routine to be called whenever the DSP is ready
to analogise [?] the next block of bits.

I can't remember, though, what bit-rates are available with the built-in
vocoders. If people are interested, I'll look it up when I get home this
evening [or Don Herrick -- are you there?]. Ah yes -- just remembered
that one of the vocoders churns out 13Kbit/sec with *very* acceptable
quality [for voice -- music sounds like a heap o' crap when pushed through
this particular vocoder]. 

So this could be stuffed into a regular V.32bis modem and transmitted fast 
enough to give real-time speech. With its 16MHz V30 CPU, the Quaderno should 
be more than ready for the task of real-time encryption in software. If my 
memory serves me, there's also a built-in vocoder which compresses to 
2400bits/sec [!] -- the speech program which ships with the Quaderno, 
however, doesn't offer this as an option, so I've yet to try it. Probably 
pretty damn bad, though.

Another thought -- the Quaderno's DSP will record and play at the same
time, and V.32bis is full-duplex. So full-duplex conversations on the
above scheme are quite possible. Could be fun -- how to turn a good
3KHz analogue voice line into a fair 13Kbit digital voice line!

And, as mentioned recently in alt.security, you can also use the speech
digitiser for acquiring data with a high degree of randomness, which 
you then encrypt with a part of itself to produce data which is "truly" 
random. 

Paul

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