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From: pmc@caen.engin.umich.edu (Paul S McClay )
Newsgroups: comp.sys.handhelds
Subject: Re: Dual tones for HP28S (and HP48)
Summary: Maybe with two calcs
Keywords: HP28S dual tones
Message-ID: <1990Oct23.182155.15578@engin.umich.edu>
Date: 23 Oct 90 18:21:55 GMT
References: <1990Oct17.210043.19196@rodan.acs.syr.edu> <4d928c2e.20b6d@apollo.HP.COM>
Sender: news@engin.umich.edu (CAEN Netnews)
Organization: The University of Michigan, Ann Arbor
Lines: 32


Given the poor resolution of the HPn8 tone generators, I'd be surprised if one
could fake DTMF.

You could use two calculators. Have one generate row tones and the other do
column tones. With two 28s, you could just press the same number key on both
at the same time.

How many 48 owners still have their old 28's?  Use the 28 to generate a tone
and instruct the slave 48 to generate the other.

This is, of course, entirely silly. Imagine James Bond trying to dial a phone
with two large calculators, one of which is floppy. But I had to try...

It didn't work. The tones may not have been loud enough. (Imagine James with
two calcs and an amplifier) Or, worse I fear, the frequency resolution may
not be even remotely good enough. As I recall, the DTMF specs allow for
sloppy generators but don't recall just how sloppy.

---------------
Question for 48 users: How does your beeper sound? My 28 produces very clear
tones but the few 48s I've heard are quite fuzzy.
---------------

Anyone had better luck?

  -Paul
--
-- -  -    -        -                -                -        -    -  - --
Paul McClay                            "Where are we going?"   "Planet 10!"
pmc@caen.engin.umich.edu               "When?"                 "Real soon!"
         "I have neither given nor received aid on this exam."