Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!ut-sally!husc6!mit-eddie!mit-amt!jh From: jh@mit-amt.MEDIA.MIT.EDU (John Underkoffler) Newsgroups: sci.electronics Subject: DTMF Message-ID: <1377@mit-amt.MEDIA.MIT.EDU> Date: Fri, 17-Jul-87 15:51:40 EDT Article-I.D.: mit-amt.1377 Posted: Fri Jul 17 15:51:40 1987 Date-Received: Sat, 18-Jul-87 16:42:57 EDT Organization: MIT Media Lab, Cambridge, MA Lines: 22 Posting-Front-End: GNU Emacs 18.44.1 of Mon Jun 1 1987 on media-lab (berkeley-unix) Does anyone know who (if anybody) is making DTMF decoder chips? Neither the TI nor the Motorola "Communications Databooks" as recently as 1985 shows that any such chip exists (although there are plenty of DTMF encoder chips available). Ideally, I'd want a chip which accepts an analog input and produces either a digital hex output (in the range 0-15)or a "row and column" output indicating the position of the button on the imagined phone from which the signal came. The point of all this is that I'd like to selectively activate one of sixteen (or twelve, or whatever) devices by radio remote control, and it seemed to me that one of the easiest ways to realize this would be to follow the phone company's lead and transmit voice-frequency DTMF tones (via disemboweled walkie-talkie); each target unit could then be constantly receiving the same radio frequency transmission; simple logic stuff inside the unit would then read the output of the local DTMF decoder chip and decide if it should activate the associated mechanism. Comments? Ideas? Insults? John "Wombat Stomper" Underkoffler alias "jh@media-lab.media.mit.edu"