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Article #1017Re: RS-232 for voice
From: andrew
Date: Sat, 29 Jul 1989 18:42
Date: Sat, 29 Jul 1989 18:42
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1484 bytes
Hmm. Lets assume that we can get away with somewhat poor quality. Okay... Let's assume 8 data bits giving a 48 dB dynamic range ( 20 * log (2^number of bits) ). Next assumtion: highest serial rate _routinely_ available for RS-232 transmission: 19.2k baud = 1.92k bytes/sec. Next assumtion: the setup will be along the lines of: Microphone ---> amp ---> ADC ---> computer ---> serial link ===== ======== serial link ---> computer ---> DAC ---> amp ---> speaker. Nyquist says then that the highest relevant frequency that can be sent with a sample rate of 1.92 kHz is 960 Hz. Just possibly passable... but still pretty terrible for a human voice. Probably still could be understood, though. This could be fiddled with, of course... using 5 data bits (at 5N1 and 19.2 k baud), you should still be able to get a 30 dB dynamic range and a 1371 Hz bandwidth... figures which *in theory* should give quite reasonable results. (transmission time/sample = 365 us). Question: The theory seems to work... but does nature agree??? Anyone have experience with applications? -Andrew. Bitnet: andrew@kean.mun.ca
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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!garfield!leif!andrewShow Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!garfield!leif!andrew From: andrew@kean.mun.ca Newsgroups: sci.electronics Subject: Re: RS-232 for voice Message-ID: <9185@kean.mun.ca> Date: 29 Jul 89 18:42:33 GMT Organization: Computing Services, Memorial University Lines: 32