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From: cfogg@milton.u.washington.edu (Chad Fogg)
Newsgroups: comp.dcom.telecom
Subject: Re: IRIDIUM: Motorola's New Cellular Phone System
Message-ID: <10597@accuvax.nwu.edu>
Date: 7 Aug 90 14:39:32 GMT
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In article <10448@accuvax.nwu.edu> you write:

>Voice:
>	The system is designed as an entirely digital communications
>system with 8KHz bandwidth available for each voice channel. Vocoders

Is this 8KHz sample rate or 8KHz frequency bandwidth?  The former
would imply a data rate equal to ISDN's B channel (8bits*8KHz= 64000
bits/sec).  If I understand audio sampling correctly, the frequecy
range is roughly equal to half the sample rate.

>operating at 4.8 kilobits per second are employed in the user units to
>recreate the audio signals and in the gateways to couple to the analog
>PSTNs.

>Data:
>	The system is designed to allow a user to substitute a data
>link in lieu of a voice link which would operate at a rate of 2400
>baud.

2400 bps is kind of a dissapointment when the voice channel is
operating at 64,000 bps.


Chad
cfogg@milton.u.washington.edu