[time-nuts] WWV/WWVH audio simulator?

DaveH info at blackmountainforge.com
Sun Jan 5 14:57:55 EST 2014


DERP -- you are right.  T1 does 24 voice channels, not 16.

Thanks for the heads up!
Dave 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Robert LaJeunesse
> Sent: Sunday, January 05, 2014 11:33
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] WWV/WWVH audio simulator?
> 
> The US POTS is digitized at 8KHz sample rate, so Nyquist says 
> the highest frequency you can accurately digitize is 4KHz. 
> Allow some for a (fancy digital) filter and 3400Hz is about 
> the best you can expect. As for T1, almost right. The 8K 
> samples per second are u-law processed to 8 bits each for 
> transmission down the line, at 1.544 Mb/s a T1 line handles 
> 24 streams, plus 8K bits per second of supervisory data. Yes, 
> a nice round 193 bits per frame. 
> 
> Bob LaJeunesse
> 
> 
> 
> >________________________________
> > From: DaveH <info at blackmountainforge.com>
> >To: 'Discussion of precise time and frequency measurement' 
> <time-nuts at febo.com> 
> >Sent: Sunday, January 5, 2014 1:53 PM
> >Subject: Re: [time-nuts] WWV/WWVH audio simulator?
> > 
> >
> >This is by design
> >
> >The POTS (Plain Old Telephone System) specifies a bandwidth 
> of 300Hz to
> >3,400Hz. 
> >
> >http://en.wikipedia.org/wiki/Plain_old_telephone_service
> >
> >They are trying to cram as many channels into as little bandwidth as
> >possible and the greater the frequency response they 
> provide, the more
> >bandwidth it takkes and the fewer channels they can provide.
> >
> >T1 lines were originally developed to bring 16 voice channels into a
> >building that didn't have enough copper circuits.
> >
> >Dave
> >
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