Clear Channel on a T1

Thu Mar 22 22:49:31 UTC 2001

On Thu, Mar 22, 2001 at 10:19:35PM +0000, Ron Buchalski wrote:
> Forcing the 8th bit to a '1' isn't done to maintain timing.

	Huh?

> The 8th bit was forced to a '1' to maintain ones density on the T1 line.  
> Early T1 specs did not allow more than 15 consecutive zeros to be 
> transmitted because the T1 repeaters along the line rely on periodic pulses 
> to keep their oscillators active. It was not a problem for voice circuits, 

	Yes, and this was necessary to prevent those repeaters from losing
sync -- thus maintaining timing.

	--msa