Re: The doors of perception (was Re: Repeater latency)

["Nic Roozeboom" <Nic_Roozeboom@msn.com>]

>At 7:34 PM -0700 7/23/03, Nic Roozeboom wrote:
>>In my understanding, one only refers to latency when it involves a time interval during which there is >>uncertainty.

>Actually, I have always used jitter as the range of timing uncertainty. Latency I've always used as a close >synonym of delay.

>So, for example if something varied between 7.5 ms and 12.5 ms you could say it had a latency of 10 ms with >+-2.5 ms jitter, or a latency of 7.5 with + 5 ms of jitter.

They are indeed rather close synonyms/concepts... Let me try:

 

Delay (simple): a constant phase relationship in time between and input event and output event.

 

Latency: a time interval within which an output event may be counted on to occur as the result of an input, but its actual time to occurrence may not be counted on, and may depend on an unknown variable.

 

Jitter: the difference between the time an output event is intended to occur, and its actual time of occurrence (OK, I sort of stole this last one from somewhere).

 

The time it takes the bus to take you from A to B is delay. The time it takes you to get on the bus depends on when you arrive at the bus stop, and when it happens to arrive for you to get on. Jitter is the bus's performance to schedule. Or when the bus driver is hopped up on caffeine.

 

Nic