On 23/12/2012 00:11, Hal Murray wrote:
In article <kb4hoe$9cm$1...@dont-email.me>,
David Taylor <david-tay...@blueyonder.co.uk.invalid> writes:
I wonder how I could get the delay figures for my own modem? The only
data I can extract is: Latency: ~20 milliseconds, RTP jitter - up: 4
milliseconds, down: ~0.12 milliseconds.
You can measure the delays. After the typical client-server
exchange you have 4 time stamps. If you assume the network
latency is symmetric you can compute the clock offset.
If you assume both clocks are accurate you can compute
the network delays.
If you collect a bunch of data, it's reasonable to assume
that the lowest delays are when the queues are empty. Any
longer delays are due to queuing.
Fascinating to see you have less delay on the slower upstream!
The queuing delays depend upon the traffic. You control that.
Thanks for that suggestion Hal. I've written a program to do just that,
and I am seeing down delays of a moderately consistent 4 ms, and up
delays of between 20 and 30 ms.
The program was interesting in that measuring times to better than 15 ms
resolution on Windows requires interpolation, and I had already
developed that from for code I found on the Internet. I think this was
it's first use "in anger".
http://www.satsignal.eu/ntp/TSCtime.html
--
Cheers,
David
Web: http://www.satsignal.eu
_______________________________________________
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions
