On 28.02.2009, 00:47 Tom Van Baak <[email protected]> wrote: >> Thanks a lot for taking the time to do these measurements Tom. >> >> If I am interpreting the data correctly the ADEV stays below >> 3E-(8+tau) out to tau=1000s and is above that for tau=10000s. So the >> Thunderbold is indeed not suitable for VLBI at 40-50MHz with >> integration times longer than 1000s.
> I'm not sure what you mean by the expression: 3E-(8+tau). For > example, if you plug in tau = 1000s into that equation, you get > 3e-1008, which isn't right. Your are right, of course. I just realized I made the same mistake in my previous post. The ADEV requirement is 3E-9 * tau at tau or equivalently 3E-(9+x) at tau = 1Ex. > Also how does this compare with your earlier requirement of > 3 ns at 1 second (which would be 3e-9). I'll help, but I'm a bit > confused what your performance goal is and how that relates > to 50 MHz. At f = 50MHz the period is T = 1/f = 20ns and a 50 degree phase error corresponds to T*50/360 = 2.7ns = 2.7E-9s (or 3ns at 46 Mhz). Since the phase error must be below 50 degrees over the entire signal integration time the required ADEV decreases with the integration time d as 2.7E-9 * tau at tau = d. > /tvb _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
