[time-nuts] Tbolt time constant

[Tom Van Baak]

> Does the longer time constant actually make a "better" frequency standard, or 
> does it just push the noise from one frequency region to another?  Has 
> anybody with gear good enough to measure close in noise looked at the 
> spectrum for different time constants?

Hal,

Last I checked - phase noise, as in L(f), is the same for all
time constants.

Frequency stability, as in sigma(tau), ADEV, etc. typically
improves as the TC increases, out to 1000 s. The default of
100 s works pretty well for normal environments. But if your
sat visibility and voltages and temperature and air currents and
local seismic (vibration, shock, kids playing, doors closing, etc.)
environment is unusually stable then you could bump the TC
beyond 100, maybe even near 1000. I run my best TBolts
closer to 300.

For some time constant plots, see:

http://www.leapsecond.com/pages/tbolt-tc/

/tvb