[time-nuts] New NTBW50AA

[Tom Van Baak]

> I get a spread of around 300ppt, that means I'm always within
> 300x10^-9 Hz of 10MHz or .0003Hz at 1GHz? 

Note "300 ppt" is a "fractional frequency", unit-less value, so
at 10 MHz, 300e-12 * 1e7 Hz =  0.003 Hz
at 1 GHz, 300e-12 * 1e9 Hz = 0.3 Hz

> I suppose the ppt spread is pretty much a function of how stable the osc is once
> other factors like temp, antenna position, sat acquisition, etc, are optimized?

Yes and no; it's a complicated subject. For now, just two points:

A measure of frequency implies some measurement duration. A given TBolt may be off by more than 1e-11 in frequency over seconds or minutes even though if you measure over a day it is accurate to less than 1e-13. This is one problem with interpreting the "OSC" value.

A second problem is that a TBolt can't really know its own accuracy; that requires an external frequency reference, so take the PPS and OSC with a grain of salt. However, in general, the TBolt will steer its 10 MHz oscillator so as to minimize the PPS and OSC values. As such they can be used as a rough idea of how well the unit is performing.

/tvb