[time-nuts] PRS-10 input and output calibrations

[Magnus Danielson]

On 04/22/2012 10:47 PM, bg at lysator.liu.se wrote:
> With factory default settings with 2 PRS-10s, connecting 1PPS_out from one
> unit to 1PPS_in on the other, would not align the 1PPS_out pulses. They
> were off by several hundred of ns. It was probably an operator error
> somewhere. We just did not find the error in the time frame we had
> available.

Interlocking two oscillators like that might be a really bad idea, as 
the PLL will have a gain, so risk having a gain loop, especially when 
the oscillators have the same default parameters being setup. This is 
similar to the form of long PLL chain analysis that has been simulated 
using a single PLL and a delay-loop. The peaking gain at the PLL 
bandwidth is what kills it.

If there is input and/or output non-linearities in the latest 
calibration parameters, that may be a reason they locked up in a strange 
situation.

Using a common PPS pulse as input and then compare the output PPS pulses 
is a much more valid test.

Cheers,
Magnus