[time-nuts] 1 PPS Correction Problem using DS1123LE-50 Delay Line

[Martyn Smith]

Hello,

I am using a LEA-6T GPS chip with the DS1123LE-50 delay line to correct the 
jitter of the 1 pps output from the GPS chip.

The correction works very well, dropping the peak to peak jitter of the 1pps 
output from about 20 ns to < 3 ns.

However, I randomly get a big jump of the 1 pps pulse, by many 
millisceconds.

After lots of research, checking code and hardware, it seems the DS1123LE-50 
chip randomly produces it's own long pulse.

I have monitored the pulse going into and out of the delay line

The input pulse remains constant (I can't remember exactly the pulse width, 
I think 10 us).

But suddenly a large output pulse of many milliseconds appear.

Some chips don't seem to have this problem.  Other chips can go wrong, 20 
times in an hour, then run perfectly for a day or so.

I am blaming my software guy, he is blaming the chip.

Has anyone else used this delay line and seen anything similar?

This chip is now apparently obsolete, but I don't want to change yet as I 
have a few years worth of stock of these chips.

Regards

Martyn