[time-nuts] Advantages & Disadvantages of the TPLL Method

WarrenS warrensjmail-one at yahoo.com
Sun Jun 13 17:29:15 UTC 2010

Magnus Posted

>"The TPLL is a mid-tau stability test, since it's sweet-spot is in the
>0,1 - 1000 s range. Short-term is better handled in LPLL phase-noise

Mostly agree, it is a mid-tau device, but also consider:

The simple TPLL can be used to find the 1ms to 10 ms ADEV as good and maybe? 
better than ANYthing else.
AND I use it to find the drift and ADEV of my dual oven HP 10811's out to 
weeks, so there is no long term limit.
(the trick is to control the DUT and not the Reference when doing long term 
I find the TPLL method is useful for MUCH more than just getting ADEV data.
As such it's "sweet spot" extends from below 0.004 ms  (250 Hz)
all the way up to >> weeks, when the DUT is the controlled Osc.

ALSO the simple TPLL is very Good and useful for seeing and measuring the 
effects of temperature, line noise, vibration, PS,  load, and just about 
everything else that effects the frequency stability of an oscillators below 
1 KHz or so.
So if you are just thinking about the TPLL for taking ADEV data from 0.1 to 
1000 sec, then you're are missing 90% of the other useful stuff it can do as 
good or better than most anything thing else out there, and all for the same 
$10 (my cost).

If still in doubt about some of the TPLL's other high end performance 
capabilities, try the swinging osc test with ANYthing else and see if you 
can match the simple TPLL's performance.

If one would make a list for the non ADEV uses and advantages of the simple 
It would indeed be very long list, and it does not take any fancy write up 
to see that, just a bit of open minded thinking.

BTW, with a couple of minor configuration changes, the TPLL BreadBoard can 
be transformed into a LPLL,
so the usefulness of the basic Universal TPLL BB circuit has even more 
In fact one could make yet another list of all the additional things it can 
do with no added cost,
just by changing a few jumpers and values.
But those things are for later discussions, one windmill at a time.


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