Re: 15ps and falling

On Jun 24, 4:44 pm, "colin" <colin.ro...@xxxxxxxxxxxxxxxxxx> wrote:
"MooseFET" <kensm...@xxxxxxxxx> wrote in message

news:1182726208.630438.316680@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

On Jun 24, 1:54 pm, whit3rd <whit...@xxxxxxxxx> wrote:
[....]
Yow! Most optical sensors are capacitive output impedance, with
photomultipliers and maybe avalanche diodes the exception.

I PMT plate looks like a very high resistance in parallel with a
capacitor. The capacitance limits the frequency responce.

I have 5.76e9 samples per day so I get a lot of the resolution from
averaging.
3 days will give me about 0.1ps for 25ns resolution per single pulse.


Yes, that sort of method is quite a good way to improve the
measurement. I have had a few troubles when doing this so I will
suggest them as things you need to watch out for.

(1)
If the experiment and the measurement system can crosstalk, the really
high frequencies from the experiment can sneek into the clock circuit
of the measurement system. This makes the two try to lock together
and modulates the time base.

(2)
The measurement assumes that the timing of the pulse slides to all
posible times in the cycle of the timebase. This is almost always
true but sometimes gremlins will get in and make it not true. These
gremlins only seem to act when the lights are off over night.



the mechanical noise is a lot worse than this atm.
the noise from comparing the two channels from one encoder is quite low.

Colin =^.^=


.

Relevant Pages

  • Re: 15ps and falling
    ... The capacitance limits the frequency responce. ... days will give me about 0.1ps for 25ns resolution per single pulse. ... the mechanical noise is a lot worse than this atm. ...
    (sci.electronics.design)
  • Re: 15ps and falling
    ... I PMT plate looks like a very high resistance in parallel with a ... The capacitance limits the frequency responce. ...
    (sci.electronics.design)