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HP 5335A Timer / Counter - Anything i should know?
tkamiya:
I have HP53131A hooked into GPSDO.
Problem with Allen deviation is I really don't understand it and I lack facility to actually measure that kind of precise and repetitive measurement. I've purchased GPIB interface, so I might try it at some point in time. For this experiment, I used HP53131A in frequency A mode and used long gate time.
Here's a picture of 3010. Other than these two mysterious stickers, they are identical to everyday 10811-6011. It came out of parted out HP8568A upgraded to B. Right now, these are available for like 60 dollars so I may buy a few and keep them in my stock.
I wish I can make use of my Rubidium stuff but just their size and heatsink requirement, and power is stopping me. It works with switcher but it is really recommended to use a linear supply. I had 3 of them running concurrently and it definitely made the room much warmer, so that's a problem, too.
I think I'm becoming a time-nuts.... I'm already a test equipment anonymous.
FriedLogic:
Plotting ADEV and similar is only part of the analysis. They are designed to look at random noise processes, but there are a lot of systematic processes also going on. These may show up on an ADEV plot, but it's not usually the best way to investigate them.
Oscillators can be sensitive to temperature, pressure, humidity, magnetic fields, etc., and the best way to check for this is usually to keep a log of them to add to plots of the frequency and phase. These can be processed in various ways by averaging, removing drift, measuring correlation, etc. to understand the behaviour of the oscillator in different situations, and so give the best chance of optimising its performance. The effects can also be delayed, which further complicates things.
Although ADEV is often quoted for short times like 1-100s, it's valid over any time period, so you can still get some use from it even it you don't have a very fast and high resolution counter.
One slight complication with the 53131A/53132A/53181A is that their frequency modes do not do a single 'Gate Time' measurement, but rather do what is effectively a lot of overlapping 'Gate Time'/2 measurements. This adds some filtering, and also a triangular weighting to measurement, and the ADEV of measurements done with them will be low compared with the actual ADEV. It is still useful for comparing with measurements done on the same or similar counters.
tkamiya:
OCXO is good at short term. Not so at long term.
Rb is good at long term. Not so at short term.
Cs is great but not so with my budget.
Hm is super great but not even a possibility at home.
I am going to experiment with GPS trained Rb trained OCXO. That's the best I can do.
I wonder how do we even know Cs is wrong when it IS the standard....
Dr. Frank:
--- Quote from: tkamiya on February 23, 2019, 02:19:06 am ---OCXO is good at short term. Not so at long term.
Rb is good at long term. Not so at short term.
Cs is great but not so with my budget.
Hm is super great but not even a possibility at home.
I am going to experiment with GPS trained Rb trained OCXO. That's the best I can do.
I wonder how do we even know Cs is wrong when it IS the standard....
--- End quote ---
Cs, like Rb has a small dependency on magnetic fields, so you have to cancel these externally.
This dependency is much, much smaller than Rb.
The primary clocks were all compared against each other, and that median will define the UTC.
Comparison is done by bi-directional satellite links, or by GPS.
PS: You already have all tools on hand to make stability studies, and to analyse the collected data on any wanted way, ADEV, MADEM, freq. deviation.. all inside TimeLab, which also has a complete data collection routine for these commonly used counters.
GPIB access, and a few BNC cables, and you're done. One of your standards has 1pps for sure, so that would be a good starting point.
It's much easier to do, than you think!
tkamiya:
What I really need is a GOOD understanding of time device management. That inter-dependency of nature (Cs vs Rb vs XO) of medium (short term vs long vs very long) also needs to be clear. I'm going to have to get the setup ready and follow along existing resources such as TimeLab. Since there does not seem to be one "best method", I'm thinking there won't be one device that does all.
Maybe I'll make two identical setup and do a controlled comparison study. I have a stack of Rubidium modules. It should be quite interesting.
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