[time-nuts] Re: Build a 3 hat timestanp counter

[hans-georg at lehnard.de]

Hi Magnus, 

I got the E1740 last year on ebay for 80EUR and wrote a quick to dirty
software for it. This is my thread about it:
https://www.eevblog.com/forum/testgear/hp-e1740a-time-interval-analyzer-292384/msg3718660/#msg3718660


It has 2 channels and can timestamp any edge up to 80 Mhz.
It is possible to measure with one channel, with 2 channels and the
difference between them. 
I hope to see a difference between the direct input and the TLV3501. 

I also have 2 Acam 2 channel TDC AS6501 with DDR-LVDS outputs and 10ps
resolution. With this it should be possible to sample up to 12,5 MHz
with a FPGA. This will be my next project. 
There is also the AS6500 which has 4 channels, but can only be read out
via SPI. 

For the LTC6957 I will use the circuit from here:
https://ohwr.org/project/wr-low-jitter/uploads/74305092be60598e9bffd39d59489594/Daughterboard_V2.pdf
Page 4. 

Hans-Georg  

Am 2022-05-29 18:35, schrieb Magnus Danielson via time-nuts:

> Hi Hans-Georg,
> 
> On 2022-05-28 17:04, Hans-Georg Lehnard via time-nuts wrote: 
> 
>> Hello Magnus,
>> 
>> I understood that simply sampling 3 channels fast and averaging does not
>> solve all the problems ;-).
> Sure, I just want to illustrate how various approaches could allow you to get the most out of the hardware you have. 
> 
>> I have a HP E740A time interval analyzer that I might use for my
>> oscillators.
>> The HP-TIA has 50ps resolution, can sample 10 Mhz directly but has only
>> 512K sample memory. For longer recordings I can use the histogram
>> function. I still need to do some work on my software for that, but that
>> might be the fastest way to get results.
> Does the E1740A have a high speed time-stamping port? The 5371A and 5372A have that as an option, so if one could have some suitable hardware process on those time-stamps, it would be something. 
> 
>> Attached is a picture of my HP10811 and another one that someone made
>> for me as a comparison to other TIAs.
>> 
>> The third pic shows another meter i have  with TLV3501 and TDC7200
>> without averaging compared to an FA2.
>> 
>> I will keep trying with the TDC7200 and maybe better with the LTC6957
>> and only one channel.
> 
> Yes, to try different approaches. The LTC6957 is a very cool little chip.
> 
> Cheers,
> Magnus
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