[time-nuts] New Timestamping / Time Interval Counter: the TICC

[Bob Camp]

Hi

Without doing a bunch of actual *work* I’m not sure what is inside the guts of the board. Being 
lazy I’ll just guess ….

There appears to be a 10 MHz time base input and a pair of measurement inputs. In a lot us will 
be comparing to a “house standard”. That standard has a pps output that is related directly to 
the 10 MHz reference. If I can uniquely identify one edge (out of 10 million edges) as the right 
edge, I can use the 10 MHz as my pps reference. Put another way, I don’t really need to measure
a pps input from the house standard if I’m already locked up in phase to the 10 MHz. All I need to
do is to tag an edge / reset a counter. 

The advantage of this is that I may not need another fancy TDC chip to set up the reference. I can
use *both* inputs for DUT’s rather than using one as a reference.

Part of the reason I’m guessing this would work is the claim that boards can be stacked for multiple 
input setups ….

Bob

> On Nov 27, 2016, at 7:36 AM, timeok <timeok at timeok.it> wrote:
> 
> 
>   Hi John,
> I have planned to buy two TICC.
> An interesting feature would be to be able to do two simultaneous acquisitions,
> and Timelab as real time display,using the two indipendent input channels and the 10Mhz clock as single reference.
> Luciano
> www.timeok.it
> 
> 
>   From "time-nuts" time-nuts-bounces at febo.com
>   To "Discussion of precise time and frequency measurement" time-nuts at febo.com
>   Cc
>   Date Wed, 23 Nov 2016 10:48:57 -0500
>   Subject [time-nuts] New Timestamping / Time Interval Counter: the TICC
>   Counters with resolution below 1 nanosecond are difficult. They require
>   either outrageous clock speeds, or interpolators that are typically a
>   bunch of analog components mixed with black magic and stirred by
>   frequent calibration. The very best single-shot resolution that's been
>   commercially available is 22 picoseconds in the HP 5370A/B, with jitter
>   somewhat more than that. My 5370B has an one-second noise ADEV of about
>   4x10e-11.
> 
>   With the help of some very talented friends, I've been working on a new
>   counter called the "TICC" with <60ps resolution and similar jitter,
>   based the Texas Instruments TDC7200 time-to-data-converter chip. The
>   noise ADEV is about 7x10e-11, not much worse than the 5370,
>   but here's the trick: the TICC is an Arduino shield (mounting a Mega
>   2560 controller) that weighs a couple of ounces, requires *no*
>   calibration, and is powered from a USB cable!
> 
>   The TICC is implemented as a two-channel timestamping counter. That
>   means it can measure or two low-frequency (e.g., pulse-per-second)
>   inputs against an external 10 MHz reference, or it can do a traditional
>   time interval measurement of input against the other. It can also
>   measure period, ratio, or any other function of two-channel timestamp
>   data. (And by the way -- multiple TICCs can be connected to yield 4, 6,
>   8, or more synchronized channels, though we haven't tested this
>   capability yet.)
> 
>   I've attached a picture of the TICC prototype as well as an ADEV plot of
>   a 17+ day run of multiple measurements taken by two TICCs, and also
>   showing the TICC noise floor. The good news behind that plot is that
>   there are more than 6 million data points behind these results, and
>   there was not a single glitch or significant outlier among them.
> 
>   There's more information available at http://febo.com/pages/TICC
> 
>   The software is open source (BSD license) and is available at
>   https://github.com/TAPR/TICC -- the current version seems be reliable
>   but there are still features to add and a *lot* of cleanup to do; it's
>   currently ugly and very much a work in process.
> 
>   As always, I'll be making the TICC available through TAPR. We're still
>   finalizing details, but we expect the price to be less than $200 for a
>   turn-key system: TICC mounted an Arduino with software loaded and
>   tested for basic functionality. We hope to ship the TICC by February.
> 
>   I'll post a note in a week or two with final price and ordering
>   information. As a heads up, we will probably offer a small discount for
>   pre-orders. TAPR is a shoestring non-profit group and the up-front cost
>   to manufacture this unit will frankly be a challenge for us. Getting
>   pre-orders will help our cash flow significantly, so we ask you to keep
>   that in mind.
> 
>   John
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