[time-nuts] New Timestamping / Time Interval Counter: the TICC
kb8tq at n1k.org
Sun Nov 27 09:24:38 EST 2016
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 ….
> 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.
> From "time-nuts" time-nuts-bounces at febo.com
> To "Discussion of precise time and frequency measurement" time-nuts at febo.com
> 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
> 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.
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