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

Christopher Hoover ch at murgatroid.com
Wed Nov 23 15:42:53 EST 2016

That TI TDC7200 really is a nice part.

Neat project!   Will buy .  Two thumbs up.

On Wed, Nov 23, 2016 at 7:48 AM, John Ackermann N8UR <jra at febo.com> wrote:

> 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
> on the Texas Instruments TDC7200 time-to-data-converter chip.  The
> one-second noise ADEV is about 7x10e-11, not much worse than the 5370, but
> here's the trick:  the TICC is an Arduino shield (mounting on a Mega 2560
> controller) that weighs only 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 one 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 one 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 on 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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