[time-nuts] TICC TAPR and TimeLab

[John Ackermann N8UR]

Some answers below.

John

On 7/3/20 10:54 AM, w8ycm--- via time-nuts wrote:
> New guy here needs help using the TAPT TICC and Timelab software
> 
>   
> 
> The TICC documentation, I am sure, is sufficient to those in the community,
> but to someone who has only lurked around the edges, there are a few
> questions I have.   I suspect some are obvious, and some others of no
> consequence, so here goes:
> 
> M   Measurement Mode        T               default T
> S   clock Speed  (MHz)         10.000000       default 10
> C   Coarse Clock Rate (us)  100.000000      default 100
> P   calibration Periods           20              default 20
> T   Timeout                            0x05            default 0x05
> Y   sync:  master / slave       M               default M
> E   trigger Edge                    R R             default R
> D   time Dilation                    2500 2500       default 2500
> F   Fixed Time2                    0 0             default 0
> G   fudge0                            0 0             default 0
> 
> (1)     In  M (Measurement mode), what is the use for the “  L     TimeLab
> interval mode “?  Should it only be used with Timelab? If “Yes” skip  and b:

"TimeLab" mode is a special configuration for doing three-corner hat 
measurements.  Don't use it unless you know what those are, and why they 
may not work. :-)

> 
> a.                    In  M (Measurement mode), the  functions of the T/P/I,
> modes are reasonably obvious,
> 
>        but with ones should be used with Timelab to compute Allan Deviation.
> 
>

TimeLab works in "normal" fashion with either time interval, or one or 
two channel timestamp, data.  Of course, you need to configure TimeLab 
to match what's coming out of the TICC.

> b.                    Are any of the Measurement modes of particular use in
> other Timelab functions?

You could probably kludge the period data mode to work with TimeLab, but 
that one would not normally be used for a typical stability analysis. 
It shows the period (inverse of frequency) of the input channel.

****
All of the following questions could be answered with, "Leave them alone 
unless you're doing hardware or software development" but I'll try to 
provide some info.  To make much sense of it, you would need to study 
the TICC schematics and source code, and also spend some quality time 
with the TDC7200 chip data sheet.

> (2)      In  M (Measurement mode), what does one do with “ D     Debug
> mode”?

Nothing, unless you're working on the code.  That mode outputs the raw 
data values used within the system and is for testing purposes.


> (3)      What is the rational for selecting a  particular “Coarse Clock
> Rate” value?

The Coarse Clock needs to match the hardware configuration.  Unless 
you're changing the TICC hardware (or the PIC divider chip), don't 
change this.


> (4)      What is the rational for selecting a particular  “calibration
> Periods” value?

Trade-off of measurement speed vs. calibration accuracy.

> 
> (5)      What is the rational for selecting a particular  “Timeout” value?

Trade-off of measurement speed vs. proper operation.

> (6)      What is the rational for selecting a particular  “time Dilation”
> value?

There's a small non-linearity in the TDC7200 chip output and this value 
compensates for that.  It's determined experimentally and seems to be 
about the same in all units.

> (7)      What do the “Fixed Time” options do, and why?

It's an experimental configuration option that in theory could provide 
slightly less jitter in the results.  We haven't proven whether or not 
it actually does.

> (8)     What do the “Fudge” options do, and why?

These allow you to "trim" the results to account for slightly differing 
cable lengths or path delays.  By experimental adjustment, you can use 
there to match the channel A and channel B results to compensate for 
these variations.  It's not normally necessary to mess with them.

John