[time-nuts] New TIC test run

Bob Stewart bob at evoria.net
Sun Mar 9 11:40:19 EDT 2014


Hi Anders,

I just put the schematic up at http://www.evoria.net/AE6RV/TIC/TIC2.bmp  However, there are some caveats: I did not have to use the level shifter Q1/Q2.  I am not yet using VR1.  (Actually the one I bought failed for some reason.)  R4 is actually 2.4K, and C1 is not being used.  The capacitors in the 18F2220 PIC are sufficient without C1.

I'm not sure what you mean by "what is the range".  The ADC is 10 bits wide.  The output varies from about 150 to about 500 units over 360 degrees of phase error without the Voltage Ref.  It should be twice that when I get that in and working; though I am worried that it might clip on the high side so...

The red data, as it says on the plot, is the 53345B.  The blue data is from the TIC.  The transfer function is nonlinear, and I have made no effort to correct for this.  

I've had a day to play with it, and I'm amazed at the precision of this thing.  It's like taking the 5334B and adjusting the focus knob.  Of course it's not as accurate, due to the way it works, but it will fit my needs well in my GPSDO.

Bob - AE6RV



>________________________________
> From: Anders Wallin <anders.e.e.wallin at gmail.com>
>To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>Sent: Sunday, March 9, 2014 3:19 AM
>Subject: Re: [time-nuts] New TIC test run
> 
>
>
>
>Do you have the schematic for this online somewhere?
>what is the range of the interpolator?
>which TIC is the red/blue points? the blue data looks like it is aliased somehow, perhaps a number that is truncated/rounded badly?
>
>
>
>
>On Sat, Mar 8, 2014 at 9:46 PM, Bob Stewart <bob at evoria.net> wrote:
>
>I put my TIC to hardware, and have started testing it.  Here is a sample run comparing it against the 5334B with an off frequency OCXO.  I've scaled and rotated to tried to cancel out the length of the cables to the 5334B.  Still early days with it, yet.
>>
>>
>>http://www.evoria.net/AE6RV/TIC/TICvs5334B.png
>>
>>Bob - AE6RV
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