[time-nuts] Frequency subtraction with D-flip flops

EWKehren at aol.com EWKehren at aol.com
Tue Jun 25 17:48:34 EDT 2013


In the Austron 2110 is a dual D FF Mixer along with circuitry to get 100 Hz 
 out. I did a board using 2 XTAL Filter stages and you can get 1 E-12 using 
a 100  MHz period counter. Using my previously mentioned Ping Pong counter 
at 200 MHz  and Offset of 1 Hz at 5 MHz you get 1 Hz out. Resolution is 1 
E-15, there is  some jitter and quite a bit of AV. Presently we use a PTS 40 
to generate the  offset but it will be replaced by an AD9913 DDS. Schmitt 
trigger jitter is not a  problem since the ping pong counter functions like 
time stamp and with two  synchronizing stages does not miss a single count. The 
2 by 2.5 inch board with  out any other additions allows you also to do AV 
measurements as long as one of  the inputs is offset by 1 or 10 Hz.  The DDS 
is a piggy back board and only  is needed if you want to measure frequency 
at high resolution. For AV the board  does every thing.
We plan on using it for long term monitoring using 5/10 Hz out and average  
at least 10 counts. Resolution 1 E-14. Data will be recorded on a USB  
stick.
Key components are a MAX 3000 32 macro G/A two 16F633 PIC's and one 16F688  
PIC output is RS 232. Basically the same board Corby now uses with a few 
more  functions in the G/A.
Bert Kehren
 
 
In a message dated 6/25/2013 4:07:01 P.M. Eastern Daylight Time,  
timenuts at binsamp.e4ward.com writes:

(Original seems to have got lost - try again)

> More  recently  we  are  using   two   D   FF's  for  mixing  in A/V
> applications and very  high resolution frequency  measurements with
> up to 1 E-15  a second using output frequencies from 0.5 Hz  to 100
>  Hz.

> Do to attachment limitations if you want more info  contact  me off
> list and I send you some  scans.

> Bert Kehren

Bert,

This  is very interesting. Can you explain in more detail how you can
reach 1e-15 in 1 second with those offset frequencies?

Can you  give the input frequencies, the IC type, and how you measure
the  output?

Thanks

Mike  M
_______________________________________________
time-nuts mailing list  -- time-nuts at febo.com
To unsubscribe, go to  
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the  instructions there.



More information about the time-nuts mailing list