[time-nuts] Need to measure frequencies of two sources simultaneously

Magnus Danielson magnus at rubidium.dyndns.org
Wed Oct 23 08:58:08 UTC 2013


Hi Rick,

On 10/22/2013 11:19 PM, Richard (Rick) Karlquist wrote:
> We have two sources and we want to be able to measure their
> frequencies at the same time.  We want to get a time record
> of frequency each second.  Apparently, what is meant
> by a "two channel" frequency counter is that you get the
> frequency of either channel A or channel B but not both
> at once.  Some can also measure the ratio of A to B, but
> that doesn't work for us.
>
> We seem to be left with using a separate counter for each
> source and doing data logging with time stamping.  We can then
> reconstruct the two frequency records after the fact in a spread sheet.
> There is the problem of synchronizing the time stamping
> clocks in the two counters.
>
> Can anyone on the list point me to a true two channel
> counter that would just measure the two sources?  We are
> working around 200 MHz, but could possibly prescale.
>
The HP5372A can pull this one off. It doesn't do it straight out of the
box, but it will time-stamp from both sources at the same time into it's
memory. Reading it out and post-processing it yourself (isn't hard,
considering that the Programmers Manual goes into length into explaining
how to do it) is needed. Could  probably dig up code I've made before.
The HP5372A goes to 500 MHz on both A and B channels.

Cheers,
Magnus



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