[time-nuts] Modulation Domain Analysis

Tim Shoppa tshoppa at gmail.com
Wed Jun 17 06:50:21 EDT 2015


There is a commonly used kind of pulse train analyzer that records and then
dumps timestamps (absolute and/or delta) of low-to-high and high-to-low
transitions for analysis on a computer. Is there a name for this method? I
first saw it being used in the 80's to debug and reverse-engineer
broadcast-over-POTS codecs and GCR floppies, but I'm sure it existed well
before that.

This is similar to e.g. Tom's PICPET but we didn't use it for precision
timestamping - we used it as a kind of generic computer front end for
various pulse train modulation analysis.

Maybe "Time-Stamping Counter" is the generic term for the device? Is there
a phrase for data recovery/inspection using the recorded data?

Tim N3QE

On Tue, Jun 16, 2015 at 3:54 PM, Robert Gilchrist Huenemann <
bobgh at razzolink.com> wrote:

> I stumbled onto the time nuts list from a posting on modulation domain
> analysis a couple of weeks ago. I am enjoying the discussion.
>
> I want to comment on modulation domain analysis, or phase digitizing. This
> is a technique that uses a period mode frequency counter, or two such
> counters back to back, to recover the modulation history of a frequency
> modulated waveform.
>
> This technique was first used in the HP9540 automated transceiver test
> system. This system was described in the August 1973 HP Journal. The HP9540
> used a single HP5326 period mode counter with a 10 MHz clock. At that time,
> no counter was available with a higher clock frequency.
>
> A breadboard system was assembled as part of the HP9540 development effort
> which used two HP5326 counters back to back. To insure that alternate
> periods were measured, the second HP5326 ran off the gate output of the
> first. However, it was realized that the characteristics of the HP9540 and
> its specific application were such that two counters were not required.
> Please refer to my HP Journal article for details.
>
> The HP9540 was developed at HP's Automatic Measurement Division. This
> division was disbanded in 1974.
>
> Modulation Domain Analysis and Phase Digitizing were terms that came into
> use with the later development of specialized stand alone instruments that
> combined computational capability, back to back period mode counters,
> higher clock frequencies, interpolation and algorithms for various
> measurements. All of these were worthwhile improvements on the basic
> technique first used in the HP9540.
>
> I would be happy to answer questions. Thank you for allowing me to post
> this information.
>
>
> Robert Gilchrist Huenemann, M.S.E.E.
> 120 Harbern Way
> Hollister, CA 95023-9708
> 831-635-0786
> bobgh at razzolink.com
> https://sites.google.com/site/bobhuenemann/
> Extra Class Amateur Radio License W6RFW
> IEEE Life Member 01189471
>
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