[time-nuts] Modulation Domain Analysis
Robert Gilchrist Huenemann
bobgh at razzolink.com
Wed Jun 17 10:07:45 EDT 2015
Thank you for your comments. I was not aware of the TVC501. I have ordered
a copy of the manual.
It is interesting that this instrument only had analog outputs. You did not
mention any digital outputs, so I assume it had none.
Several vendors made system in a box type instruments with various plug ins,
including counters. Were any of them big sellers? Don't know.
From: "Bill Byrom" <time at radio.sent.com>
Sent: Tuesday, June 16, 2015 7:18 PM
To: <time-nuts at febo.com>
Subject: Re: [time-nuts] Modulation Domain Analysis
> On a related subject: Tektronix TVC501 Time-Interval to Voltage Converter
> (cousin of the modulation domain analyzer)
> I have worked as an Application Engineer at Tektronix for over 25 years.
> In the early 1990's we developed the TVC501, which was a time interval
> to voltage converter. I'm doing this from memory (since it's hard to
> find references on the Internet) but I believe it had a time interval
> counter with about 50 ns resolution. The counter output was subtracted
> from a user-settable reference time, then multiplied by a user-settable
> gain before driving an 8-bit D/A. The analog voltage output was updated
> at each measured interval, up to about 2 million updates/sec. This
> architecture allowed the user to see small changes in large time
> intervals on either an analog or digital oscilloscope or other
> instrument. So you could see changes in the period of the power line
> frequency with around 100 ns resolution, and use the oscilloscope
> voltage level trigger features to capture timing aberrations. The TVC501
> was a single-wide TM500 plug-in unit.
> The TVC501 had two BNC inputs, and could sense the width or period of
> signals on one input, or the time interval between edges on the two
> inputs. It was a rather specialized product, and I don't think we sold
> many of them. In 1995 we discontinued nearly the entire TM500/TM5000
> line. Some of these products were sold by Tegam for a few years.
> Bill Byrom N5BB
> On Tue, Jun 16, 2015, at 05:17 PM, Richard (Rick) Karlquist wrote:
>> That's interesting. I worked for the HP Santa Clara Division
>> from 1979 until just before it was closed in 1998. I
>> forget who "invented" MDA at SCD, but it was hyped like
>> it was some new concept and I never heard anything about
>> the HP9540.
>> Many times someone would come to me and ask me about
>> some "new" bright idea they had, and I would tell them
>> "Yes, I can confirm that your idea is excellent, because
>> I read the original paper on it that was published in
>> 19XX." It is interesting that people would often get
>> mad at me, as if it is my fault they reinvented the wheel.
>> If only I known about your HP Journal article, I could
>> have throw it up to the "innovators" at SCD.
>> Before I worked for HP, an HP Journal article came out
>> about fractional-N synthesizers, and everyone at Zeta
>> Labs was anxious to use the technology in the Zeta
>> Labs designs. Except one guy, who pointed out that
>> he had invented frac-N 11 years previously, and he
>> called it "digiphase." I've never heard anyone at
>> HP ever acknowledge that guy.
>> Rick (now retired from HP/Agilent/Keysight)
>> On 6/16/2015 12:54 PM, Robert Gilchrist Huenemann 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
>>> bobgh at razzolink.com
>>> Extra Class Amateur Radio License W6RFW
>>> IEEE Life Member 01189471
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