[time-nuts] Modulation Domain Analysis
time at radio.sent.com
Wed Jun 17 22:05:59 EDT 2015
Bob, the TVC501 was one of many Tektronix TM500 (manually controlled)
and TM5000 (manual or GPIB controlled) plug-in instruments and power
supplies. Some of these were very popular, such as the PS5004 precision
programmable power supply and DC5009 programmable counter. The TM500 non-
programmable modules were offered for over 20 years, from 1972 till the
early 1990's. http://w140.com/tekwiki/wiki/TM500_system
The Spectracom 8163 was a third party WWVB receiver which was powered by
a TM500 mainframe. A number of other companies produced modules which
were powered by TM500 mainframes.
Bill Byrom N5BB
On Wed, Jun 17, 2015, at 09:07 AM, Robert Gilchrist Huenemann wrote:
> Thank you for your comments. I was not aware of the TVC501. I have
> a copy of the manual.
> It is interesting that this instrument only had analog outputs. You did
> mention any digital outputs, so I assume it had none.
> Several vendors made system in a box type instruments with various plug
> including counters. Were any of them big sellers? Don't know.
> Bob Huenemann
> 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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