1. Home
  2. Electronics Computer-Aided Design
  3. Increment/Decrement Control Loops

Increment/Decrement Control Loops

"Jim Thompson" in news: snipped-for-privacy@4ax.com...

I haven't seen the original, but from the description here, it sounds like a good old digital integrator. In case anyone who is reading this has not run into or thought about it, a digital up-down counter is precisely a DSP integrator for a one-bit input ("+- 1"). (At times in the past we made very good use of that property, and other properties of one-bit arithmetic, in digital filters for oversampling data converters.) And an integrator is the heart of many control loops.

In the early days of digital forays into the system-simulation world pioneered by analog computers (more on those in classic books by Jackson, and by Korn and Korn), people built special-purpose digital integrators, and then made loops out of them that would solve differential equations over time, just like electronic analog computers did. They were called Digital Differential Analyzers (DDAs). A single digital integrator in an AGC control loop would be a grandchild of those.

-- Max

Reply to
Max Hauser
Loading thread data ...

Anyone know the history of Increment/Decrement Control loops?

There's a paragraph on page 56 of the October "Microwaves and RF" magazine about AGCing a VCO using an up/down counter and D-A in an increment/decrement control... touting it as if it's the next best thing to sliced bread.

But I hardly think it's novel... I was setting the timing of automobile ignition systems in 1968, but used a squirt of charge into/out-of a capacitor to increment/decrement.

The paragraph references an IEEE article in October's "IEEE Transactions on Instrumentation and Measurement", which I can't access since I object to $35/month for the privilege (as I noted today as I renewed my memberships).

Maybe someone who subscribes to that service can look it up?

Thanks!

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

[snip]

That's what I thought, too.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

Try looking for "single-speed floating control". I think it's a really old and not-so-great control strategy.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Sounds pretty much like the old 'huff-and-puff' VFO stabiliser the radio hams used. regards john

Reply to
john jardine

I thought it worked rather well. My scheme looked at dwell, decided if it was early or late and moved a threshold accordingly... this happened _after_ firing so was not subject to noise from the spark.

Just like having an elf sitting there turning a knob just a small amount after each firing ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

If you choose a fixed increment that is small enough it closes at "left-right-left-right-left......" ;-)

Driving a big-assed T-bird (400+CID) in 1968, up and down 101 (near Sunnyvale) at over 100MPH, I was never able to cause the ignition to stumble... scared the hell out of my boss, though ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

I think it generally works better if the elf moves the knob more for large differences and less for small differences.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Perhaps I should elaborate. Waveform form (simplified, it's more rounded) from magnetic pickup in distributor:

_ _ _ / | / | / | | / | / | / | /

----------------------- THRESHOLD | / | / |_/ |_/

Downstroke is firing. When ramp crosses threshold power device (driving coil) turns on. So this crossing determines "dwell".

Device control is simple-minded (my preference :)...

Device has three states:

Off... Fired Saturated, coil charging Current mode, regulated at 5.5Amp

So I only look at two conditions... when firing occurred was I in saturation or in current regulation.

If device was in saturation, dwell didn't start soon enough so I decrement the threshold. If device was in current regulation dwell started too soon so I increment the threshold.

Worked like a champ.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

I will send you a copy if that is your real email address.

Reply to
Tom Seim

I have already been sent a copy, Thanks! (The header E-mail address is false... read the SIG to obtain a valid E-mail address.)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.