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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Re: Hi John posted by john curl on June 13, 2003 at 15:24:22:
""The Sound Technology seems happy enough, so long as I can process out the noise""JCI wasn't worried about the noise..I worry that the ST1700 has limitations and error sources that have not been characterized.
""I am using a TWO STEP process""JC
I know..It's the same process we use to find millivolt levels buried in the 100 volt terminal voltage we have when we rapidly ramp superconducting magnets over a kiloamp per second..We need to spot very small perturbations to detect quenches, and have less than 40 milliseconds to do so..otherwise, the super exceeds about 1000 degrees C and becomes toast.
So, I have no problems with the two step process. Just concerned with the nulling process and the way the test equipment can introduce funnies at that time..That's why my questions..
What I was seriously considering is putting together a really good IA, and running the cable under test from the inverted to non inverted..letting the IA's CMRR be responsible for signal nulling..
That way, I can drop a coupla vishay's in, and a coupla very low value metal films to max out the CMRR, toss the whole kit and kaboodle into a temperature controlled chamber (or at least heat sink the vishays to a temp controlled aluminum plate in an insulated enviro., and worry about notching and gain afterwards. I'm also curious to see how many bits accurate my 24 bit card really is..
But, to do what I want, I have to worry about ground loops, and spurious pickup of the drive oscillator harmonics into the shield.
My technique will work best with an oscillator built in total isolation, IOW.. batteries. I don't need the output reference for null, the IA does that..The method is simplified when there is no gain or phase shift to worry about, like the standard commercial units..
Your last post, the one I'm responding to?? Excellent, thank you..
Cheers, John
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Follow Ups
- Hi John - jneutron 19:05:25 06/13/03 (0)
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