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Re: Open source workshop at Auckland, NZ

From: Macy
Subject: Re: Open source workshop at Auckland, NZ
Date: Thu, 10 Jul 2014 07:20:35 -0700


I wish I could be there to offer to present results of last two months of 
effort building a set of scripts/functions for octave, and developing a 
protocol of sequences, to enable doing enhanced circuit simulation - doing what 
I call, .tranoise analysis in LTspice, which combines .noise and .tran into a 
single analysis. 

Very useful simulation tool combining .noise with .tran analyses into a single 
analysis step in order to make the circuit simulation results more realistic. 
The time waveforms are 'fuzzy' like caused by the presence of noise, and 
importantly the spectrum plots have calibrated noise floors, actually look like 
spectrum analyzer plots. 

The concept for creating this additional tool set, .tranoise, came about while 
I was doing some analyses of non-linear signal processing, mixer design. 
LTpsice and PSpice do not make it easy to see what's happening when trying to 
gain understanding. Using .tranoise one gains tremendous insights into the 
expected circuit operation, to actually see 'bumps' caused by noise around each 
harmonic without having to build the circuit.

In another example, I discovered that an OpAmp circuit's noise output actually 
increases to something like 3 times when you drive the OpAmp into slew rate 
limit. LTspice and PSpice do NOT predict this condition at all!

Thus, the combination of octave and LTspice have become valuable 
simulation/learning tools. 

There were additional octave tools [concepts and functions] to save time for 
the kernel(?) to solve analyses. The technique was to replace sections of mixer 
and filter circuitry with octave functions. Even, functions for injecting noise 
[like transmission links] and applying analog filtering, etc. Using octave 
functions to replace linear circuit sections greatly sped up analyses AND 
gained much more understanding of performance of a non-linear circuit and/or 
predicting the overall system responses.

Essentially, the octave/LTspice tool set was to enable bouncing back and forth 
between time and frequency domains to really gain some understanding what's 
going on in non-linear circuitry.


PS: Included in these results are functions similar to or almost duplicating 
many existing System/Filtering Tools, but these 'new' specific functions are a 
'simplified' form and were written for any Engineer who is used to working with 
complex polynomials to represent system response AND wants to easily display 
signal points throughout their design. Again, bouncing back and forth between 
time and frequency domains.

--- address@hidden wrote:

From: Bart Verleye <address@hidden>
To: address@hidden
Subject: Open source workshop at Auckland, NZ
Date: Thu, 10 Jul 2014 10:12:48 +1200


I'm organising an open-source workshop at the University of Auckland on 
14 August. Are there any octave experts from NZ on this list that would 
be keen to give a little demonstration of octave, and perhaps also help 
with the hands-on session after the presentation?


Dr. Bart Verleye
Centre for eResearch
Level G, Room 409-G21
24 Symonds St.
Auckland 1010
New Zealand
+64 (0) 9 923 9740 ext 89740

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