Re: [Qucs-help] Switched from Trapezoidal to Gear: still no delay; also WYSInWYG

[Claudio G. <cla...@vi...>]

Hello,
I think I posted an answer yesterday but apparently I addressed it to 
you only and not also to the list. I've attached it here below.

I can now confirm that the RLCG line does NOT work as expected in a 
transient simulation; only its DC characteristics are used, so there 
will be no propagation delay.

Regards,
  Claudio



> Hello Bruce,
> I seem to remember that only the ideal transmission lines, which 
have
> a constant delay vs frequency, are properly modelled in the 
transient
> simulations.The other lines are assumed to have the same behavior as 
at
> DC (i.e. a short circuit). Frequency domain response is fine.
> And, yes, Qucs(ator) should output a warning message for this...
> 
> Regards,
>   Claudio





>----Messaggio originale----
>Da: "Bruce Waters" <the...@ya...>
>Data: 28-ott-2016 2.50 PM
>A: "quc...@li..."<quc...@li...>
>Ogg: [Qucs-help] Switched from  Trapezoidal to Gear: still no delay;	
also WYSInWYG
>
>Hi, 
>   During re-research of the lit I found this passage in the Qucs 
docs and thought it might help my "RLCG missing delays" conundrum: 
>====== P176 Tutorial Workbook passage ================= 
>With the explicit numerical integration routines, like the 
trapezoidal 
>routine, numerical instability results if the simulation time step 
be-  
>comes much larger than the smallest time constant in a circuit. 
Hence, to  achieve successful completion of a simulation the 
integration time step must be reduced which in turn makes the overall 
simulation time increase  significantly. The implicit Gear algorithm 
(footnote 5) 
>does not suffer from this problem and is the natural choice for 
circuits  
>with components that have widely differing time constants. 
>========================================== 
>I switched from Trapezoidal to Gear for my Transient Simulation in 
my 
>EgRLCG_prj  but found no apparent joy.   That is, I still see no 
delay in  oneSeg RLCG transmission line component. 
>     I do not know if you are OK with my journaling my efforts in 
this  
>forum (Qucs-help) and I will cheerfully take it offline or just go 
silent  
>wrt the minutia of this topic if you ask.  Otherwise, I will 
accumulate the  breadcrumbs of my quest here since other RLCG 
transmission line  
>testers or experimenters  may enjoy some benefit by lurking.  
>    I would like to apologize to my readers for formatting anomalies 
in  
>my posts and especially in the digests. I will comment that there 
are  
>distinct differences between the texts as I composed them and the 
way   they appear as posted, notably unwanted reflows, missing spaces, 
extra 
> "?"s, etc.   WYSIWYG seems to have issues across mail editors, 
pasting  
>from pdf's, operating systems, mailing list packages, and digest 
tools. 
> I will seek to reduce these annoyances whenever I can 
but  (frankly) 
> content, prompt interaction, and effort minimization will 
remain  higher   priorities than absolute pristine form.  Perhaps 
someone can suggest a magic-bullet to resolve WYSInWYG corruption in a 
wholesale fashion.  
> Low effort please, and, no, I am not going to switch to another 
OS,  but 
> I might, for example, set some specific line-length in the Yahoo 
mail 
>composition editor if someone knows what benefit will result and can 
describe the specifics as they pertain to Qucs-help(like a 
linelen<x.)     
>Thanks, 
>thewildotter     
>  

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