84 lines
2.3 KiB
Plaintext
84 lines
2.3 KiB
Plaintext
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* Fourier Series Function for SPICE
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.control
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begin
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if ($argc lt 4)
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echo Error: Too few arguments.
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echo ' 'Spectrum produces a plot containing a fourier series transformation of
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echo ' 'the specified vectors
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echo usage: spectrum startfreq stop step vec [[vec] ...]
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goto bottom
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end
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if ( time eq time )
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foreach vec $argv[4-len]
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if ( $vec eq $vec )
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else
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goto bottom
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end
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end
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else
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echo ' 'Spectrum can not work without a time vector from a transient analysis.
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goto bottom
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end
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set dt=$curplot
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set title=$curplottitle
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set curplot=new
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set scratch=$curplot
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let span={$dt}.time[length({$dt}.time)-1]-{$dt}.time[0]
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if ($argv[3] gt 0.999/span)
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let fpoints= ( $argv[2] - $argv[1] ) / $argv[3] +1
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if (fpoints < 2)
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echo frequency start stop or step not correctly specified
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goto cleanup
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end
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else
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echo Error: time span is not long enough for a step frequency of $argv[3] Hz
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goto cleanup
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end
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let lent = length({$dt}.time)
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set lent = "$&lent"
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let nyquist = {$lent}/2/span
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if ($argv[2] gt nyquist)
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echo Error: The nyquist limit is exceeded, try a frequency less than "$&nyquist" Hz
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goto cleanup
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end
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set fpoints="$&fpoints"
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set curplot=new
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set spec=$curplot
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set curplottitle=$title
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set curplotname='Spectrum Analysis'
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let frequency=vector( $fpoints )*$argv[3]
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dowhile frequency[1] < ( $argv[1] + 1e-9 )
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let frequency = frequency + $argv[3]
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end
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foreach vec $argv[4-len]
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let $vec = vector( $fpoints ) + j(vector( $fpoints ))
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reshape $vec [{$fpoints}]
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end
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set curplot=$scratch
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let npers=1
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let test = span-2/$argv[3] + 1e-9
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while test > 0
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let npers = npers + 1
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let test = test-1/$argv[3]
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end
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let ircle = 2*pi*max(-1,({$dt}.time-{$dt}.time[{$lent}-1])*{$argv[3]}/npers)
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let win = 1 - cos(ircle)
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let ircle = npers*ircle
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let circle = ircle * ({$spec}.frequency[0]/$argv[3] - 1)
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let k=vector( $fpoints )
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foreach k "$&k"
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let circle = circle + ircle
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foreach vec $argv[4-len]
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let tmp = win*{$dt}.{$vec}
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let {$spec}.{$vec}[{$k}] = 2*(mean(cos(circle)*tmp),mean(sin(circle)*tmp))
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end
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end
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label cleanup
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destroy $scratch
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unset fpoints dt scratch spec vec k title lent
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label bottom
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end
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