schmitt

Abstract

A schmitt trigger (a comparator with hysteresis).

Description

Implements a schmitt trigger, which is a comparator with hysteresis. Whenever the input is higher than khigh, output is 1 and stays 1 until input drops beneath klow.

Output is 1 if the input is higher than khigh if signal is increasing
Output is 0 if the input is lower than klow if signal is decreasing

Note

schmitt is particularly useful for implementing effects like a noise gate, to avoid fast opening and closing at the threshold. It can be further refined together with lagud to add attack / release times to the opening of the gate or with trighold to assure a minimum open time for the gate

Port of pd/else's schmitt

Syntax

xout  schmitt xin, khigh, klow

Arguments

xin: input signal (k- or audio rate). The rate of xin must match the rate of xout
khigh: high value of the comparator, output is 1 whenever input is higher than this
klow: low value of the comparator, output is 0 whenever input is lower than this

Output

xout: output value of the comparator (0 or 1). Rate of xout is the same as xin

Execution Time

Performance (k or audio)

Examples

<CsoundSynthesizer>
<CsOptions>
-odac           
</CsOptions>

<CsInstruments>
sr     = 44100
ksmps  = 64
nchnls = 2
0dbfs  = 1

/* Example file for schmitt opcode

    To be used inside csoundqt

    aout schmitt ain, khigh, klow
    kout schmitt kin, khigh, klow

    schmitt is a schmitt trigger (a gate with hysteresis), out is 1 if higher than khigh,
    0 if lower than klow

*/

chn_k "high", "r"
chn_k "low", "r"
chn_k "signal", "w"
chn_k "out", "w"

instr 1
    khigh chnget "high"
    klow chnget "low"

    ain = oscili:a(1, 0.25)*0.5+0.5
    aout schmitt ain, khigh, klow

    chnset ain[0], "signal"
    chnset aout[0], "out"

endin

</CsInstruments>

<CsScore>
i1 0 100

</CsScore>
</CsoundSynthesizer>


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Credits

Eduardo Moguillansky, 2019