this Gstreamer CODE performs many functions...
1. it creates a SINE WAVE at 740hz that connects to the upper port of the ladspa ZAMGATE SIDECHAIN PLUGin(ladspa-zamgate-ladspa-so-zamgate)
2. it creates an input port for receiving a CPO's//CW keyer's harsh square wave audio output, that it will use to trigger the SINE WAVE at 740hz to pass through the ZAMGATE upper port in exact timing precision with the original SQUARE WAVE cw note
3. it will set the RISE/fall time and weight by zamgate's controls
(attack=5 release=5 threshold=-31 sidechain=true)
4. it will filter the ZAMGATE pure sine wave trapezoidal wave shape output into a raised cosine edged output(audiowsincband mode=band-pass lower-frequency=600 upper-frequency=800 length=424 window=3 low-latency=true)