Comments - High Performance Raspberry Pi4 /midi keyed\ Morse Code Practice Oscillator with a tracking BP filter - QRQcw2024-03-28T11:42:01Zhttps://qrqcwnet.ning.com/profiles/comment/feed?attachedTo=1993813%3ABlogPost%3A135034&xn_auth=noHigh Performance Raspberry Pi…tag:qrqcwnet.ning.com,2022-07-22:1993813:Comment:1350172022-07-22T15:48:32.205ZChuck aa0hwhttps://qrqcwnet.ning.com/profile/chase
<p><span>High Performance Raspberry Pi4 /555 keyed\ Morse Code Practice Oscillator with a tracking BP filter</span></p>
<p><span><iframe allowfullscreen="" frameborder="0" height="315" src="https://www.youtube.com/embed/Pj90ZCno_R0?wmode=opaque" width="560"></iframe>
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<p><span>this is a follow up video from the first one here:</span></p>
<p><span><a href="https://youtu.be/ZcEXe5LHCQE" target="_blank">https://youtu.be/ZcEXe5LHCQE</a></span></p>
<p><span>in this video, instead of using…</span></p>
<p><span>High Performance Raspberry Pi4 /555 keyed\ Morse Code Practice Oscillator with a tracking BP filter</span></p>
<p><span><iframe width="560" height="315" src="https://www.youtube.com/embed/Pj90ZCno_R0?wmode=opaque" frameborder="0" allowfullscreen=""></iframe>
</span></p>
<p><span>this is a follow up video from the first one here:</span></p>
<p><span><a href="https://youtu.be/ZcEXe5LHCQE" target="_blank">https://youtu.be/ZcEXe5LHCQE</a></span></p>
<p><span>in this video, instead of using MIDI to key the PI4 CPO...a simple 'keyed' TLC555 square wave oscillator is keyed and the output of the 555 sends its square wave at 7Khz to the PI4's USB sound card's LINE INPUT</span></p>
<p><span>then 'inside' the PI4, it goes straight over to the sidechain input of ZAMGATE which is holding back a pure sine wave at 1Khz...once the sidechain port is triggered by the incoming 7Khz square wave from the TLC555(which is being keyed by FLdigi's serial port RTS pin/ground, connecting the 555's pin 4 to its pos rail) it allows the pure sine wave at 1Khz to pass through the upper gates, and go into the 1Khz bandpass filter.... the output of the bandpass filter goes to a RECRI KEYER SDR LO-MIXER module that allows any CW PITCH to be chosen while still tracking the bandpass filter's width and 'Q'... no matter what freq the LO chooses the CW pitch to be...</span></p>
<p><span>to get the proper CW element length to match the incoming 555 cw element length....the threshold setting of ZAMGATE is set using FLdigi to send dits out at 120 wpm - which should each be at 10 milliseconds length... then the threshold setting of ZAMGATE is adjusted to match the 555 dit length - outputting a 10 ms cw element length of the pure sine wave connected to its upper ports...</span></p>
<p><span>the PURE SINE WAVE oscillator, filter and LO-MIXER are all modules from</span></p>
<p><span>Recri Keyer: <a href="https://github.com/recri/keyer" target="_blank">https://github.com/recri/keyer</a></span></p>
<p><span>ZAMGATE is a plugin from: <a href="https://www.zamaudio.com/" target="_blank">https://www.zamaudio.com/</a></span></p>