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	<title>Comments on: Signal processing tips from Hackaday</title>
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	<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/</link>
	<description>All about electronics and circuit design</description>
	<lastBuildDate>Mon, 18 May 2026 12:24:19 +0000</lastBuildDate>
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		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1878079</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 14 May 2026 20:35:00 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1878079</guid>
		<description><![CDATA[I too have studied and run signal processing simulations on mathematical software and these are my conclusions. 

Oversampling on the playback end meaning the DAC side is pointless because there is no new information between the samples. Just interpolation. Now over-sampling on the recording end meaning the ADC side makes total sense with at least 8x the Nyquist bandwidth given 2 samples per cycle at the Nyquist limit. At that oversampling bandwidth point you can show near perfect waveform reconstruction. 

Anti-aliasing filters for 44.1kHz is at the Nyquist limit for a 20kHz analog waveform signal. So the filter is very restricted in design. My simulations show that you cannot make an IIR filter work however an FIR filter does work well for best faithful reconstruction of the input signal. 

That leaves the last question which is the optimal order for the FIR filter as the order is determined by the number of series cascading of first-order filters. Now that I don’t really know which order is optimal because it is a balance of tolerating how much aliasing error you allow against impulse response and delay, damping factor, and the real bandwidth contained in musical signal. 

It is strange that some designers claim no digital or analog filters in the playback system and also no aliasing error for a 44.1kHz source sampling. 
Did they get the recording studio to record the CD with a 4kHz analog LPF at the microphone? 

Maybe this is helpful to you?

https://www.facebook.com/share/p/1LqGkfb9QY/]]></description>
		<content:encoded><![CDATA[<p>I too have studied and run signal processing simulations on mathematical software and these are my conclusions. </p>
<p>Oversampling on the playback end meaning the DAC side is pointless because there is no new information between the samples. Just interpolation. Now over-sampling on the recording end meaning the ADC side makes total sense with at least 8x the Nyquist bandwidth given 2 samples per cycle at the Nyquist limit. At that oversampling bandwidth point you can show near perfect waveform reconstruction. </p>
<p>Anti-aliasing filters for 44.1kHz is at the Nyquist limit for a 20kHz analog waveform signal. So the filter is very restricted in design. My simulations show that you cannot make an IIR filter work however an FIR filter does work well for best faithful reconstruction of the input signal. </p>
<p>That leaves the last question which is the optimal order for the FIR filter as the order is determined by the number of series cascading of first-order filters. Now that I don’t really know which order is optimal because it is a balance of tolerating how much aliasing error you allow against impulse response and delay, damping factor, and the real bandwidth contained in musical signal. </p>
<p>It is strange that some designers claim no digital or analog filters in the playback system and also no aliasing error for a 44.1kHz source sampling.<br />
Did they get the recording studio to record the CD with a 4kHz analog LPF at the microphone? </p>
<p>Maybe this is helpful to you?</p>
<p><a href="https://www.facebook.com/share/p/1LqGkfb9QY/" rel="nofollow">https://www.facebook.com/share/p/1LqGkfb9QY/</a></p>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1872000</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Wed, 25 Feb 2026 23:32:56 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1872000</guid>
		<description><![CDATA[Autotune

https://www.facebook.com/share/v/1GTRGQznME/]]></description>
		<content:encoded><![CDATA[<p>Autotune</p>
<p><a href="https://www.facebook.com/share/v/1GTRGQznME/" rel="nofollow">https://www.facebook.com/share/v/1GTRGQznME/</a></p>
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	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1869035</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Tue, 20 Jan 2026 21:49:04 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1869035</guid>
		<description><![CDATA[https://www.nearity.co/blog/audio-recording-on-android?srsltid=AfmBOoqpFKFrEklvSqKxBfprtyxy79PHqEcg_H4IMuZIfKHIqQZ-DCRG]]></description>
		<content:encoded><![CDATA[<p><a href="https://www.nearity.co/blog/audio-recording-on-android?srsltid=AfmBOoqpFKFrEklvSqKxBfprtyxy79PHqEcg_H4IMuZIfKHIqQZ-DCRG" rel="nofollow">https://www.nearity.co/blog/audio-recording-on-android?srsltid=AfmBOoqpFKFrEklvSqKxBfprtyxy79PHqEcg_H4IMuZIfKHIqQZ-DCRG</a></p>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1869026</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Tue, 20 Jan 2026 21:36:46 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1869026</guid>
		<description><![CDATA[https://www.peak-studios.de/en/opus-audio-codec-bei-youtube/]]></description>
		<content:encoded><![CDATA[<p><a href="https://www.peak-studios.de/en/opus-audio-codec-bei-youtube/" rel="nofollow">https://www.peak-studios.de/en/opus-audio-codec-bei-youtube/</a></p>
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	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1869025</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Tue, 20 Jan 2026 21:35:04 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1869025</guid>
		<description><![CDATA[https://www.bestcaraudio.com/testing-youtube-audio-quality/]]></description>
		<content:encoded><![CDATA[<p><a href="https://www.bestcaraudio.com/testing-youtube-audio-quality/" rel="nofollow">https://www.bestcaraudio.com/testing-youtube-audio-quality/</a></p>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1869024</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Tue, 20 Jan 2026 21:34:34 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1869024</guid>
		<description><![CDATA[https://support.google.com/youtube/answer/2853702?hl=en
Choose live encoder settings, bitrates, and resolutions]]></description>
		<content:encoded><![CDATA[<p><a href="https://support.google.com/youtube/answer/2853702?hl=en" rel="nofollow">https://support.google.com/youtube/answer/2853702?hl=en</a><br />
Choose live encoder settings, bitrates, and resolutions</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1867998</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 01 Jan 2026 17:03:16 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1867998</guid>
		<description><![CDATA[https://opensoundmeter.com/]]></description>
		<content:encoded><![CDATA[<p><a href="https://opensoundmeter.com/" rel="nofollow">https://opensoundmeter.com/</a></p>
]]></content:encoded>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1867910</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 01 Jan 2026 15:29:20 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1867910</guid>
		<description><![CDATA[Friture is a real-time audio analyzer.

It works on Windows, macOS and Linux. It is free and open source.

https://friture.org/index.html?fbclid=Iwb21leAO52BljbGNrA7nYFmV4dG4DYWVtAjExAHNydGMGYXBwX2lkDDM1MDY4NTUzMTcyOAABHsDYHbvngj6kTMgB281Sb4rn0um0eWhTE0ApU0mgNbXfMRJxeXY-6xqEYXUA_aem_YVAGa_9z6yolvLJAzu9vRw]]></description>
		<content:encoded><![CDATA[<p>Friture is a real-time audio analyzer.</p>
<p>It works on Windows, macOS and Linux. It is free and open source.</p>
<p><a href="https://friture.org/index.html?fbclid=Iwb21leAO52BljbGNrA7nYFmV4dG4DYWVtAjExAHNydGMGYXBwX2lkDDM1MDY4NTUzMTcyOAABHsDYHbvngj6kTMgB281Sb4rn0um0eWhTE0ApU0mgNbXfMRJxeXY-6xqEYXUA_aem_YVAGa_9z6yolvLJAzu9vRw" rel="nofollow">https://friture.org/index.html?fbclid=Iwb21leAO52BljbGNrA7nYFmV4dG4DYWVtAjExAHNydGMGYXBwX2lkDDM1MDY4NTUzMTcyOAABHsDYHbvngj6kTMgB281Sb4rn0um0eWhTE0ApU0mgNbXfMRJxeXY-6xqEYXUA_aem_YVAGa_9z6yolvLJAzu9vRw</a></p>
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	<item>
		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1867905</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Thu, 01 Jan 2026 15:26:18 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1867905</guid>
		<description><![CDATA[https://github.com/prydin/param-eq]]></description>
		<content:encoded><![CDATA[<p><a href="https://github.com/prydin/param-eq" rel="nofollow">https://github.com/prydin/param-eq</a></p>
]]></content:encoded>
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		<title>By: Tomi Engdahl</title>
		<link>https://www.epanorama.net/blog/2020/03/11/signal-processing-tips-from-hackaday/comment-page-5/#comment-1867701</link>
		<dc:creator><![CDATA[Tomi Engdahl]]></dc:creator>
		<pubDate>Sat, 27 Dec 2025 22:36:13 +0000</pubDate>
		<guid isPermaLink="false">http://www.epanorama.net/newepa/?p=184678#comment-1867701</guid>
		<description><![CDATA[Just downloaded https://friture.org/index.html, this is open source, free software that looks useful if combined with a decent soundcard. I have built some PreAmps which sound excellent but I want to do some approximate frequency response measurements, so something to try over the break.

Has anyone any thoughts on this or other recommendations?
https://www.facebook.com/share/p/1DUgYTheDZ/]]></description>
		<content:encoded><![CDATA[<p>Just downloaded <a href="https://friture.org/index.html" rel="nofollow">https://friture.org/index.html</a>, this is open source, free software that looks useful if combined with a decent soundcard. I have built some PreAmps which sound excellent but I want to do some approximate frequency response measurements, so something to try over the break.</p>
<p>Has anyone any thoughts on this or other recommendations?<br />
<a href="https://www.facebook.com/share/p/1DUgYTheDZ/" rel="nofollow">https://www.facebook.com/share/p/1DUgYTheDZ/</a></p>
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