# Need some explaination on Tides (frequency domain)

I was reading tides manual when I saw this

“Amplitude scale/offset errors are more likely to occur in the high range – the reason being that smoothing has to be applied to some sections of the waveform to prevent aliasing.”

Can someone explain me what this exactly means?

Thanks!

As fas as I get it it means that the waveform is being smoothed to prevent aliasing (it’s a digital waveform) and this can cause some errors where single points of the waveform are not where they are supposed to be, but have a different amplitude. This is more likely to happen in the higher frequencies. But I’m sure somebody else can explain this better than I have…

Tides’ conversion frequency is 48kHz. It implies that no harmonic above 24kHz can be reproduced (that’s above your hearing range anyway).

If Tides is set to produce a tone at 10kHz, only the fundamental (at 10kHz) and the first harmonic (20kHz) will be produced. All the other harmonics will be missing. The difference won’t be audible, but if you look at the signal with a scope, you’ll notice that it will have a lower amplitude and a different shape than what you would have obtained with an analog triangle oscillator (which contains additional harmonics, those you can’t hear).

Okay, so it’s more a matter of unaudible harmonics/frequencies right? Anyway I love this module, especially the vco mode, so I will get one as a third osc in my system! Great design as always

> Okay, so it’s more a matter of unaudible harmonics/frequencies right?

Yes. But because they are missing they make it look like the waveform has the wrong amplitude or shape when you look at it with a scope.

Got it! Thank you! Can’t wait to see/hear the new modules

Oh it’s even easier that I thought. Well that’s normal anti-aliasing isn’t it? Not really an error, just something you do to prevent frequencies above Nyquist to fold back into the spectrum…