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Most accurate signal generator

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loop123:

--- Quote from: gf on April 02, 2024, 12:15:04 pm ---
--- Quote from: ebastler on April 02, 2024, 11:11:50 am ---It's really a simple conversion as long as a fixed sample rate is always used. 10,000 samples in 200 ms, 50 samples per ms, 1 sample per 20 µs.

--- End quote ---

Btw, just to clarify: I had calculated my plots at 48kSa/s (which is a commonly used audio sample rate).
1 seconds = 48000 samples, 200ms = 9600 samples, etc.

Unfortunately, I was lazy. I should have labeled the time axis in seconds (instead of samples) to avoid confusion.

--- End quote ---

Ok. I'm familiar with 48kSA/s since my Audacity uses that audio sample rate too. Let's say the audio sample rate is 2000kSA/s instead of just 48kSA/s then you can already see the jagged edge noise in the 900Hz, right?

gf:

--- Quote from: loop123 on April 02, 2024, 01:14:32 pm ---Ok. I'm familiar with 48kSA/s since my Audacity uses that audio sample rate too. Let's say the audio sample rate is 2000kSA/s instead of just 48kSA/s then you can already see the jagged edge noise in the 900Hz, right?

--- End quote ---

No, it is not a matter of the sample rate (48kSa/s is more than enough for this signal), and it's not a matter of sampling.
It is a matter of filtering. Feeding an analog white noise signal though a corresponding analog filter would have the same effect.

Btw, it's not difficult to do the same simulation in Audaity, too. I'm not familiar with this program, still I was able to find all the tools within a couple of minutes. Create one track and fill it with a sine wave. Create a 2nd track and fill it with white noise. Create a 3rd track by mixing the two tracks. Apply lowpass filter to the 3rd track. Done. See attachment.

loop123:

--- Quote from: gf on April 02, 2024, 01:49:01 pm ---
--- Quote from: loop123 on April 02, 2024, 01:14:32 pm ---Ok. I'm familiar with 48kSA/s since my Audacity uses that audio sample rate too. Let's say the audio sample rate is 2000kSA/s instead of just 48kSA/s then you can already see the jagged edge noise in the 900Hz, right?

--- End quote ---

No, it is not a matter of the sample rate (48kSa/s is more than enough for this signal), and it's not a matter of sampling.
It is a matter of filtering. Feeding an analog white noise signal though a corresponding analog filter would have the same effect.

Btw, it's not difficult to do the same simulation in Audaity, too. I'm not familiar with this program, still I was able to find all the tools within a couple of minutes. Create one track and fill it with a sine wave. Create a 2nd track and fill it with white noise. Create a 3rd track by mixing the two tracks. Apply lowpass filter to the 3rd track. Done. See attachment.

--- End quote ---

I didn't know Audacity can do them. I only used them to display waveforms in my amplifier. Why did you create the 3rd track. What are you trying to demonstrate so I can do more of them. Thanks.

GigaHurts:
hey man, did you try a 555 timer? :D

but in all seriousness, that is quite an accuracy you are asking for :) not available for cheap. And if it was, you still probably don't have a cheap way of measuring it. And even if you have, you probably don't have a cheap way of calibrating it

loop123:

--- Quote from: gf on April 02, 2024, 01:49:01 pm ---
--- Quote from: loop123 on April 02, 2024, 01:14:32 pm ---Ok. I'm familiar with 48kSA/s since my Audacity uses that audio sample rate too. Let's say the audio sample rate is 2000kSA/s instead of just 48kSA/s then you can already see the jagged edge noise in the 900Hz, right?

--- End quote ---

No, it is not a matter of the sample rate (48kSa/s is more than enough for this signal), and it's not a matter of sampling.
It is a matter of filtering. Feeding an analog white noise signal though a corresponding analog filter would have the same effect.

Btw, it's not difficult to do the same simulation in Audaity, too. I'm not familiar with this program, still I was able to find all the tools within a couple of minutes. Create one track and fill it with a sine wave. Create a 2nd track and fill it with white noise. Create a 3rd track by mixing the two tracks. Apply lowpass filter to the 3rd track. Done. See attachment.

--- End quote ---

Ok I tried Audacity generator and mixing. I first created white noise in 1st track. then apply 1000kHz filter to the white noise. In the first screenshot I added a 50Hz sine wave in 2nd track and mix in 3rd track. There is noise.



In the following image I added a 900Hz sine wave in 2nd track with the same white noise 1000kHz filtered in first track and mix in 3rd track. The jagged edge is not seen.



If the above methods are correct. Can we just say that in the 900Hz.  There is simply less noise per sine wave compared to the 50Hz in first image that is why there is no jagged edge in the 3rd track?

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