# jfdo

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Thank you.
2. ## Accuracy of Audio Sampling and FFT

Hi all, I am intending to feed an audio signal of a guitar into the scope input (through a microphone and amplifier) of Analog Discovery and then take the FFT to find the frequency components. I would like to know what factors are affecting the accuracy of sampling an audio signal that feed into the scope input of Analog Discovery and taking the FFT of that signal? Thank you. Best Regards
3. ## Generating a travelling wave

Thank you again. I was stuck in some work and could not write earlier. Yes, that's correct, it is the 5Hz periodic modulation of the signal amplitude that I have heard. That means it is not a basic 5Hz sin or cosine. It is the amplitude modulation of the 155Hz and 150Hz signals. In that case can we say periodicity of the beating is 200ms (1/5 Hz) and therefore frequency of the beating is 5Hz? Frequency of the actual signal (modulation) is 152.5 Hz. In that case can I say it was the 152.5 Hz amplitude modulated signal with 5Hz envelop (5Hz periodicity) that I h
4. ## Generating a travelling wave

Hi @ xc6lx45, Thank you for the detail and nice feedback. Yes, sure, I agree that the beat tone we hear due to the interference of the two sounds (tones) at the ear. This is similar to two coherent light pulses (or signals) interfere at some location in space or at the photo-diode or photo detector. What I did was, I combined the two signals (150Hz and 155Hz) from W1 & W2 (wave generator 1 & 2) and fed into an mono audio amplifier. I was able to hear some periodic tone with much higher amplitude (sound intensity). I guess, higher amplitude indicates some sort of inte
5. ## Generating a travelling wave

Hi Attila, Input to the scope channel 1 is the combined outputs (through two 10k resistors) from W1 and W2. is was the same output fed to the home made mono audio amplifier,. I can hear the beat signal. Can not see that in the attached FFT spectrum. I increased the time base to 6ms/div. I can see the two peaks corresponding to 150Hz AND 155 Hz. But I thought should e able to see the 5Hz frequency line(peak) in the FFT. Do you think the time/frequency resolution is not enough? Thanks
6. ## Generating a travelling wave

Thanks. Actually it is a good idea to create using the basic functions than custom. I had two signals with 150 and 155Hz. But still the FFT did not show this. But I calculated the beat frequency by measuring the period of the beat signal in the scope channel 1 (please see the attached) and that provided the answer. But not the FFT? Any idea? Thanks
7. ## Generating a travelling wave

Many Thanks Attila. I tried with two 5 kOhms resistors to combine the two signals from the W1 and W2 (wave generators of Analog Discovery) and fed into my home made audio amplifier (LM386). It worked well producing the beat note. The Audio output from Analog Discovery was fed into the external audio amplifier. I used two custom made signals using the following equations W1 : sin(2*PI*30*X) W2: sin(2*PI*31*X) X was set to 0 to 1. And the Frequency was set to 5Hz. In this way should the frequency of W1, f1= 150Hz signal and frequency of W2, f2=155Hz?
8. ## Generating a travelling wave

Thank you Attila. So I can use either two 5kOhms resistors in series with w1 and w2 or two 1uF capacitor? Does the capacitor needs to be electrolytic (with +/- terminals)? thanks again.
9. ## Generating a travelling wave

Thank you Attila for the suggestion. Yes, that's right I can generate the FM signal and 500Hz signals using Analog Discovery. I have the Analog Discovery. To generate the beat we need to combine the two signals from wave Generator 1 and 2, isn't it? Can I just combine the two outputs from W1 and W2 or do I need any resistors (as I have indicated in the attached schematic?) or impedance matching circuit or any proactive circuit to protect the Analog Discovery? If so what would be the best circuit that I should use? Any suggestions or practical circuits you may know? By the way
10. ## Generating a travelling wave

Hi All, I wonder whether we can generate a travelling wave using Analog Discovery? or crate beats in some wave. My intention is to wave beating with two waves with slightly different frequencies. I did a Python animation to show the students of wave beating. But it would be more relevant if I can show with real world experiment with sound waves. I appreciate if anyone can shed some light. I was thinking to set a fixed frequency (say 500Hz) in one channel and sweep the frequency in the other channel around 500Hz (say. 490Hz to 510Hz). Not sure whether this will prod
11. ## Audio amplifier in Analog Discovery

Many Thanks Attila. Does this specs valid for Analog Discovery too? Because, what I have is Analog Discovery and NOT Analog Discovery 2. Cheers
12. ## Audio amplifier in Analog Discovery

Thank you Bianca. Cheers Fernando
13. ## Audio amplifier in Analog Discovery

Hi, Does anyone know whether Analog Discovery has a mono audio output or stereo output? According to the Analog Discovery documentation and schematics it is an stereo output? But When I connected via a stereo audio jack it drives only one speaker, suggesting a mono audio output. Is that correct? Thanks
14. ## Math function in "Wavegen_Custom"

Many Thanks Attila for the clarifications. That was helpful. Cheers Fernando
15. ## Math function in "Wavegen_Custom"

Hi, I tried the following but it didn't output anything. Perhaps the syntax is not right! Any suggestions? ( X < 0.25)? 0: (0.25 <= X <= 0.5 )? 0.5*sin(2*30*PI*X): ( 0.5 < X)? ( 0.5*sin(2*10*PI*X)+0.5*sin(2*10*PI*X) )