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Questions tagged [dbfs]

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4
votes
3answers
259 views

Precise 5th and 7th harmonics of a sampled sine wave

Does anyone know in decibels (to 1/100th of a dB) what the theoretical 3rd, 5th and 7th harmonic of a 0dB fs 24-bit (i.e. full-level; 0dB = -8,388,607 to 8,388,607) sampled sine wave without dither ...
0
votes
2answers
50 views

What should my reference value be when converting FFT bin amplitudes to dB?

I want to transform my FFT output values into a dB scale, but I'm struggling to determine the function I should run each bin amplitude through. My understanding of the decibel scale is that a value ...
2
votes
2answers
332 views

Measuring microphone Signal to Noise ratio (SNR) with A-weighting

Foreword: I have already read Applying A-weighting and user @endolith's A-weighting code I would like to measure the SNR of a microphone with the same method applied by the main manufacturers, that ...
0
votes
2answers
4k views

Avoiding “RuntimeWarning: invalid value encountered in log10” when converting FFT data to dBFS

I've attached some code below that I'm having some issues with. Basically, I need to write a function to get the dBFS value of a signal at a specified Hz value, at a given channel in a .wav file. ...
1
vote
0answers
373 views

calculating SNR from dbfs (using spectrograms)

I've the spectrogram of both noise and signal (both 5 seconds). Below image shows an example of the signal spectrogram: The colour of the spectrogram shows the intensity in dbfs (from 0 dbfs to -120 ...
0
votes
1answer
198 views

Get dB full scale value of a group of wave samples

I am trying to compute the dBFS value of a group of samples (stereo wave file), according to this formula: $$p_{RMS} = \sqrt{\frac{ x_1^2 + x_2^2 + \ldots}n } $$ $$dbFS = 20\log_{10}\frac{ p_{RMS}}{...
4
votes
3answers
18k views

FFT to spectrum in decibel

Here is a 10 seconds-long 440hz sine wave normalized at $0\textrm{ dBFS}$. When computing the STFT (with the code below) of this audio file, I noticed that ...
0
votes
1answer
950 views

Power Spectrum in dBFs

I'm trying to get the spectrum of my signal in dBFS units. I'm not sure what is the refernce that I should devide by. I computed the power spectrum as follows: 1) FFT normalized to the number of ...
5
votes
1answer
6k views

Is it only me or matlab's periodogram's function is confusing?

I am really confused with matlab's periodogram. First of all, it says in the documentation that its unit is "dB per unit frequency". What does that really mean? I just don't quite get it. Second of ...
1
vote
0answers
482 views

Converting musicg spectrogram output to dBFS

I'm trying to convert musicg Spectrogram output to dBFS. With 16-bit signed integer PCM audio, and an FFT length of 2048, I'm trying to analyze the spectrogram for an audio file to determine things ...
6
votes
1answer
9k views

Converting raw I/Q to dB

I am getting I/Q data from a software-defined radio. I want to do some stuff on signals in the data, but only if it exceeds a certain range. What is the general procedure to get dB (dBm, or anything)...
4
votes
2answers
1k views

dBFS scaling and spectrum

I am trying to replicate the spetrum as given in Audacity and other commercial software... I am getting crazy with the correct scaling needed in order to have dBFS (with reference to a full scale sine ...
9
votes
2answers
10k views

How to compute dBFS?

I asked myself how to compute dBFS (dB full scale) from a value of sample between 1 and -1? and in general?
0
votes
2answers
793 views

Matching an LPC Magnitude Spectrum to FFT Magnitude Spectrum

I'm trying to get an LPC magnitude spectrum to match to an FFT magnitude spectrum. Basically I want the peak height in the LPC Spectrum to match the peak height in the FFT Spectrum. Thanks to ...