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TSW14J57EVM: Interpretation of fundamental power in dBFs within HSDC

Prodigy 80 points

Replies: 3

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Part Number: TSW14J57EVM

Hello

I have managed to import off-line some data coming from the eval board in object connected with ADC12DJ3200EVM.

I have a doubt regarding the parameter displayed by HSDC after performing a real FFT, that is "Fund. dBFs". 

How can the tool calculate the dBFs of the fundamental without inserting the ADC model (I am not able to put any ADC model within the tool)?

thanks ain advance for the support

cheers

max

  • Hi Max,

    Since the FFT is derived from the codes that are captured, the number of bits will determine what is full scale, for example 2^14 = 16384 codes, then we know the bounds of the fullscale signal 0 to 16383. We don't need to input what the voltage reference is (or any other parameter besides sampling frequency) since the data converter has already done this work for us.

    Best Regards,

    Dan

  • In reply to dBrock:

    Hi Dan

    thanks for the explanation.

    If I understand correctly in case I have e.g. 2048 captured output codes peak-to-peak for a 12 bit ADC (4096 codes) it means that fundamental is roughly -6dBFs, isn't it?

  • In reply to Massimiliano Foggia:

    Hi Max,

    Yes, that's correct.

    20*log10(2048/4096) = -6.02 dBFS

    Best Regards,

    Dan

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