Hello,
I'm have a problem with the fft-function. via a logic analyzer, I collect 4096 samples of
a 9.765625kHz sinus, sampled at 10MHz, so 1 period = 1024 samples.
>From those 4096 samples, I use 1024 of them (so 1 period) as an input for the
fft-function. With the result of the fft, I calculate the SINAD.
Now the problem : The SINAD is influenced by the starting point of the 1024
samples, i.e. the phase of the sinus when the sampled data is AD-converted.
The SINAD is maximum when the first sample is the positive maximum of the
sinus-function.
I tought that when I have 1 period at the input of the fft, the result isn't dependant
of the starting phase.
Am I wrong? If so please tell me.
If not, is there a problem with the fft-function.
Everybody, Merry Christmas and a Happy Newyear.
Thanks in advance,
Wouter Dejaeghere
Test Department
Siemens BCB
Oostkamp-Belgium
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I'm have a problem with the fft-function. via a logic analyzer, I collect 4096 samples of
a 9.765625kHz sinus, sampled at 10MHz, so 1 period = 1024 samples.
>From those 4096 samples, I use 1024 of them (so 1 period) as an input for the
fft-function. With the result of the fft, I calculate the SINAD.
Now the problem : The SINAD is influenced by the starting point of the 1024
samples, i.e. the phase of the sinus when the sampled data is AD-converted.
The SINAD is maximum when the first sample is the positive maximum of the
sinus-function.
I tought that when I have 1 period at the input of the fft, the result isn't dependant
of the starting phase.
Am I wrong? If so please tell me.
If not, is there a problem with the fft-function.
Everybody, Merry Christmas and a Happy Newyear.
Thanks in advance,
Wouter Dejaeghere
Test Department
Siemens BCB
Oostkamp-Belgium
---------------------------------------------------------------------
This is the "vrf" maillist, managed by Majordomo. To send messages to
this maillist, just email to "vrf@lvld.hp.com". Subscriptions and
unsubscriptions are done through the address "vrf-request@lvld.hp.com".
If you need details, just send a message containing the text "help"
to "vrf-request@lvld.hp.com".
---------------------------------------------------------------------