Hi everybody... i am new in signal processing.
something about me... i am a student of software Engineering, My name is
Juan and i live in Argentina.
I am migrating one application developed in VEE (Agilent) to c++. This is
my new task in my work. This application analyzes signals and then... use
that info to set some alarms.. Nothing complicated... so far..
everything goes fine.. until i have to use ifft. I did make a fft
algorithm to do everything... but when i do the ifft... the output data
from VEE (agilent) was not the same as my algorithm. So... I decide to
implement FFTW. And i have the same problem...
i have this input data. (size = 2048)
Agilent(VEE) c++
magnitude phase
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
0.276 , @[EMAIL PROTECTED]
0.276 , 121.5
0.2061, @[EMAIL PROTECTED]
0.2061, -72.03
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
0 , @[EMAIL PROTECTED]
0 , 0
... ... ... ...
and the output data from the VEE (agilent)
-7.860034643685586E-005
-7.871299096183408E-005
-7.88070606286872E-005
-7.888302098921511E-005
-7.894133976812804E-005
-7.898248647698485E-005
-7.900693202945827E-005
-7.901514835816201E-005
-7.900760803327236E-005
-7.898478388317609E-005
-7.894714861737379E-005
-7.889517445186702E-005
-7.882933273725408E-005
-7.875009358975982E-005
-7.865792552541923E-005
-7.855329509763516E-005
-7.843666653832641E-005
...
and this is the output from c++ (FFTW)
0: 0.000235391 : 0.0241332
1: -0.000100984 : 0.0241359
2: -0.000437429 : 0.0241348
3: -0.000773924 : 0.0241297
4: -0.00111045 : 0.0241208
5: -0.00144697 : 0.024108
6: -0.00178348 : 0.0240913
...
I think that could be the type of the input data... because in agilent is
a waveform. And in my c++ application is real data..
In/out (FFTW)
data=(fftw_complex* ) fftw_malloc( sizeof( fftw_complex ) * (SIZE/2+1) );
ifft_result=(fftw_complex* ) fftw_malloc( sizeof( fftw_complex ) * (SIZE)
);
I am relative new in the Signal Processing... so i would need some help...
and if you know some books.. And excuse me for my English :D
have a nice day...:cool:
|
