On Fri, May 15, 2009 at 8:18 AM, feldmaus <feldmann_mar...@gmx.de> wrote: > Hi Gnuradio folks, > > i am analysing the spectrum from 1MHz to 2Mhz. I splitted this Spectrum > into 3 parts: > 1MHz - 1,333MHz > 1,333MHz - 1,666MHz > 1,666MHz - 2MHz > > Therefore i used the Analysis Filterbank. Because i am searching for si > function > in the time domain as a response of a peak in the frequency domain, i want > to use a band pass filter in the Analysis Filterbank. > Do i have to use the band pass filter or can i sill use the low pass filter. > The response should be another one by using the Low pass filter ? > > But my main Problem is, that my signal goes down in the second and third band. > I doesn't know why. > > Here is my Flow Graph: > Usrp Source --> Analysis Filterbank+Band pass filter --> Selector --> > fft sink graph > > My band pass looks like this: > samp_rate=1e6 > Intermediate Frequency of the usrp= 1MHz > firdes.complex_band_pass(1.0, samp_rate, samp_rate*0, samp_rate*1/3, > samp_rate*0.01) > > Any hints how to correct this ? > Did i anything wrong ?
So you are looking at 1MHz of spectrum with a sample rate of 1Msps complex centered at 1MHz coming in from the USRP? Or do you receive a complex stream directly from the USRP at baseband? The CIC filter has roll off which could be your culprit? Do you have a spectral plot of your bands as well as the entire incoming spectrum? Brian _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
