Re: [Discuss-gnuradio] io_type configuration for uhd.single_usrp_source

[Yan Nie]

> well, sizeof(complex<short>) == sizeof(float), which means gnuradio will
> let you connect those blocks, but that definitively wont work.
> 
> For the UHD source, use COMPLEX_FLOAT32. For the FIR filter, use complex
> input.
> 
> gnuradio-companion might help you a lot:
> http://en.wikipedia.org/wiki/GNU_Radio_Companion

I appreciate your reply. I changed the io type for UHD source and type of the 
input for FIR filter, and got them matched, which leads the final result to the 
right direction, but still not quite right. It is just a simple trial to detect 
a 100kHz sinusoid signal and down convert the frequency to 1kHz. I am expecting 
a 1kHz sinusoid wave from plotting, but it only gave some irregular oscillation 
at the beginning. I am still confused that what could be the problem here?

u2=uhd.single_usrp_source(device_addr="addr=192.168.10.2",io_type=uhd.io_type_t.COMPLEX_FLOAT32,num_channels=1)
u2.set_samp_rate(250e3)
treq = uhd.tune_request(freq)
tr = u2.set_center_freq(self.treq)
decim_coeffs = gr.firdes.low_pass(1.0,
                              5e3,     #sampling frequency
                              2e3,        #cutoff frequency
                              .1e3,
                              gr.firdes.WIN_BLACKMAN)
decim_filter = gr.fir_filter_ccf(1,decim_coeffs)
dst = gr.file_sink(gr.sizeof_gr_complex,filename)
connect(self._u2, self.decim_filter,self.dst)


Thank you so much for your help

with thanks,
Yan