[Discuss-gnuradio] 16Mhz bandwidth when using 8bit sample?

[hanwen]

Hi, all,

 

I've just found that the USRP can be configure to 8bit sample by the following code.

    width = 8
    shift = 8
    format = self.u.make_format(width, shift)
    print "format =", hex(format)
    r = self.u.set_format(format)

And it is already in the usrp_fft.py and usrp_oscope.py.

 

So I guess that USRP may sample high up to 16Mhz bandwidth when using 8bit sample. Because 8 bit can save the bandwidth of USB interface. That is 32Mbytes/s / 2bytes/sample = 16samples/s.

 

But when I execute the follwing code, I get no spectrum or waveform in the window.

$ ./usrp_fft.py -8 -d 4

$ ./usrp_oscope.py -8 -d 4

 

If I don't use the "-8" parameter, only "-d 4", spectrum or waveform turns out, also, a lot of "u0".

 

Why? hehe:)