On Thu, May 28, 2009 at 12:42 AM, Josh Blum <j...@joshknows.com> wrote: > >> Apologies for the wrong information. I don't mean to side track the >> original query, but I have a couple of questions. >> >> I found this in the FAQ. >> >> "Regarding the bandwidth, we can sustain 32MB/sec across the USB. All >> samples sent over the USB interface are in 16-bit signed integers in >> IQ format, i.e. 16-bit I and 16-bit Q data (complex) which means 4 >> bytes per complex sample. This resulting in a (32MByte per sec/4Byte) >> 8Mega complex samples/sec across the USB." >> >> So I guess here we are assuming that we are using usrp_s() ? >> > > Everything is 16 bits. usrp_c just casts the interleaved shorts into floats, > whereas usrp_s leaves the interleaved shorts as they are. That is why the > min and max values are +/- 2**15 even in floating point. > >> Also, since the ADC only has 12bit precision, are the extra bits used >> to retain precision as we go through the CIC and Halfband filters? >> > > Also, being byte-aligned is a key issue here. Imagine what would happen if > the host had to shift every sample in memory. > >> If I were to use the std_4rx_0tx.rbf and usrp_s() to receive 4 >> channels. Then am I correct in saying that I need to have a >> deinterleaver with 8 channels after the usrp_s() from which I will >> club channel 0 and 1 into a new complex stream (similarly for channel >> 2 and 3 etc) to get 4 complex streams? >> > > does the usrp_s/c answer clear this up for you? > > -Josh >
Thanks Josh, That clears things up for me. Regards, Karthik _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
