Re: [Discuss-gnuradio] TX/RX simultaneously using one USRP board

[John Gilmore]

> Just curious, why did you first fm_demod and then fm_mod.
> You could also do:
> src = usrp.source_c (0, rx_decim)
> dst = usrp.sink_c (0, tx_interp)
> if_filter=gr_fir_filter_ccf(1, if_filter_coeffs)
> self.connect (src, if_filter, dst)

By adding a few blocks to the FPGA (like the FIR filter and a feedback
buffer), the implementation could avoid pushing these samples across
the USB entirely, without any changes to the Python code!

[This will become much more useful in later USRPs that have bigger
FPGAs.  You could pull out a few received signals, e.g. two or three
FM transmissions out of a wide band, translate each to a different
frequency, mix the results together and feed it out the transmit path,
all on the USRP.  While simultaneously having some control channels
that run across the USB to be processed by host system software.
Sounds like a great design for a cellular radio base station.]

        John