[Discuss-gnuradio] Receiving on both sub devices at the same time (LFRX)

[Einar Thorsrud]

Hi all helpful GR people  :)

I am trying to combine the two sub device on a LFRX card, but I can not 
find any documentation on the USRP dual source. GRC has it's own block 
"grc_usrp.dual_source_c", but using this (configured with GRC) I get the 
error:

TypeError: __init__() got an unexpected keyword argument 'side_b'

How can this be overcome?

I am not able to find a dual source from the plain GR library, but it 
may exist? However, I have tried to use two separate USRP sources and 
specify separate sub devices on the two:

self.usrp_source_0a = usrp.source_c(0, 64) # Decimation factor: 64
#self.usrp_source_0a.db(0, 0) # Side A, sub device A
usrp.selected_subdev (self.usrp_source_0a, (0,0)) # Side A, sub device A
self.usrp_source_0a.set_rx_freq(0, 0) # Set frequency 0 Hz

self.usrp_source_0b = usrp.source_c(0, 64) # Decimation factor: 64
#self.usrp_source_0b.db(0, 1) # Side A, sub device B
usrp.selected_subdev (self.usrp_source_0b, (0,1)) # Side A, sub device B
self.usrp_source_0a.set_rx_freq(0, 0) # Set frequency 0 Hz

This however also fails. It seams the reason is that the USRP is already 
taken by the first instance:

usrp_open_interface:usb_claim_interface: failed interface 2
usb_claim_interface: couldn't claim interface
usrp_basic_rx: can't open rx interface

What then is the correct way to receive on both sub devices on the same 
time?


- Einar