RX Mux value with dissimilar d'cards, USRP1

GNU Radio
1

Hi-

Is it possible to receive simultaneously from 1 WBX card, and 1 BasicRX
card, on the same USRP1? Attempting this with GRC gives:
“Cannot compute dual mux when mixing quadrature and non-quadrature
subdevices”

I understand that the WBX is quadrature while the BasicRX is not, so
this
should require 3 of the 4 ADCs.

The WBX is in side A, the BasicRX is in side B, RXA slot.

ADC0 gets WBX I.
ADC1 gets WBX Q.
ADC2 gets BasicRX.
ADC3 is ignored.

An RX Mux value of 0xF210F210 should accomplish what I want, but I see
this
note: “All Q’s must be 0xf or none of them may be 0xf”, which this
violates.
What gives? Where is this constraint coming from?

-Steven

2

On Tue, Oct 12, 2010 at 10:16:31AM -0400, Steven C. wrote:

The WBX is in side A, the BasicRX is in side B, RXA slot.
-Steven
The constraint comes from the implementation of the rx mux in the
FPGA. It’s configuration register contains a single bit that feeds
zeros to the Q input of all DDCs or not.

Details on the s/w to h/w mapping can be found in usrp_standard.cc
near line 469.

The software presents an interface that is more orthogonal than what
the fpga currently implements.

Eric