According to the spectrum analyzer, there's nothing being
transmitted in the 900 MHz band around me, so that is
actually fine. The biggest unknown could be what you are
saying about how they combine in the RSSI circuit (which I'm
not sure how it works).
I am not gaining any more insight when using over-the-air
antennas, so I used 2 USRPs as transmitters and 2 as
receivers, connected them directly with SMA cables (and
attenuation), and used Derek Kozel's B210_Phase_Viewer on the
receive side to see whether they were aligned after each run.
And I am noticing that they are not. The first run produced a
125 degree phase offset, while the second one produced a 3
degree phase offset, and this continues to fluctuate after
each run (see attached). Note that I am using the code that I
pasted above to transmit.
I must be doing something wrong with the code, or not wrapping
the timed commands around the correct code. I am not sure
though. Thanks again.