I while ago we bought two USRP2. When they came we tested them with the
usrp2_fft programs. Also we had two USRP1 and used USRP_oscope to see
the waveforms produced
by USRP2. Everything seemed to work OK. Then we didn’t do anything with
the USRP2 for a while.
I few days ago I tried using them again and discovered I couldn’t
transmit or receive anything.
I saw in the mailing list that those who got an SD-Card labeled
“9/22/08” must update their
firmware so I updated the firmware using the images from the site. Now I
can receive(?) but
I can’t transmit. I mean no signal is transmited from the USRP2’santenna
because if it where I
would see it in usrp_oscope. Samples however are send from the PC to
USRP2 because the leds on
the Ethernet port light when I run a program like usrp2_siggen or
something of my own.
Does anyone has any idea about what’s wrong? How do I check if the
transmit frequency has been
set OK? In another message it was mentioned that there is no PGA on
USRP2. Then what does
set_gain() in a usrp2 sink or source?
I also noticed something about the received signal. First the noise
variance seems to change when
there is a signal and when there is not. Is this normal? Is there some
AGC circuit that causes this?
If so can I disable it from code. I haven’t noticed anything similar in