Transmission Test/ Can't set initial frequency

GNU Radio
1

Hi All,

I’m using the USRP1 and the RFX400 connected to the A side of the board
for my senior project. I’m using windows vista with cygwin and gnuradio
3.2.2. I am able to use usrp_siggen.py to wirelessly transmit a 400 MHz
wave. I checked this by using a spectrum analyzer. The spectrum was
slight shifted up by about 20 MHz but that’s a problem for another day.

My main issue is that when I’m trying to test that the board can receive
signals by using a signal generator connected to an antenna sending a
400 MHz sine wave at 19 dBm and the usrp_fft.py file. I input:

python usrp_fft.py -f 400M -d 16 -R A

The GUI pops up but I see a message at the bottom of the GUI that says
“Failed to set initial frequency.” The display shows a is centered at 0
Hz with a bandwidth of 4 MHz. Under the gain slider of the GUI, it says
Fs@USB: 4M and Flex 400 Rx MIMO B. Also, I see in Cygwin under my
command, it says:

usb_control_msg failed: usb_control_msg: sending control message failed
win error: A device attached to the system is not functioning.

I’ve tried having the antenna connected to the RX and the RX/TX port but
the results remained the same. Is there a way to resolve this so I can
ensure that my board can receive signals? Thank you very much for the
help.

-Daniel

2

I retested the board and noticed that it consistently transmitted
signals at 50 MHz above the frequency I set it to. Even when I ran
usrp_siggen at 350 MHz, 50 MHz below the 400-500 MHz range, the board
was able to transmit but on a spectrum analyzer, the highest signal
strength was seen at 400 MHz. What is the cause for this offset when
the board was not modified?

Also, I can’t consistently set the center frequencies usrp_fft or
usrp_oscope files. It’ll open with a center frequency of like 350 MHz
or 400 MHz set, but if I try to set the frequency to another value, it
may fail or say “OK.” It seems random. I’ll have a frequency entered
into the center frequency text box and if I just keep pressing enter,
the status message will vary from “OK” to “Failed to set frequency.”
Why is this? Thank you for anyone who is able to help or just give any
advice.