Folks, I found the error: The “U” characters indicated an underrun to my USRP transmitter. I reduced the sample rate form 5e6 to 2e6, and the underrun indicators went away.
My problem in my receiver was that I was zoomed in to much in frequency span in my FFT display to see that I was indeed receiving my signal. Aaron From: Chesir, Aaron M. Sent: Friday, March 15, 2019 10:21 AM To: [email protected] Subject: Strange "UUUU" pattern Folks, I have a simple QPSK modulator feeding its output into the input of my USRP transmitter. I notice two oddities: 1. The status window at the bottom produces a sequence of “U” characters until I stop the run, and 2. The receiver does not detect any presence of any signal (I have a receive process on another computer feeding the output of the RTL SDR to an FFT, and is attached to this email) When I replace the QPSK modulator at my transmitter with a simple cosine generator, the receiver shows the presence of the signal with no problem, and I don’t see those strange “U” characters at the source GRC process. Can someone offer suggestions at what I should fix? Thanks, Aaron
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