USRP PSK built-in example VI ... not working

[js7777]

hi, i am trying to get the USRP PSK Tx and Rx example to work:

in my VI, its just the base example, modified with a text file read-in on the transmitter, and a text file writer on the receiver. Its operation is to read a binary sequence from a text file, modulate that bitstream to a carrier, save the modulated bitstream (for checking that the right data has been modulated), then transmit (using 1 USRP 2901, from channel 0 TX1, to channel 1 RX2 with the coaxial cable and -30dB attenuator). That then receives the signal, de-modulates the bitstream and saves the bitstream to a text file.

I have got it to work perfectly with BPSK but any of the other modulation formats (QPSK, pi/4DQPSK, 8PSK, 16PSK, OQPSK etc) that are built in to the example don't work at all.

Not sure if this is user error, a setting issue on the front panel, a code fault within the example or a fault with my modifications .... but surely it wont work for BPSK if my modification was wrong.

Attached the VI's, the receiver sub-VI and the three text files to link to the front panel file paths. As i said, it works perfectly with BPSK but not at all with any of the others.

Hope i can find a solution or get some advice with this, thanks!  🙂

J

[js7777]

forgot to say,

that with the input/output files, if the transmitter program is started before the receiver or vice-versa, then the binary bits will be offset - but its just a case of scrolling and finding a match in the receiver output file to match up the bitstream, easily done because its only a short 32-bit sequence being sent and it has sections with 00000 and 0000 to match up too.

also, any suggestions on how i can add a header to set both tx and rx programs to sync up (without a timer as eventually my project will be used on two separate PC's for Tx and Rx) will be a great help.

Thanks again,

J