On Mon, Nov 25, 2013 at 12:26 PM, Naceur <naceuram...@gmail.com> wrote: > Hello list, > > I got questions re the WX GUI Constellation Sink block: > > 1/ Could anyone give descriptions of what is > > * Theta ? > * Loop bandwidth ? > * Max Freq ? > * Mu ? > * Gain Mu ? > * Symbol Rate ? > * Omega Limit ?
This block basically uses the M&M clock recovery block: http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1clock__recovery__mm__cc.html And the Costas loop block: http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1costas__loop__cc.html That should explain much about those parameters. The Theta value is the phase rotation of the locked constellation. So you can readjust a QPSK that sits on the +/-1 +/- 1j points to the x and y axes by setting theta to pi/4. > 2/ What are the essential params of the block to adjust, for my case I am > receiving a BPSK signal (Params @ Tx are: 10 MHz samp_rate, ow_format sc8, > Samples/Symbol = 4, Spread signal with a 11 chips code), > > I set: > sample_rate = 10 MHz, > Frame rate = 512, > Constellation Size = 512, > M = 2, Drop the frame rate. You're trying to display 512 frames/second, which is too fast for you to even see and asking your computer to do a lot of extra work. The default of 5 should be enough. > 3/ Once the constellation plotted it freezes and "O"s appears in the > terminal section of GRC ? > What am I doing wrong ? > > Regards, That indicates not enough processing power. You're now trying to do too much in the graph for your processor. Can you try a lower symbol rate signal to start off with? Get the feel for the parameters and setup and try to understand the performance limitations before jumping right in to your full signal. But also, just dropping the frame rate as I suggest above should give you back a lot of processing time. Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
