Re: [Discuss-gnuradio] QPSK demodulation problem
Do we have a QPSK (not a DQPSK)Demodulator available and operational in gnuradio??? Ahmet Hasim Gokceoglu wrote: hi, I am trying to implement a QPSK receiver with GNU radio using the board RFX2400 where I take the input from signal generator. The symbol rate of signal generator is 1Msym/sec sending a constant pattern of 0010 and i have set the decimation in USRP to 16 to have 4 samples per symbol. I suppose that I have done the calculation correct since the ADC rate is 64 Msa/sec. Ahmet, I'm not sure I understand how you are generating your input signal. What signal generator? Is this an external sig gen, or are you somehow generating the signal with GNU Radio? Also, are you using the dqpsk.py for the DQPSK mod/demod functions? I wasn't sure if you were building your own QPSK receiver. Since i am not very familiar with the parameters of frequency and timing synchronization blocks i have just used the default ones: costas_alpha=0.15 mu=0.05 omega_re_limit=0.5 These defaults were set because they worked with the implementation or the receiver. They should be fine. When I look at the demodulated bit stream by reading the file rx_unpack.dat (which should supposedly be showing the demodulated bits) what I get is arbitrary 0's and 1's which has nothing to do with the pattern 0010 that I am sending. Does anybody have any idea where might be the problem? Again, it will depend on how you are generating the input symbols. If you are using the packet modulator code we have in /digital/benchmark_tx.py, the packets transmitted are first whitened. The file rx_unpack.dat is captured before the signal is dewhitened. You can turn whitening off by looking at gnuradio-core/src/python/gnuradio/packet_utils.py in the unmake_packet function for how. If you are not using the benchmark_tx to generator your symbols and are sending over the 0010 bit stream, what you are doing is sending over a very specific pattern (0 degree shift followed by a 90 degree shift) that will bias the recovery loops. Try sending a longer more random sequence. Secondly I am recording the data before and after the frequency/time synchronization block so that I can plot the constellation points before and after the synchronization. I suppose that the recorded data is in the format [I Q] so for example when I read [32 64 128 196] then 32 is the decimal equivalent of the first 8 bits of I and 64 is the decimal equivalent of last 8 bits. SÄ°milarly 128 is the first 8bits of Q and 196 is the last 8. Can anyone validate this ? and how about the sign, how is it determined? If you're using file_sink(gr.sizeof_float, file.dat), the output is 32-bit float for the I and 32-bit float for the Q. It's standard IEEE 754 or whatever style. You can use the Python/Matplotlib tools we have in gr-utils/src/python for plotting these files. They are installed into your system now (/usr/local/bin unless you changed the prefix) and called gr_plot_*. You can look at the constellation with gr_plot_const.py filename Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] QAM modules in gnuradio
Hello, I am new user of gnuradio. I would like to know if there are python programs alrady available for QAM transmissions using the usrp. (4-QAM or 16-QAM should be ok). Tony Akedjo North Carolina State University Electrical And Computer Engineering ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Question about gr-wxgui
I am new to Gnuradio and I am having hard time to install gr-wxgui. When I run configure in the gnuradio3.0.2 source directory I get the following message: * Traceback (most recent call last): File string, line 1, in module File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/__init__.py, line 45, in module from wx._core import * File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/_core.py, line 4, in module import _core_ ImportError: libexpat.so.0: cannot open shared object file: No such file or directory Not building component gr-wxgui. ** But libexpat.so.0 is on my computer an is located at /usr/local/lib It seems like I need to add some Path statements, but I don't know how. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Re: Question about gr
I am using Fedora 8.0 . Do they have anything about it? Tony -- On Mar 21, 2008, at 12:10 PM, [EMAIL PROTECTED] wrote: ImportError: libexpat.so.0: cannot open shared object file: No such file or directory But libexpat.so.0 is on my computer an is located at /usr/local/lib It seems like I need to add some Path statements, but I don't know how. Can you tell us what OS / version you're trying this on? If it's Linux, make sure ldconfig knows to look in /usr/local/lib (see, e.g., Broken libtool on Debian and Ubuntu at the bottom of http://www.gnuradio.org/trac/wiki/UbuntuInstall ). This update needs to be done -before- configure is executed -- On Mar 21, 2008, at 12:10 PM, [EMAIL PROTECTED] wrote: I am new to Gnuradio and I am having hard time to install gr-wxgui. When I run configure in the gnuradio3.0.2 source directory I get the following message: * Traceback (most recent call last): File string, line 1, in module File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/__init__.py, line 45, in module from wx._core import * File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/_core.py, line 4, in module import _core_ ImportError: libexpat.so.0: cannot open shared object file: No such file or directory Not building component gr-wxgui. ** But libexpat.so.0 is on my computer an is located at /usr/local/lib It seems like I need to add some Path statements, but I don't know how. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Question about gr-wxgui
I am using Fedora 8.0 . Do they have anything about it? Tony -- On Mar 21, 2008, at 12:10 PM, [EMAIL PROTECTED] wrote: ImportError: libexpat.so.0: cannot open shared object file: No such file or directory But libexpat.so.0 is on my computer an is located at /usr/local/lib It seems like I need to add some Path statements, but I don't know how. Can you tell us what OS / version you're trying this on? If it's Linux, make sure ldconfig knows to look in /usr/local/lib (see, e.g., Broken libtool on Debian and Ubuntu at the bottom of http://www.gnuradio.org/trac/wiki/UbuntuInstall ). This update needs to be done -before- configure is executed -- On Mar 21, 2008, at 12:10 PM, [EMAIL PROTECTED] wrote: I am new to Gnuradio and I am having hard time to install gr-wxgui. When I run configure in the gnuradio3.0.2 source directory I get the following message: * Traceback (most recent call last): File string, line 1, in module File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/__init__.py, line 45, in module from wx._core import * File /root/Desktop/wxPython-src-2.8.7.1/wxPython/wx/_core.py, line 4, in module import _core_ ImportError: libexpat.so.0: cannot open shared object file: No such file or directory Not building component gr-wxgui. ** But libexpat.so.0 is on my computer an is located at /usr/local/lib It seems like I need to add some Path statements, but I don't know how. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
