On Fri, Feb 3, 2012 at 1:13 PM, Ben Hilburn <b...@ettus.com> wrote: > Tom - maybe you can correct me if I'm wrong, here? > > I think you are asking about the changes Tom made to the general loop > formula, the details of which you can find here: > > http://www.trondeau.com/blog/2011/8/13/control-loop-gain-values.html > > Cheers, > Ben >
Ben, yep, that should explain it a bit better. Shashank, also, the theta value is a constant rotation for the constellation. If your QPSK symbols, say, are located at (+/-1) + j(+/-1), the rotation is 45 degrees (I think that's how the default slicing works) as described in the block's documentation: theta any constant phase rotation from the real axis of the constellation Tom > On Thu, Feb 2, 2012 at 7:14 AM, shashank gaur <shashankg...@ieee.org>wrote: > >> Hello >> >> First of all Thank you very much for your support >> I was able to run the program on two different USRP and it was >> successful. >> >> But still I have some new problems. Actually I am doing my masters >> project on gnuradio and usrp. >> I am trying to make a BPSK transmitter and receiver(Attached GRC Files), >> then use it further in my project. My mentor suggested to use MPSK Receiver >> for the receiver part but I am not sure about Loop Bandwidth and Theta as >> the solution my mentor gave is for the old version of gnuradio. Can you >> help me with understanding these parameters? >> Right now when I start my receiver program on a usrp the number plot >> varies around 0.5 (which I guess is normal when there is no transmission) >> but when I start transmitter the value goes high to 0.6 or 0.7 (It should >> be lower than 0.3). >> I am using following parameters for the same >> >> M = 2 for BPSK >> >> Theta = 0 (I was not sure about this so I put it 0) >> >> Loop Bandwidth= ????? (I dont knw what to put here) >> >> Min Freq = -0.05 >> >> Max Freq = 0.05 >> >> Mu = 0.5 >> >> Gain Mu = 0.001 >> >> Omega = 8 >> >> Gain Omega = 0.000001 >> >> Omega Relative Limit = 0.0001 >> Also I tried to use Costas loop and Clock Recovery MM with same >> parameters but they are also not working. >> It would be great help if anyone can help me understand these parameters. >> >> Shashank Gaur >> >> >> >> On Fri, Jan 27, 2012 at 9:38 PM, shashank gaur <shashankg...@ieee.org>wrote: >> >>> Hello all >>> Thank you very much for such prompt response. >>> >>> @Marcus: I understand the problem now and will try to implement the Rx >>> and Tx on different USRP on Monday. The weeekend has already started here >>> in France. >>> @Andrew: I will also get back with exact result of the commands but what >>> I remember for uhd_find_devices the result was the device address that is >>> 4d9de875 and in uhd_usrp_probe it detected all the available RX and Tx (it >>> has Flex900). >>> Apologies for the delay but cannot access the usrp before Monday. The >>> mentor doesnt allow me to have usrp at home. Hope you understand >>> Thanks again for your time >>> >>> shashank gaur >>> >>> On Fri, Jan 27, 2012 at 9:18 PM, Marcus D. Leech <mle...@ripnet.com>wrote: >>> >>>> ** >>>> On 27/01/12 03:00 PM, Andrew Davis wrote: >>>> >>>> Type " uhd_find_devices " into console, then " uhd_usrp_probe " then >>>> give us the results, and the code for the program you're trying to run. >>>> >>>> On Fri, Jan 27, 2012 at 9:39 AM, shashank gaur >>>> <shashankg...@ieee.org>wrote: >>>> >>>>> Hello >>>>> >>>>> I am simply trying to build a transmitter and receiver for bpsk >>>>> modulation and demodulation using mpsk receiver at receiving end. I am >>>>> using USRP1 (Flex900 Daughter boards) with Gnuradio Companion 3.5.0rc0 on >>>>> Ubuntu 10.10. >>>>> >>>>> When I run either (trransmitter or receiver) of any grc applications >>>>> first the grc executes it successfully and when I run other the grc gives >>>>> following error. >>>>> linux; GNU C++ version 4.4.5; Boost_104200; UHD_003.003.001-8ff8f20 >>>>> >>>>> Traceback (most recent call last): >>>>> File "/home/sunny/Examples/top_block.py", line 105, in <module> >>>>> tb = top_block() >>>>> File "/home/sunny/Examples/top_block.py", line 40, in __init__ >>>>> num_channels=1, >>>>> File >>>>> "/usr/local/lib/python2.6/dist-packages/gnuradio/uhd/__init__.py", line >>>>> 93, >>>>> in constructor_interceptor >>>>> return old_constructor(*args, **kwargs) >>>>> File >>>>> "/usr/local/lib/python2.6/dist-packages/gnuradio/uhd/uhd_swig.py", line >>>>> 2003, in usrp_sink >>>>> return _uhd_swig.usrp_sink(*args, **kwargs) >>>>> RuntimeError: LookupError: KeyError: No devices found for -----> >>>>> Device Address: >>>>> serial: 4d9de875 >>>>> >>>>> >>>>> I think it has something to do with USRP UHD Source/Sink block >>>>> parameters. >>>>> Either the grc is not able to recognize the daughter board or there is >>>>> problem with hardware. may be I am wrong. >>>>> Please help me to recognize the error. >>>>> Thank you very much for your time >>>>> Shashank Gaur >>>>> >>>>> _______________________________________________ >>>>> Discuss-gnuradio mailing list >>>>> Discuss-gnuradio@gnu.org >>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing >>>> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> Just so we're clear here. If you're trying to run your RX and TX as >>>> two separate processes, against the >>>> same USRP1, that won't work. You'll need to have two independant >>>> USRP1s, or collapse your RX and >>>> TX into a single combined program--only one process can have a >>>> "handle" against each USRP1 at a time. >>>> >>>> >>>> >>>> >>>> -- >>>> Principal Investigator >>>> Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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