This is the grc file if someone would like to run it on their setup. On Mon, Oct 12, 2015 at 9:00 AM, abhinav narain <[email protected]> wrote:
> Hi,
> I am trying to transmit -1,0,1 { [1]+ 100*[0]+[-1] }, basically BPSK lot
> of 0s filled in between at certain frequency. I have few questions.
> "Constellation object" has 3 symbols ([1+0j,-1+0j,0+0j]) mapped to symbol
> map-> [0,1,2] respectively. I agree that constellation with size 3 is
> weird but that is what I want. I want the decision boundaries to be at
> -0.5, 0.5 for bits and anything between that to be given symbol=2 which i
> can discard later on. I am currently doing this in baseband, but I will
> eventually trasmit at a some frequency X.
>
> I have the following baseband setup grc (
> http://postimg.org/image/8k7g1o375/ , grc file is attached).
> I have few problems which I am unable to fix since yesterday -
> 1) The constellation after channel is stable (as expected) but it goes
> weird
> after the polyphase clock sync and costas loop (
> http://postimg.org/image/pyg8h2vlh/ , attached image-
> constellation_before_after_costas.png) and hence I don't get the expected
> output of equally spaced 1, 0 in the decoder output (
> http://postimg.org/image/a58cc35cj/ , attached image-
> custom_decoder_0_1_2_output.png)
>
> 2) If I set the order of costas loop as 3 (size of constellation) my
> flowgraph doesn't work at all. I have used the parameters after reading
> some example code
> in gnuradio folders and web and i guess they are correct. Please correct
> me if I am wrong.
>
> Thanks,
> Abhinav
>
clock_3_testing.grc
Description: application/gnuradio-grc
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