How is a particular polarity picked for the pilot tones in each symbol with 52 subcarriers in GNU Radio? I can see the list in the OFDM Carrier Allocator block but where is this exactly happening in the code?
On Mon, Mar 20, 2017 at 3:37 PM, Bastian Bloessl <[email protected]> wrote: > Hi, > > On 03/20/2017 09:17 PM, Qurat-Ul-Ann Akbar wrote: > > Hi, > > > > Thank you. I got it! I have another question. In the OFDM Carrier > > Allocator block, there are 127 values for pilot symbols each of them > > either (1,1,1,-1) or (-1,-1,-1,1). The pilot frequencies are > > (-27,-7,7,21) according to IEEE 802.11 standard. But I do not understand > > why are there 127 symbol values. Can you kindly explain that ? > > The four values indicate the four pilot symbols (on subcarriers -21, -7, > 7, 21). With 802.11, the pilots change polarity based on a predefined > sequence (of length 127). It is in this exact format also in the > standard (Section 18.3.5.10 of the 2012 version). > > Best, > Bastian > > > > > > > On Mon, Mar 20, 2017 at 12:09 PM, Bastian Bloessl <[email protected] > > <mailto:[email protected]>> wrote: > > > > Hi, > > > > > > > On 20 Mar 2017, at 17:50, Qurat-Ul-Ann Akbar < > [email protected] > > <mailto:[email protected]>> wrote: > > > > > > If I want to make changes in the PHY hierarchical block, can I > just make changes in the grc file available in the examples folder and then > recompile ? Because I cant file a .cc file in the lib folder in IEEE_802.11 > module and the source code for most blocks is in there. > > > > > > > I’m afraid I don’t get the question, but if you don’t see any .cc > > files in the lib folder, you might want to clone the repository > > again, because actually there are some > > > > https://github.com/bastibl/gr-ieee802-11/tree/next/lib > > <https://github.com/bastibl/gr-ieee802-11/tree/next/lib> > > > > If you only change the flow graph in GRC, you don’t have to > > recompile the module (i.e., recompile c++ code). Just click on the > > “generate” button (or press F5) this will rebuild the PHY. Then the > > other flow graphs will automatically use the new version of the PHY. > > > > Best, > > Bastian > > > > >
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