Ahmed Zaheer <[email protected]> writes: > I was trying to implement Direct Sequence Spread Spectrum in gnuradio. In the > transmitting flowgraph I am using GLFSR source to multiply it with the file > which I am transmitting. At the receiver end I am able to receive it by > multiplying it with same GLFSR source with the same values. But there is no > acquisition being done. I am seeing a block named PN Correlator. But I don't > know what this block does and where should I use this block in the flowgraph. > My question is does anybody know what the PN Correlator block does and is it > performing the acquisition or not. > > Any help/comments would be greatly appreciated. > > Regards.
Ahmed, After taking a look at digital_pn_correlator_cc.cc, I think it's a serial code acquisition block as described in its header. The output will be cross-correlation of PN sequence and input samples. Input sample pointer is advanced by noutput_items samples for each call, and the output value is derived from multiplying input samples by PN sequence, both are length of whole PN sequence. If you think noutput_items to be one, then it will be easier to understand this code. So, yes, it's serial search code acquisition to my understanding. If you monitor the output of digital_pn_correlator, you should see a spike when the acquisition is achieved, and the interval between two spikes will be roughly the length of PN sequence due to noise effect. I think its input is time domain samples from your front-end. This is my understanding of this block. Hope it helps. Best Regards, Albert -- Albert Chun-Chieh Huang(黃俊傑) Blog: Random Notes, http://alberthuang314.blogspot.com/ _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
