On Tue, Aug 12, 2008 at 11:47 AM, Jason Uher <[EMAIL PROTECTED]> wrote:
>>I will be using gold codes as the PN sequences. >> >> Is it possible to purely implement in software instead of programming the >> FPGA. As the rate is only 2Mbps isn't it possible to implement in software >> only given we have a good computer to work with ? > > The 'quick and dirty' option would be to just make vectors containing > the gold codes you want to use then put them in a repeating vector > source. There is a Galois form LFSR stream generator: gr.glfsr_source_b(degree, repeat=True, mask=0, seed=1) If the mask is not specified, it will choose one from an internal table and generate a maximal length PRN sequence of length 2**degree-1, otherwise it will use the mask for the taps and you can implement your own polynomial. The degree is valid from 2-32. The seed value is put into the LFSR as its initial value, and the repeat parameter will cause the sequence to repeat indefinitely instead of just once. The _b suffix indicates that it will create samples of item size 1 (bytes). These are unpacked; that is, the PRN sequence is transmitted in the LSB of each byte. Two of these wired into the inputs of gr.xor_bb will give you a Gold code, provided you have the correct mask and seed for each of them. -- Johnathan Corgan Corgan Enterprises LLC http://corganenterprises.com/ _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
