On Tue, Aug 12, 2008 at 11:47 AM, Jason U. [email protected]
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
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.
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