Practical use of Gold Codes

On Sep 25, 9:25 pm, John <sampson...@gmail.com> wrote:
> On Sep 25, 2:31 pm, Jaco Naude <naude.j...@gmail.com> wrote:
>
>
>
> > >> Why Gold codes? What are you trying to accomplish by that?
>
> > I am trying to create a simple DSSS Modem, similar to the that
> > described inhttp://www.altera.com/literature/fs/fs14_dsss.pdf
> > The type of spreading sequence does not matter. Gold codes are the
> > easiest to implement on a Xilinx FPGA using the SLR16 macro.
>
> > >> So you don't know how to multiply a complex number by a real number or what?
>
> > I know that the complex spreading sequence has c_r and c_i codewords.
> > c_r is a gold code obviously, but is c_i = 0 or is it another gold
> > code? That was the question really. I know how to multiply a real
> > number with a complex number.
>
> > John thanks for the answer. However Jerry said yes to my initial
> > thoughts that c_i = 0. Thanks for that as well. Maybe it is dependent
> > on the application? However it does not look like this is the place to
> > find that out.
>
> > Thanks for the replies.
> > Jaco
>
> Even if the imaginary spreading code is zero at the transmitter, which
> as I said before is not the typical case, you will not want to
> despread with zero imaginary at the receiver. This is because the
> complex received signal is in general scaled and rotated by the
> channel. Despread the real and imaginary both by the real spreading
> code used in transmit. The resulting peaks will look like Aexp(j*phi)
> and -Aexp(j*phi) where phi is the phase shift seen in the channel and
> A is related to channel gain and transmit power.
>
> John

Thanks for all the help,
Jaco