hi ed, That was really nice of you to help me and wow your way to doing it, is just great. I will do the same thing too. Thanks for being so nice to allow me to share the code, but I want to work on it by myself. I am not a very good programmer and I think if I keep working on Gnuradio I will improve my skill at programming. But if I am stuck I will send a mail on this discussion board to ask for suggestions.
Thanks once again to you and all on this group Ali On Wed, Sep 17, 2008 at 10:05 AM, Ed Criscuolo <[EMAIL PROTECTED]>wrote: > mir murtuza ali wrote: > >> hi all >> >> i want to spread binary data read from a file using a PN sequence. The PN >> sequence is generated by a LFSR. Is there any gnuradio block that can help >> me do this. The gr.glfsr_source_b generates the sequence continously. If >> there isn't any block that can help me do this, can you suggest a way to >> implement a new block for doing this. I thought of a way but that requires a >> block to have two input streams at different rates which i think is not >> possible in gnuradio. One stream that reads from the file and the other >> stream that is actually the output coming from the pn sequence source. >> >> any ideas or suggestions ? >> > > > I wrote a simple "digital upsampler" block to do exactly this. It takes in > a binary stream at the lower data rate and upsamples it to match the > PN "chip" rate. It differs from the interpolator blocks in that it > inserts the nearest correct value (1 or 0) instead of simply inserting > zeros. > > For example, with a 100KHz data rate and a 400KHz chip rate, > the 100KHz stream > > 1 0 1 0 1 0 ... > > gets upsampled to the 400KHz stream > > 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 ... > > instead of > > 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 ... > > The block takes parameters of the input and output frequencies, > and computes the upsample ratio, which can be non-integer. > > Once you have the data upsampled to the chip rate, its a simple > matter to take it and the output of the glfsr and run them thru > an XOR block, yielding the PN spread baseband, ready for a > PSK modulator. > > I'd be happy to share the code. What's the preferred way > on this list? > > a) In-line with message > b) Message attachment > c) Other > > @(^.^)@ Ed > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -- Mir Murtuza Ali Graduate Student Center for Wireless Communications University of Mississippi University, MS 38677
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