Please help - i am stuck - spreading data and bpsk

GNU Radio
1

hi,
Can someone please tell me how to do this?

I want to generate DSSS with BPSK modulation in gnuradio but I have a
few
doubts that couldn’t be cleared even after a lot of looking for an
answer.

The DSSS transmitter block diagram from various books shows that i have
to
XOR the input data with the PN sequence to spread and then BPSK
modulate. My
doubt is

  1. I did the same and then BPSK modulated using the gnuradio DBPSK
    modulation without the diff encoder block but I am having trouble in
    acquisition at the receiver. I am using the method described in the book
    “Fundamentals of Global Positioning System Receivers” by Tsui. Maybe I
    am
    doing something fundamentally wrong at the transmitter.

  2. Someone on this list suggested BPSKmod-> RRCFilter ->SPREADING. If
    samples per symbol were 1 then I can just multiply the symbol with the
    PN
    sequence but as it is always greater than 1 I cannot figure out how I
    can
    spread. Can someone please help me here?

  3. Is it possible to remove the RRC filter completely and instead use
    (1+0j)
    and (-1+0j) symbols to modulate the carrier and still get good results
    at
    the receiver? If it is possible then life would be easier as I don’t
    have to
    worry about the problem mentioned above in 2.

  4. If anyone can share the transmitter block diagram of a GPS
    transmitter
    then I think it can be of great help as it has a DSSS modulation scheme.
    All
    i found on the internet was block diagrams but my concern is about pulse
    shaping and none of these diagrams show nothing about that.

I did put in an effort to find answers by myself for a long time but as
I
couldn’t find an answer I am writing for a little guidance.

Thanks