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

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. 
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? 
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. 
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