DSSS bandwidth

Hi

If I want to design a DSSS data tranmitter with BPSK modulation and 56Kbit/sec
datarate,f=1250MHZ,what is the bandwidth of generated signal ,how we calculate it?

please give formula or links.

First, the bandwidth of BPSK-modulated signal is twice that of the original baseband signal. That means the BPSK-modulated bandwidth is 112 KHz.

Then, since you are using DSSS, you need orthogonal codes that you will multiply your signal with. Examples of orthogonal codes are Walsh codes, Hamard codes, etc.

Those codes consists of n bits (usually n=2,4,8,...), therefore the final bandwidth is equal to n times the BPSK-modulated bandwidth.

For exapmle, if you use 8-bit Walsh codes, the DSSS bandwidth will be: 8*112k = 896 kHz.

HTH

Regards