I want to build a system that can transmit data through 2-way radios as far as possible. I use the "line-in" as the input of the baseband signal in the transmitter and use the "audio out" as the output in the receiver. The RF modulation scheme seems to be a NBFM and the bandwidth of their audio input and output are about 2kHz-4kHz. The bit rate should be more than 64bits/s. I think there are many systems that work like this.
I was plan to use 64-MSK with RS code and interleaving at first but one of my workmate insist DSSS+BPSK without any coding. Personally, I don't think DSSS is a good choice in this situation.
I want to know who is right? Which one is better and why. Are there any mature schemes that I can choose?