I'm using the Texas Instrument transceiver cc1101 at 430-440 [MHz] and I'm wondering what the best modulation technique is for long distance transmission. This transceiver offers several modulation schemes: 2-FSK 4-FSK GFSK MSK ASK Ook
What should I pay attention to if I want to use the best one to transmit for at least 5 [Km]?
I am using a power amplifier to achieve increased transmission distance, I also know that a lot falls into the aspect of using directional antennas and other factors such as direct line of sight. Knowing this, I want to know if what I should focus on to achieve my goal is the BER of these techniques or something else.