Radio communication techniques involve the transmission and reception of information using radio waves. These techniques include amplitude modulation (AM) and frequency modulation (FM), which vary the strength or frequency of the signal to encode information. Additionally, digital modes like PSK31 and FT8 allow for efficient data transmission over radio frequencies. Another important aspect is the use of antennas, which convert electrical signals into radio waves and vice versa. Techniques such as Doppler shift and spread spectrum enhance communication reliability and security. Overall, these methods enable effective long-distance communication in various applications, from broadcasting to emergency services.