In which mode is the lower sideband emphasized while transmitting?

The mode where the lower sideband is emphasized during transmission is J2B. This mode, known as single sideband amplitude modulation (SSB), specifically utilizes lower sideband (LSB) modulation for voice communications.

Understanding why J2B is appropriate involves knowing how single sideband modulation works. In single sideband transmission, only one of the sidebands (upper or lower) is transmitted, which eliminates the need for carrier frequency and reduces bandwidth usage. J2B designates the use of amplitude modulation with the lower sideband specifically included for voice signals, making it very efficient for long-distance radio communication.

The other options pertain to different types of modulation and transmission characteristics:

H3E is a type of phase modulation that utilizes both sidebands and typically includes a carrier, while J3E also transmits SSB but emphasizes the upper sideband. F3E refers to frequency modulation with a full carrier. This distinction in modulation types helps clarify why J2B is the correct answer for emphasizing the lower sideband.