Which of the following statements is true?

In J2B mode, two tones are indeed used to transmit information. This mode of transmission is a form of frequency shift keying (FSK), which utilizes two distinct frequencies to represent binary data. The "J" in J2B indicates that it is a simple data transmission mode, while the "2B" indicates the use of two tones in reference to the binary information being transmitted.

This is crucial because the effectiveness of any communication system, particularly in maritime and emergency scenarios as governed by GMDSS regulations, hinges on the ability to transmit data accurately and reliably. By employing two tones, J2B can clearly differentiate between the binary states (ones and zeros), which ensures that the intended information is properly transmitted and understood.

In contrast to this, the other statements do not accurately describe the characteristics of J2B mode. For instance, while an RF carrier is commonly used in various forms of communication, it is not specifically a requirement of J2B mode since the mode primarily focuses on transmitting data using frequency shifts rather than a continuous carrier wave. Additionally, stating there is only a single tone in J2B or that H3E mode features only the mentioned carrier and sidebands fails to capture the fundamental mechanics that distinguish these