Practice Test Geeks(FMF) Fleet Marine Force Practice Test
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Combat Communications Flashcards

6 cards from real FMF practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Combat Communications flashcards as text

  1. A Marine operating a frequency-hopping, encrypted radio net can hear the net control station, but their own transmissions are received as garbled audio. Power, antenna, and frequency settings are confirmed correct. What is the MOST likely cause of this communication failure?

    Answer: The wrong COMSEC key is loaded, or the Time of Day (TOD) is incorrect.

    In a frequency-hopping, encrypted net, all radios must have the correct Communications Security (COMSEC) key and be synchronized with the correct Time of Day (TOD). A mismatch will cause the encryption and hopping pattern to be out of sync, resulting in garbled or no communication, even if the base frequency is correct.

  2. Which of the following BEST describes the primary function of the Single Channel Ground and Airborne Radio System (SINCGARS) in Frequency Hopping (FH) mode?

    Answer: To rapidly change frequencies during transmission to prevent enemy jamming and interception.

    The primary feature of SINCGARS in Frequency Hopping (FH) mode is its ability to change frequencies over 100 times per second across a specified range. This makes it extremely difficult for an enemy to intercept the transmission or effectively jam the communications.

  3. A patrol makes initial contact with a significant enemy force, and the report must be sent immediately, taking precedence over all other radio traffic. Which message precedence proword should be used?

    Answer: FLASH

    The order of message precedence from highest to lowest is FLASH (Z), IMMEDIATE (O), PRIORITY (P), and ROUTINE (R). FLASH is reserved for initial enemy contact reports or operational messages of extreme urgency.

  4. The AN/PRC-117G is known as a "multiband" radio, giving it great versatility. This is due to its ability to operate across which of the following frequency bands?

    Answer: Very High Frequency (VHF) and Ultra High Frequency (UHF), including SATCOM.

    The AN/PRC-117G operates in a wide frequency range from 30 MHz to 2 GHz. This covers the VHF band (for line-of-sight communications like SINCGARS) and the UHF band (for line-of-sight and satellite communications), making it a highly versatile multiband radio.

  5. You are attempting to establish communication but cannot hear the distant station. You have already checked your radio's power, volume, frequency, and antenna connection. According to standard troubleshooting procedures, what is a logical next step?

    Answer: Attempt to contact the station using a different radio.

    A key step in troubleshooting is isolating the problem. By trying a different radio (if available), you can quickly determine if the fault lies with your specific piece of equipment or with another factor, such as range, terrain, or an issue with the distant station. This is a more logical and efficient step than assuming the fault or performing maintenance beyond the operator's level.

  6. What is the primary purpose of Communications Security (COMSEC)?

    Answer: To deny unauthorized persons information derived from telecommunications and ensure the authenticity of such communications.

    COMSEC encompasses all measures taken to protect telecommunications from unauthorized interception and exploitation while also ensuring that the communications are authentic. This includes using encryption, controlling cryptographic keys, and implementing secure procedures.