Section-h: Maritime Safety Information (m.S.I.): Key Topic #51: Navtex-1: Operations:

51H1 How is mutual interference on 518 kHz among NAVTEX stations avoided?

A. All stations transmit at the same time but stations are limited to daytime operation only to reduce the radius of propagation.

B. Transmitter power is limited, station assignment codes are not shared by other NAVAREAS and stations alternate between daytime and nighttime operations.

C. Transmissions scheduled on a time-sharing basis, power limited and station assignment codes are geographically separated.

D. Station codes are not shared by other NAVAREAS, transmissions scheduled on a time-sharing basis and power is limited.

51H2 When do NAVTEX broadcasts typically achieve maximum transmitting range?

A. Local noontime

B. Afternoon

C. Sunset

D. Middle of the night

51H3 What should a GMDSS Radio Operator do if a NAVTEX warning message is received but it contains too many errors to be usable?

A. Do nothing. Vital NAVTEX messages will be repeated on the next scheduled broadcast.

B. Contact the NAVAREA coordinator and request a repeat broadcast.

C. Initiate a request for Category A, B, L and D messages.

D. Listen to appropriate VHF weather channel for repeat warnings.

51H4 Which of these cannot happen when a paper model NAVTEX receiver runs out of paper?

A. The unit is unable to print messages and all subsequent MSI broadcasts may be missed until the paper is replaced.

B. The system will automatically change from receiving MSI by NAVTEX to receiving it by SafetyNET^TM so that no messages will be lost.

C. It may give off either an audible and/or visual alarm.

D. MSI messages may be missed because the unit cannot print them out.

51H5 Which of the following is the primary frequency that is used exclusively for NAVTEX broadcasts internationally?

A. 2187.5 kHz

B. 518 kHz

C. 4209.5 kHz

D. VHF channel 16 when the vessel is sailing in Sea Area A1, and 2187.5 kHz when in Sea Area A2.

51H6 What is the transmitting range of most NAVTEX stations?

A. Typically 50-100 nautical miles (90-180 km) from shore.

B. Typically upwards of 1000 nautical miles (1800 km) during the daytime.

C. Typically 200-400 nautical miles (360-720 km).

D. It is limited to line-of-sight or about 30 nautical miles (54 km).

Answers: 51H1 - C 51H2 - D 51H3 - A 51H4 - B 51H5 - B 51H6 - C

Section-h: Maritime Safety Information (m.S.I.): Key Topic #52: Navtex-2: Programming:

52H1 How is a NAVTEX receiver programmed to reject certain messages?

A. The transmitting station's two-digit identification can be entered to de-select reception of its broadcasts.

B. By choosing a message category's single letter (A-Z) identifier and then deselecting or deactivating.

C. By entering the SELCAL of the NAVTEX transmitting station.

D. By pressing "00" in the transmitter's ID block.

52H2 How can reception of certain NAVTEX broadcasts be prevented?

A. Stations are limited to daytime operation only.

B. Coordinating reception with published broadcast schedules.

C. The receiver can be programmed to reject certain stations and message categories.

D. Automatic receiver desensitization during night hours.

52H3 Which of the following statements is true?

A. No NAVTEX receiver can be programmed to reject category A, B, D and L messages since they are mandatory to be received via NAVTEX.

B. Upon entering a new NAVTEX station's broadcast range, the GMDSS Radio Operator enters the station's SELCAL number.

C. The GMDSS Radio Operator can select the "None" option in the message category menu.

D. A GMDSS Radio Operator may choose to program certain NAVTEX receivers to reject category A, B, D and L messages if they are being received by another MSI system.

52H4 What means are used to prevent the reception of unwanted broadcasts by vessels utilizing the NAVTEX system?

A. Programming the receiver to reject certain stations and message categories.

B. Operating the receiver only during daytime hours.

C. Coordinating reception with published broadcast schedules.

D. Automatic receiver de-sensitization during night hours.

52H5 What statement is true regarding the control the operator can exercise over the NAVTEX receiver's operation?

A. The operator can set the unit to automatically reject any and all categories of messages if the ship desires to not receive them.

B. Upon entering a coastal area for the first time, the operator enters code KK to indicate "ready to receive NAVTEX".

C. To reduce the number of messages, the operator can select code 00 to indicate "not in coastal passage".

D. The operator can set most units to reject all messages except navigation, meteorological warnings, and search and rescue messages. If the unit will reject such messages it may be unsafe to do so.

52H6 Which messages are mandatory to be received and should not typically be rejected or disabled by the operator of a NAVTEX receiver?

A. Navigational warnings, meteorological warnings, SAR information.

B. Meteorological warnings, SAR information, Pilot Service Messages.

C. Meteorological warnings, meteorological forecasts, navigational warnings.

D. SAR information, navigational warnings, ice reports.

Answers: 52H1 - B 52H2 - C 52H3 - D 52H4 - A 52H5 - D 52H6 - A