Section-j: mf-hf Equip. And Comms: Key Topic #97: mf-hf Propagation-2; Day-Night-Winter-Summer:

97J1 A ship has been communicating effectively on 16 MHz during daylight hours with a shore station at a distance of 3500 miles. Toward late afternoon and evening what effect would be noticed?

A. Communications should gradually deteriorate and become impossible on this frequency at night.

B. Communications should be maintained with slight improvement in the signal received from the shore station.

C. The gray line effect will prevent communications after dark.

D. Communications should improve and peak at night.

97J2 A ship at anchor has been communicating with a shore station approximately 200 miles distant on a frequency in the 4 MHz band through mid-morning. Toward the late afternoon and evening, what effect should be noticed?

A. Communications should be maintained with slight improvement in the signal received from the shore station.

B. Communications should gradually improve and peak at night and early morning.

C. Communications should slowly deteriorate but may be continued throughout the night.

D. Communications should gradually deteriorate and become impossible on this frequency by night.

97J3 At mid-day in the summer, what would be the best choice in attempting to communicate, using SITOR (NBDP) with a shore station some 1800 miles distant?

A. VHF-FM

B. Lower HF bands

C. Higher HF bands

D. MF

97J4 At mid-night, what would be the best choice in attempting to communicate, using SITOR (NBDP) with a shore station some 800 miles distant?

A. VHF-FM

B. Higher UHF bands

C. Communications are impossible at this distance.

D. HF bands

97J5 At mid-day, what would be the best choice in attempting to communicate with a shore station some 75 miles distant?

A. MF

B. VHF-FM

C. 22 MHz band

D. 16 MHz band

97J6 How can a GMDSS operator determine the best frequency band to choose for a SITOR (NBDP) transmission to a shore station?

A. By consulting propagation tables.

B. Listen to shore station "free signals" and choose the band with the strongest signal.

C. If static interference is present, try lower bands first.

D. During nighttime, choose higher frequencies. Choose lower frequencies in the daytime.

Answers: 97J1 - A 97J2 - B 97J3 - C 97J4 - D 97J5 - A 97J6 - B

Section-j: mf-hf Equip. And Comms: Key Topic #98: mf-hf dsc Controller Alert/Call Response:

98J1 The Distress Alarm sounds and the screen readout no longer contains the particulars of the Distress:

A. The particulars are rarely routed to the printer so it is of no use to examine the printer.

B. Examine the Transmitted Data Directory or the printer to recover the information.

C. Call the Distress vessel on the DSC frequency and request a retransmission.

D. Examine the Received Data Directory or the printer to recover the information.

98J2 A DSC Distress call is received by your vessel and your transceiver frequency display reads:

Transmit = 4207.5 kHz and Receive = 4207.5 kHz with J3E emission -- what information can you infer from this?

A. The DSC call requested voice on 4207.5 kHz simplex but the requested alternate frequency is improper.

B. The DSC controller decoded the requested voice frequency as 4207.5 kHz simplex and your DSC controller has automatically set-up your transceiver and therefore the requested alternate frequency is correct.

C. The DSC call came in on 4 MHz DSC. You should set-up your transmitter and respond on the appropriate voice follow-on frequency of 4177.5 kHz.

D. The DSC call came in on 4 MHz DSC. You should set-up your transmitter and respond on the appropriate voice follow-on frequency of 4207.5 kHz.