GMDSS普通操作员 第02讲：Passage 29 第02讲：Passage 29.ppt

航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 航运系航海教研室 Passage 29 On the MF and HF bands, one frequency in each band is allocated for distress, urgency and safety purposes. These frequencies are programmed into the DSC equipment for selection when necessary; also in each band there are both national and international call and reply frequencies for routine call. Whenever possible, national channels should be used for routine calls, e. g., on MF 2,187.5 kHz is used only for distress/safety; 2,189.5 kHz is used internationally for ship/shore calls; 2,177 kHz is used internationally for ship/ship calls and for shore/ship calls. Passage 29 On the VHF band, Channel 70 is used for distress/safety as well as routine calling. In the case of a routine “All Ships” call the power output should not exceed one watt. An example situation would be to contact a nearby ship. Some DSC installations have provision to reduce the power level from 25 watts to one watt automatically. The actual band chosen will depend on the distance involved. A list of DSC frequencies is given Admiralty List of Radio Signals. Passage 29 1. What is the best title of the passage? A. Allocation of Frequencies for DSC. B. 2,189.5 kHz in DSC Service. C. Channel 70 in DSC Service. D. None of the above. 正确答案：A Passage 29 2. How many frequencies are there in MF and HF bands for distress, urgency and safety purposes? A. Only one. B. Six. C. Five. D. Two, 2,18 7.5 kHz and 8,414.5 kHz. 正确答案：B Passage 29 3. How to comprehend the sentence ... 2,189.5 kHz is used internationally for ship/shore calls; 2,177 kHz is used internationally for ship/ship calls and for shore/ship calls? A. 2,189.5 kHz will be used to call a ship station by CRSs. B. 2,177 kHz will be used to call a CRS by ship stations. C. 2,189.5 kHz and 2,177 kHz must be used in pair between ship stations. D. 2,177 kHz can be used independent