UNIT 7 COMMUNICATION

1. UNIT 7COMMUNICATION VHF

2. VHF is an acronym for Very High Frequency, and describes radio signals on frequencies between 27 and 156,4 MHz.

4. VHF frequencies are ideal for short-distance communication.

5. The range of VHF signals is limited to line of sight because the radio waves of VHF do not bend around the curvature of the earth.

6. Coast stations are commercial radio stations that exist to make telephone connections between ships at sea and telephone subscribers ashore

7. ITU regulations state that a station must always identify itself each time that it makes transmission.

8. Coast stations will be identified by the use of their geographical name followed by the type of service that they provide .e.g. Colombo Radio.

9. The correct identification of coast and shore radio stations will be found in the ITU List of Coast Radio Stations.

10. DSC is used to alert the called station and to agree a working channel. • The communication is then carried out on that working channel.

11. The coast station will send a DSC acknowledgement and part of that acknowledgement will include the working channel that they wish to use.

12. Tune the VHF radio to that channel and begin the call.

13. The coast station will ask for the telephone number that you want and how the call is to be paid. • Then they will ask you to stand by while they connect you.

14. Normally the coast station transmits a series of beeps while you are standing by. • This to let other vessels know that the channel is occupied and they should not try calling on that channel.

15. When the coast station has your party on the line, they will tell you to go ahead.

16. Channel 16is not used for communications other than those relating distress, safety and urgency situations.

17. Channel 70 • Routine calls on VHF cover all non-emergency traffic. • Channel 70 is used with DSC not only for distress, urgency and safety calls but it is used for routine calls as well.

18. Channels 15 and 17 • The numbers which VHF channels should be selected for intership use are channels 15 and 17 may be used for on board communications during manoeuvring and docking operations.

19. Answer the questions • 1- Is VHF used for short distance or long distance communication?

20. 2- Why is the range of VHF signals limited?

21. 3- What is the purpose of coast stations?

22. 4- How is a coast station identified?

23. 5- What is the channel 16 used for?

24. ETYMOLOGY • Coast< Latin, costa, side • Tele-< Greek, tēle, far off < Indo-European, kwel-, distant, remote

25. SOME WORDS Stand by (v)-To hold on the line

26. Receive (v)-To get the transmitted sounds or images Send (v)-To cause to be transmitted to another place

27. Transmit (v)-To broadcast over the airwaves

28. Try to find the antonyms of these words in the text. disagree x…………………. disconnect x…………………. exclude x…………………. finish x…………………. low X………………….

29. Rewrite the following sentences using the words in brackets. 1- ( but ) Routine calls can be made on channel 70. / MF/HF channels are not allowed for routine calls.

30. 2- (before) Semaphore had been used for transmission of messages for a long time / Telegraph was invented.

31. 3- (either…. or) DSC calls can be made to individual ships or groups of ships.

32. Match the two columns. Column AColumn B …1-Aldis a-vessel …2-Morse b-operator …3-Coast c-bell …4-Ship d-call …5-Visual e-lamp …6-Distress f-code …7-GMDSS g-station …8-Commercial h-communication

33. Which is not true regarding VHF? a. VHF stands for Very High Frequency b. Its frequencies between 27 and 156.4 MHz c. It is used for short distance communication d. VHF is not included GMDSS e. VHF Channel 16 is primarily used for distress, urgency and safety calls.

34. Which is not true regarding VHF? d. VHF is not included GMDSS