VHF Channel 16

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nzpilot1181

138 posts

Master Geek
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#71652 14-Nov-2010 21:32

Can anyone on here explain how VHF channel 16 is linked throughout the country? I can hear Maritime NZ almost anywhere I go but can hardly ever here the station they are addressing (another vessel) unless they are close by. With the abscence of a repeater why is it I can hear Maritime NZ but not other vessel. Would it not work similar to channel 80 where ALL signals are repeated?

Cheers

NZCPL(A) Category B Flight Instructor

BlakJak

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#404655 14-Nov-2010 22:40

You're sure it's not just because you're comparing a high power fixed station with awesome antenna to a 25w mobile set on a whip?

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nzpilot1181

138 posts

Master Geek
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#404657 14-Nov-2010 22:44

possibly, or how is it possible (without the aid of a repeater) that maritime can pick up a small 1 watt signal almost anywhere in the harbour

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nickd

447 posts

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#404683 15-Nov-2010 01:26

Maritime Radio remotely monitor Chan. 16 and High Frequency from their Ops centre in Avalon. While it is possible they can broadcast on all of them at once, I've never heard it.

So your scenario may be something similar to this: I am on one side of Rangitoto, you are on the other. I call MR, they respond to me. You can't see me, so can't hear my call, however, you can hear MR respond because their isn't a mountain between you and the shore.

BlakJak

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#404754 15-Nov-2010 10:27

nzpilot1181: possibly, or how is it possible (without the aid of a repeater) that maritime can pick up a small 1 watt signal almost anywhere in the harbour

Careful with what you assert :-)

Coverage Maps:

http://www.maritimenz.govt.nz/Publications-and-forms/Commercial-operations/Shipping-safety/Maritime-radio-VHF-coverage-channels-map.pdf

Note the bottom bit, the map is based on a 25W radio with antenna >4m above waterline.

Straight line from Auckland Coastguard at Mechanics Bay to Waiheke Island is a shade over 20km.
You may well achieve that on a 1W handheld with absolutely nothing in the way, but you'd probably struggle with it. More often what happens is your signal is picked up by someone else and a mayday-relay is done, I expect.

It is possible to work significant distances without the aid of repeaters, if you place your radio/antenna correctly and have nothing to obstruct you.

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oxnsox

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#404773 15-Nov-2010 11:04

Channel 16 isn't a repeater based service it's a simplex channel, however that doesn't mean that the equipment is located at mechanics bay.

A repeater rebroadcasts both sides of the conversation from its advantaged location on high ground, this gives it good range and coverage. Whereas the CH-16 hardware (which maybe at the same location for optimal coverage) for Maritime Radio is only broadcasting their signal. As nickd says it means you may-not hear the other vessel if it's not 'line of sight' (land mass in the way) to you.

nickd

447 posts

Ultimate Geek
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#404777 15-Nov-2010 11:10

The other alternative if there is no landmass in the way is you are in a not very populated area. MR joins a few of the areas together to make less work for them. That other person could be way up the coast but still on the same VHF16 area, you hear MR because you are in the same area, but not the other party because the line of sight distance is too great....if that makes any sense. Can't really explain it very well.