VHF repeaters

[ab1974 1]

Was reading the below article on Australian VHF repeater stations and was wondering how this worked in NZ. (Need to do my VHF licence - only have my UK one!).

 

Anyone care to shed some light?

 

http://www.mysailing.com.au/news/making ... -repeaters

[ab1974 1]

Anyone know the answer to this one??

[Grinna 2]

Sorry, I'm not understanding the question?

 

There are both simplex and duplex frequencies here in NZ ... just the same as described in that article. The repeaters work on the duplex channels in exactly the same way as they do as described in that article. You may need to subscribe to a particular organisation in order to use some repeaters operating on duplex channels (e.g. Coastguard) .... although I don't think subscriptions are policed.

 

Essentially, simplex channels are good for line of sight communications, while the duplex channels allow a much greater range and communication with stations beyond the immediate line of sight becomes possible.

 

If you want a list of duplex channels then you probably should pick yourself up a copy of the New Zealand Marine Radio Handbook.

 

http://www.marine-radio.co.nz/

 

There are a bunch of simplex channels (16, 13, 6, 8, 67, 68, 69, 71, etc) and there are a bunch of duplex channels (80, 81, 82, 83, 84, 85, 86, 25, 74, 1, 3, 4, 5, etc). Best to have a look at the marine radio handbook and/or do your VHF operators certificate to see which is used for what.

[ab1974 1]

Thanks Grinna - answered the question. Just wanted to know if the simplex and duplex channels were the same in NZ as they are in Australia as described in the article.

[Grinna 2]

yeah, think the channels are pretty much universal (apart from the US and Canada) but the actual use for the duplex channels may vary.

 

e.g. Channels 80-86 are duplex channels reserved for Coastguard here in NZ, Ch25 is NZ Maritime Radio working channel (duplex), while channels 1,3,4,5 and 60-66 are duplex channels for other repeaters. Elsewhere in the world that may not be the case.

 

Obviously, there are some standards - like Ch16 is distress (simplex), Ch13 is intership navigation (simplex), Ch70 is DSC only, etc. Don't know how universal some of the other channel allocations are though.

[wheels 543]

Yes We are on international channels and so is Oz.

We don't have DSC operating in NZ though. I don't know about Oz on that one.

[Guest]

This may be off topic a bit but seeing the original question has been answered.... Wondering what the story is with dsc in NZ. I hear coastguard are not going to instal it in the near future so is it of any use here?

[wheels 543]

No it's just a pretty red button on the front panel.

I have never really looked into it's pro's and con's over someone making a direct Ch16 distress call, apart from two immediate points that come to mind.

Pro = Push a button and it is all done for you.

Con = Imagine Kids with that tempting little red button. They cause enough problems as it is, but at least authorities hear a voice and can usually tell it is a Kid.

[rigger 47]

DSC will work in NZ amongst the radios fitted with it - but no coast station supports it.

 

You need to have an MMSI number (has 9 digits).

 

MSA or the powers that be decided many years ago that it did not offer any significant advantage and imposed extra costs on the govt and vessel owners.

 

If the VHF is linked to a GPS the Distress call will included your position.

I have a handheld VHF / GPS that is DSC equiped and will do that.

[Guest]

If the VHF is linked to a GPS the Distress call will included your position.

I have a handheld VHF / GPS that is DSC equiped and will do that.

 

How does the GPS position get automatically transmitted? Does it display on the receiving radios screen or something? Is it automatically locked in or saved?

[rigger 47]

Sorry do not have a screen shot to show what is displayed.

but..

The radio gets the position from the GPS and transmits it when the Distress button or send call button is pressed

Some radios you have to manually enter the position.

 

It is displayed as text on the receiving radios screen - if it is capable of it.

[Guest]

It is displayed as text on the receiving radios screen - if it is capable of it.

 

And locked in or saved as well?

 

So if I have a GPS enabled VHF radio that is, for arguments sake, on channel 16, and a transmission is received by me, the transmitting vessels GPS position will be displayed on my VHF?

[wheels 543]

Yes, that is assuming the DSC button was pushed on the transmitting radio. A normal transmittion on 16 from a non DSC or a DSC radio does not put out that info. The recieving radio keeps that info on screen till you delete it.

Remember that ch16 is line of site'ish and so between boats, you have a limited range. Ch16 to Maritime Radio is a lot further range due to most transmitters being on high land points. So it is a shame that maritime do not use the facility, or at least, do not officially anyway. I am not sure if they do unofficially.

[rigger 47]

I did point out in another thread that over a number years working in areas covered by DSC coast stations I only ever received 1 genuine distress message - and I had already heard the voice mayday on VHF 16 - received huge numbers of false alerts - so many that a number of people I know just hit the cancel button to silence the alarm.

Same problem that has occured with the old style EPIRBS - way too many false alerts.

[Guest]

Thanks for that Wheels.

 

Same problem that has occured with the old style EPIRBS - way too many false alerts.

 

I'm not sure that there will be any fewer false alerts with the new 406mHz GPS.....there just won't be quite as much of a wild goose chase to track it down.

[idlerboat 116]

DSC and Australia.

It is important to relise that I lot of large vessel no longer (if they ever did) have a full time radio operator monotoring 24 hours a day.

The on board ability to understand English can be very poor.

The advent of DSC has meant that (regardless if it is legal or not) a lot of large vessels rely on it soley

From experience, you can call, but chances are they wont anwser. I had a bulk carrier change direction , at night, and just miss running us down. The local marine rescue , (over 10 nautical miles away) heard us 5 over 5 and logged our lon and lats, so our radio was working just fine. I tried , before and after the incident....they just didnt anwser.

 

Let me quote from the Australian marine radio operators handbook.

With time, traditional labour-intensive Aural watchkeeping by ship and limited coast stations may change to automated DSC electronic watchkeeping.....

 

!!!They allready have !!!

Without DSC your VHF may be usless !!

 

In all practical purposes...Unless you are going to instigate an all ships alert you have to have the vessels MMSI number. The only way to get this while underway is to have AIS on board.....YEP more dollars.

 

DSC is now used as a forerunner to an Aural May Day message.

Sadly, without doing this the closest ship may not even hear you.

 

DSC protocal and use is now a major section in the Australian VHF operators licence test. This test is an agreement internationaly

The two Coast radio stations, Willuna and Charlieville, that are Australias HF stations are trigged only by HF DSC

MMSI 005030001

2187.5 khz is not monitored

[rigger 47]

In all practical purposes...Unless you are going to instigate an all ships alert you have to have the vessels MMSI number. The only way to get this while underway is to have AIS on board.....YEP more dollars.

 

You can also buy the ITU publication of Ship Stations and download updates before setting off. Not much of a solution.

 

2187.5 khz is not monitored

 

2187.5 kHz is one of the DSC monitored frequency - I think you were meaning 2182 kHz

[idlerboat 116]

Hi Rigger....

No I do mean 2187.5 .

 

The Australian main stations (Wilunna and Charleville) ((The Australian Maritime Saftey Authority Radio network, operated by AusSAR ((Australian search and rescue)) High powered .

DO NOT monitor DSC in this band.

They do monitor all other HF dsc distress and urgency freq.

They are automatic stations that are connected to Canberra.

 

The main limited coast stations may, but they are only required to operate out to 200 nautical miles. There are nine of these stations. Named "Coast Radio Stations

For example "Coast Radio Melbourne"

They provide a continuous coverage of the whole Australian coast .

They are no longer required to monitor 2182 (Aural) due to its limited propogation.

All other limited coast stations, such as Coast guard , VMR, and now the NSW amalgamated service "Marine Rescue NSW" may or may not monitor 2182 or 2187.5 , but the 24 hour a day services, usuly do. That is because they are more local and 2182 suits that purpose (limited propogation)

All limited coast stations here cover VHF 16 and usualy 156.525 (VHF DSC).

Cheers

[rigger 47]

Thanks for that Idler

FYI - according to the GMDSS course that I recently did GMDSS equiped ships have to monitor 2187.5

 

Just been reading that Aussie is declared as area A3 for coverage which requires HF coverage - not MF coverage which explains clearly why they are not monitoring 2187.5

[Guest]

!!!They allready have !!!

Without DSC your VHF may be usless !!

 

In all practical purposes...Unless you are going to instigate an all ships alert you have to have the vessels MMSI number. The only way to get this while underway is to have AIS on board.....YEP more dollars.

 

DSC is now used as a forerunner to an Aural May Day message.

Sadly, without doing this the closest ship may not even hear you.

 

Yes AIS is more hard earned cash but in 40+ knots, breaking waves and negative visablity while you are in a shipping channel it will be the best money you ever spent, it saved out bacon and beats pushing the red button or making that call!