Invisible Communications

Congestion, mis-use and interference on VHF channels, particularly 16, 67, and 77, has become an increasing problem in recent years. Particularly in heavily populated boating areas such as between Port Stephens and Port Hacking, there are not enough simplex channels available for non-commercial boat to boat traffic. Channel 77 is the only one specifically allocated for that purpose, and at times it is extremely busy. This encourages the impatient and ignorant to illegally use other channels, often 16 or 67 which should be a no-no as their prime function is safety and distress (other than for an initial call, then transfer to another channel). Other simplex channels such as 72, 73 and 74 are used by VMR’s as their working channels, and they justifiably get somewhat annoyed if they are used for boat to boat traffic.

Of all the 55 or so channels you will find on your VHF radio, only 20 are simplex, that is they transmit and receive on the same frequency for direct communication. Take out 16, 67 and 70 (DSC),  and those allocated to port operations, navy, and the VMRs, and we are left with 77 as being the only simplex channel available (legally) for recreational boat to boat traffic. No wonder some people get frustrated and impatient when trying to call their mates on another boat, and resort to other, illegal, channels. What can be done?

Repeaters can often provide the answer, and an increasing number are coming into operation around Australia, including NSW. Those who have cruised in Queensland waters will be familiar with them, as they have been widely used there for years. More recently SA, Tasmania and Victoria have commissioned repeaters which provide excellent coverage of their coastlines. Aside from their availability for boat to boat traffic, repeater channels are also available to VMR stations, providing them with additional working channels, and often, greater radio coverage. At last NSW has realised their benefits, and commissioned several in recent years, usually without telling anyone.

Of the 55 channels in your VHF radio, five are allocated for repeaters - 21, 22, 80, 81 and 82. They are duplex channels, which means the transmit and receive frequencies are different, and you cannot use these channels to communicate unless in range of a repeater. Use of a repeater can give much increased range as they are usually located well above sea level, providing both transmitting and receiving boats are within line of sight range of the repeater. For example if a boat is 30 miles south of a repeater and another 30 miles north of the same repeater, they should be able to communicate. For two boats to communicate on a repeater channel, both must be within range of the same  repeater. Direct boat to boat communication is not possible on a repeater channel except through the repeater itself. In addition to the benefit of increased range, in many busy boating areas they can provide an excellent alternative to channel 77.

The latest information we can find for NSW regarding the location and coverage of repeaters is as follows, from north to south:

Channel          Repeater Location                             Coverage Area (approx)

22                    Cape Byron                                          Qld border to Ballina

21                    Yamba                                                 Ballina to 10nm N of Red Rock

80                    South West Rocks                                Coffs Harbour to Kempsey

21                    Middle Brother Mtn (nr Port Maquarie)        SW Rocks to Seal Rocks

80                    Mt Sugarloaf  (nr Newcastle)                Broughton Is to Broken Bay

21                    Kilcare Hts (nr Gosford)                       Norah Head to Port Hacking

22*                  North Head (Sydney)                           Norah Head to Stanwell Park

81                    French’s Forest (Sydney)                     Kilcare to Port Hacking

82                    Maddens Plains (north of Wollongong) Tuggerah lakes to Jervis Bay

81                    Cambewarra Mountain (Nowra)         Kiama to Kioloa

80                    Round Hill (nr Batemans Bay)            Jervis Bay to Bermagui

81                    Mt Imlay (nr Eden)                               Bermagui to NE Bass Strait

* Weather forecasts are broadcast by Marine Rescue Sydney on channel 22 several times during the day.

To check whether you are within range of a specific repeater, other than by listening for traffic, select its channel, and make sure your “squelch” control is properly adjusted. Now press your “transmit” button for about a second, release it, and you will hear a brief burst of noise. This is known as the repeater “tail”, and will only be heard if you are within range of that repeater. There is no such tail on simplex channels.

Details of repeater locations and channels in other States may be found on the following web sites:

Tasmania www.mast.tas.gov.au

Queensland www.msq.qld.gov.au (links safety/marine radios/vmr groups)

SA www.transport.sa.gov.au

Victoria www.marinesafety.vic.gov.au (click on "publications" then find  "VHF Repeater Network")

Marine Rescue NSW is pleased to announce the commissioning of a new marine repeater. The repeater is located [at Maddens Plains] near Bulli to the north of Wollongong and operates on VHF Channel 82.

Initial testing showed a shore-based coverage from Lake Macquarie in the north to Ulladulla in the south. Propagation modelling has shown that it can reach out to 50 to 60 nautical miles offshore at the widest point of its footprint.

The repeater provides superior range to a normal simplex channel like Channel 73 because unlike most bases that are at or near sea level, the repeater is located at a much higher elevation. The antennas for the Channel 82 repeater are situated approximately 400 metres above sea level. Repeaters are designated for vessel movements and the safety of vessels and persons. This means they can be legally used as an alternative working channel, however please keep personal chatter to a minimum, as others use the repeater too, including marine rescue units.

Marine Rescue Port Kembla maintains a listening watch on channel 82, and Marine Rescue Sydney (Terrey Hills) monitors 82 with other channels. Both of these bases operate 24 hours a day, 7 days a week.

An updated map of the NSW VHF Marine repeaters has been put on the MR NSW website. Note the addition of the Wollongong repeater.

http://www.marinerescuensw.com.au/index.php/marine-radio-network/

[Edit: This link is now out of date. We are searching to try and find if the graphic has been put somewhere else on the new page]

Thanks to Ron (above) for sending some Google Earth overlays of Australia's VHF marine repeaters. These are very good maps - well worth printing and taking with you on your cruise.

You can view the maps at:

http://invisiblecommunications.com.au/news-and-links/50-repeaters.html

or navigate to them by clicking the "next" link at the bottom of each page until you have scrolled through.

Please note these maps are based on radio frequency licences which have been issued, so indicate that the channel has been allocated for that particular position. A licence does not indicate that the repeater is installed and operational. However, in most cases, the repeater is up and running. We will endeavour to quality control the maps as time goes on. However, they are still a valuable tool for finding and using repeaters as you travel.

Please do write in here or email with updates and corrections so we can get this resource accurate and maintain it.

Hi

I'm new to this forum and live in Western Australia.
It was noticed that there was no information on VHF Repeaters in this State.

I currently educate people regarding Maritime VHF and have a complete list of coast stations along our coast including Repeaters, Frequencies , MMSI, call signs, phone no’s and locations .

This I could share so that it could be included in your excellent information.

Hello

RRoland

No info on WA repeaters indeed!  Wash yr mouth out with soap at once.

The google earth map of Australia by states in a post above this one shows 29 repeater allocations around the coast of WA.  No doubt some may not yet be installed or are no longer operational.

These allocations were taken off the ACMA database late last year.  If you have more up to date info it'd be handy to put it up so the ACMA database could be checked.

Would you like me to show you how to check their database?

regards

Hi Jenkins and all,

We're working on getting some of Roland's WA info online, but also plan to soon check and update the other info already up. If you have anything to share, please do so.

I'm well versed in using the ACMA database, but it takes real users to ascertain what's actually out there in service. Sadly, phone calls to local VMR units often yield poor or contradictory results.

Let me clarify: I have every respect and gratitude for our volunteers, it's just that VHF marine repeaters are too much of a patchwork quilt in Australia there is often confusion.

The PNG Government has taken the initiative and recently issued a tender for 18 repeaters to provide communications. Australia, how about a similar type of project to get everything standardised?

Kind regards,

NEW SOUTH COAST REPEATER

Marine Rescue NSW and the CYCA SOLAS trusts have jointly funded a new VHF repeater at Cambewarra Mountain (Nowra) to provide much-needed marine radio coverage on the NSW South Coast.

The channel 81 repeater covers from Kiama (north) to Kioloa (South), and at least 22 nautical miles to sea.

MR NSW is very proud of the fact that $36,000 was spent on this project, and rightly so, as our volunteers are to be applauded not only for their fundraising but also their day to day efforts. The CYCA SOLAS trusts contributed $18,300 of the total.

As an experienced radio technician (who has just delivered 18 VHF marine repeaters for a PNG government tender), I am curious as to what was delivered in this project. You get a lot for $36,000 - if anyone can enlighten me I would be very interested.