VK Logger Ham Radio Forum Archive

Beware, there is indeed repeater stations for AIS signals around the coast.

Im currently picking one up, I believe it appears to be coming from Portland Lighthouse, MMSI 005030204, grid - QF01SN.

The only way that I have been able to work this out is by running DX Maps software called AIS DX AGGREGATOR.
Here is an image of what it shows me - This is a snap shot of the AIS DX Aggregator running above the Shipplotter program. I have drawn an arrow on the Aggregator program showing the only DIRECT signal heard at that instance is from Portland Lighthouse. The rest of the signals marked with (R) at the ends have all been sent via a repeater station. So on the background map, most of the ships around Portland, Mt Gambier area (see green markers), in this instance are from a repeater station, pressumed to be Portland Lighthouse as its the only direct signal being heard from that area.

The only way to tell if you have a direct signal is to look at the listing of what your decoding on AIS DX Aggregator. If there is NO (R) at the end then its direct signal. If there is a (R) then is been retransmitted via a repeater.

Most signals from Melbourne I see here are direct signals. I have seen on occassion a repeater as mentioned coming from Portland Lighthouse, and another close to Adelaide, but physical location is unknown at present. Will update if I find out more info.

Also, as you can see in the attached image below, the DX Maps AIS listing, filters out all repeater signals and only shows direct signals, which is very good. It would be a huge mess otherwise.
I have drawn a arrow to the Portland Lighthouse spot on this one. All signals listed here are direct signals.
Unfortunatley on Shipplotter and across to Marine Traffic.com they both show ALL signals which includes repeater signals. So its not possible to tell if your hearing a signal directly, just by viewing those two alone.

Hello Leigh

The best way to tell is to look at the MMSI - the station's ID number.

MMSI's with two leading zeros are allocated to land stations.

Rgds
Glenn

Glenn,
I have to disagree with you about the MMSI number. You can not tell looking at the MMSI that a signal has been heard at your station either directly or via a repeater.
While a MMSI number with 00 at the start may indicate a land based station (such as many lighthouses), thats fine, and are still good beacons, but without using DX Maps Aggregator, you do not know if you have heard that station direct or via a repeater. This is clearly shown in the first screen shot I posted. ALL the MMSI number listed on the middle section have been sent via a repeater EXCEPT THE ONE WITHOUT THE (R) at the end as indicated with the arrow. That signal MMSI 005030204 is from Porland Lighthouse directly. This signal below it MMSI 005030048 is King Island Lighthouse, but has been sent to me via a repeaeter (R). Considering Portland Lighthouse is the only signal being heard direct from that lot, I can only assume thats its also the station acting as the REPEATER in this instance for all the other (R) marked signals.

You CAN get ship MMSI numbers that have been sent out or repeated, via a repeater. There is no difference to the MMSI number of the ship. See all the other MMSI numbers posted in that middle list. They all are not direct from the ships but have been heard via repeater station, hence the (R) listing at the end.

Ahhh, thanks.

Located one of the AIS repeaters in southern Western Australia this morning.
I was able to hear its signals numerous times until sunrise, its 2809 km from here

And this is it -
Its location on map is here -
Here is a map of Shipplotter showing ALL the many signal was would have otherwise thought I was getting scattered up the coast of WA. But, alas, its not true. You can see on the DX Aggregator interface, marked in green is the direct signal from the repeater and all other signals shown on map have been REPEATED from the repeater station.
This is a bit of a bummer, as at one stage, when I first came into the radio room this morning, I thought I had broken the 3000 km mark, but on further investigation this was not the case, although I was hearing the repeater at 2809 km, which is a new PB for me anyway. But would love to break the 3000 km mark.
So people in VK6 (or anyone else), need to be aware that you may not be hearing as for as you think on direct tropo path, there is some serious repeating going on along the VK6 coast.

Nice one Lee, I've been hearing lots of VK2's & 3's with my meager setup this morning. Must have been something in the air ...

Hauke

I must tell my mate from AMSA (the C'wealth Gov't marine agency that operates the AIS network) about your DX.

He will be most impressed.

Thanks guys, nice to crack some big paths now and then.

If anybody knows of any repeater in Brisbane area maybe? I can't hear any just direct signal from ships .

73

Sinisa

Im fairly sure I've identified another AIS repeater, this one in South Australia, Cape Jervis Lighthouse on the north east side of the Kangaroo Island ferry route.
I'd like to verify this again, but am 90% sure this station is also acting as an AIS repeater site.

Below is a zoomed in image of the site with the MMSI number 005030269.
And zoomed out.

Hi Leigh,

This link should find most of the AIS sites licensed by AMSA around Australia.

http://web.acma.gov.au/pls/radcom/clien ... O=20000768

I can narrow down the list for WA by doing a search on postcodes (6000-6999) & frequency range (161.975MHz-162.025MHz) through the ACMA site and end up with a couple of dozen sites all along the WA coast line.

Cheers,

Rob...
VK6LD

Rob,

Thanks for the list.

Many Lighthouses have AIS transmitters, but not all are repeaters is the problem.

I wonder if there is a way to find out which ones are retransmitting the ship signals (repeater)?

Rob,

Ive just written to the Aust Maritime Safety Authority to see if they can advise which stations are set up as repeaters. Will advise if they respond.

there's one at cape shank in Victoria , as well as on the hill behind point Lonsdale , I have the pics of the one at cape shank on the pc some where , its housed inside the light house , with two antennas off the side of the rail of the said light house

Hi VK3XRI,

Sorry I missed your post till now.

When you say behind Point Lonsdale, would you mean the site I call Murradoc Base? This one is not a repeater, but it does transmit all the virtual marker information for around the bay.

Not sure where Cape Shank is ?

Cape Shank is to the E of Port Phillip heads.