AIS Marine Traffic Tracking (tropo indicator)

[VK4DU]

My pleasure.

73
Glenn

[VK2KRR]

Was keeping it a secret, but now is probably a good time to tell you about the new marine tracking station set up by Bob ZL3TY from Greymouth, NZ. Bob is running a 5 ele yagi for 162 MHz.
Bobs stats page is here - http://www.marinetraffic.com/ais/statio ... eader=true
He is currently hearing over 2000 Km. I believe at least one of the signals is a 2 watt class B transponder.

Will let these images speak for themselves -

ZL3TY Fri night 3 hr map

Hepburn ZL3TY path

[VK2KRR]

A zoomed in map of the VK2 coast showing just some of the signals. Ive highlighted the 2 Watt transponder thats been logged.
Its quite possible that ZL3TY is hearing a lot more than this, but this is whats been logged with the tracking server only.

ZL3TY map showing 2 Watt Transponder heard

[VK2KRR]

Out of interest, Bob has given us some great data here. Whats happening is what commonly can occur to produce New Zealand to Australian east coast paths. I'd personally call this a frontal type duct, which tends to build up on the leading edge of some fronts that line up on a good angle between Australia and New Zealand across the Tasman sea. This can also occur on appropriately lined up low pressure troughs, as is commonly seen down the Queensland coastal area, which is what happened last weekend. You have warm moist tropical air feeding down from the north. Shown quite well on Weather Zone MSLP maps you can see the red arrows mean hot above average wind temps, feeding in from the north. In the current case it would appear the low pressure trough is just ahead of the cold front, and the cold front is pushing up from the SW, moving the whole lot to the north east.

WZ MSLP

Rain Radar/Lightning map, with area of signal shown due to radar enhancement via the increased tropo activity just before the front line where the lightning is showing.

Radar WZ

On the cloud map, ive highlighted the part of the coast where the majority of the signals are propagating from at this stage.

WZ cloud lightning

[ZL1UJG]

Hi,
For my AIS setup I am using a Yaesu FRG8800 HF receiver, with integral 118 to 174 MHz converter. I have made a 9600 Baud connection to the diode discriminator which outputs to the back of the HF Rx. The Rx + converter is a little deaf (~ 7 dB) and made a preamp for masthead using a BF988 Mosfet and other junkbox parts.(Bandwidth ~ 6 MHz).

The antenna is currently a discone but will be putting up a marine band whip, when the howling wind drops...

This all feeds into a netbook, which has a partially busted screen (from dropping it twice when sending zzz's)

I am about 40 km inland so will keep an ear out to see if anything decodes, under favorable conditions. With analogue TV going off we need an alternative.

Most of the discriminator mods I have seen are for IC discriminators, so will see if it all works

Kevin

[VK2KRR]

Hi Kevin,

Sounds good.

Do have have a Marine Traffic.com stats page that we can keep an eye on ? or are u just using it locally in shack ?

[ZL1UJG]

Hi,
Just having the setup in the shack/shed at the moment, although It could be connected through eventually, when I confirm the system is working.
Its a bit of a Heath Robinson setup, with various mods to the old FRG8800, (Discriminator mod, DC up coax mod, homemade LNA), but should be ok.

Kevin

[VK2KRR]

As of around midnight, Phil VK5AKKs marine tracking station is hearing out to 1685 Km. One at Esperance and one between Albany and Esperance.

VK5AKK 1685 Km

[ZL1UJG]

Hi,
Has anyone had any success feeding the mic port on a laptop, rather an a line input?
During recent days I think I can sometimes hear the data. I have just purchased a ext USB sound card which has a line input so will see if that helps.

Kevin

[VK6ADF]

Hi,
Has anyone had any success feeding the mic port on a laptop, rather an a line input?
During recent days I think I can sometimes hear the data. I have just purchased a ext USB sound card which has a line input so will see if that helps.

Kevin

What software are you using for AIS? Ship Plotter, if you are not using it already, has a signal page where you can view the incoming signal and see if it is big enough or clipping.

[ZL1UJG]

I am using Aismon plus the other one with the waveform displayed that you mentioned. The level looks good with about half display taken up. The output from the rx is via a 10uf DC blocking cap. I wonder if its a time constant issue. Will see soon as a cheap USB audio box with line input is on its way
Kevin

[VK3SMC]

I use a laptop and feed audio through the Microphone port, i have had to drop the level using a 10K and 1K resistors, but after doing that, the audio level is spot on and i get great decode.

Cheers
Simon
VK3SMC

[ZL1UJG]

Hi,
Got my Ext Soundcard with line input. Wired it up, now getting 100% Paging POCSAG decodes which wasnt getting before on Mic input. Waveform looks more peaky as seen on images. Will leave it running...

[ZL1UJG]

Hi,
Good news and bad news.

Overnight the system using AISmon reported 2 type 1,2,3 message ID's and 1 type 5.
The number of syncs has dropped right down, was running into many, many hundreds overnight, and was only 168, so the system appears to be working.

However Shipplotter which was running in parallel, which had the unusual decode some days ago, when using the mic input, came up with nothing?...

So dont know. I may have to connect through to see what data comes up.

Kevin

[VK2KRR]

Hi Kevin

Thats good that it appears to be working properly now. I dont use AISmon so im not sure what the set up of it is or if it sends to the other program (shipplotter) or not.

I dont use soundcard audio here. The way mine is set up is the data from my AIS RX feeds via my router into my computer. I firstly use a program called AIS Dispatcher. As the name suggests this decodes the raw data and dispatches it to other IP addresses, which I have it sending to my Shipplotter program so I can see a visual display and get a bit more data out of it, and it also sends to Marine Traffic.com site so people can see it online.

Hopefully someone else can offer some suggestions to you.

[ZL1UJG]

Hi Leigh,
Just finished my Sunday morning MS QSO session. South Island is not a good direction for me, as its like firing through that rock behind your QTH...

The cheap ext USB sound card, is now stuck to the old netbook with some double sided tape.
The netbook has been dropped a few times, but still works although the screen is worse for wear.

I have downloaded a AIS decoder programme and saved any new decodes from AISmon to a file, which then should be able to be decoded to see what I can hear.
Once I am happy with the operation will then look at connecting AISmon through to the Marinetraffic site.

Hamilton has mountain ranges at distance in most directions so it will be interesting to see what I can decode, and from where.

Kevin

[VK6ADF]

Hi,

However Shipplotter which was running in parallel, which had the unusual decode some days ago, when using the mic input, came up with nothing?...

I can't say for sure either as I also don't use audio input to the PC for my processing either, mine arrives via ethernet, but quite often when using audio in programs depending on the setup you can only use soundcard on one program at a time. To use more you either have to point the software at the sound mixer rather than select line or mic in or what most people seem to do is use audio stream transfer software like Virtual Audio Cable. http://software.muzychenko.net/eng/vac.htm

[ZL1UJG]

Hi,
I know what you mean about programs taking hold of the audio stream. But in this case both programmes show audio input, so will what happens.
I suspect the signals received were maybe a dusk or dawn enhancement. Its raining here now so I dont expect too much this evening.

I think its about 100km to any port activity (Auckland orTauranga). There is a coastal beacon about NNW which probably the closest source. Any ship activity is going to be well offshore from here in the west direction (offshore fishing ships) so it will be interesting to see where the decodes are from.

Antenna is a simple marine band whip.

Kevin

[9A4CU]

Great AIS reception in Kariong,NSW by VK2EFM !Well done!

[ZL1UJG]

Hi, Had one successful decode today on AISmon. From Tauranga, as a ship was leaving. Distance is ~ 95km, over a mountain range.
Listening on a VHF dipole at work, could hear more AIS signals, so its down to location here.
There were about 79 syncs/errors during the day

The ShipPlotter program didnt see anything so that is switched off for the time being.

Kevin