VHF / UHF HAM Radio Antenna ... and AIS?

[Dockhead]

Originally Posted by s/v Jedi

Next thing I need is a N2K to Ethernet converter. To get stuff to the iPads etc.

cheers,
Nick.

There are several ways to do that.

If you had a Navico plotter, you could use GoFree, and not only get your data on your IPads, but remotely operate the plotter and radar, too. You don't even need to buy the GoFree module; it's all standard Ethernet, so you can just plug in any domestic WiFi terminal via a built-in Ethernet port.

There are a few different WiFi bridges which will work with any system. Here's just one of them: Chetco SeaSmart N2K WiFi Gateway | Blue Heron Marine Electronics

If you already have a USB bridge like the Actisense (the one I bought), you can just share the connection with other computers over WiFi, from a computer connected by USB.

I think it's not too hard. GoFree is the coolest application, however, of this. You can operate your radar from your bunk, if you like

[s/v Jedi]

Originally Posted by Dockhead

There are several ways to do that.

If you had a Navico plotter, you could use GoFree, and not only get your data on your IPads, but remotely operate the plotter and radar, too. You don't even need to buy the GoFree module; it's all standard Ethernet, so you can just plug in any domestic WiFi terminal via a built-in Ethernet port.

There are a few different WiFi bridges which will work with any system. Here's just one of them: Chetco SeaSmart N2K WiFi Gateway | Blue Heron Marine Electronics

If you already have a USB bridge like the Actisense (the one I bought), you can just share the connection with other computers over WiFi, from a computer connected by USB.

I think it's not too hard. GoFree is the coolest application, however, of this. You can operate your radar from your bunk, if you like

I already have full nav + AIS + radar on my iPad using the Ethernet gateway in Furuno and MaxSea TimeZero. But my searches for plain converters were still NMEA0183 and the wait is for more choice as I'm not certain the current offerings will work trouble free. I'll check out that SeaSmart though, tnx!

[Air Raiders]

HEllo All you Amateurs with desire to transceive AIS via 2 meter.

I have looked into decription the AIS signal on 161.975, 162.025 dual frequencies.
The Decription mode is 9.6 kbit/s Gaussian minimum shift keying (GMSK) modulation over 25 or 12.5 kHz channels using the High-level Data Link Control (HDLC) packet protocol.

So, please can someone explain how I can decript the GMSK modulaiton for use on my 2 meter Kenwood, with built in TNC, ARPS?
I am at a loss for how to do this..

Any help ???

KC5EBM

[s/v Jedi]

Originally Posted by Air Raiders

HEllo All you Amateurs with desire to transceive AIS via 2 meter.

I have looked into decription the AIS signal on 161.975, 162.025 dual frequencies.
The Decription mode is 9.6 kbit/s Gaussian minimum shift keying (GMSK) modulation over 25 or 12.5 kHz channels using the High-level Data Link Control (HDLC) packet protocol.

So, please can someone explain how I can decript the GMSK modulaiton for use on my 2 meter Kenwood, with built in TNC, ARPS?
I am at a loss for how to do this..

Any help ???

KC5EBM

I have not had the urge to try that yet. I think the raw data could be demodulated using the TNC but decoding that data into AIS messages on the display will need code hacking. If somebody hacks the d710, one could program it to be AIS transponder I think.

For now, you'll probably end up using a PC with software to do this...

[Whisper 2]

Hi Jedi,

You seem like a very knowledgeable young man! I am trying very hard to take advantage of my mast being down for re-rigging and maintenance. I have pulled a very ropey coax out and plan to install RG 213U to a Shakespeare 5400-XT 3db Antenna. I was planning to connect this to my VHF/AIS Splitter. I also have a YAESU HF Transceiver with a backstay Antenna. Could you furnish your opinion on my proposed set-up please. I am circumnavigating and currently in Malaysia but my communications, especially VHF/AIS have been going steadily worsening?

[ohgary]

Originally Posted by denverd0n

A Diamond mobile antenna? How are you going to mount that? I might be mistaken, but I thought that all of Diamond's mobile antennas were designed for the vehicle to provide the ground plane. In other words, you can't just mount one of those antennas on top of a mast and expect it to work.

Why not, If you mounting it on the mast you have a hug amount of metal below it for a ground plane.... If not there are plenty of no GP mount mounts to use.

[Whisper 2]

Thanks Gary. The Shakespeare is a little heavier than the normal whip so I am beefing up the mount. Thanks for your time.

[s/v Jedi]

Originally Posted by Whisper 2

Hi Jedi,

You seem like a very knowledgeable young man! I am trying very hard to take advantage of my mast being down for re-rigging and maintenance. I have pulled a very ropey coax out and plan to install RG 213U to a Shakespeare 5400-XT 3db Antenna. I was planning to connect this to my VHF/AIS Splitter. I also have a YAESU HF Transceiver with a backstay Antenna. Could you furnish your opinion on my proposed set-up please. I am circumnavigating and currently in Malaysia but my communications, especially VHF/AIS have been going steadily worsening?

Your setup will work but there are some pointers:

- I recommend you get the AIS version of that antenna https://www.defender.com/product3.js...9062&id=771793

- This antenna has a length of coax connected to it. For a masthead install you need to cut that very short, then install a connector on so that you can connect it to your RG213 using a barrel coupler. I recommend you tape the heck out of that connection and secure it to the antenna mount or on top the masthead. I used an adhesive lined heat shrink tube for it... must've been 1" diameter or so.

- Shakespeare does have a better antenna now, the 6400-R Phase III but check if it covers the AIS frees good enough for your transponder (but it has a connector so no pigtail cable needed): https://www.defender.com/product.jsp...060&id=3019820

[Jon Hacking]

Originally Posted by Whisper 2

... plan to install RG 213U to a Shakespeare 5400-XT 3db Antenna. I was planning to connect this to my VHF/AIS Splitter...

Whisper, as a Ham for 25 years, I strongly suggest that you NOT use a splitter, & instead install a 2nd antenna.

1. I've had no end of problems getting splitters to work correctly
2. A 2nd antenna is usually cheaper than a splitter
3. A 2nd antenna gives you redundancy should your main antenna fail
4. If the splitter fails, you lose BOTH your VHF & your AIS

Yes, your range will drop a bit with your AIS antenna mounted lower down (you can't put both antennas on your masthead) but most splitters cut received signal strength down by half, affecting both your VHF & AIS.

[Whisper 2]

Hi Jon I just read your statement again. Yes I understand about the Splitter problem for that reason I will be mounting two antenna on top of the mast but they will not both be working at the same time so in effect although the coax's will be all the way to my instruments one will be purely back up and disconnected. I have a backstay antenna set up for the SSB and another emergency antenna on my Gantry bars about 4m from sea level the coax of which is also run to the instruments but disconnected.

[s/v Jedi]

Originally Posted by Whisper 2

Hi Jon I just read your statement again. Yes I understand about the Splitter problem for that reason I will be mounting two antenna on top of the mast but they will not both be working at the same time so in effect although the coax's will be all the way to my instruments one will be purely back up and disconnected. I have a backstay antenna set up for the SSB and another emergency antenna on my Gantry bars about 4m from sea level the coax of which is also run to the instruments but disconnected.

Whisper you can’t have two antennas at the masthead, not even when only one is in use. The inactive one is tuned to the frequency so will start resonating. Think of two tone forks: you strike one for a tone and when you hold the second of the same tone next to it, it will sound as well.
You must put the second antenna on your upper spreaders. Keep 10 feet (3 meters) vertical distance between VHF antennas.

The advice to use separate antennas for VHF and AIS is good. I’m using a Vesper splitter which works good but is very expensive. For HAMs, you can often use a dual band VHF/UHF antenna for marine VHF as well and some marine VHF antennas (incl. the cheap 3’ long 3dB sailboat stainless whip) do good enough on a dual band HAM antenna. When you have a dedicated AIS antenna, you get more flexibility

[S/V Illusion]

Originally Posted by s/v Jedi

Whisper you can’t have two antennas at the masthead, not even when only one is in use. The inactive one is tuned to the frequency so will start resonating.:

In theory, there may be some parasitic effect but that doesn’t actually happen in practice because of how most marine VHF antennas are DC coupled to their feed lines making them appear widely separated in terms of electrical length because of the different feed line lengths.

Parasitic interaction could happen if you are also using a splitter and have two antennas in close proximity but the splitter creates far worse problems than anything else.

[Whisper 2]

OK I didn't know about an un-connected antenna being a problem but your explanation makes sense, this is all good info as I haven't started installation yet. So new set up will be the one antenna on mast top running to the splitter for VHF/AIS. The SSB will be on the backstay as before, and I have the emergency antenna on the gantry bar.. However I will now look into the practicalities of another antenna on the top spreader in case the splitter doesn't perform.