AIS starting from scratch what's best way to go at the moment?

[Rusty007]

B&G now have a all in one VHF with AIS transmit.



https://www.bandg.com/en-nz/bg/type/...is-rxtx-v60-b/

[Q Xopa]

Originally Posted by Rusty007

B&G now have a all in one VHF with AIS transmit.



https://www.bandg.com/en-nz/bg/type/...is-rxtx-v60-b/

Well 'almost'.
I asked about these a few days ago. I got a reply, "not yet released, and no release date set yet".

[Neptune's Gear]

The Navico VHF60b is about to be released. I've (Im a navico dealer) been told it will be available next month in NZ. I have one backordered for my own boat and demo...

[Dragon Lady]

Hi all,

I have decided to go with the Raymarine AIS700 class B, whilst not the cheapest it fits in with my existing ST60 system and Axiom multi function display. I have had good service from my existing Raymarine system so hopefully that will continue. Thanks for all the great advise and hope everyones systems works well for them DL.

[Ambler]

Good choice.
I upgraded to this same unit as well. This unit has SOTDMA which means more transmit power and when in crowded shipping areas this class B transponder actually communicates with the surrounding class A's transponders and time slots in so it doesn't get drowned out by them.
It also has the antenna splitter built in.

Originally Posted by Dragon Lady

Hi all,

I have decided to go with the Raymarine AIS700 class B, whilst not the cheapest it fits in with my existing ST60 system and Axiom multi function display. I have had good service from my existing Raymarine system so hopefully that will continue. Thanks for all the great advise and hope everyones systems works well for them DL.

[capn_billl]

Originally Posted by FabioC

From some of the posts in this thread, I do not quite understand the reasons for going for an antenna splitter. In my experience, having a dedicated antenna would be worth the (manageable) additional hassle and the incremental expense. Could you please elaborate on the rationale behind the splitter? Thank you!

Climbing up a 68 foot mast to install one more (expensive) item to destroy when I go under a bridge?

[capn_billl]

Originally Posted by Tillsbury

Any AIS transmitter without it’s own GPS isn’t a legal one.

Not true, there are several on the market with GPS inputs.

[s/v Jedi]

Originally Posted by capn_billl

Not true, there are several on the market with GPS inputs.

I’m afraid you’re wrong. They all have internal GPS receivers, you probably confused that with external GPS antenna’s

[tanglewood]

Originally Posted by s/v Jedi

I’m afraid you’re wrong. They all have internal GPS receivers, you probably confused that with external GPS antenna’s

I think both are true.


AIS devices have to have their own GPS that is part of the GPS. That's true. Sometimes the antenna is internal, and sometimes it's external.


But a number of GPSs also accept GPS data from an external GPS. This is particularly true for Class A AIS where providing an external GPS input is mandatory, and the internal GPS is strictly as a backup.

[Simi 60]

Originally Posted by capn_billl

Climbing up a 68 foot mast to install one more (expensive) item to destroy when I go under a bridge?

You could always use the first set of spreaders or a rail.

Of course if you are hitting bridges with your mast an aerial is the least of your issues.

[Cpt Pat]

There are pros and cons on having a splitter:


Pros:

• You can use the VHF antenna and coax you probably already have installed at the best possible location: your masthead.
• Provisioning two VHF antennas in close proximity will cause them to "couple," detuning and raising the VSWR of both antennas and causing unwanted directivity. Two VHF antennas should be installed at least one wavelength apart. For the Marine Band: that's 2 meters. You have a very unusual masthead if you can achieve that much separation (but I've seen it done with a horizontal extension pole).
• A separate AIS antenna installed anywhere except the masthead can be shadowed, detuned, and made directive by metal structures (the mast, stays, boom, etc.).
  
  
  Cons:

• Having two separate antennas is electronically less complex, so there's less to go wrong electronically (but more to fail physically).
• Either antenna can be a backup for the other.
• Connecting two radios to the same antenna through a splitter can cause difficult-to-troubleshoot mutual interference caused by either radio's internally generated noise. Unless the splitter is internal to the AIS transponder: the designers of both radios (VHF transceiver and AIS transponder) assumed their unit would have a separate dedicated antenna.
• AIS transmission blanking: when transmitting on the VHF transceiver, you are not sending AIS data through a splitter.
• Some splitters have an RF preamp to increase receive sensitivity. My experience is that preamp only amplifies noise with no beneficial effect on reception range.
• The splitter may end up being a casualty in a lightning hit. Preamps don't like lightning-induced transients.
• A second antenna and coax may cost less than a quality splitter.

My advice if you use a splitter: have a backup antenna in a less ideal but useable location for the AIS, and configure your system so you can eliminate the splitter in an emergency. End result: you still end up with two antennas.


N8QH

[Cpt Pat]

Originally Posted by tanglewood

This is particularly true for Class A AIS where providing an external GPS input is mandatory, and the internal GPS is strictly as a backup.

Correct for Class A. And both the backup internal and external GPS receivers each need an antenna.

The external "GPS" receiver for my Class A is one of the multiple satellite system receivers, technically a Global Navigation Satellite System (GNSS) receiver. I'm using both US GPS and Russian GLONASS. If you intend to install an external GPS receiver, you might want to look at one of the new GNSS receivers that supports GPS, GLONASS, and Galileo (example: https://digitalyachtamerica.com/prod...s160-nmea0183/).

[s/v Jedi]

Originally Posted by tanglewood

I think both are true.


AIS devices have to have their own GPS that is part of the GPS. That's true. Sometimes the antenna is internal, and sometimes it's external.


But a number of GPSs also accept GPS data from an external GPS. This is particularly true for Class A AIS where providing an external GPS input is mandatory, and the internal GPS is strictly as a backup.

Tough crowd
I assumed this was about class B transponders, not class A

[Cpt Pat]

Originally Posted by s/v Jedi

Tough crowd
I assumed this was about class B transponders, not class A

I believe the general point was: "you can use an external receiver even when an internal receiver is provided." One has the option of provisioning a GNSS receiver that utilizes positional data from an external source for AIS, and my point is that using a source that utilizes multiple constellations (GPS, GLONASS, Galileo) provies added accuracy and redundancy. It's not a Class A versus Class B issue.

I've been very happy with the improved performance from using a GNSS receiver that provides a positional solution combining GPS and GLONASS. Now that Galileo is coming on line, I plan to upgrade to a receiver that uses all three sources. The cost is down to < $200.

I've found that GPS and GLONASS (presumably Galileo as well) reception fades when the receiver has to "look through" a wet sail, and having twice the number of receivable satellites gives a corresponding improvement in reliability. I never experience a "lost lock." That was occasionally an issue using only GPS. AIS is useless without positional data.

[s/v Jedi]

Originally Posted by Cpt Pat

I believe the general point was: "you can use an external receiver even when an internal receiver is provided." One has the option of provisioning a GNSS receiver that utilizes positional data from an external source for AIS, and my point is that using a source that utilizes multiple constellations (GPS, GLONASS, Galileo) provies added accuracy and redundancy. It's not a Class A versus Class B issue.

I've been very happy with the improved performance from using a GNSS receiver that provides a positional solution combining GPS and GLONASS. Now that Galileo is coming on line, I plan to upgrade to a receiver that uses all three sources. The cost is down to < $200.

I've found that GPS and GLONASS (presumably Galileo as well) reception fades when the receiver has to "look through" a wet sail, and having twice the number of receivable satellites gives a corresponding improvement in reliability. I never experience a "lost lock." That was occasionally an issue using only GPS. AIS is useless without positional data.

I believe a class-B transponder uses the internal GPS receiver, never an external one. Mine has a 50 channel receiver that supports all the constellations