GPS antenna to feed into AIS reciever

For a little bit more than the combined cost of GPS and the NASA unit, you could get a Matsutec hp-33a ais transponder .

This has GPS, the display, and will output NMEA 0183 to the VHF.

That sounds very attractive!.
I googled the Matsutec spec but the documents are not very clear on the GPS. Am i correct in thinking the unit has an inbuilt GPS which has a bare wire nmea 0183 outlet which I could connect to my DSC VHF?
 
All AIS transponders have in built GPS to allow them to comply with standards and connecting to your vhf should be straight forward
 
I agree with dolabriform, the Matsutec is a great bit of kit that will give you everything in one box. I am sat in front of mine right now and it is happily letting me know who is going in and out of the harbour.
If you go this route, make sure you buy the hp-33a and not the hp-33, as that is just the GPS unit without the AIS.

The transponder option (rather than an AIS reciever) raises a number of queries for me.
Does the transponder transmit ones own boats position automatically or can it be selected "off" while still receiving data on other boats positions? Is relaying of ones own position while sailing heavy on battery usage?. And finally is there a requirement to register details of ones own boat or does the MMSI registration take care of that?
 
Usually they have a silent mode that can be enabled by and external switch to stop transmitting, as far as registration is concerned it’s via ofcom as an NRV to your ships licence as it’s a transmitter.
 
The transponder option (rather than an AIS reciever) raises a number of queries for me.
Does the transponder transmit ones own boats position automatically or can it be selected "off" while still receiving data on other boats positions? Is relaying of ones own position while sailing heavy on battery usage?. And finally is there a requirement to register details of ones own boat or does the MMSI registration take care of that?

There is an option in the menu to switch off the transmitter side of the unit, this then means that it is acting as a receiver only. In the box there is a GPS antenna and plenty of cable, there is also NMEA0183 output and cable (which I have linked to a Digital Yachts WiFi sender, so the iSalor can show the AIS targets). The only thing you need to add is a VHF antenna or a splitter for your mast head one.
The MMSI is entered, if you want to on set up. If you don’t enter the MMSI then the unit will only act as a receiver.

As for battery use, I don’t have the manual near by, but I think it states 2A, but most of that will be the colour display.
 
Do you have an example of one that isn’t? Does it have a PPS input for the timing?

Pete

I don't think you'd need a pulse per second input to sort out the timing of AIS.
It's a requirement for class B AIS transponder to use an internal GPS source, but not Class A.
This might be because a class A ship might have reliable position info from other sources, like inertial nav.
Or just that the class A spec is older and intended for professionals.
 
I don't think you'd need a pulse per second input to sort out the timing of AIS.
It's a requirement for class B AIS transponder to use an internal GPS source, but not Class A.
This might be because a class A ship might have reliable position info from other sources, like inertial nav.
Or just that the class A spec is older and intended for professionals.

I suspect that we're only discussing the difference between a GPS receiver and a GPS antenna. ;)

Richard
 
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