Tugw
Well-Known Member
Can anybody tell me if i need to use the NMEA output of,say a chartplotter,to feed the AIS or can i just chuck a GPS antenna on the thing? if so what type?
Thanks Troops
Thanks Troops
NASA AIS
- Thread starter Tugw
- Start date
Viscount
Well-Known Member
I have one of these. It needs a VHF antenna to pick up the AIS signal. The purpose of the NMEA input is to allow the NASA to overlay the AIS data onto the GPS data and present to a chart plotter suitably equiped to decode and display both data sets. In my case, I use a PC with Oziexplorer.
I believe that the existing VHF antenna can be used with a splitter to couple to both radio and NASA but I just mounted a second antenna for simplicity.
I believe that the existing VHF antenna can be used with a splitter to couple to both radio and NASA but I just mounted a second antenna for simplicity.
Dave_Seager
Well-Known Member
According to the manual on tthe NASA website it does need a GPS input to tell it the boat's position.
It is obvious really. How else can it determine the position of ships transmitting AIS data relative to your boat?
It is obvious really. How else can it determine the position of ships transmitting AIS data relative to your boat?
Elessar
Well-Known Member
Are you talking about the AIS that displays on a chartplotter or the one that displays on its own little screen?
If the former, it needs no GPS connection, just a VHF aerial.
However if you have a raymarine plotter fed with a NMEA GPS, the NMEA can only be set to the same speed for input and output.
Therefore when the charplotter is set to acces the AIS in (36000 i think) then the output to the DSC VHF will no longer work.
In this case, feed the NMEA output of your mushroom to the DSC radio and the NASA AIS in parallel. Set the NMEA speed on the chartplotter to the AIS speed. The AIS will feed the GPS data at the higher NMEA rate so hey presto everything works.
Tugw
Well-Known Member
I think there may be some misunderstanding,The type of AIS i have is the NASA Radar type(not a true radar)it doesnt need an external display,I have a chartplotter but the NMEA output is faulty(internal wiring) so my question was if i need to feed the GPS data in from a chartplotter or if it is possible to feed the data direct from an antenna to the AIS
T
timbartlett
Guest
You need to supply it with the NMEA 0183 RMC sentence from somewhere -- could be a chart plotter, hand-held GPS, or a "black-box" GPS (most of them look more like white mushrooms).
Plugging in a GPS antenna will not do.
The manual is on http://www.nasamarine.com/pdfs/AIS radar.pdf
Tugw
Well-Known Member
Thanks for the info,Next question----can you suggest any suitable antenna?
T
timbartlett
Guest
If you mean "which VHF antenna" -- pretty well anything will do (I don't mean a rusty coathanger!, but any marine VHF antenna. The AIS frequencies are at the upper end of the marine VHF spectrum, so one that is tuned to AIS will give slightly better results.
V-tronix do a helical (springy) one that is good for pushpit mounting.
If you mean "which black-box/white mushroom GPS", then the obvious choice is probably Garmin 17X, but Marine Electronic Services do their own version of it at a fraction of the price -- and there are others.
Martin_J
Well-Known Member
The 'Nasa AIS Radar' as it is called... the one with the built in display does need an NMEA input for GPS position as you all rightly say.
The OP then wanted clarification if this requirement could be served just by using a simple GPS antenna - a bit like the small mushrooms as seen on many pulpits.
There is more than one type of GPS antenna/mice/mushroom (whatever you like to call them) available. Some are just an antenna that effectively extends the GPS aerial from an internal location (not what you want). Some on the other hand contain the GPS box of tricks and provide either a USB output (to connect direct to a USB laptop port)... and others provide an NMEA 0183 output that can be connected direct to the input of the NASA unit.
One thing about these mushrooms that output NMEA is that (1) they need a power supply and (2) they cost about the same as a small fixed GPS with display! Either look for an NMEA GPS ANTENNA or look for a small fixed GPS with very low power consumption.
Regarding the VHF reception side... some use splitters.. I'd prefer to install a separate aerial that can be used if the main masthead aerial was lost for any reason (and also don't like the idea of breaking into the main aerial cable for any reason).
The OP then wanted clarification if this requirement could be served just by using a simple GPS antenna - a bit like the small mushrooms as seen on many pulpits.
There is more than one type of GPS antenna/mice/mushroom (whatever you like to call them) available. Some are just an antenna that effectively extends the GPS aerial from an internal location (not what you want). Some on the other hand contain the GPS box of tricks and provide either a USB output (to connect direct to a USB laptop port)... and others provide an NMEA 0183 output that can be connected direct to the input of the NASA unit.
One thing about these mushrooms that output NMEA is that (1) they need a power supply and (2) they cost about the same as a small fixed GPS with display! Either look for an NMEA GPS ANTENNA or look for a small fixed GPS with very low power consumption.
Regarding the VHF reception side... some use splitters.. I'd prefer to install a separate aerial that can be used if the main masthead aerial was lost for any reason (and also don't like the idea of breaking into the main aerial cable for any reason).
Elessar
Well-Known Member
I have the MES one. NMEA out, never missed a beat and less than £100. The price for me makes the MES one the obvious choice.
Tugw
Well-Known Member
Elessar
Well-Known Member
yep thats the one.
Bought in excel 2008 and it does what it says on the tin with no problems.
Tugw
Well-Known Member
Excellent,Thank you