Pete
Legendary Member
- Joined
- Apr 12, 2005
- Messages
- 1,167
- Status
- OWNER - I own a Hatteras Yacht
- Hatteras Model
- 48' LRC (1976 - 1981)
I have purchased an ICOM MXA-5000 AIS receiver to integrate into my present navigation system. The current system is PC based, using a Thinkpad T42 running Maptech Chart Navigator Pro, Northstar 941D GPS, and a Simrad/Robertson AP20 autopilot. The setup allows for Chart Navigator Pro to steer the boat along a predefined route.
The reason I am writing this thread is to see if anyone has tried successfully to do this or something similar? It looks more involved than the various AIS receiver vendors would indicate in their sales literature. So what's new ? ? ?
Now to get a little technical. All my communication links in the navigation system are running NMEA 0183 protocol at 4800 baud. That is the standard up until the appearance of AIS receivers. Their NMEA specifications call for 38.4K baud. So most AIS receivers allow you to attach the GPS output to the AIS unit and provide the function of integrating the two data streams into one at 38.4K for output to the computer. So far so good. You then go into the hardware control of Windows XP and set the serial port to run at 38.4K baud. Still doing OK until you realize that the computer serial port speed setting applies to both its send and receive speed. So the computer now wants to send NMEA autopilot sentences to the AP at 38.4K. The AP20 does not understand 38.4K sentences. This is the problem. You have the computer serial port running at 38.4K baud to receive the AIS integrated sentences, and thus sending sentences to the AP at 38.4K baud, but the autopilot can only receive 4800 baud sentences.
Two thoughts include buying a multiplexer to supply all the units with the speeds they need (a couple are available), and buying a PC Serial port card to give me a second serial port on the computer. Both should work, but who knows? Thus my quest for real world experience and some info on what has actually worked?
Thanks,
Pete
The reason I am writing this thread is to see if anyone has tried successfully to do this or something similar? It looks more involved than the various AIS receiver vendors would indicate in their sales literature. So what's new ? ? ?
Now to get a little technical. All my communication links in the navigation system are running NMEA 0183 protocol at 4800 baud. That is the standard up until the appearance of AIS receivers. Their NMEA specifications call for 38.4K baud. So most AIS receivers allow you to attach the GPS output to the AIS unit and provide the function of integrating the two data streams into one at 38.4K for output to the computer. So far so good. You then go into the hardware control of Windows XP and set the serial port to run at 38.4K baud. Still doing OK until you realize that the computer serial port speed setting applies to both its send and receive speed. So the computer now wants to send NMEA autopilot sentences to the AP at 38.4K. The AP20 does not understand 38.4K sentences. This is the problem. You have the computer serial port running at 38.4K baud to receive the AIS integrated sentences, and thus sending sentences to the AP at 38.4K baud, but the autopilot can only receive 4800 baud sentences.
Two thoughts include buying a multiplexer to supply all the units with the speeds they need (a couple are available), and buying a PC Serial port card to give me a second serial port on the computer. Both should work, but who knows? Thus my quest for real world experience and some info on what has actually worked?
Thanks,
Pete
