OpenCPN not seeing dAISy output

[Lomax]

I got my dAISy AIS receiver in the post today; a beautifully made unit which works very well - I was able to pick up several ships using only a simple dipole antenna, despite not having line of sight to the sea. But while I can see the successfully received AIVDM messages (and lots of failed ones too!) by connecting to the dAISy unit over a serial console, no NMEA messages make it through to Open CPN. I have added a connection to /dev/ttyACM0 (same port I'm successfully connecting to with a console) with the baud rate set to 38400 (again, same that works in console), yet even after rebooting, and replugging the dAISy, with no other applications running, no messages appear in OpenCPN's NMEA debug window, and no ships show up on the chart. I have already checked that I'm a member of the "dialout" group (and I'm able to connect through a console as "myself"), so a permission issue seems unlikely. Any ideas?

[petter5]

You have added the connection to opencpn, but are you sure you have checked x the connection to enable it ?

/Petter

[Lomax]

Originally Posted by petter5

You have added the connection to opencpn, but are you sure you have checked x the connection to enable it ?r

Good thinking - yes I have!

[petter5]

see this link to get some more practical info: https://mvcesc.wordpress.com/2015/04...pi-2-with-ais/

The article says 9600 baud, but I think the default speed is 38400 as you mentioned in your first post.

[Lomax]

Originally Posted by petter5

see this link to get some more practical info: https://mvcesc.wordpress.com/2015/04...pi-2-with-ais/

The article says 9600 baud, but I think the default speed is 38400 as you mentioned in your first post.

Thanks, I think I already read that article - I've spent a few hours trying to figure this out on my own and in the process I've probably read most of what's out there on OpenCPN + AIS...

[fgd3]

By an interesting coincidence I spent much of my day dealing with the same issues you raised. My dAISy arrived today. Lacking a BNC connector I thought I would try a 1/2 wave monopole. I had a reel of wire just the right diameter to slip inside the center connector on the dAISy so I cut a 36" length and took my new toys down to the boat. I booted up the computer, connected my GPS and dAISy to the USB ports, started OpenCPN, and opened the Connections dialog box.

I added a connection for /dev/ttyACM0, set the speed to 38400, and waited for the AIS targets to appear.

The dAISy light blinked green ever five seconds, telling me it was working. With no antenna connected that was all I expected. I slipped my 3' monopole into the connector and was happy to see some 1/4 second green flashes. But I saw a lot of 1/4 second red flashes, too. They signify invalid AIS messages.

I had no NMEA messages from ttyACM0 and no AIS targets. I tried the rubber ducky antenna from my handheld with no better results. Then I disconnected the antenna cable from my fixed VHF radio and touched the center pin of the PL-259 connector to the center contact of the BNC connector. I still didn't have any NMEA messages but I had a screen full of AIS targets. I didn't expect it to be that easy.

You can stick a 3' wire in the back of your VHF radio and pick up weather broadcasts (and other transmissions) because the radio is a lot more sensitive than the dAISy. Just don't key the mike with that antenna setup. But if you want to get AIS messages on the dAISy you're going to need a decent antenna with higher gain than a simple wire or a home-brew dipole. Try what I did. Make a temporary connection to your VHF antenna and you'll see AIS targets with no further effort. Then order a good VHF antenna. I found this one on eBay:

TRAM 1600-HC 35 - Inch VHF Marine Antenna | eBay

It comes with 15 feet of RG58A/U cable terminated with a PL-259 connector and claims a 6db gain. Get a male BNC to SO-239 adapter to use with your dAISy. Should your main antenna fail you can use your AIS antenna as a spare for the VHF radio.

Fabbian

[Lomax]

Originally Posted by fgd3

I disconnected the antenna cable from my fixed VHF radio and touched the center pin of the PL-259 connector to the center contact of the BNC connector. I still didn't have any NMEA messages but I had a screen full of AIS targets. I didn't expect it to be that easy.

Thanks Fabbian, I'll try a better antenna, but I've monitored the output from the dAISy directly and I've definitely seen ships being picked up without error - with no corresponding NMEA message appearing in OpenCPN. Even if I access the configuration menu on the dAISy and set it to output NMEA test messages, the NMEA debug window in OpenCPN fails to show any incoming messages.

[fgd3]

Originally Posted by Lomax

Thanks Fabbian, I'll try a better antenna, but I've monitored the output from the dAISy directly and I've definitely seen ships being picked up without error - with no corresponding NMEA message appearing in OpenCPN. Even if I access the configuration menu on the dAISy and set it to output NMEA test messages, the NMEA debug window in OpenCPN fails to show any incoming messages.

How did you monitor the output directly? I would have liked to do that when I was testing antennas but I don't know how. Do you get NMEA messages from the dAISy? How do you know the ships are being picked up without error?

I expected to see some kind of NMEA messages from the dAISy but never did, even when I was getting AIS targets. I even disabled my GPS connection but it didn't help. As long as I get the AIS targets I can live without the NMEA messages in the debug window, but it is a mystery I would like to solve if I can.

Fabbian

[Lomax]

I just had a thought - since I also use a USB GPS receiver on the machine that's running OpenCPN, but have not had it plugged in while testing the dAISy, I thought it may be that GPSD "steals" the ttyACM0 port where the dAISy appears, since this is normally assigned to the GPS. Alas, I tried with the GPS plugged in as well, and the dAISy appearing as ttyACM1, removed the old connection to dAISy from OpenCPN and added a new connection for ttyACM1 with the same baud rate - the NMEA debug window now shows the messages from my GPS, but nothing from the dAISy - even when setting it to send out test messages.

[Lomax]

Originally Posted by fgd3

How did you monitor the output directly?

If you're on Linux it's as easy as

screen /dev/ttyACM0 38400

with ttyACM0 being the virtual serial port that the dAISy is connected to. Once connected you should see the messages appear on your screen, and you can press "Esc" to access the configuration menu, from where you can tell the dAISy to send out test messages.

[fgd3]

Originally Posted by Lomax

I just had a thought - since I also use a USB GPS receiver on the machine that's running OpenCPN, but have not had it plugged in while testing the dAISy, I thought it may be that GPSD "steals" the ttyACM0 port where the dAISy appears, since this is normally assigned to the GPS. Alas, I tried with the GPS plugged in as well, and the dAISy appearing as ttyACM1, removed the old connection to dAISy from OpenCPN and added a new connection for ttyACM1 with the same baud rate - the NMEA debug window now shows the messages from my GPS, but nothing from the dAISy - even when setting it to send out test messages.

My laptop has two USB ports, so I didn't have to worry about GPSD. I just plugged a device into each port. I guess that's why I got the NMEA debug messages from the GPS but not from the dAISy.

Fabbian

[fgd3]

Originally Posted by Lomax

If you're on Linux it's as easy as

screen /dev/ttyACM0 38400

with ttyACM0 being the virtual serial port that the dAISy is connected to. Once connected you should see the messages appear on your screen, and you can press "Esc" to access the configuration menu, from where you can tell the dAISy to send out test messages.

Thanks. I'll try that when I'm back out at the boat again.

Fabbian

[Lomax]

Originally Posted by fgd3

My laptop has two USB ports, so I didn't have to worry about GPSD. I just plugged a device into each port.

Which USB port you plug the device into doesn't control what /dev/ACMnn port the device gets assigned, it's the order that you plug them in that matters - Linux will assign the next available port name, unless you have configured a device to use a particular port name every time.

[fgd3]

Originally Posted by Lomax

Which USB port you plug the device into doesn't control what /dev/ACMnn port the device gets assigned, it's the order that you plug them in that matters - Linux will assign the next available port name, unless you have configured a device to use a particular port name every time.

My GPS was already plugged in to the same port I always use for it. I added the dAISy to the second port, so I didn't have to deal with any surprised in port assignments.

In Windows the USB ports seem to be mapped to COM ports. If you move a device from one USB port to another it gets a different COM port number.

Until now I haven't had more than one device to plug into my Linux computer.

The GPS has a name like /dev/ttyUSB0. I don't know why the dAISy came up as /dev/ttyACM0.

Fabbian

[bcn]

On an ARM system running Debian we have

/dev/ttyUSBn for the GPS
/dev/ttyACMn for the AIS receiver (em-trac R100)
where n may alter between 0 and 1 when hot plugging a device after it gets stalled for example.
So you will have to change the connection settings after hot-plugging then.

Plus a serial output to get GPS to the radio
/dev/ttyS1

Remember that Serial Ports - including virtual ones - can only have one owner at a time. If you hook the output to a terminal, OCPN won't get it.
Or running the configuration daemon of the AIS while listening.

If you want to split the signal for different channels you need a multiplexer like the build-in one of OCPN. Or GPSD. Or Kplex...
And in the case of COM ports one port for each connection.


Lomax,

can we see a screenshot of your connection settings menu perhaps?
With the COM port selector drop-down?

Hubert