AIS reception in Shotley

[PaulRainbow]

I've got a Garmin VHF 300i AIS fitted to the boat, connected to my laptop to view the AIS with OpenCPN. Some days it all works flawlessly, others the AIS data doesn't work as it should. Ships i can see at Felixstowe might be missing, the two lightship atons are missing and vessel data is slow to get updated. I've checked all of the hardware and it's down to either a fault in the AIS or patchy reception in the marina at Shotley.

So my questions is, anyone else here have an AIS receiver in Shotley and if you do, do you ever notice any of those issues ?

 

[sailorman]

i assume you have "anchored /moored" toggled as on

 

[PaulRainbow]

i assume you have "anchored /moored" toggled as on

Yes. One day i turn it on and everything pops up really quick and updates as it should, another day it takes ages for vessels to appear and then doesn't update them properly. Tried different antenna's, NMEA 0183 multiplexor or N2K interface, noting made a difference. Only thing it can be is intermittent fault on the AIS set, or poor reception in the marina, as far as i can see.

 

[ex-Gladys]

I have a separate AIS300, and turn it off inside Harwich harbour, and it always picks up everything whenever turned on, and I spend a fair amount of time in Shotley

 

[sailorman]

Yes. One day i turn it on and everything pops up really quick and updates as it should, another day it takes ages for vessels to appear and then doesn't update them properly. Tried different antenna's, NMEA 0183 multiplexor or N2K interface, noting made a difference. Only thing it can be is intermittent fault on the AIS set, or poor reception in the marina, as far as i can see.

COM port settings ?????

 

[PaulRainbow]

COM port settings ?????

All as they should be. It works some days and doesn't work on others, without my changing anything.

Tried it with both of my VHF antennas, one masthead the other on the pushpit.

Tried several different bits of software, chart plotting programs and basic NMEA data readers, always the same results.

Had the AIS connected to a multiplexor sending NMEA 0183 data via Bluetooth then tried using NMEA 2000 via an Actisense NGT1.

So, i've changed everything after the AIS and the antenna, which to my mind can only leave an intermittent fault with the receiver (which receives VHF and AIS) or intermittent bad reception in the marina. Either would be odd, as when it doesn't work properly it does receive VHF and does receive some AIS data.

 

[Bru]

If you're not seeing ships over the river at Felixstowe I'd rule out intermittent bad reception

That just leaves either the antenna, antenna cable or the AIS receiver

With so many AIS transmitters so close, I'd provisionally rule out the antenna and cable too on the grounds that it would have to be the worst connection in the world not to see stuff a few hundred yards away

So that leaves the most likely source of the problem being the most expensive one to fix (sorry!)

 

[pvb]

Have you checked the AIS menu on OpenCPN, to be sure that "Hide moored AIS targets" is unchecked?

 

[sailorman]

All as they should be. It works some days and doesn't work on others, without my changing anything.

Tried it with both of my VHF antennas, one masthead the other on the pushpit.

Tried several different bits of software, chart plotting programs and basic NMEA data readers, always the same results.

Had the AIS connected to a multiplexor sending NMEA 0183 data via Bluetooth then tried using NMEA 2000 via an Actisense NGT1.

So, i've changed everything after the AIS and the antenna, which to my mind can only leave an intermittent fault with the receiver (which receives VHF and AIS) or intermittent bad reception in the marina. Either would be odd, as when it doesn't work properly it does receive VHF and does receive some AIS data.

I some times have to swap com ports to wake the thing up or just unplug the usb & reinsert it in the same port

 

[PaulRainbow]

Have you checked the AIS menu on OpenCPN, to be sure that "Hide moored AIS targets" is unchecked?

Yes. It's not failing to show moored targets, could be any old targets, when it's not working correctly i might see a pilot boat at 23 kts, which should update every 2 seconds, it could be several minutes before it updates. Between the days where it works and the days that it doesn't, no setting get changed. I could leave it one evening, working, switch on in the morning and it's not working correctly.

 

[sailorman]

Yes. It's not failing to show moored targets, could be any old targets, when it's not working correctly i might see a pilot boat at 23 kts, which should update every 2 seconds, it could be several minutes before it updates. Between the days where it works and the days that it doesn't, no setting get changed. I could leave it one evening, working, switch on in the morning and it's not working correctly.

Ships are transmitting nearer 6 mins than 2 seconds

i would suggest the lappi is forgetting what com port is in use

 

[PaulRainbow]

I some times have to swap com ports to wake the thing up or just unplug the usb & reinsert it in the same port

Tried that. I even changed from NMEA 0183 to N2K, still the same. I've changed every bit of hardware after the VHF/AIS, tried two different antennas and even wired it all up straight to the batteries (fully charged).

With the AIS connected to the shipmodul multiplexor there is a "data" light on the multiplexor. When everything is working as it should the light steadily flashes, when things are not working properly the light only flashes now and again.

When i set the N2K network up i added a N2K GPS receiver. There was a constant stream of data coming from the N2K network, including rapid updates (fractions of a second). AIS data was sporadic at best.

My feeling is it has to be the VHF/AIS.

 

[sailorman]

Tried that. I even changed from NMEA 0183 to N2K, still the same. I've changed every bit of hardware after the VHF/AIS, tried two different antennas and even wired it all up straight to the batteries (fully charged).

With the AIS connected to the shipmodul multiplexor there is a "data" light on the multiplexor. When everything is working as it should the light steadily flashes, when things are not working properly the light only flashes now and again.

When i set the N2K network up i added a N2K GPS receiver. There was a constant stream of data coming from the N2K network, including rapid updates (fractions of a second). AIS data was sporadic at best.

My feeling is it has to be the VHF/AIS.

Wowa ole son, your way too far under the bonnet for me

 

[PaulRainbow]

Ships are transmitting nearer 6 mins than 2 seconds

i would suggest the lappi is forgetting what com port is in use

If it's forgot what port to use, how does it display some targets and not others or fail to update at the required intervals ?


Static information is 6 mins.

Ship at anchor 3 min
Ship 0-14 knots 12 sec
Ship 0-14 knots and changing course 4 sec
Ship 14-23 knots 6 sec
Ship 14-23 knots and changing course 2 sec
Ship >23 knots 3 sec
Ship >23 knots and changing course 2 sec

 

[sailorman]

If it's forgot what port to use, how does it display some targets and not others or fail to update at the required intervals ?


Static information is 6 mins.

Ship at anchor 3 min
Ship 0-14 knots 12 sec
Ship 0-14 knots and changing course 4 sec
Ship 14-23 knots 6 sec
Ship 14-23 knots and changing course 2 sec
Ship >23 knots 3 sec
Ship >23 knots and changing course 2 sec

How long b 4 they nxt update ??????

 

[PaulRainbow]

How long b 4 they nxt update ??????

Those are the intervals. Ship 14-23 knots and changing course 2 sec, means every 2 seconds, for example.

When mine works as it should, i can see the pilot boats and tugs moving around Harwich/Felixstowe in real time, more or less.

 

[PaulRainbow]

After days of not working correctly, just turned it on and everything is working fine. Currently have 31 vessels, including bases and atons, with one of the pilot boats coming into Harwich at high speed, updating his dynamic data every 2 seconds.

 

[ex-Gladys]

Bloody electronics. We're on our fortnight cruise, currently in Dover and in the last two days the Tacktick kit scream "no power" when there is, with the Hull transmitter showing fully charged and connected! Just remade the connections at both ends. Even swapped hull transmitters, same on both...

 

[PaulRainbow]

Bloody electronics. We're on our fortnight cruise, currently in Dover and in the last two days the Tacktick kit scream "no power" when there is, with the Hull transmitter showing fully charged and connected! Just remade the connections at both ends. Even swapped hull transmitters, same on both...

Perhaps we should buy paper charts and a nice old brass compass

 

[Bru]

Perhaps we should buy paper charts and a nice old brass compass

Cheers, do me out of a job wouldya. Harumph

I suppose I could retrain as a compass swinger and chart corrector