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AIS Receiver Troubleshooting

Your AIS Receiver has been tested at the factory before being shipped to you. The receiver has been certified to work correctly before it ships. We have had very few cases of a unit arriving at a customer in a state where it failed to operate, so if your unit is not working, it is likely there is a configuration or environmental issue that is causing the problem.
NOTE: Please read the warranty conditions in the documentation that came with the product or that can be downloaded online The warranty does not cover failure due to incorrect installation issues, so check – and double check – the power leads to the unit before connecting the unit.

This troubleshooting guide is an ongoing effort to provide you with straightforward and effective tools for diagnosing and correcting the most common AIS receiver problems. If you encounter an issue with your AIS receiver, check to see if it matches one listed below. If so, carefully follow the instructions to resolve the problem. If your problem is not listed, please let us know. We will be happy to help you find a solution.


How can I confirm correct AIS receiver operation?

I don’t see any LED light activity when I turn the power on to the unit.

Everything seems to be working correctly and LEDs are flashing, but no serial data is output from the unit.

I am using a terminal emulator to test the unit but I am seeing garbled random data instead of valid AIS sentences.

ISSUE: How can I confirm that my AIS receiver is operating correctly?

Before connecting the AIS receiver to a computer or chart plotter, please ensure that the power is OFF to the AIS receiver while making the connection.

Once you are sure that the wiring to the external device is correct, proceed with powering on the AIS receiver. Failure to follow these instructions can result in damage to the AIS receiver.

If your AIS Receiver is working properly, you should experience the following:

  • You should see the LEDs light momentarily when you apply 12VDC power to the unit.
  • For Smart Radio models, normally, if an antenna is connected, you should see the red LED flash on and off at random intervals. This indicates radio signals are being received by the unit. It does not necessarily mean that these radio signals are AIS transponder signals; simply that there is radio reception of some type coming in on the AIS frequency.
  • The channel LED(s) will flash each time a valid AIS sentence is sent out the serial connection. This LED flashes for a very short period of time for each sentence so it may be difficult to see the green flashes. If necessary, lower the room lights where the unit is installed and look directly at the LEDs – not at an angle. If you do not have a VHF antenna connected or if you are not close to shipping traffic with AIS equipped transponders, you will not see any activity on the green LED.
  • Serial data is output from the unit at 38400 baud by default. The easiest way to confirm that the unit is outputting valid serial data is to:
    • Turn the power off to the unit.
    • Connect the unit to an operational serial port on a computer. Use the serial or USB cable that came with the unit (and a serial-to-USB converter if necessary). Run a terminal emulation package on the computer (e.g. HyperTerminal or PuTTY on a Windows-based PC) and set the program for the correct COM port and 38400 baud.
    • Turn on the power to the unit.
    • Smart Radio Only: The SR162 will output a diagnostic message to the terminal screen, the SR161 will not. This message will be similar to:
    • All Receivers: If you have a VHF antenna attached and are close to shipping traffic, you should see raw AIS sentences similar to:

This may take several seconds to appear on the screen if you are far away from traffic or if there are only a few ships close by.

    • Smart Radio Only: If you are not close to shipping traffic and want to test your unit, enter <SPACE> then <ENTER> in the terminal window. You should see output similar to:
SR162 AIS Receiver
RECE FRQ R1F1619750
RECE FRQ R2F1620250
If the above steps succeed, your AIS Receiver is working correctly. If you have problems with the display of AIS information, the problem resides with the display, display settings or connection from the AIS unit to the display. See AIS Display Troubleshooting.

I don’t see any LED light activity when I turn the power on to the unit.

LIKELY CAUSE: Power is not getting to the unit.
  1. Start by checking there is 12vDC power on the power wires with a volt meter. Do not use 24vDC unless the unit is rated for it and definitely do not use 110VAC power with your AIS Receiver. You will damage the receiver. Check to make sure the polarity of the power wires is correct (typically, red is positive, black is negative ground).
  2. Check the LEDs in a low light condition with no light directly shining on the unit. Look at the LEDs straight on – not at an angle.
  3. Check the inline fuse (if present) to ensure it is not blown and replace it if necessary. If the fuse is blown you almost definitely have a power issue (e.g. too much power or power spikes due to fluctuations for example when you start your engine). Resolve the power issues before attempting to apply power to the unit again.
  4. If you are sure you have a correct power configuration, turn the power off to the unit and wait one minute and reapply power. Do this several times if necessary. There is an internal relay built into the microprocessor that will trip if too much power is applied to the unit. It will normally reset itself once the power is off and proper power is supplied to the unit.
  5. Double check to see if the unit is functioning correctly by connecting it to a computer and using a terminal emulation package to test serial output in case the LEDs have burnt out. If the LEDs have burnt out then the unit will need to be repaired or replaced.
If none of these steps resolve this issue, it is likely that your unit has been damaged. The most common problems we have seen are damage from incorrect power wire installation, incorrect voltage, or damage from lightning. Your unit should be returned to the place where you bought it for replacement or repair. If the unit is still within the warranty period and the warranty conditions have been respected, then the unit will be repaired or replaced without charge.

Everything seems to be working correctly and LEDs are flashing, but no serial data is output from the unit.

LIKELY CAUSE: Bad serial cable or adapter
  1. Try using the unit with a different serial cable to see if this resolves the problem. We have seen two instances of a bad serial cable resulting in no data reaching the computer. If everything works correctly with a different serial cable, contact your supplier for a replacement serial cable.
  2. If you have access to another computer, try the unit with another computer. It is possible that the problem is with the serial port adapter not the cable. See the next step if the unit works correctly with another computer.
If this does not resolve the problem, It is possible the serial port is not working correctly or is set up incorrectly:
  1. Check to make sure you have the baud rate set to 38400 baud.
  2. Keep in mind that serial data will only be transmitted by the AIS Receiver if valid transponder signals are being received. If there is no AIS traffic, the unit will not output any serial data.
  3. If you are using a unit with built-in USB or USB Serial Adapter such as the Sabrent units, ensure that the drivers are installed on your computer. These drivers are included on the CD that comes with the USB device. The AIS Receiver will not be recognized by the computer if the drivers are not correctly installed. If necessary, uninstall the drivers and install them again. Be sure to follow the driver installation instructions exactly.
  4. If you have access to another computer, try the unit with another computer. It is possible that the serial port adapter is not working correctly on the first computer. If the AIS Receiver works correctly with the second computer then it is likely that you have a bad serial port. Either get the serial port repaired or use a USB to Serial Adapter to connect your AIS Receiver to your computer.
  5. Try a different serial device (e.g. GPS) on the serial port with the correct baud rate for that device and see if you get valid data. If you see valid GPS data then the serial port is OK and the problem may be with the serial connection from the AIS Receiver. We have only seen a couple of suspected case where the serial connector on the receiver was non-functional or the RS232 internal IC was damaged so this is not a common problem. If you suspect this is the case, contact support to discuss next steps.

I am using a terminal emulator to test the unit but I am seeing garbled random data instead of valid AIS sentences.
LIKELY CAUSE: Baud rate is set incorrectly or serial cable is faulty
  1. Ensure that the baud rate for your application is set to 38400 baud.
  2. Try another serial or USB cable

    If the above steps do not resolve the problem, it is possible the serial output processor has been damaged. Please contact support.