User's Manual

53
TROUBLESHOOTING
P200 receives AIS signals normally, but no one in the surrounding can see me, why?
 AIS Class B transmission range limitation: an AIS Chartplotter transmitting range of
5-7 miles in perfect conditions. The AIS receiver in the transceiver will typically see
Class A vessels that are 20-30 miles away or even more in excellent conditions. The
major reason is that all AIS Chartplotters transmit at 2 watts vs. the 12.5 watts that
Class A transceivers typically use. This difference in power impacts on the
transmission range of each transceiver type. For this reason, it is quite possible
that Class A vessel can be seen, but Class B vessel might not be seen.
 VHF antennas interference: if you are using a dedicated AIS/VHF antenna for your
transceiver, be sure that it is placed at least 6 ft (1.83 m) away from other VHF
antennas or vertical metal objects and ideally install the antenna on a different
vertical plane from other VHF antennas. In several tests, mounting two VHF
antennas next to another typically reduces the transmitting range to both
antennas by 50-70%.
 GPS is not fixed: If your GPS antenna is not connected or setup correctly, your
transceiver will see other vessels fine, but you will not be sending out your vessel
position. All AIS transceivers need a good GPS fix before it can send out any type of
transmission. The color and state of the LEDs on the transceiver indicate if the unit
is in transmission mode or not.
 The location of VHF antenna is directly related to AIS transmitting range. The VHF
antenna should be installed at mast as high as possible.
Even though my P200 is transmitting, why do some vessels with AIS take a long time
to see my vessel name or not see it at all?
 AIS Class B users should keep in mind that Class B transceivers do not broadcast
position updates as often as Class A commercial transceivers. As with Class B
transceivers, the full static information, such as vessel’s names, the transmission is
broadcasted every 6 minutes; however, MMSI and dynamic information, such as
position, update will only be sent out every 3 minutes if the vessel is moving
slower than 2 knots. To add to this, if the receiving party is using non-standard
dual channel receiver (a single channel receiver), then in perfect conditions, the
receiver will get your full static information every 12 minutes and your MMSI and
dynamic information every 6 minutes if you are moored.
My MMSI is being received by other vessels but my vessel name is not shown on their
chart plotter or PC, why?
 Older software and AIS displays may not be fully compatible with Class B
transceivers. In some of these cases, older equipments might only have Class B
127258
Magnetic Variation
129026
COG & SOG, Rapid Update
129029
GNSS Position Data
129539
GNSS DOPs