NGT-200 USER MANUAL
NGT-200 UM.E 20210520-02
70
9.5.2.2 Step-by-step plan of checking the AIS station (Class A or Class B)
Use the
TEST VHF /
TEST AIS
menu section to do all the checking!
Step 1 ------------------------------------------------------------------------------------------
Enter
TEST AIS / TEST AIS CLASS A
or
TEST AIS / TEST AIS CLASS B
Menu depending on AIS station under test.
In common AIS station A class is to transfer location report – message 1 at about
10 seconds interval, alternating А and B channels, and AIS station class B –
message 18 with about 3 minutes interval, alternating А and B channels. Besides,
the station has to transfer static information – message 5(Class A) and message
24a/24b(class B) at about 6 minutes interval, also alternating А and B channels.
For each of the received messages the tester DSP controller calculates the deviation
of the frequency (frequency error) and power level;
The operation algorithm in this case is as follows:
a)
Tester performs slot synchronization, measures power level of received
signals and frequency deviation.
b)
Tester transmits the request to AIS station for message 5 (In TEST AIS/
TEST AIS Class A mode) and for message 24 (In TEST AIS/TEST AIS
Class B mode) in one minute.
c)
After the message 5 or message 24 is received by tester the tester transmits
the “virtual ship” message with increased relatively to AIS station
coordinates on 0.1 nautical mile and with MMSI 413999998.
d)
After all these operations the status bar will be completed and tester will ask
to save the data by pressing F2 key for further processing.
e)
Tester sends the request 111 in CH70 –
“Report ship’s name”
in TEST
AIS/Test AIS Class A mode and waits for 20 seconds for AIS Station
respond, if the respond is received, the DSC note will be displayed on line 6.
Data processing is shown on the screen in sixth line by means of four-cells line.
Each status bar item corresponds to the following information:
1 - Channel A (161.975 MHz) power output and frequency;
2 - Channel B (162.025 MHz) power output and frequency;
3 - Message 1 or Message 18 - transient data, transferred according to the
station inner time schedule;
4 - Message 5 or Message 24 – static vessel’s data.
The result of “virtual ship” message transmitting will be displayed in AIS station
LCD in view of new vessel with MMSI 413999998.
