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AIS VDL Capacity Calculator - Number of Slots per Minute (FRAME)
This is a SIMPLE calculator which can be used in assiting the planning of an AIS coverage area. It is used in terms of our disclaimer notice.
This calculator does not take into account the dynamics of a RF environment. It only uses the AIS update rates as specified in the respective standards. Binary and safety related messages for both ships and base stations must me included in the Base Station FATDMA (slot reservation) calculation. Only Base Stations and AtoN's within direct coverage area of one another should be included for a total coverage are calculation.
This calculation includes units at anchor transmitting every 3 minutes, static and voyage releated messages transmitted every 6 minutes and AtoN and Base Station units with a transmission schedule exceeding 1 minute intervals. These transmissions are averaged out and included in the one minute time frame. As a result, values with fractions can occur.

AIS CLASS A No.of Units
At anchor and speed less than 3 knots
At anchor and speed greater than 3 knots
Speed 0 to 14 knots
Changing course and speed 0 to 14 knots
Speed 14 to 23 knots
Changing course and speed 14 to 23 knots
Speed greater than 23 knots
Changing course and speed greater than 23 knots
AIS CLASS B/CS No.of Units
Speed less than 2 knots
Speed greater than 2 knots
Total number of AIS S&R units
No.of Units Update Rate
Provision has been made for a 4 different AtoN groups with update rates. In each of them the Number of AtoN units and respective update rates can be keyed in. The update rates of Messages 6, 8 and 14 must be included in the entry made by the user. Message 21 is a 2 slot message; it is deemed in this calculation that Messages 6, 8 and 14 are 2 slot messages. The update rate is the interval in minutes (1 to 60) in which the AIS AtoN is scheduled to transmit.
Total number of Base Stations

number of slots in a block (1-5)

number of blocks in frame

FATDMA detail (includes messages 6,7,8,12,13,14,16,20,22)

number of dgnss station

slots per transmission (1-4)

update rate in minutes

DGNSS (msg17) stations included in the total number of base stations specified above:



Slot Percent

AIS Class A Totals:

AIS Class B/CS Totals:

AIS S&R Totals:

AIS AtoN Totals:

AIS Base Station Totals:

AIS Grand Totals:

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