Weather Station Message

Registrant: 
Saint Lawrence Seaway Development Corporation
Message number: 
6
DAC: 
366
FI: 
1
State: 
in force
Used by: 
Saint Lawrence Seaway Development Corporation
Number of slots (max): 
5
Reporting Rate: 
Each individual Seaway message has an assigned update interval established by the Seaway Traffic Management System (TMS). However, the AIS network may elect to retransmit any messages, system resources permitting, at more frequent intervals.
Permitted as from: 
09/03/2002
Technical point of contact: 

U.S. Department of Transportation 
John A. Volpe 
Transportation Systems Center
55 Broadway 
Cambridge, MA 02142

Details: 

 

 Parameter    Number of bits    Description 
Designated Area
Code
10 The Designated Area Code will be 366 for the United States or 316 for
Canada depending on the location of transmitter.

Function Identifier

6 FI=1
 Reserved  2  
 Message ID  6  Message Identifier = 1 (00 0001 in binary) 
 Binary Data   Max 768 Message contains 1 to 4 weather station reports, each structured defined in next table.
 Total Number of bits   Max 792  = 24 + N*192  
     N Total Bits   (Slots Required) 
     1 216 bits   (2 slots) 
     2 408 bits   (3 slots) 
     3 600 bits   (4 slots) 
     4 792 bits   (5 slots) 

Weather Station Report

 Parameter    Number of bits    Description 
 Timetag  20  Month, Day and Time of measurement, See UTC Time
 Station ID  42  Seven 6-bit ASCII character ID 
 Longitude  25  Longitude in 1/1000 minute (±180 degrees, East = positive, West = negative. 181 degrees = not available) 
 Latitude  24  Latitude in 1/1000 minute (±90 degrees, North = positive, South = negative. 91 degrees = not available) 
 Wind Speed  10  Average Wind Speed in 1/10th Knot (0-102,2 knots, 1022 = 102,2 kts or greater, 1023 = not available) 
 Wind Gust  10  Wind Gust in 1/10th Knot (0-102,2 knots, 1022 = 102,2 kts or greater, 1023 = not available) 
 Wind Direction  9 Quantized to 16 compass points (Seaway only);

Direction, 0-359 degrees, 511 = not available. For Saint Lawrence Seaway, refer to table below for descriptions of quantized values.

 

See Wind Direction Quantization 

Atmospheric
Pressure
14

Expressed in 1/10

 

th millibars. (16383 = not available)

Air Temp 10 Temperature in 1/10th of a degree Celsius (signed) (-511 to 511 valid range, -511 = -51.1°C or less, 511 = 51.1°C or greater, -512 = not available)
Dew Point 10 Temperature in 1/10th of a degree Celsius (signed) (-511 to 511 valid range, -511 = -51.1°C or less, 511 = 51.1°C or greater, -512 = not available)
Visibility 8 Visibility in 1/10 kilometers.
(0-254, 254 = 25.4km or greater, 255 = not available)
Water Temp 10 Temperature in 1/10th of a degree Celsius (signed) (-511 to 511 valid range, -511 = -51.1°C or less, 511 = 51.1°C or greater, -512 = not available)
Total Number of bits 192