Rev:
1.00
Date:
11.22.2013
Page:
35 of 40
AIMMS-20
OPERATING MANUAL
Document-P/N:
AIMMS20-OM
© Aventech Research Inc. 2013. All Rights Reserved.
A.3.1 Data Block, Standard Meteorology Packet (ID = 0)
Byte #
Description
Var. Type
Scale
5
Time (UTC), hours
Char.
1
6 Time
(UTC),
minutes
Char.
1
7
Time (UTC), seconds
Char.
1
8
Temperature (deg. C) – lsb
9
Temperature – msb
Signed int.
100
10
Relative humidity (fraction from 0 to 1) – lsb
11
Relative humidity –msb
Unsigned int.
1000
12
Barometric pressure (Pa) – lsb
13
Barometric pressure – msb
Unsigned int.
0.5
14
Wind flow vector N component (m/s) – lsb
15
Wind flow vector N component – msb
Int.
100
16
Wind flow vector E component (m/s) – lsb
17
Wind flow vector E component – msb
Int.
100
18
Wind speed (m/s) - lsb
19
Wind speed (m/s) - msb
Int.
100
20
Wind direction (deg. true) – lsb
21
Wind direction (deg. true) – msb
Unsigned int.
100
22
Status flag: bit 0 (wind status)
0 = not valid 1 = valid
Char. 1
Status flag: bit 1 (purge status)
0 = purge off, 1 = purge ON
Char. 1
Status flag: bit 2 (GPS solution status)
0 = GPS solution bad, 1 = GPS solution good
Char. 1
Notes:
1) Wind flow vector points in the direction to which the wind is blowing.
2) Wind direction is reported in accordance with standard meteorological
convention, i.e. direction wind is blowing from.
3) The following conditions must be met for a valid wind solution: a) wind
measurement system must be calibrated; b) airspeed must exceed a
threshold value of 30 m/s (~60 knots); c) valid navigation solutions available
from both GPS processors; d) a minimum number of four matched satellite
pairs must be visible.
4) Wind speed and wind direction output are damped by a 20-point moving
average (20 of the latest wind solution updates, eg. 5Hz update = 4 s
damping).
