The WindSonic wind speed and direction sensor is based on proven ultrasonic technology from Gill Instruments.
To change the setting of a WindSonic sensor from the default factory settings, it is possible to communicate with the sensor direct from a PC using HyperTerminal (or similar terminal emulation package).
Use the WindSonic RS232 Configuration Cable for easy connection to a PC and power supply.
The WindSonic sensor uses the time of flight method of air velocity measurement.
There are four ultrasonic transducers arranged as two pairs at right angles to each other. Each pair is used to measure the component of the wind in the direction between the transducers.
For example if one pair is on a North South line and the other pair is on an East West line then the North South component VN and the East West component VE are measured. These are then combined to give the actual wind speed and direction.
Wind angle A = arctan ( VE / VN )
Wind speed S = sqroot ( VE 2 + VN 2 )
To look at how the component measurements are done we will take the example of the North South transducer pair:
A pulse of ultrasonic sound is transmitted by the North transducer and the time T1 it takes to travel to the South transducer is accurately measured. The time T2 is then measured for an ultrasonic pulse to travel in the opposite direction from the South transducer to the North transducer. These times are affected by the wind blowing along the line between the transducers. For example if there is some wind blowing from a Northerly direction, then the time taken for the ultrasonic pulse to travel from N to S will be shorter than from S to N.
The time for the pulse to travel from N to S is given by
T1 = L / ( C + VN )
and the time for the pulse to travel from N to S is given by
T2 = L / ( C - VN )
L is the distance between the transducers and
C the speed of sound
From this the northerly component of the wind can be found from
VN = L ( 1/T1 - 1/T2 ) / 2
and the speed of sound from
C = L ( 1/T1 + 1/T2 ) / 2
The WindSonic default serial output is as follows:
Q is the anemometer identifier. Can be set to any character Q to Z
DDD wind direction in degrees relative to sensor axis
SSS.SS wind speed
U Units M m/s, N knots, P mph, K km per hour, F ft per min.
AA status 00 ok, 01 axis 1 failed, 02 axis 2 failed, 04 axis 1 & 2 failed, 08 NVM error, 09 ROM error
CC checksum Exclusive OR of all characters between <STX> and <ETX> as a two character hexadecimal value.
<STX> is the ASCII character with a value of 2
<ETX> is the ASCII character with a value of 3
<CR> is the ASCII carriage return character with a value of 13
<LF> is the ASCII line feed character with a value of 10
Data is output at 9600 baud with 8 data bits and no parity.
Details of other output options and configuration instructions are given in the user manual supplied with WindSonic.
The WindLogger is designed for remote, affordable data logging from a WindSonic sensor.