MetPak Weather Station

Overview

The WindSonic sensor with ultrasonic technology provides extremely accurate and reliable wind data. With no moving parts, the sensor is virtually maintenance free and easy to install - ideal for isolated locations and harsh environments.

Temperature and humidity is measured using a Rotronic Hygroclip HC2-S3 probe placed in a naturally aspirated radiation shield. Barometric pressure is measured within a durable UV Stabilised white thermoplastic vented enclosure.

The MetPak weather station is supplied with digital SDI-12, RS232 & 422 outputs.

Data from the MetPak can be stored using the SpaceLogger W10 (WindLogger) and SpaceLogger W8 Wireless data loggers, providing a compact affordable logging solution for long term data collection.

You can link your MetPak to our WeatherFile.com website which delivers a clean and clear display of your weather data in real time.

The MetPak is also available as a base station with optional remote wind sensor.

MetPak Weather Station Measures
• Wind speed • Wind direction • Air temperature • Relative humidity • Barometric pressure • Dew point

Units of Measurement
• knots, m/s, km/h, mph, ft/min • degrees • °C or °F • % RH • hPa, mbar, mmHg, InHg

Accuracy
• Wind Speed ±2% of reading @ 12m/s • Wind Direction ±3° @ 12 m/s • Air temperature ±0.1°C • Relative humidity ±0.8% @23°C • Barometric pressure ±0.5hPa

Range
• Speed 0.01 to 60 m/s (116 knots) • Direction 0 to 359° (no dead band) • Temperature -35°C to +70°C • Relative humidity 0-100% RH • Barometric pressure 600-1100hPa

MetPak Weather Station Benefits
• Lightweight, compact and durable complete weather station • Ultrasonic wind sensor with no moving parts • Low start up wind speed (0.01 m/s) • True 0 to 360° operation • Serial data output options • Easily pole mounted • Low power consumption for remote monitoring

Applications
• Agriculture • Emergency response • Pollution control and plume modelling • Education • Weather Forecasting • Transport • Aviation • Environmental monitoring • Industrial controls • Road Weather Stations • Coastal Weather Stations • Sports stadium and outdoor events • HVAC & Building Automation Control

What does it output?

MetPak can be configured using the free MetView software provided to select the output rate and units of measurement that suit the application.
The MetPak automatically transmits a status code with each output to indicate the operating status of each of the sensors. This ensures accuracy and reliability.

The MetPak default serial output is as follows:
Setting	Function
Comms Levels	RS232
Baud Rate	19200
Data Connection	Data Bits 8, Parity None, Stop Bits 1, Flow Control None
Output rate	1Hz
Message Mode	Continuous
Message Format	Wind Direction (degrees), Wind Speed (metres/Sec), Barometric Pressure (hecto pascals), Humidity (percent), Temperature (degrees C), Dew Point (degrees C), Power Supply (volts), Status Code (00) Checksum (hex number)
Output Sentence	Comma Separated Variable
Node Address	Q
Message terminator	Carriage return and line feed
Power up message	On

Example Data String:

<STX>,Q,DDD,SSS.SS,PPPP.P,HH.H,T.T,WW.W,VV.V,AA,<ETX>,CC<CR>,<LF>

Where
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
PPPP.P barometric pressure
HH.H relative humidity
T.T temperature
WW.W dew point
VV.V power supply voltage
AA status 00 ok, 01 anemometer axis 1 failed, 02 anemometer axis 2 failed, 04 anemometer axis 1 & 2 failed, 08 NVM error, 09 ROM error, 67 Temp/Humidity/Pressure or anemometer reading failed.
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

Details of other output options and configuration instructions are given in the user manual supplied with MetPak.

 

Configuring the MetPak

To change the setting of a MetPak weather station from the default factory settings, it is possible to communicate with the instrument direct from a PC.

MetPak can be configured using:

• A terminal program such as MS Windows HyperTerminal.
• MetSet Configuration Software: MetSet is a free software package that allows the user to configure the output and display data provided by the MetPak II. The simple interface features a range of drop-down selection boxes, providing the ability to enable or disable existing sensors and adjust output rates.

MetView software is also provided free with each weather station, offering a clear, intuitive display of the current weather conditions.

MetView features five gauges: Temperature, Humidity, Pressure, Wind Speed and Wind direction. There is also a digital readout of Dew Point.

How Ultrasonic Wind Sensors Work

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 V^N and the East West component V^E are measured. These are then combined to give the actual wind speed and direction.

Wind angle  A = arctan ( V^E / V^N )

Wind speed  S = sqroot ( V^{E 2} + V^{N 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 + V^N )

and the time for the pulse to travel from N to S is given by

T² = L / ( C - V^N )

where
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

V^N = L ( 1/T¹ - 1/T² ) / 2

and the speed of sound from

C = L ( 1/T¹ + 1/T² ) / 2

Physical	Dimensions		370mm height (overall) 290mm standoff (max) from face of mounting pole 142mm width
	Weight		1.1 kg (including bracket)
	Mounting		Vertical pipe mounting 25mm to 50mm diameter
	Material		UV Stabilised white thermoplastic with gloss white painted aluminium mounting bracket (with moulded plastic V-block and stainless steel U-bolt)
Performance	Wind speed	Range	0.01 to 60 m/s (0.02 to 116 knots)
		Accuracy	±2 % @ 12m/s
		Resolution	0.01 m/s
		Threshold	0.01 m/s
		Units of measure	m/s, knots, mph, km/hr, ft/min
	Wind direction	Range	0 to 360° (no dead band)
		Accuracy	±3° @ 12m/s
		Resolution	1°
		Response time	0.25 sec
	Air temperature	Range	-35°C to +70°C
		Accuracy	± 0.1°C
		Resolution	0.1°C (0.1°F)
		Units of measure	°C, °F or K
	Relative humidity	Range	0-100% RH
		Accuracy	± 0.8% @ 23°C
		Resolution	0.1% RH
		Units of measure	% RH
	Barometric pressure	Range	600-1100 hPa
		Accuracy	±0.5hPa
		Resolution	0.1hPa
		Units of measure	hPa. mbar, mmHg, InHg
	Dew point	Accuracy	± 0.15°C @ 23°C ambient temp and 20°C dew point
		Resolution	0.1°C (0.1°F)
		Units of measure	°C or °F
Sensors	Wind speed & direction		WindSonic ultrasonic sensor
	Temperature, relative humidity & dew point		Rotronic HygroClip model HC2-S3 compensated for temperature dependency. Radiation shield 6-plate naturally aspirated
	Barometric pressure		Solid state device compensated for temperature dependency -20°C to +70°C
Outputs	Digital outputs		RS232, RS422 or SDI-12
	Baud rates		1200 (SDI-12) - 9600-57600 (ASCII RS232, RS422)
	Protocols		ASCII or SDI-12 V1.3
	Output rate		0.25, 0.5, 1 Hz or polled mode
	Parameters output		Polar wind speed and direction or U & V vectors, barometric pressure, humidity, temperature, dew point, power supply voltage, MetPak status code, checksum
			click on the Overview tab for details of the default serial output
Power	Power requirements	RS232, RS422	5 to 30 V dc 36 mA (output 1second) @ 12 V
		SDI-12	12 V nominal (9.6 to 16 V dc) < 36 mA
Environmental	Temperature		Operating range: -35°C to +70°C Storage range: -40°C to +80°C
	Humidity		Operating range: 0% to 100% RH
	Protection Class		IP65
Miscellaneous	Calibration		Factory calibrated
	Software		MetView - free software providing the means for configuring the MetPak II and reading output data

The manufacturer reserves the right to amend the specification and therefore the information in this document may be subject to change

Data Sheets
	MetPak Weather Station Data Sheet - Issue 2

User Manual
	MetPak Weather Station User Manual - Issue 9
	MetPak Base Station User Manual - Issue 2

Case Studies

Our following Case Studies give an overview of how this product applies to different sectors.
Please click on the title below to read the full case study.

	Agriculture
	Aviation
	Construction
	Education
	Emergency Services
	Environmental Monitoring (with SpaceLogger Data Loggers)
	Environmental Monitoring (with Wind Systems)
	Health & Safety Monitoring
	Marine, Ships & Harbours
	Outdoor Sports
	Research
	Tower Cranes
	Transport Safety
	Weather