Using NI Wi-Fi Data Acquisition and LabVIEW to Create a Virtual Barometer

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"We successfully used NI Wi-Fi DAQ and LabVIEW software to meet the goals of our virtual barometer project. NI Wi-Fi DAQ gave us many conveniences in collecting data and results by correlating weather and the changes in pressure during a period of time. "

- Rodney Tan , UCSI University

The Challenge:
Designing a device to forecast weather by measuring the rate of change in atmospheric pressure.

The Solution:
Using NI Wi-Fi data acquisition (DAQ) and NI LabVIEW software to create a flexible, accurate virtual barometer.

Author(s):
Rodney Tan - UCSI University
Lau Chai Ying - UCSI University
Teh Foong Li - UCSI University

Introduction

Rain causes floods, traffic jams, landslides, accidents, and many other inconveniences. We created a virtual barometer for the sake of safety as well as to avoid these inconveniences. Measuring changes in atmospheric pressure is the most common way to forecast changes in weather because weather patterns are detected in regions of high and low pressure. According to research performed by meteorologists, decreasing atmospheric pressure indicates storms, rain, and windy weather. Meanwhile, rising atmospheric pressure indicates fair, dry, and colder weather.

System Overview

Figure 1 shows a system overview of our virtual barometer. The system consists of an integrated silicon pressure sensor (MPXA4115AC6U series), an NI Wi-Fi DAQ unit containing an NI cRIO-9215 and NI WLS-9163 modules, and LabVIEW (see Figure 1).

Our virtual barometer’s pressure sensor detects the atmospheric pressure and outputs the signal in voltage form. The pressure sensor reads the atmospheric pressure from 15 kPa/ 112.528 mmHg up to 115 kPa/ 862.716 mmHg, with an output range from 0.2 V to 4.8 V. The system needs 5 V to power up the pressure sensor. The system sends output from the pressure sensor to the NI cRIO-9215, which is connected to an NI WLS-9163 to provide the wireless connectivity to send the data to the computer. The NI Wi-Fi DAQ unit acquires the voltage changes produced by the pressure sensor. The data collected displays on the front panel of the virtual barometer. We used LabVIEW to analyze the collected data with mathematical formulas to perform the weather forecasting.

The virtual barometer user interface shows a waveform chart, pressure gauge, bar, picture ring, and three buttons. The waveform chart displays the atmospheric pressure changes for a period of time. The system gathers data every 10 minutes to plot the chart. Pressure gauges and pressure bars show the value of the current atmospheric pressure.

There also are three buttons with different functions. The FORECAST button shows the user the result of weather forecasting through a picture ring. The picture ring is the background of the virtual instrument. If fair weather is predicted, the background changes to a sunny view. Reversely, if rain is predicted, the background changes to a rainy view. The GET DATA button saves the value of the atmospheric pressure at a particular moment to a file allocated by the user. Lastly, the STOP button stops the functionality of the virtual instrument.

By carefully observing the pressure on the waveform chart, the user can forecast local weather using the simple guidelines in Table 1. The relationship of the weather and the change in atmospheric pressure is compared (see Figures 2 and 3).

For more accurate data and results, the user can place the NI Wi-Fi DAQ unit outdoors on a wide empty space. The user can connect a power supply adapter and pressure sensor to the printed circuit board that connects to the NI cRIO-9215. The results are shown on the computer through the virtual instrument without connecting the computer to the NI Wi-Fi DAQ unit (see Figure 4).

Conclusion

We created the virtual barometer to demonstrate local weather forecasting a few hours into the future. We successfully used NI Wi-Fi DAQ and LabVIEW software to meet the goals of our virtual barometer project. NI Wi-Fi DAQ gave us many conveniences in collecting data and results by correlating weather and the changes in pressure during a period of time.

Author Information:
Rodney Tan
UCSI University
No. 1 Jalan Menara Gading, UCSI Heights
56000
Malaysia
Tel: 0173078955
Fax: 0391013606
rodneyt@ucsi.edu.my

Next Steps

Download LabVIEW

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