1. Measuring and Monitoring Data
Data Logging

2. It’s getting hot in here
Think about the last weather forecast you saw on television.
How much information were you given about the weather for the day?
Temperature
Light
Moisture
Movement
Pressure
Temperature for the morning and night
Number of daylight hours
Humidity in the air
Wind speed
Air pressure
All of this information is obtained from sensors that are there to collect the data.

3. Changes in the weather affect many different people.

4. The data used to create weather reports is usually received from remote (far away) sensors which download data to computers.
The data doesn’t usually come from people standing on mountains saying whether it’s raining or windy! That might be too difficult, dangerous, boring or uncomfortable for them to do.
The data from the sensors helps the forecasters to make judgements about the weather.
Forecasters can tell how many centimetres of rain have fallen anywhere in the country on that day!
The data can also be analysed to make predictions and take decisions about the weather for the week and the month ahead.

5. Types of sensors

6. Monitoring the water for acidity
A pH sensor is used to measure the pH level of liquids, including seawater.

7. Why do we monitor the environment?
If the sea water pH goes down to 6.0, crustaceans, insects and some plankton species disappear.
Certain mosses start to invade the water as the pH approaches 5.0, and some types of fish will die.
Below pH 5.0 the water will be full of dead fish.
Animals that feed on fish, such as waterfowl, will be affected and the amount of birds will also decrease as there will be no food for them to eat.

8. What happened?

9. Can you work out the sequence of events?

10. Sensors in everyday life
Here are some of the sensors used in everyday life. See if you can match each sensor to where it is used.

11. This process is called data logging.
Data from sensors is captured and logged on to a computer where it can be read, recorded and analysed.
This process is called data logging.
Sensors come in two kinds – analogue and digital.
The data from analogue sensors needs to be converted to digital form to be understood by a computer.

12. A data logger is the device to which analogue sensors are attached
A data logger is the device to which analogue sensors are attached. There can be more than one sensor attached.
It acts as an Analogue to Digital Converter. This means that it converts the analogue voltage into digital signals which can then be processed by a computer.
The data logger is attached to a computer.
A piece of software (a program) enables all the data to be transmitted from the data logger to the computer. Graphs and charts can then be created using the data that has been collected.
ADC
sensors

13. Sometimes data is transmitted electronically via satellites, radio links and telephone lines. This is called remote data logging.
On other occasions, data is stored in the data logger and then downloaded to the computer. This can be useful if you are gathering data on a field trip when you may not have computers with you. The data can be downloaded to the computer when you return.
Data loggers can also be connected directly to a computer to record data.

15. Different sensors are used to monitor different things.

17. For the record
Recording data using a data logger has many advantages to data being recorded by a human being.

18. Summary
Many of the changes around us can be recorded using sensors.
Types of sensors include pressure, light, temperature, moisture and movement.
Data is captured and logged onto a computer through a data logger.
There are two kinds of sensors – analogue and digital.
The data logger acts as an Analogue Digital Converter by converting analogue voltage into digital signals.
What can I remember?
The End