WEEK 3 : INTRODUCTION

Assalamualaikum to all viewers. This is the updated for our FYP. We are being supervised by our lecturer Miss Norrolhoda, lecturer of electrical section. Before we proceed to other stage of making our project we would like to briefly explain about our project and we hope it can make people understand how this project function as a title given. Firstly we would like to talk about what is wind speed meter and how many types of wind speed meter and then we will explain about the circuit functionality. A wind speed meter or other named anemometer is a device that is used to measuring a speed of wind. the word anemometer came from greek word anemos mean wind. This device is commonly used in meteorology or aerodynamics measurement instrument.   The first known description of an anemometer was given by  Leon Battista Alberti around 1450. There is two classes of anemometer. Those that measure wind speed and those that measure wind pressure but nowadays an anemometer have both information. There is a lot of anemometers :-

1. cup anemometers
2. windmill anemometers
3. hot wire anemometers
4. laser doppler anemometers
5. sonic anemometers

For this project we are using the sonic or ultrasonic method in our project. Now we would like to explain how this ultrasonic anemometer functioned. An  ultrasonic anemometer uses sound to measure wind speed. It sends a sound signal from a fixed transmitter to a fixed receiver, and by measuring the time it takes for the sound to arrive, can compute the speed of sound. Wind speed will increase or decrease the speed of sound depending on whether it is a tail wind or a head wind. By measuring the speed of sound in both directions the wind speed along that axis can be calculated from the difference of the two measurements. A two axis or three axis instrument can measure total wind speed. For more information you can watch this video to understand more about how it work.

 

 So that is how the ultrasonic anemometer and ultrasonic theory worked. Now we will explain how our circuit of ultrasonic anemometer function based on schematic diagram.

 Figure 1 is a schematic for ultrasonic transmission and reception circuit diagram for this anemometer. As you can see there is two transducer X3 and X4 used in this circuit as an interchangeable transmitter and receiver. The transducer operate at the usual ultrasonic frequency o 40kHz. The transmission pulses are generated by a PIC microcontroller that you can see in figure 2. The route that the pulses take through IC3 is selected by the logic level applied to its pin 10, also controlled by PIC. So when pin 10 held low, the pulses are routed from IC3 pin 3 to pin 1, and out to transducer X3. Then the pulses transmitted to transducer X4 that acted as receiver at this time. Now the received pulses from transducer X4 are routed to IC3 pin 12 and then the pulses will pass through the analogue amplification circuit. When IC3 pin 10 is held high, the pulses are routed from IC3 pin 3 to pin 5, and this time the transducer X4 become a transmitter and transmitted the pulses to transducer X3 that become a receiver. The pulses pass via pin 14 to pin 13 and so out to the amplifier. Then the pulses from this ultrasonic circuit will to PIC and we can see the output displayed on the LCD display. Figure 2 shows the control circuit for this ultrasonic anemometer. This control circuit is using the PIC 16F628 to generating and sending pulses to the ultrasonic transducer, and for timing the return of the received signal. Then the result of its calculation are output to the 2-line 16-character alphanumeric LCD label as X2. The PIC is operated at 20 MHz set by the crystal X1 in conjunction with capacitors C3 and C4. For power source, this circuit is using a 9V PP3 battery to powered it. Although any DC supply between 7V and about 15V could be used and it will be regulated down to 5V by regulator IC2. Capacitors C1 and C2 encourage stability in the power lines. That's all for this time, we give an update for our FYP next time. Thanks for spend your time to view this blog. Assalamualaikum.