wireless data transmission
DESCRIPTION
This Lesson Plan show pupils the principle of wireless transmission through a “remote control”.TRANSCRIPT
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
WWIIRREELLEESSSS DDAATTAA TTRRAANNSSMMIISSSSIIOONN
Lesson Plan
Author: Prof. Orivaldo Gonçalves de Mello (E.E. Pe Simon
Switzar)
Students from 11th and 12th grades from E.E. Pe Simon Switzar
Raphaela Rodrigues
Tatiane Aparecida Dantas de Brito
Ricardo Guedes de Oliveira
Supervision Prof. Marisa Almeida Cavalcante (PUC/SP) e Prof.
Cristiane Rodrigues Caetano Tavolaro (PUC/SP)
July 2009
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Introduction
It is important to recognize that the pupils have the intention to learn, but
perhaps not what the school currently intends to teach them. That is, the education
project many times has little to see with the learning project.
Thus, what Physics must search in high school is to assure that the inquiry
ability rescues the inquiry spirit, the desire to know the world we inhabit. Not only in a
pragmatic way, as immediate application, but expanding the understanding of the
world, in order to consider new questions and, perhaps, to find solutions. In teaching
Physics questioning must be stimulated and not only giving answers to ideal situations.
Physics also must be understood as culture, in a way that the school has the duty to
assure the access of the population to part of the knowledge produced. It is not about,
however, to abandon the contents or to go for generalities; the contents must be
explored with severity, but they must go though criteria based choices and adjusted
didactic treatment, so that it is not a lot of formulas and disarticulated information.
History alone is not enough, as it is necessary to go beyond the process and
understand it, to guarantee the inquiry. Far from meaningless empty slighted
knowledge, it is needed to teach “how things work”.
It is in this perspective that we consider this activity where specific content
related to the electricity and Modern Physics will be approached, in order to
understand a little more “How things work”.
Through a very simple electric circuit it will be possible to understand the
principle behind wireless communication systems what it will allow the pupils a
contact with specific contents of electricity, but applied to devices present in their
daily life, such as the technology involved in the use of remote controls, infra-red
alarms, optical fiber cables, amongst others.
The whole activity was articulated in order to make possible to develop abilities
and skills as:
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
To understand that tables, graphs and mathematical expressions can be
different forms of representation of the same relationship, with potentialities and
limitations, to be capable to choose and make use of the most appropriate language in
each situation, and being able to translate between themselves the meanings of these
many languages.
To elaborate analytical reports presenting and discussing data and results,
either through experiments or critical evaluation of situations, using, whenever
necessary, of appropriate Physics language.
Objective
To show pupils the principle of wireless transmission through a “remote
control”.
Content
The content approached in this activity makes it possible to treat the following
structured topics:
Sound, image and communication treated in 11th
grade
Rooster and Structured Topicss
This activity can be explored in either 11th
or 12th
grade, depending only on the
questions that you wish to answer.
Structured topic 4: Sound, image and information (11th
grade)
To place ourselves in the contemporary world it is necessary to understand the
current means of communication and information, that has in its base the production
of images and sound, processes of capture, codifications and forms of register and the
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
reestablishment of its signals in the receivers. To study these mechanisms means to
propitiate abilities to understand, to interpret and to deal appropriately with
technological apparatuses, as the television, CDs and DVDs players, the computer, the
cinema or photography.
Structured topic 3: Electromagnetic equipment and Telecommunications (12th
grade)
Most devices and equipment that are part of our daily life require electric
energy for its functioning, allowing the execution of different functions as to
illuminate, to heat, to cool, to centrifuge, to triturate, to emit sounds and images, and
so on.
Moreover, a significant part of the available information nowadays circulates
the planet through electromagnetic waves, and it does not need a medium for its
transmission. Which processes and phenomena occur inside the devices so that the
same electric energy provides many different effects? How radios and televisions
transmit information? The understanding of the electromagnetic world that is in our
daily life is indispensable to allow the adjusted, efficient and safe use of devices and
equipment, beyond conditions to analyze, to make choices and to improve its use.
Activity
Number of classes needed for the activity: 4 classes
First class
-To explain the objective of the experiment, its relation to the daily life;
The remote control is a device of ordinary usage in our daily life, therefore we
are going to demonstrate that each key has a different frequency, and this varies from
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
one brand to another. We are going to use a reception system for this demonstration
that consists of a phototransistor connected to the sound board of the computer,
where the reading is made through Audacity Software.
Materiais ued for its functioning
a) Remote control. Its function is send infra red signals to the
phototransistor.
Fig.1: Remote controls
b) Phototransistor. Its function is to convert the infra red signals in electric
signals that will be sent to the computer’s sound board.
Fig. 02: Phototransistor
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
c) Support with a 470 ohms resistor. The resistor detects electric current
variations and the Potential difference in its terminals.
d) Cables in which one of their ends has two alligator clips and on the other
end an audio “Jack mono” connector. The alligators connected to the terminals of
the 470 ohms resistor make the connection to the PC (In the sound board port).
e) 9 - volt batteries. Experiment’s main power source.
Fig.03: resistance in series with a LED, battery and phototransistor. Signal being
captured by the alligator clips in parallel with the resistance.
f) The connector for the classmate PC must be connected to the “mic” port
(pink).
g) LED to indicate the functioning of the circuit.
Fig. 04: jack connector connected to the “mic” port of the classmate PC.
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
h) Audacity software, available on the Internet and essential to analyze the
signals sent by the remote control.
(http://audacity.sourceforge.net/download/)
Fig. 05 shows an example of signal observed from pushing a key of a remote
control in front of the phototransistor of the circuit of fig.02 and 03.
Fig. 05: Audacity screen.
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Figure 6 shows the complete equipment to make the reading of the wireless
transmission.
Fig. 06: Complete overview of all the utilized components.
Instructions to turn on the components:
The electrical resistance, the LED, the phototransistor and the battery must be
connected in series, constituting the receiving system.
Figure 07 shows the electric circuit’s diagram.
Fig. 07: Diagram of the electric circuit of the receiving system.
phototransistor
resi
sta
nce
battery
LE
D
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Important!!! Hint about polarity:
Both the LED and the phototransistor must be connected respecting the
polarity for their conduction. To verify if this polarity is being respected follow
these procedures:
2. If it turns on its polarity is correct. If it does not turn on change the
polarity of the battery and keep at least one of the polar regions connected not
to lose reference.
1. Connect only the LED in the circuit of fig.07, removing the
phototransistor and verify if the LED turns on.
2. If it turns on its polarity is correct. If it does not turn on change the
polarity of the battery and keep at least one of the polar regions connected not
to lose reference.
3. After that connect the phototransistor and shed a beam of light on it
(a lantern or a laser tip) and see if the LED turns on.
4. If it turns on the polarity of the phototransistor is correct.
5. If it does not turn on invert the phototransistor’s polarity (do not
move the battery as the polarity of the LED must also be respected).
6. After that put the remote control in front of the Phototransistor and
press any key. Observe the LED. It will blink with the frequency of the remote
control.
Capturing the signal
a. With the circuit mounted place an “alligator” beside the resistor
and the other on the opposite side (so that the two are parallel to the electrical
resistance).
b. Connect the exit of the “alligators” to the computer’s sound
board.
c. Do the reading on the Audacity software (Reading of time in
seconds).
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Second Class
Do the experiment.
a. Put the equipment together and start the Audacity software, pressing the
program’s record button, leaving the time in seconds.
Fig. 08: changing Audacity’s configuration so it is possible to measure time in
seconds
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
b. Press a key of the remote control in front of the phototransistor.
Fig. 9: Remote control being used in front of the transistor
c. Observe the graph that the software received from the remote control. Amplify
the signal by clicking on the software’s magnifying glass.
Fig.10: an example of measurements taken of the time interval of each signal
parcel.
d. To measure put the cursor over the signal and select the time interval
correspondent to a period of wave.
e. Write down each time interval that you feel is important and also calculate the
frequency of each remote control.
f. “Export” the archives as wav file in the Audacity so that it is possible to read it
in any machine. Give each file a name key_remote control (for example key
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
1_control Sanyo DVD), thus it will be possible to easily locate the measurement
done for posterior analysis.
g. Repeat this procedure for different remote controls.
Third Class
From the time in seconds that the software has measured you will be able to
calculate and analyze the frequency of each, as f = 1/T.
Examples of graphs showing signal emitted:
Fig.11: Universal Control - Power – code
(http://picintelproforivaldo.blogspot.com/2009/09/controle-universal-power.html).
Fig.12: Universal Control - Power – signal showing the period of wave
(http://picintelproforivaldo.blogspot.com/2009/09/controle-universal-power.html).
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Fig. 13: LG Control - Power – code
(http://picintelproforivaldo.blogspot.com/2009/09/codigo-e-grafico-do-sinal-controle-
lg.html).
Fig. 14: LG Control - Power – signal showing the period of wave
(http://picintelproforivaldo.blogspot.com/2009/09/codigo-e-grafico-do-sinal-controle-
lg.html).
.
Fig. 15: Sanyo Control - Power – code
(http://picintelproforivaldo.blogspot.com/2009/08/codigo-da-tecla-power-do-
controle-sanyo.html).
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
Fig. 16: Sanyo Control - Power – signal showing the period of wave
(http://picintelproforivaldo.blogspot.com/2009/08/codigo-da-tecla-power-do-
controle-sanyo.html).
Fourth Class
Analyze the results
To analyze the results the teacher should ask students to compare:
1. Signals from different keys in the same control
2. Same key from different remote controls.
Students have to answer the following questions:
For the same remote control and different keys:
a. What happens with the signal frequency? Is it the same? Does it change from
key to key?
b. What happens to the length of the signal? Is it the same or does it change
from key to key?
c. What happens to the maximum and minimum sequence (logical sequence)?
Does it change?
Pontifícia Universidade Católica de São Paulo
Junior Scientific initiation at PUC/SP and the development of experimental activities in
Physics using the Classmate PC
For the same key from different remote controls:
a. What happens with the signal frequency? Is it the same? Does it change from
remote control to remote control?
b. What happens to the length of the signal? Is it the same or does it change
from remote control to remote control
c. What happens to the maximum and minimum sequence (logical sequence)?
Does it change?
According to your experimental observations could you answer why a specific
remote control only works on the device it has been planned for?
Links
• Videos that show the equipment being put together
http://picintelproforivaldo.blogspot.com/2009_07_01_archive.html
• Text about analogical – digital signal conversion
http://xviiisnefnovastecnologias.blogspot.com/2009/01/texto-de-orientao-
para-oficina-de-novas.html
• Cavalcante, M.A; Bonizzia, A.,Gomes,L.C.P; Data acquisition in the physics
laboratory: an easy, simple and low-cost method for experiments in
mechanics, Rev. Bras. Ensino Fís. vol.30 no.2, São Paulo, 2008