Transcript RADIO CONTROL TRANSMITTER Overview

RADIO CONTROL TRANSMITTER Overview
In this lesson you will learn:
• Relationship between remote control
transmitters and their receivers
• Resonance
• Engineering and scientific notation
• Frequency and periods
• Various parts of the experimental
procedure
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RADIO CONTROL TRANSMITTER Resonance
The trumpet and the kettledrum
Consider a trumpet and a kettledrum, each tuned to the note of
“E,” placed in the same room.
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RADIO CONTROL TRANSMITTER Resonance
The trumpet and the kettledrum
When the trumpet plays the “E” note, the sound wave leaves the
trumpet and travels through the air.
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RADIO CONTROL TRANSMITTER Resonance
The trumpet and the kettledrum
The air molecules vibrate against the surface of the kettledrum,
making the drum vibrate with an audible noise.
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RADIO CONTROL TRANSMITTER Resonance
What is resonance?
Resonance is the induction of vibrations on a physical object by a
vibrating force having the same frequency.
A dramatic example of resonance is
demonstrated by the Tacoma
Narrows Bridge disaster. Click
“Background/Slide Shows/Tacoma
Bridge: Example of Resonance” to
see the video.
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RADIO CONTROL TRANSMITTER Glossary
Glossary
Oscillate
To swing back and forth with a steady, uninterrupted rhythm
Oscillator
A device or mechanism for producing or controlling
oscillations
Amplify
To make larger; to increase
Amplifier
To amplify an electric signal; to increase an electric signal
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RADIO CONTROL TRANSMITTER Signals
How is a signal sent from the radio control transmitter?
 A crystal is placed in the radio control transmitter
 This is part of an oscillator circuit
 The oscillator circuit sends electrons to vibrate the crystal
 The crystal begins to vibrate at its resonant frequency
 The oscillator circuit sends this signal to an amplifier
 The amplified signal travels to an antenna
 The electrical signal is changed to an airborne electromagnetic wave
Refer to “Multimedia / Vex Controller and Resonance”
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
RADIO CONTROL TRANSMITTER Signals
How does the the robotic system receive the signal from the radio
control transmitter?
• The Vex receiver uses an antenna to receive electromagnetic waves
• Changes these waves to an electrical signals
• The signal is amplified and sent ot the circuit containing the crystal
• If the amplified signal is at the same frequency of the crystal in the
receiver, then the crystal will generate a large sinusoidal signal
• This activates another circuit which activates the motor
Refer to “Multimedia / Vex Controller and Resonance”
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HORIZONTAL Antenna Test
Hypothesis
Transmitter / Receiver Range
Radio control transmission
strength is a function of
antenna height
Horizontal Antenna Test
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Materials needed
• Constructed robotic system (refer to “Resources / Signal Box
Construction”)
• Radio control transmitter
• Yard stick
• Tape measure
• Lesson 1 datasheet (modified from “Resources / Lesson Datasheet”)
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 1
• Place robotic system at
stationary point
• Turn on the Vex microcontroller
and radio control transmitter
• Make sure to have plenty of
table or floor space for this
experiment
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 2
• Lay the radio control transmitter
flat in front of the robotic
system
• Extend antenna 1” to gain
minimal reception
• Move as close as possible to
the robotic system
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Step 3
• Push the right joystick of the
radio control transmitter forward
to start the motor
• Slowly slide the radio control
transmitter away until the motor
stops moving
• Slide it back until a consistent
connection is achieved
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Step 3 continued
• When you find and maintain
a consistent signal, measure
the distance from the radio
control transmitter to the
antenna of the reciever
• Record the data in your Lesson
1 datasheet
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Step 4
• Using the yard stick, extend the
antenna to 4”
• Follow the same procedure as
in step 3
• Record the data in your Lesson
1 datasheet
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Step 5
• Using the yard stick, extend the
antenna to 8”
• Follow the same procedure as
in step 3
• Record the data in your Lesson
1 datasheet
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Step 6
• Continue to extend the antenna
in 4” increments and measure
the distance from antenna tip
to the receiver
• Record the data at each
increment
• You will have 8 distances
recorded in your Lesson 1
datasheet
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Step 7
• Run another trial of this
experiment and record the data
in your Lesson 1 datasheet
• Compare the graphs of both
experiments
• What do these results tell you
about the relationship between
transmission strength and
antenna height?
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
VERTICAL Antenna Test
Hypothesis
Pointing the radio control
transmitter away from
(rather than directly
towards) the robotic
system will result in a
stronger signal strength
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Materials needed
• Constructed robotic system (refer to “Resources / Signal Box
Construction”)
• Radio control transmitter
• Yard stick
• Tape measure
• Lesson 2 datasheet (modified from “Resources / Lesson Datasheet”)
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 1
• Place robotic system at
stationary point
• Turn on the Vex microcontroller
and radio control transmitter
• Make sure to have plenty of
table or floor space for this
experiment
IMAGE OF
CONTROLLER AND
RADIO BEING
TURNED ON
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 2
• Place radio control transmitter
upright in front of robotic
system – the antenna should
point toward the ceiling
• Extend the antenna 1” to gain
minimal reception
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 3
• Push the right joystick of the
radio control transmitter forward
to start the motor
• Slowly slide the radio control
transmitter away until the motor
stops moving
• Slide it back until a consistent
connection is achieved
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 3 continued
• When you find and maintain a
consistent signal, measure the
distance from the radio control
transmitter to the antenna of
the receiver
• Record the data in your Lesson
2 datasheet
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 4
• Using the yard stick, extend the
antenna to 4”
• Follow the same procedure as
in step 3
• Record the data in your Lesson
2 datasheet
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 5
• Using the yard stick, extend the
antenna to 8”
• Follow the same procedure as
in step 3
• Record the data in your Lesson
2 datasheet
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 6
• Continue to extend the antenna
in 4” increments and measure
the distance from antenna tip to
the receiver
• Record the data at each
increment
• You will have 8 distances
recorded in your Lesson 2
datasheet
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 7
• Run another trial of this
experiment and record the data
in your Lesson 2 datasheet
• Compare the graphs of both
experiments
• Did pointing your radio control
transmitter antenna towards (as
in Lesson 1) or away from (as
in Lesson 2) the robotic system
result in a higher signal
strength?
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TEST with obstacles
Hypothesis
Different obstacles will
affect the transmission of
signals to the receiver
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Materials needed
• Constructed robotic system (refer to “Resources / Signal Box
Construction”)
• Radio control transmitter
• Yard stick
• Tape measure
• Lesson 3 datasheet (modified from “Resources / Lesson Datasheet”)
• Sheet of paper
• Wood
• Sheet metal
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 1
• Place robotic system at
stationary point
• Turn on Vex microcontroller and
radio control transmitter
• Make sure to have plenty of
table or floor space for this
experiment
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 2
• Hold radio control transmitter at
waist height
• Tilt antenna between 45
degrees and vertical
• Extend antenna 1” to gain
minimal reception
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Step 3
• Place a piece of paper on top of
the receiver
• Make sure the antenna wire is
wrapped around the receiver
• Push the right joystick of the
radio control transmitter forward
to start the motor
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Step 3 continued
• Back away from the robotic
system until the motor stops
moving
• Walk towards the system until a
consistent connection is
achieved
• Measure the distance from the
radio control transmitter to the
receiver
• Record the data in your Lesson
3 datasheet
Vex 1.0 © Carnegie Mellon Robotics Academy Inc.
Step 4
• Continue to extend the antenna
in 4” increments and measure
the distance from antenna tip to
the receiver
• Record the data at each
increment
• You will have 8 distances
recorded in your Lesson 3
datasheet for the paper
obstacle
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Step 5
• Place a piece of wood on top of
the receiver and the antenna
• Repeat the same procedure as
in steps 3 and 4
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Step 6
• Place a piece of sheet metal on
top of the receiver and antenna
• Repeat the same procedure as
in steps 3 and 4
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Step 7
• Compare the graphs of all three
experiments
• Which material affected the
signal strength of the radio
control transmitter the most?
• Which had the least effect?
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