wireless earphones avionne maurice & jacqueline suarez advisors: prof. hassib & hedrick...
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Wireless Earphones
Avionne Maurice & Jacqueline Suarez
Advisors: Prof. Hassib & Hedrick
March 5, 2005
OUTLINE Why Wireless
Earphones? Project Description Similar Products Original Project
Specifications Actual Project
Specifications Components
Transmitters Receivers Block Diagram
Implementation Results References Questions
WHY WIRELESS EARPHONES?
Wanted to develop a device which hasn’t been explored thoroughly in the wireless field
Increase our knowledge in wireless and RF (radio frequency) technology
Construct a device which would be useful and fun to use
PROJECT DESCRIPTION
Wireless earphones are lightweight ear-clip stereo headphones made by Maxell.
The earphones will be used in conjunction with a portable audio player.
Increased range of listening.
SIMILAR PRODUCTS
Built-in FM Radio Transmitter requires no
batteries. Earphone receiver runs
only on 2 AAA batteries. The right earphone
serves as the control center.
The left earphone houses the battery compartment.
GBA-SP Wireless EarphoneGBA-SP Wireless Earphone
SIMILAR PRODUCTS
Headphones work with audio or video devices, like TVs, DVD players, computers, etc.
Transmission range about 300 feet.
Rechargeable batteries Transmitter is bulky Headphone vs. Earphone
Acoustic Research 900MHz Wireless Stereo Headphones
ORIGINAL PROJECT SPECIFICATIONS
Suppression of unwanted signals at 45 dB minimum
FM modulation Battery Life: 8 hours minimum Receiver: Ear bud size Transmission Range: 300 ft
minimum
ACTUAL PROJECT SPECIFICATIONS
Suppression of unwanted signals at 40 dB
FM modulation Battery Life of Receiver: 25 hours Battery Life of Transmitter: 25 hours Receiver: Ear-clip size Transmission Range: 200 ft
COMPONENTS
RF transmitter RF receiver Battery Earphones Antenna
OLD TRANSMITTERS Originally we had 3
different transmitters from which to choose.
Each transmitter had a wide supply voltage, long transmission range, and average in cost.
RTF3-433 FM RF Transmitter
Module
Quasi AM/FM RF Transmitter
Module
TXM-xxx-A/F FM RF Transmitter Module
OLD RECEIVERS Initially there were two receivers to
match the three transmitters. Fairly expensive – about $50.00 Dimensions weren’t very small
SILRX-xxx-A/F FM SuperHeterodyne Receiver Module QMR1-433 Quasi AM/FM Receiver
Module
NEW TRANSMITTER Tunable from 76-
108MHz Compatible with any
audio device, like a CD player or tape deck
Uses a BA1404 IC chip Transmission range is
200 feet With 9 V battery, has a
battery life of 25 hours Price: $29.95
FMST-100 STEREO TRANSMITTER
NEW RECEIVER Supply voltage range: 2.7 to 10 V Supply current: typical 8 mA Frequency range: 1.5 to 110 MHz Sensitivity: 1.5 mV With 3 V battery, has a battery life of 25 hours Price: $15.95
TDA7000 FM Radio Receiver
BLOCK DIAGRAM IMPLEMENTATION A CD player was used for the input signal.
The audio signal was then received by the FMST-100 stereo transmitter.
Within the FMST-100 stereo transmitter the signal is amplified and modulated by the BA1404 IC chip.
The signal is then transmitted and received using the antennas.
Inside the TDA7000 FM Radio Receiver chip, the signal is demodulated and amplified so it can be heard with the wireless earphones.
RESULTS Transmitter is functional Debugging completed for transmitter In the process of debugging receiver
Mount transmitter in box Increase stability of transmitter Design an antenna system
REFRENCES www.bestbuy.com www.jameco.com http://www.semiconductors.philips.co
m http://www.users.bigpond.com/cool38
6/tda7000/tda7000.html http://www.microbattery.com/Toshiba
%20Webpages/lithium%20coin%20new.htm
http://www.semiconductors.philips.com/pip/TDA7000.html
SPECIAL THANKS TO
Gene Davison
Professor James Hedrick
Professor Ekram Hassib
QUESTIONS?