Senior Project 2005 Electrical Engineering

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Senior Project 2005 Electrical Engineering
Wireless Earphones
Avionne Maurice Jacqueline Suarez
Prof. Hedrick Prof. Hassib
Why Wireless earphones?
Project Description
Wanted to develop a device which hasnt been
explored thoroughly in the wireless field

• 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.

Receiver (front)
Block Diagram Implementation
Receiver (back)
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.
Project Description
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
Based on this picture, the side bands follow the
FCC requirements. This means the carrier
frequency can only travel between -75 to 75 KHz.
It is the requirement for two adjacent radio
stations on the FM bandwidth.
This validates that the suppression of unwanted
signals is at 40 dB. Each box has a separation of
10 dB and since the signal is 4 boxes away from
the unwanted signal, there is a 40 dB separation.