Senior Design II paper
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Design SummaryThe Eye Can Hear You Project is a wireless headphone and audio television network for a sports bar application. The headphones correspond with three subsystems, triangulation for headphone location, headphone-to-television identification for audio switching and reception of wireless television audio from the master microcontroller. A tablet is used to register customers to the headphones, display headphone status and location within the dimensions of the sports bar. The tablet displays a graphical user interface hosted on an android based application. It communicates with the triangulation system by using the IOIO for Android device, connected to an XBee module. The tablet receives a serial data corresponding to the x and y coordinates of the all the headphones in use within the boundaries of the sports bar. Through the tablet the staff can view headphone location corresponding to the dimensions of the establishment along with headphone status (whether in use or not). To keep track of the headphones, the tablet will be used to register customers to a headset by storing the customer name, table number, phone number, and credit card number for collateral purposes. If a customer was to leave the boundaries of the sports bar an activity will notify the staff. The triangulation system provides the tablet with each headphones location within the sports bar. The triangulation system has four modules located in each corner of the room. Each module acts as a reference point to each of the headphones. The headphone modules read the RSSI value from each reference module and compute their position by using the trained data set table. Each headphone module then sends the mapped x and y coordinates corresponding to itself to the tablet via 2.4GHz RF serial. The tablet translates the coordinates from the serial data received into a graphical user interface. The wireless headphones consist of headphone-to-television identification, television audio reception, and triangulation interfacing. Through the groups design, a customer wearing a headphone will receive audio from the television being viewed. The design allows the user to switch between the audio of different televisions within the sports bar. Each headphone sends an infrared light pulse unique to each headphone in the direction of the user’s line of sight. This occurs when the ‘audio lock’ button located on the side of the headphone is pressed. Infrared detectors are located on each television to receive the infrared pulsing light and demodulate the signal. The identification signal is captured and calculated into a value to be compared to the headphone IDs within the network. Once a match occurs the data lines will send the headphone ID that is viewing a particular headphone to the master board. A multiplexer corresponding to each headphone will allow the microcontroller to decide which audio source to send to the headphone depending on the lines received from the television. The audio is sent via radio frequency in the 900 MHz frequency to the headphone. The headphone then receives, buffer and filters the audio signal to drive the speakers with quality audio at a desired volume range. Figure 28 displays the wireless and hardwire communication between subsystems for the “Eye Can Hear You” project. 
Figure : This diagram is divided into three subsections, the master board, the headphones, and the tablet, shown from top to bottom respectively.
Since the group is making the headphones from the ground up, the testing must be very thorough. There are many parts to the wireless headphones to test. The team must test the audio, RF triangulation, the LED transmission, and the RF receiver. Testing these parts will ensure that all parts work correctly and that no interference occurs when the project is complete. There are many ways to go about this testing. A testing method has been developed for each of these parts. The first method to test the headphones will include directly connecting the audio of the televisions and listening to the sound on the headphones. This will allow the team to check if the headphones are wired correctly. The second method to test for the headphone sound will be to connect a DVD or Blu-Ray player to the television. This will help determine the lag time between the sound and the picture and will allow the team to develop solutions, should this problem arise. The team will also test the potentiometer which will be used to control the volume. The group must make sure it is connected correctly so no audible damage will occur. The LED transmission has to be tested to make sure the LED and the IR receiver are communicating. The primary method that the team has chosen to use for this test is to connect the IR receiver to the Stellaris development board. This will also test if the MSP430 is working properly. Without the MSP430, the LED will not know what burst pattern it needs to send to the IR receiver. Therefore, this test must be done with great care. The next test will confirm the operation of the RF triangulation. Once the RF triangulation is completed, a series of tests will be run to determine if the triangulation is working accurately. The best way to test the RF triangulation is to run it how it would be run in the project. Pillars will be erected and be placed in 16’X16’ square. On top of each pillar will be a PCB with an XBee connected to a power source. One of the team members will stand in the middle of the square with a headphone atop their head. Another team member will have the tablet and be able to see the position of the headphones in the application on the tablet. The final test will determine if the RF triangulation is working properly. The RF modules for the main board will be placed on a breadboard for this test. A signal will be input (say sound from a television) and make sure that the RF modules are working. Once the team can hear sound through the headphones, the team will then test multiple channels. The team will use two breadboards with one RF transmitter in each of the boards. The team will make sure that the RF modules are broadcasting on two separate channels. The team will then transmit two different sounds through the transmitters. If they come in clearly in their respective headphones, then the test is complete. If this test does not work the team must go back and fix the receivers. This test is also good to test the RF transmitters and to make sure that the multiple channel idea works correctly.
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