Audio systems which allow the user to control the frequencies of music being played are very desirable. A system of filters, known as equalizers can control the gain of certain ranges of frequencies, thus allowing the user to choose his or her desired output level of music. The input to the equalizer will be a audio signal which consists of a sum of sinusoids. This signal will be sent through three filters: a low-pass, high-pass, and a band-pass filter. Each first-order filter will allow bass, treble, and mid-range frequencies, respectively. The low-pass filter has a cut-off frequency of 1 kHz. The band-pass filter allows frequencies between 300 Hz and 7 kHz. The high-pass filter cut-off frequency is 1 kHz. The amount that each filter is amplified depends on the frequency response of the speaker. Low frequencies are not reproduced as sound as highly as high frequencies, so the output of the low-pass filter will be amplified through a power amplifier. After the filter stage, each of the three signals will be sent through a weighted-summing amplifier. In this design, the gains of the input resistors determine the gain for each signal. Therefore, three potentiometers can be used to adjust the gain of each band of the equalizer. The final signal will then be sent through a speaker.
The idea behind what we are hoping to accomplish in this project is a voice activated lock. Our main goal is to get a servo to open a lock when a specific word and voice match is recognized. We will be employing Matlab, a microphone and the kiethley board. To set up this device we will record a tone and then when the user wants to open the lock they will try and make it again and hope to match it later on as an input. The output will be power to the small motor which will then open the lock.
The plan of this project is to produce a sonar image of an object located in a fish tank. A grid will be set up above the tank along with an ultrasound sensor. This ultrasound sensor will produce a signal and calculate the time delay based on the signal it receives from the object it is deflected off of. An image will then be produced after the ultrasound sensor is placed in each individual square of the grid. Water will not be used in the fish tank because of difficulty.
We will design a network of LEDs which will respond to an external music source. The LEDs will light up in a pattern which will be dependent on the music and a program which will control the LEDs. The music will be the input into the system, which will undergo various manipulations in order to produce a pattern of LED activity (dancing). The manipulations can include, but are not limited to, convolution and filtering.
For our lab project, we are designing an analog equalizer using 2nd order high pass, low pass, bandpass, and notch filters. We are also planning to implement the transfer functions for each filter in Matlab.
The goal for this project is to create a tuner for an instrument, specifically an acoustic guitar. A note will be played and read through a microphone where the signal will be amplified before being converted to a digital signal. The resulting wave will be analyzed in MATLAB and an output will display what note was played as well as whether the note was sharp, flat, or in tune.
An audio amplifier's rudimentary purpose is to accept a signal and alter the strength of the signal so that it is strong enough to drive the output. There are many different audio amplifier topologies, each with their own characteristic output. Our group chose to implement an amplifier using transistors and analyze its output characteristics at varying frequencies in the audible range. The group will build an amplifier and analyze how the output changes over a certain frequency ranges, as well as analyze the frequency spectrum to understand what range of frequencies the amplifier biases.
Our goal is to create a circuit that will self-destruct when the code word "boom" is spoken. This circuit would have the ability to be placed within any other circuit that the user desires, allowing unobstructed flow of data until the code word is given. Once the code word is recognized, an open circuit will essentially be created, and data will cease to be passed.
There are two inputs into this circuit. The first input is for the data that will pass unobstructed to the lone output, and the second is for the microphone that will receive the code word and thereby cause the circuit to self-destruct. The microphone will pass any noise it hears to the computer where it will be analyzed by Matlab. If the code word is confirmed, our current plan is to have an excess amount of current be released in the circuit, causing a fuse to trip and creating the open circuit.
This project is to design a three switch device that is controlled by sound. The switch will be tuned to respond to the snap of a finger. After being activated by one snap, the switch will count the number of snaps (1, 2 or 3) and turn on the corresponding light. The input would be a microphone connected to a variety of filters to convert the snap to a smooth pulse. The pulse would be fed into a 16f84 PIC microcontroller which will count the pulses. The PIC would then send a five volt signal to the relays controlling the lights.
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