Spectrum Analyzer Ray Mathes, Nirav Patel, Sagar Savant, Richard Wunderlich Group 8, ECE4006D Georgia Institute of Technology School of Electrical and Computer Engineering

Project Overview A Spectrum Analyzer that synthesizes audio input from the computer and outputs it as a physical spectrum. Input: MP3, Wave-Input, Microphone Output: Water Jets representing spectral frequencies. Features Tunable to frequency ranges to increase bin resolution Real-Time Response Group 8 - Spectrum Analyzer, 2

Design Layout Computer Pump Array Power Supply Audio P1 Winamp Altera Board P2 UP2 Input MAX7000 Chip PWM Logic Switching Circuit … FFT Plugin P15 P16 Paralell Port Group 8 - Spectrum Analyzer, 3

Software Winamp Generates signal vector from MP3, Wav, etc. Creates a 256 bit amplitude stored in an array according to frequency channel. Group 8 - Spectrum Analyzer, 4

Software (cont.) Winamp Plugin Computer Audio Winamp FFT Plugin Paralell Port Winamp Plugin Convert the amplitude into 3 bits by chopping off the lower 253 bits. Divide up the frequencies into usable bins of 16 for each pump address, 4 Bits. Allow for variation of frequency range Use API Calls for the Parallel Port to send pump address and data bits to the Altera board. Group 8 - Spectrum Analyzer, 5

Hardware Want a visually variable amplitude Solution Varying speed of pump varies flow rate Flow rate determines height of water jet Solution DC Motors vary speed with input voltage Easiest way to achieve this digitally is through Pulse Width Modulation (PWM) UP2 Input MAX7000 Chip PWM Logic Altera Board Group 8 - Spectrum Analyzer, 6

Pulse Width Modulation A PWM signal is a pulse train with varying duty cycles If the frequency of the input voltage is too high, the motor cannot turn on and off fast enough. By modifying the duty cycle, PWM reduces the voltage to the pump. Group 8 - Spectrum Analyzer, 7

7 Bit Input Want 8 steps of resolution in the height Sending 3 bits of amplitude data per pump: 3*16 = 48 bits Requires too large of a bus for parallel interface Solved through Addressing Send 3 bits for amplitude and 4 bits address data (7 bits total). Requires 16 calls from the Parallel Port to update every pump Logic continues generating PWM on each output channel until updated again. Group 8 - Spectrum Analyzer, 8

Logic 16 channels of PWM generation logic Amplitude and address decoding logic Would require a large quantity of ICs and discrete logic to implement. Solution: FPGA Group 8 - Spectrum Analyzer, 9

FPGA Altera UP-2 Board FLEX10K70 FPGA, 70,000 gates. Loses memory when powered off. MAX7000 CPLD, 2,000 gates. Maintains chip logic and memory. Group 8 - Spectrum Analyzer, 10

UP2 Board Output 16 output pins produce controllable PWM signals for each pump An output of 5V at 10 mA of current is insufficient. Group 8 - Spectrum Analyzer, 11

Chopper Circuit Purpose: Turn pumps on/off (Variable amp.) Components Darlington Transistor: Cascaded BJTs for current amplification Diode: Assist motor to discharge stored current Benefits: High current amplification Switching Circuit Group 8 - Spectrum Analyzer, 12

Attwood V500 Water Pumps Characteristics Benefits DC powered, low power consumption (1.2A, 12V) Benefits DC pumps reduce cost, powerful, amplitude control Shoots water up to 3 feet in the air without a nozzle, 350GPH Pump Array P15 P16 P1 P2 … Group 8 - Spectrum Analyzer, 13

Attwood V500 Water Pumps (cont.) Problems with solenoids Too Expensive Don’t move very far (5 inches) Overheating problems Water Pump Array 16 pumps at maximum flow rate require a lot of current Group 8 - Spectrum Analyzer, 14

Power Supply Specifications High Current Supply ~ 240 Watts (12V 20A) 16 pumps; each pump draws 1.2A max I = 16*1.2 = 19.2A Ferroresonant Transformer PWM used to obtain correct voltages Using a 10,000uF 80V filter capacitor Group 8 - Spectrum Analyzer, 15

12V/20A/240W AC to DC converting Power Supply. Power Supply Design 12V/20A/240W AC to DC converting Power Supply. Group 8 - Spectrum Analyzer, 16

Design Challenges Research absorbed a great deal of time Ordering parts is too slow of a process Need for power supply Incapable of testing pumps safely in any lab Group 8 - Spectrum Analyzer, 17

Future Development Pumps Remove the computer element Greater number of pumps to increase resolution More powerful pumps for higher amplitudes Remove the computer element Input an audio jack Use a DSP processor to do frequency tuning similar to the Winamp plugin Design a structure to allow for indoor use Group 8 - Spectrum Analyzer, 18

Final Timeline April 18 April 22 April 27 April 29 Finish power supply Finish Winamp plugin and fine tune the characteristics Build encasement for Altera board, power supply, and switching circuit April 27 Complete webpage: http://4006.iceglow.com April 29 Present Final Demo Group 8 - Spectrum Analyzer, 19

Questions? Group 8 - Spectrum Analyzer, 20