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

2. 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
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3. 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
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4. Software Winamp Generates signal vector from MP3, Wav, etc.
Creates a 256 bit amplitude stored in an array according to frequency channel.
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5. 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.
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6. 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
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7. 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.
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8. 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.
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9. 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
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10. 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.
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11. UP2 Board Output
16 output pins produce controllable PWM signals for each pump
An output of 5V at 10 mA of current is insufficient.
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12. 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
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13. 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 …
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14. 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
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15. 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
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16. 12V/20A/240W AC to DC converting Power Supply.
Power Supply Design
12V/20A/240W AC to DC converting Power Supply.
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17. 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
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18. 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
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19. 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:
April 29
Present Final Demo
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20. Questions?
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