Ahmed Saheb

1
Group 5

• Ahmed Saheb
• Jason Skinner
• Jake Ungerer
• Dallas Webster
• Instructor Dr. Dickens
• Advisor Dr. Mitra

2
Project Overview

• Design and Implement a radio control transmitter
  and receiver system for the WT BEST robotics
  competition. The system is intended to replace
  the current transmitter/receiver system. The new
  system must be user friendly and cost effective.

3
Block Diagram
Power Amp
Direct Digital Synthesizer
Micro- controller
Controller
Low Noise Amp
Band Pass Filter
Micro- controller
Receiver
Robot

Jake Ungerer
4
Controller/Microcontroller
Jake Ungerer
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Sony Playstation Controller

• DATA MSP430 URXD0 Pin 33
• 2. COMMAND MSP430 UTXD0 Pin 32
• 3. N/C
• 4. GROUND (GND) MSP430 GND Pin
• 5. VCC MSP430 VCC Pin
• ATTENTION (ATT) MSP430 P6.0 Pin 59
• CLOCK signal (CLK) MSP430 TB0 Pin 36
• N/C
• ACKNOWLEDGE (ACK)

Jake Ungerer
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MSP Transmission Packet

• 6 bits of Checksum
• All enclosed in a long long variable.
• Synch Pattern
• 1010101011
• 48 bits of Data

Jake Ungerer
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Transmit Algorithm
Upon Entering output compare Interrupt
Jump to the transfer Function
Bitwise AND data with Mask 0x01
If True then set Port 1 pin1 High
If False then set Port 1 pin1 Low
Shift mask one bit to the left And set delay to
occur again
Jake Ungerer
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MSP Receive

• Servo code has been tested
• Receive code has been tested
• Just need test with a servo

Jake Ungerer
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MSP Setup
Jake Ungerer
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DDS

• Digital Data Synthesizer
• Outputs different frequencies
• Used for FM modulation

Jason Skinner
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Schematic
Jason Skinner
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Layout
Jason Skinner
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Milled Board
Jason Skinner
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DDS output
Jason Skinner
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Amplifier System
Ahmed Saheb
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Transmitter Amplifier
7 Volts
Preamplifier
Power Amplifier
Ahmed Saheb
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Power Amplifier Layout
Ahmed Saheb
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Power Amplifier
Input -7 dbm
Output 23.92 dbm
Gain 30 db
250 mW
Ahmed Saheb
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Power Amplifier with Filter
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Transmitter Signal
Ahmed Saheb
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Band Pass Filter

• -4dBm _at_ 7MHz
• Bandwidth 20MHz

Jason Skinner
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Filter
Jason Skinner
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Filter
Jason Skinner
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Soldered LNA Board
Ahmed Saheb
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LNA Output
input -40 dbm
Output -8.66 dbm
-8.66dbm 90mV
Gain 31 db
Ahmed Saheb
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LNA Testing
Ahmed Saheb
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Testing the Amplifier System
Signal Generator
Spectrum Analyzer
Power Amp
LNA
Filters
Ahmed Saheb
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Testing amplifier System
Receiver
Transmitter
Power Amp
LNA
Filter
Ahmed Saheb
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Received Signal
Transmitting a signal 23 dbm
Received signal -11 dbm
64 mV
Ahmed Saheb
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Receiver

• Mixer-AD608 (Circuit design by Brian McDaniel,
  Layout and board by Dallas Webster and Ryan
  Hebert)
• DDS 9850- acts as the local oscillator being
  programmed by an MSP430
• RF signal directly from low noise amplifier
• Demodulator 4046B Phase Locked Loop (Chosen
  after comparison with Quadrature Detector)
• Output to LM339 Comparator to condition signal
  for MSP430 usage

Dallas Webster
31
Receiver Evolution
The Dream The Schematic The Layout The
Professional Board
Dallas Webster
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Comparator Circuit

• Circuit takes an average by charging and
  discharging a capacitor
• Hysteresis
• Removes any noise that may be caused by a jumpy
  PLL signal
• Very small value used from testing

Dallas Webster
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The Results
Time to add amplifiers!!!!
111110101010 Green Mixer Output Yellow
PLL/Comp Output with DDS, Filter, Mixer, and
PLL/Comparator
10101010100000000011111110000000011111111
Dallas Webster
Playing with Joystick
Default Output
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Results

• Actual output after transmission through air!!!
• Approximately six feet with no problems
• Antennas were not in parallel still works!!
  Like a champ
• See videos to be impressed

Data
Sync Byte
Dallas Webster
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Is the output correct?

• Green-Direct MSP output
• Yellow-Direct Comparator output
• Antennas are not in parallel
• Distance 7ft
• Output follows input without an obvious delay

Dallas Webster
36
Bit Error Rate vs. Distance

• 12 ft
• 0 BER
• 15 ft
• 5 BER
• 16 ft
• 43 BER

With less than ideal power amplifier. Under
better conditions this range should definitely
improve.
Dallas Webster
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How Long Will It Last?

• Transmitter
• Draws 340 mA total
• With a 1500mAH battery this will last
  approximately 4.411 hours
• Power 340mA7.2V 2.448 W
• Receiver
• Draws 140 mA total
• With a 1500mAH battery this will last
  approximately 10.71 Hours
• Power 140mA7.2V 1.008 W

Dallas Webster
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Conclusions

• Easy improvements
• Antenna matching
• Alignment
• Power amp (only transmitting ¼ W)
• Meet requirements
• Reliable up to 12 ft. (limited by power amp)
• Endurance
• Cost90 for transmitter/receiver pair
• Is it worth it? Considering the overall project
  costs roughly 20,000, you would have to make
  approximately 115 units _at_ 125/unit to make up
  the money spent on design/initial implementation

Dallas Webster
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Budget
40
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Questions ?