Project

# Title Team Members TA Documents Sponsor
14 PocketScope
 Aaron Holl
Caleb Peach
Rohan Nagaraj
# Team Members:
- Rohan Nagaraj (rohan14)
- Aaron Holl (amholl2)
- Caleb Peach (calebrp2)

# Problem

Most signal generators and oscilloscopes are limited to large laboratory instruments. They are also very costly and usually reserved for universities and company labs. Currently, there is no cheap, pocket-sized, convenient, and compact signal generator/oscilloscope designed for electricians, hobbyists, and engineers to use in the field while troubleshooting electrical problems.

# Solution

With advancements in microcontroller technology (specifically cheaper, smaller, and more powerful devices) our team can create a handheld, pocket-sized, two-in-one oscilloscope and signal generator. It will include an OLED screen to display a user interface with a time-versus-voltage/current plot, options for generated signals, and other features for quick measurements such as a voltmeter and ohmmeter. It will also include software based analysis tools such as FFT, curve-fitting, and the ability to export data as a CSV to a computer.

Software, ADC, and DAC functionality can be handled through an ESP32 or a similar microcontroller. Basic circuit design using op-amps and voltage dividers can be used to scale larger input signals down to ranges acceptable for the microcontroller’s ADC. The user interface software can be implemented using C and Python.

# Solution Components

## Subsystem 1: Voltage and Current vs Time

This subsystem will take a real-world signal ranging from [-20 V, 20 V] and scale it down to a 0 to 3.3 V range since this is the typical input range for a microcontroller’s ADC. We can easily do this mathematically by dividing the function by a scaling factor (implemented in a circuit with a voltage divider) and adding an offset (using an op-amp adder circuit) to get it in the suitable range. We will use a LM741 op amp to do this since it is one of the most popular and widely used op-amps in circuit design.

Our microcontroller will be an ESP-32 or STM-32 since it has an onboard ADC that can read voltages in the 0 to 3.3 V range. It also has the computing ability for small scale graphics for the waveforms vs time and can handle other DSP intensive threads.

## Subsystem 2: LCD Touchscreen

This subsystem will display our application code written in C, Python, and possibly Arduino. It will display the voltage/current waveforms, show menus for signal generation, display spectrogram readings, show analysis tool details, and provide major control over the device. We will use a LCD capacitive touch bare display which communicates with our microcontroller over SPI. Adafruit provides a suitable display (https://www.adafruit.com/product/2090) that can be used for this.

## Subsystem 3: USB-C Charging and Computer Exportability
- USB-C PCB mount on our custom PCB will allow for microcontroller programming, battery re-charging, and allow the microcontroller to export a .CSV file to a connected computer
- USB-C will support USB 2.0 at 12 Mbps since this is fast enough to import CSV data and machine code data to the microcontroller without having to worry about impedance controlled traces on D+ and D- lines.
- The UJ20-C-H-C-4-SMT-TR (USB-C PCB mount) will allow us to have this connectivity
- USB-C also natively supports a 5V power supply over the VBUS terminal, so we can use this to charge a rechargeable lithium ion battery that allows the device to be mobile

## Subsystem 4: Time varying FFT (Spectrogram) of input signal
- In software, we will implement a short time Fourier Transform algorithm to show a real-time spectrogram of the input signal
- We do this by sampling the signal in short windows and taking the FFT of the instantaneous waveform, displaying it, and then repeating the process in real time such that the user can accurately see how the frequency components of the signal change over time

## Subsystem 5: Waveform Signal Generation
User will be able to choose between the following pre defined waveform shapes we support:
- Rectangle Wave
- Triangle Wave
- Sine Wave
- Sawtooth Wave
- Pulse Signal
- Gaussian Noise function

This will be generated by the microcontroller (ESP-32 or STM32) via PWM through a GPIO pin and amplified to a 0 to 5 V range through an op-amp amplifier (again using the LM741). The frequency, phase, duty cycle, and amplitude of the waveforms can be fully customizable by the user.

## Subsystem 6: Machine Learning Algorithm for Input Waveform Analysis
- Implement a machine-learning-based parameter estimation algorithm using gradient descent to fit mathematical models to measured input waveforms
- We will base our algorithm on a Nth order polynomial fit (where N is a parametrized by the user, giving more accuracy on the fit)
- This can be used to characterize transient behavior, dynamic response, and system properties related to impulse and frequency response

# Criterion For Success
- The device needs to be portable such that the entire structure can fit comfortably in your hand and ideally within a pants or jacket pocket.
- The device needs to have a battery system that can support at least a couple hours of use, in order to serve the needs of the users who may be unable to plug the device into an outlet while using it.
- The device needs to be able to read any arbitrary signal within a -20 V to +20 V range and display them accurately on the screen.
- The screen needs to be easy to read and the interface must be concise and unobtrusive. Also the screen should be sturdy enough to be used frequently without fear of damage.
- The device needs to have an overvoltage protection system that prevents the circuits from burning out if a high voltage signal is put across the input pins.
- The metal pins that read the voltage signal must be adjustable in gap width and/or compatible with a set of detachable probes that can be placed on any two points of a target circuit.

# Alternatives
Small oscilloscopes have already been implemented and manufactured. Our solution is unique as we will implement our ideas in a cost efficient, energy efficient, space efficient manner for low voltage inputs, which is not currently available (current solutions are too big, too expensive, or too energy efficient for low voltage systems).

https://www.digikey.com/en/products/detail/owon-technology-lilliput-electronics-usa-inc/HDS1021M-N/10667422?gclsrc=aw.ds&gad_source=1&gad_campaignid=20228387720&gbraid=0AAAAADrbLlg8c4vRvwakbVmhST4aZ3Gqw&gclid=Cj0KCQiA4eHLBhCzARIsAJ2NZoIiJi_xpcOgqdLhCqINMhACTyUvaBxYUS1mqWpOtyJXAPze3dIfL64aAkQHEALw_wcB

Resonant Cavity Field Profiler

Salaj Ganesh, Max Goin, Furkan Yazici

Resonant Cavity Field Profiler

Featured Project

# Team Members:

- Max Goin (jgoin2)

- Furkan Yazici (fyazici2)

- Salaj Ganesh (salajg2)

# Problem

We are interested in completing the project proposal submitted by Starfire for designing a device to tune Resonant Cavity Particle Accelerators. We are working with Tom Houlahan, the engineer responsible for the project, and have met with him to discuss the project already.

Resonant Cavity Particle Accelerators require fine control and characterization of their electric field to function correctly. This can be accomplished by pulling a metal bead through the cavities displacing empty volume occupied by the field, resulting in measurable changes to its operation. This is typically done manually, which is very time-consuming (can take up to 2 days).

# Solution

We intend on massively speeding up this process by designing an apparatus to automate the process using a microcontroller and stepper motor driver. This device will move the bead through all 4 cavities of the accelerator while simultaneously making measurements to estimate the current field conditions in response to the bead. This will help technicians properly tune the cavities to obtain optimum performance.

# Solution Components

## MCU:

STM32Fxxx (depending on availability)

Supplies drive signals to a stepper motor to step the metal bead through the 4 quadrants of the RF cavity. Controls a front panel to indicate the current state of the system. Communicates to an external computer to allow the user to set operating conditions and to log position and field intensity data for further analysis.

An MCU with a decent onboard ADC and DAC would be preferred to keep design complexity minimum. Otherwise, high MIPS performance isn’t critical.

## Frequency-Lock Circuitry:

Maintains a drive frequency that is equal to the resonant frequency. A series of op-amps will filter and form a control loop from output signals from the RF front end before sampling by the ADCs. 2 Op-Amps will be required for this task with no specific performance requirements.

## AC/DC Conversion & Regulation:

Takes an AC voltage(120V, 60Hz) from the wall and supplies a stable DC voltage to power MCU and motor driver. Ripple output must meet minimum specifications as stated in the selected MCU datasheet.

## Stepper Drive:

IC to control a stepper motor. There are many options available, for example, a Trinamic TMC2100. Any stepper driver with a decent resolution will work just fine. The stepper motor will not experience large loading, so the part choice can be very flexible.

## ADC/DAC:

Samples feedback signals from the RF front end and outputs the digital signal to MCU. This component may also be built into the MCU.

## Front Panel Indicator:

Displays the system's current state, most likely a couple of LEDs indicating progress/completion of tuning.

## USB Interface:

Establishes communication between the MCU and computer. This component may also be built into the MCU.

## Software:

Logs the data gathered by the MCU for future use over the USB connection. The position of the metal ball and phase shift will be recorded for analysis.

## Test Bed:

We will have a small (~ 1 foot) proof of concept accelerator for the purposes of testing. It will be supplied by Starfire with the required hardware for testing. This can be left in the lab for us to use as needed. The final demonstration will be with a full-size accelerator.

# Criterion For Success:

- Demonstrate successful field characterization within the resonant cavities on a full-sized accelerator.

- Data will be logged on a PC for later use.

- Characterization completion will be faster than current methods.

- The device would not need any input from an operator until completion.

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