Lab Notebook

Video, Slides

Keeping a professional record of your design work is a requirement of the course. If maintained properly, lab notebooks serve as an official and legal record of the development of the intellectual property related to your project. It also serves as a way to document and track changes to your design, results of all tests performed, and the effort you have put into your project. A well-kept notebook will simplify writing of all required documentation for this course (design review, final paper, etc) as all of the information in those documents should already exist in your notebook. Finally, keeping a notebook is simply good engineering practice and likely will be required by future employers, so it is a good idea to get in the habit of maintaining one now.

The Book

Any notebook with permanent bindings designed for laboratory record keeping is acceptable. Notebooks should have pre-numbered pages and square grids on their pages. We will not accept normal spiral-bound notebooks, as these are not permissible in court since pages can be easily replaced. While most of you probably won't be taking your design to court, we want to teach you to get into the habit of keeping legally acceptable records. Some of you may decide you do want to patent your project, so it will be very beneficial to have given yourself the legal advantage from the start.

Electronic Notebook

Alternatively, lab notebooks may be kept digitally as Markdown documents in a Git repo on Github or Gitlab, as in the example below. See a complete example of a 445 Git repo here.

notebooks/
├── alex/
│   ├── README.md
│   └── an_image.png
├── pouya/
│   └── README.md
└── nick/
    ├── README.md
    └── another_image.png
	

Notebook entries:

Each complete entry should include:

  1. Date
  2. Brief statement of objectives for that session
  3. Record of what was done

The record will include equations, diagrams, and figures. These should be numbered for reference in the narrative portion of the book. Written entries and equations should appear on the right-hand page of each pair. Drawn figures, diagrams, and photocopies extracted from published sources should be placed on the left-hand side, which is graph-ruled. All separate documents should be permanently attached to the notebook. All hand-written entries must be made in pen.

Overall, the book should contain a record that is clear and complete, so that someone else can follow progress, understand problems, and understand decisions that were made in designing and executing the project.

What to include:

There is always something to record:

Suppose you are only "kicking around" design ideas for the project with someone, or scanning library sources. Your objective is what you're hoping to find. The record shows what you found or what you decided and why, even if it isn't final.

One of the most common errors is to fail to record these seemingly "unimportant" activities. Down the road, they may prove crucial in understanding when and where a particular idea came from.

Submission and Deadlines

Lab notebooks must be submitted at lab checkout on Reading Day. If you are unable to attend lab checkout, please make arrangements with your TA ahead of time.

Phone Audio FM Transmitter

Madigan Carroll, Dan Piper, James Wozniak

Phone Audio FM Transmitter

Featured Project

# Phone Audio FM Transmitter

Team Members:

James Wozniak (jamesaw)

Madigan Carroll (mac18)

Dan Piper (depiper2)

# Problem

In cars with older stereo systems, there are no easy ways to play music from your phone as the car lacks Bluetooth or other audio connections. There exist small FM transmitters that circumvent this problem by broadcasting the phone audio on some given FM wavelength. The main issue with these is that they must be manually tuned to find an open wavelength, a process not easily or safely done while driving.

# Solution

Our solution is to build upon these preexisting devices, but add the functionality of automatically switching the transmitter’s frequency, creating a safer and more enjoyable experience. For this to work, several components are needed: a Bluetooth connection to send audio signals from the phone to the device, an FM receiver and processing unit to find the best wavelength to transmit on, and an FM transmitter to send the audio signals to be received by the car stereo.

# Solution Components

## Subsystem 1 - Bluetooth Interface

This system connects the user’s phone, or other bluetooth device to our project. It should be a standalone module that handles all the bluetooth functions, and outputs an audio signal that will be modulated and transmitted by the FM Transmitter. Note: this subsystem may be included in the microcontroller.

## Subsystem 2 - FM Transmitter

This module will transmit the audio signal output by our bluetooth module. It will modulate the signal to FM frequency chosen by the control system. Therefore, the transmitting frequency must be able to be tuned electronically.

## Subsystem 3 - FM Receiver

This module will receive an FM signal. It must be able to be adjusted electronically (not with a mechanical potentiometer) with a signal from the control system. It does not need to fully demodulate the signal, as we only need to measure the power in the signal. Note: if may choose to have a single transceiver, in which case the receiver subsystem and the transmitter subsystem will be combined into a single subsystem.

## Subsystem 4 - Control System

The control system will consist of a microcontroller and surrounding circuitry, capable of reading the power output of the FM receiver, and outputting a signal to adjust the receiving frequency, in order to scan the FM band. We will write and upload a program to determine the most suitable frequency. It will then output a signal to the FM transmitter to adjust the transmitting frequency to the band determined above. We are planning on using the ESP32-S3-WROOM-1 microcontroller given its built-in Bluetooth module and low power usage.

## Subsystem 5 - Power

Our device is designed to be used in a car, so It must be able to be powered by a standard automobile auxiliary power outlet which provides 12-13V DC and usually at least 100W. This should be more than sufficient. We plan to purchase a connector that can be plugged into this port, with leads that we can wire to our circuit.

# Criterion for Success

The device can pair with a phone via bluetooth and receive an audio signal from a phone.

The Device transmits an FM signal capable of being detected by a standard fm radio

The Device can receive FM signals and scan the FM bands.

The digital algorithm is able to compare the strength of different channels and determine the optimal channel.

The device is able to automatically switch the transmitting channel to the predetermined best channel when the user pushes a button.