Preliminary Design

Problem Background

Modern ham radios are often "black boxes," with proprietary designs hindering the hands-on learning central to amateur radio’s mission of “advancing the radio arts.”

Problem Analysis

Newer generation wireless systems operate at microwave frequencies above the 6 meter amateur radio band. System complexity of microwave RF systems has resulted in a reduction of homebrewed amateur experimentation with greater reliance on commercial options for interacting with the microwave spectrum.

This reduction in homebrewed radio equipment has also further diminished consumer understanding of these systems, to the point of not recognizing their presence. To this effect, students are entering the RF field with less contemporary knowledge with reduced exposure.

Features

This project is an open-source, modular platform that demystifies radio technology by exposing its core subsystems.

​This platform provides a transparent, hands-on prototyping system for students and hobbyists to explore ​ham radio design, embedded systems, and communication system principles.​

The system integrates a complete RF signal chain, an audio subsystem, battery management with USB-PD, and a central microcontroller running FreeRTOS to control peripherals via I2S, SPI, and I2C.​

Approach

Taking a modular approach inspired by the prototyping systems established by companies like Adafruit, SparkFun, and later used by Arduino, the outcome of this senior design work is a development kit capable of demonstrating system integration of the various subsystem nodes described herein.

This approach allows for the use of multiple communication interfaces between interconnecting nodes. Notably, instead of a "daisy-chain" approach seen in existing prototyping systems, there is a centralized microcontroller whos communication interfaces are broken out over these standard connectors.

Requirements

System must be capable of two-way communication All design material including code must be open source HMI shall enable user interaction of devices through peripherals
System PCB modules will be custom designed RF features must allow for amateur repeater operation Guided instructional videos must be accessible for easier interaction System documentation must be accessible and easily repeatable (including standard safety guidelines) End product must be presented as an educational kit

Decision Analysis

The concept of a Modular Arduino "Modulino" is expanded from I2C "Inter-Integrated Circuit" serial communications interfacing over SparkFun Qwiic (also known as Adafruit Stemma QT) 4-pin JST connectors to the Adafruit EYESPI 18-pin FPC connectors used in SPI Display prototyping products.

Solution Analysis

Through the use of standard interconnects, this project builds upon ecosystems previously established for device evaluation boards to allow the testing of several embedded devices.

• Power Modulino nodes negotiate and use USB power to supply power to all subsystems.
• HMI and Audio Modulino nodes provide a user interface for which different test and operating modes can be selected for the system.
• ESP32 Modulino node provides the required hardware interfaces between all subsystems.
• RF Modulino nodes demonstrate the use of the prototyping system as both a baseband and wireless communication system as an amateur radio experiment.

Effectiveness Criteria

The solution must be effective in providing experimentation materials that follow the Test Plan of the project. The effectiveness of the designed elements is measured by the successful translation into paired lab material built from the initial test criteria into educational content.

Hardware

Hardware documentation must be traversible and accurate to the assembled hardware. Assembled hardware must be utilized by at least one lab activity.

Firmware Criteria

Firmware documentation must describe system startup and test procedures. Procedures must be related to subsystem functionality and utilized by at least one lab activity.