--- title: UWAA project briefs 2024 author: peter date: 2024-03-05 10:40:20 +0800 categories: [UWAA] # Blogging | Electronics | Programming | Mechanical tags: [electronics, projects] # systems | embedded | rf | microwave | electronics | solidworks | automation # image: assets/img/2024-03-05-UWAA-project-briefs-/preview.png toc: true --- Updating this as I add new projects this year. # Telemetrum ground station The Telemetrum's Teledongle ground station is out of stock everywhere. We should make our own. ## Success criteria - Receive signals from the [Telemetrum](https://altusmetrum.org/TeleMetrum/) flight computer over a distance of at least 10 kft. - Send data to a computer over USB virtual COM port in a format which can be interpreted in real time by the [AltosUI flight monitoring software](https://altusmetrum.org/AltOS/). ## Scope - Make a PCB which contains a cheap microcontroller with USB support and the CC12xx or CC11xx radio transceiver. - Make sure the PCB has mounting holes so it can fit into a case. - Use an SMA connector. - Create software to copy the data from the receiver to the computer over USB through an intermediate MCU. ## Hints and notes - You must read this [protocol specification](https://altusmetrum.org/AltOS/doc/telemetry.html) for the AltusMetrum devices. Luckily, the Teledongle does minimal processing of the raw data, it only encodes it into an ASCII format before transmitting it over serial. - You should look at the schematics and PCB layout for the Teledongle for inspiration https://altusmetrum.org/TeleDongle/. - I advise you don't use the NXP LPC11U14 since a cheaper microcontroller can do well - [!] PRO TIP: Use JLCPCB's part library to save on money! It tends to be cheaper per unit than buying from distributors online since JLC buys the parts at wholesale prices. - You should consider using the [basic parts library](https://jlcpcb.com/parts/basic_parts) to place passives (resistors, capacitors). On Altium, all components in this library will have a `JLC_PN` attribute. - Using extended parts outside the basic library list will incur a $3 USD fee per unique part, but when assembling 5 boards this still beats distributor prices. Of course, if a part is in the basic library it should be used if possible - You may decide to use this alternative site to look up parts since JLC's parametric search isn't great https://yaqwsx.github.io/jlcparts/ - Try to place all/as many components on one side of the board only so you can use economic PCBA, which only places parts on one side. - Feel free to ask me for Altium training, and I will probably need to talk about RF design considerations ## Future development - Make this a module card which can go into a standalone battery powered ground station which does not need a laptop to use. This can be helpful if our laptops run out of energy and there are no generators. # Analog video transmitter ## Success criteria - Receive at least 1 minute of video over a 10 kft LOS distance ## Scope - Make a prototype setup to transmit and receive analog or digital video - Use a raspberry pi to overlay text containing telemetry such as altitude, position, etc. - Does not need to be a PCB yet ## Hints and notes - To be honest, I am not quite sure how this stuff works and I'm interested in learning as well - Two ways I can see this being done: - 1. Use a project like wifibroadcast[[1](https://befinitiv.wordpress.com/wifibroadcast-analog-like-transmission-of-live-video-data/)][[2](https://hackaday.com/2015/06/13/wifibroadcast-makes-wifi-fpv-video-more-like-analog/)] which transmits digital video. Check out the link for more information. - 2. Use a COTS analog 2.4 GHz video transmitter and receiver. Search 2.4 GHz video transmitter for examples. The TX6722 and RX6788 appears to be a common combination for 2.4 GHz band. - Consider the differences in quality, error handling and bandwidth required when deciding between analog and digital video - I'll update this once we get past a prototype # Software defined gnss receiver ## Success criteria - Get position and altitude of the rocket through all stages of flight, including stages which exceed the velocity and/or altitude limitations of commercial GNSS receivers (510 m/s, 59,000 ft. See: [Coordinating Committee for Multilateral Export Controls](https://en.wikipedia.org/wiki/Coordinating_Committee_for_Multilateral_Export_Controls?&useskin=vector)) # Scope - Make a prototype/MVP system for doing this. It doesn't need to fit into a rocket or require self-powering at this current design phase. I will update the project when we have an MVP working. - Test doing the post-processing on a single board computer. - Record enough data from launch to landing # Hints and other notes - Capture raw [IQ](https://en.wikipedia.org/wiki/In-phase_and_quadrature_components?&useskin=vector) data from an SDR and do the post-processing in something like [GNSS SDR](https://github.com/gnss-sdr/gnss-sdr). Select an appropriate SDR which can digitize the L1 C/A GPS signal - This exists https://www.rtl-sdr.com/rtl-sdr-tutorial-gps-decoding-plotting/, but it seems to require a computer with windows installed to process the data. # Future development - Miniaturize this setup and add a power system for use on a rocket - Make a custom RF frontend specialized for the GNSS signals which is cheaper than buying an SDR - Is it possible to use an FPGA to process this signal in real-time? (It's apparently really hard to do... I searched and the latest real-time implementation is from 2013)