Project

# Title Team Members TA Documents Sponsor
61 Automatic Motorized Satellite Tracker/GroundStation & Down Converter Subsystem/RF frontend
 Jumana Schmidt
Rishan Patel
Wiley Tong
 Jason Jung design_document1.pdf
proposal1.pdf
# Automatic Motorized Satellite Tracker/GroundStation & Down Converter Subsystem/RF Frontend
Team Members:
Jumana Schmidt (jumanas2)
Wiley Tong (wileyt2)
Rishan Patel (rishanp2)

# Problem:
There are over 14,000 satellites orbiting the Earth. From real-time weather images, pictures of our Sun, HAM radio, to leaked unencrypted military communications, each satellite is transmitting a variety of readily available data. Some of this data can even be life saving or critical to our infrastructure. With such intriguing information available, it is no wonder why there has been a growing interest in satellite communications for so many different communities. However, accessing satellite data directly or indirectly typically requires either internet based services, expensive tracking hardware, RF experience, and a lot of manual setup. For off-grid users, remote communities, and students learning RF/satellite communication, this creates a large barrier: even if the satellites are transmitting overhead, it’s hard to reliably aim an antenna, lock the signal, and turn that RF into usable decoded output.

Many relevant or interesting satellites, including those for weather, are low Earth orbiting (LEO), which require real-time tracking through the sky, either manually or a motorized mount. There are no commercial and affordable hands-free, motorized antenna mounts, and none of them are truly hands-off and automated. They also usually transmit in L-band and/or in S-band. So even though most of the equipment to start can be homemade or cheap, such as an antenna, some free software, and a basic software defined radio dongle (like a RTL-SDR), these microwave band signals can still be hard or impossible to properly receive and decode due to limited range. An MMDS or frequency downconverter is required for both a cheap option like an RTL-SDR and even a step up to a $300 Hack RF One. Additionally, there are not many commercial and affordable downconverters available As a result of both of these obstacles, receiving any updated critical/useful data is often impractical, inconsistent, or too costly for most people to try.

# Solution:
Our overall goal is to help make radio and satellite tracking/reception more accessible for educators, researchers, remote communities, survivalists, and radio enthusiasts alike. To accomplish part of this task, we seek to address two of the most inaccessible and unaffordable aspects: live tracking and making those microwave transmissions receivable by cheaper SDR’s. More specifically, we will create an affordable automatic, motorized satellite tracker/receiver and a custom S-band frequency downconverter.

# Solution Components:

## 1. Motorized Antenna Mount

- RTL-SDR: $30
Antenna & Dish parts: Usually negligible (could be free depending on the sources & band type)
- Azimuth Motor: $28
https://www.amazon.com/gp/product/B0FMY17QRT/ref=ewc_pr_img_3?smid=AVTJBJ76BDD27&psc=1


- Elevation Motor: $37
https://www.amazon.com/dp/B0C69W2QP7/ref=sspa_dk_detail_1?pd_rd_i=B0C69RSJNT&pd_rd_w=dJt1j&content-id=amzn1.sym.386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_p=386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_r=5H73NB21EDBPJSF5WR2Y&pd_rd_wg=dDyFo&pd_rd_r=79ee8ae1-1e2f-4b6f-bd54-edc53447b320&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM&th=

- 9 DOF IMU: BNO055 $9

- Lazy Susan Bearing: $15

- MCB & Power Management + parts: $8 + Negligible
Esp32: $8
- Mount Brackets: Machine Shop

## 2. Down Converter Subsystem/RF frontend
The RTL-SDR has a max frequency of 1.75 GHz. In order to receive and demodulate S band signals we need to build a down converter that brings 2-3.5 GHz signals into range of the RTL-SDR. The down converter is an analog heterodyne: the RF signal from the antenna will be multiplied by a 1.5 GHz local oscillator signal using an rf mixer.

This submodule would require:
- RF LNA (SKY67151-396LF)
- S band bandpass filter (BPF-AS1600-75+)
- active RF mixer (LT5560EDD#PBF)
- pll synth (LMX2531LQ1910E/NOPB)
- possibly include mcu to control pll
- oscillator reference clock (UCE4031035LK015000-10.0M)
- IF filter (built from LC components or use a detector)
- SMA connectors
- SMD rlc components
- SMD balun, tapped transformers

There will be two boards: LNA and filter board connected directly to the antenna to reduce loss, the down converter board that feeds into the RTL-SDR. Making the LNA and down converter into separate modules also makes testing easier. Even if the more complex downconverter fails the LNA module can be saved.

# Criterion For Success:
For the motorized antenna mount, we will have succeeded if the device is relatively affordable and able to smoothly automatically track a satellite, given streamed live TLE coordinates from a computer. We want the user to be able to just connect the antenna, SDR, and filters of their choice one time, and be able to send scheduled coordinates to start tracking a satellite any time. And the S-band downconverter will have been confirmed to work if we can receive S-band satellite communications on much lower, easily accessible frequencies.

## S-Band Satellite Options:
- Hinode Solar B: 2256 MHz
- Jason-3: 2215.92 MHz
- Blue Walker 3: 2245
NOAA 20: 2247.5 MHz

In the future, we’d hope to have a dashboard for data collected and logs, to make it into a more automated, full ground station. We also hope to build an adjustable down shifter so that the module can downshift signals beyond 3 GHz.

# Alternatives:

## Motorized Antenna Mount
- Ant Runner Pro: $500
## S-band Down Converter

- RTL-SDR Blog Wideband LNA + Bias Tee $28
https://a.co/d/0g0wGGSv
- Nooelec HAM It Down: $90-125
https://www.nooelec.com/store/ham-it-down.html?srsltid=AfmBOooLr50utjbiAL63G1_oEChwrt4FRbUYePs9j1fTbOP_XoPrxOto
- Sysmo S-band Cavity Filter: $80 (not always available)
https://shop.sysmocom.de/S-Band-cavity-filter-2170-2300-MHz/cf2235-kt30

Illini Voyager

Cameron Jones, Christopher Xu

Featured Project

# Illini Voyager

Team Members:

- Christopher Xu (cyx3)

- Cameron Jones (ccj4)

# Problem

Weather balloons are commonly used to collect meteorological data, such as temperature, pressure, humidity, and wind velocity at different layers of the atmosphere. These data are key components of today’s best predictive weather models, and we rely on the constant launch of radiosondes to meet this need. Most weather balloons cannot control their altitude and direction of travel, but if they could, we would be able to collect data from specific regions of the atmosphere, avoid commercial airspaces, increase range and duration of flights by optimizing position relative to weather forecasts, and avoid pollution from constant launches. A long endurance balloon platform also uniquely enables the performance of interesting payloads, such as the detection of high energy particles over the Antarctic, in situ measurements of high-altitude weather phenomena in remote locations, and radiation testing of electronic components. Since nearly all weather balloons flown today lack the control capability to make this possible, we are presented with an interesting engineering challenge with a significant payoff.

# Solution

We aim to solve this problem through the use of an automated venting and ballast system, which can modulate the balloon’s buoyancy to achieve a target altitude. Given accurate GPS positioning and modeling of the jetstream, we can fly at certain altitudes to navigate the winds of the upper atmosphere. The venting will be performed by an actuator fixed to the neck of the balloon, and the ballast drops will consist of small, biodegradable BBs, which pose no threat to anything below the balloon. Similar existing solutions, particularly the Stanford Valbal project, have had significant success with their long endurance launches. We are seeking to improve upon their endurance by increasing longevity from a power consumption and recharging standpoint, implementing a more capable altitude control algorithm which minimizes helium and ballast expenditures, and optimizing mechanisms to increase ballast capacity. With altitude control, the balloon has access to winds going in different directions at different layers in the atmosphere, making it possible to roughly adjust its horizontal trajectory and collect data from multiple regions in one flight.

# Solution Components

## Vent Valve and Cut-down (Mechanical)

A servo actuates a valve that allows helium to exit the balloon, decreasing the lift. The valve must allow enough flow when open to slow the initial ascent of the balloon at the cruising altitude, yet create a tight seal when closed. The same servo will also be able to detach or cut down the balloon in case we need to end the flight early. A parachute will deploy under free fall.

## Ballast Dropper (Mechanical)

A small DC motor spins a wheel to drop [biodegradable BBs](https://www.amazon.com/Force-Premium-Biodegradable-Airsoft-Ammo-20/dp/B08SHJ7LWC/). As the total weight of the system decreases, the balloon will gain altitude. This mechanism must drop BBs at a consistent weight and operate for long durations without jamming or have a method of detecting the jams and running an unjamming sequence.

## Power Subsystem (Electrical)

The entire system will be powered by a few lightweight rechargeable batteries (such as 18650). A battery protection system (such as BQ294x) will have an undervoltage and overvoltage cutoff to ensure safe voltages on the cells during charge and discharge.

## Control Subsystem (Electrical)

An STM32 microcontroller will serve as our flight computer and has the responsibility for commanding actuators, collecting data, and managing communications back to our ground console. We’ll likely use an internal watchdog timer to recover from system faults. On the same board, we’ll have GPS, pressure, temperature, and humidity sensors to determine how to actuate the vent valve or ballast.

## Communication Subsystem (Electrical)

The microcontroller will communicate via serial to the satellite modem (Iridium 9603N), sending small packets back to us on the ground with a minimum frequency of once per hour. There will also be a LED beacon visible up to 5 miles at night to meet regulations. We have read through the FAA part 101 regulations and believe our system meets all requirements to enable a safe, legal, and ethical balloon flight.

## Ground Subsystem (Software)

We will maintain a web server which will receive location reports and other data packets from our balloon while it is in flight. This piece of software will also allow us to schedule commands, respond to error conditions, and adjust the control algorithm while in flight.

# Criterion For Success

We aim to launch the balloon a week before the demo date. At the demo, we will present any data collected from the launch, as well as an identical version of the avionics board showing its functionality. A quantitative goal for the balloon is to survive 24 hours in the air, collect data for that whole period, and report it back via the satellite modem.

![Block diagram](https://i.imgur.com/0yazJTu.png)