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 | 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 |
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