University of Colorado Department of Aerospace Engineering Sciences ASEN 4018 Conceptual Design Document (CDD) PRATT9: Passive Radio Frequency Autonomous Tracking Tool 9 Monday 30th September, 2019 Project Customers Name: Sam Gagnard Email: [email protected] Phone: 720-454-7806 Team Members Name: Kieran O’Day Name: Yang Lee Email: [email protected] Email: [email protected] Phone: 203-414-5282 Phone: 720-755-1076 Name: Quinton Nietfeld Name: Ryan Cameron Email:[email protected] Email: [email protected] Phone:402-659-2020 Phone: 720-360-5351 Name: Colton Ord Name: Zaki Laouar Email: [email protected] Email: [email protected] Phone: 303-453-9065 Phone: 720-324-1519 Name: Mamdooh Alkalbani Name: Richard Folsom Email: [email protected] Email: [email protected] Phone:303-378-9347 Phone: (720) 244-6143 Name: Zachary Arbogast Email: [email protected] Phone: 775-574-8302 Contents 1 Nomenclature 4 2 Project Description 5 2.1 Purpose..................................................5 2.2 Concept of Operations..........................................5 2.3 Functional Block Diagram........................................6 2.4 Functional Requirements.........................................7 3 Design Requirements 8 3.1 Functional Requirement (FR): Receive RF signals from satellites in various conditions, with multiple orbit geometries..............................................8 3.1.1 Design Requirement DR: Half-Power Beam-Width (HPBW) of the Receiver ≤ 10◦ for the worst case L-band bandwidth (1.5Ghz).............................8 3.1.2 DR: The receiver will have an ideal gain of 25 dB for the worst case for the L-band bandwidth (1.5Ghz).............................................8 3.1.3 DR: The receiver will be able to receiver frequency within the L bandwidth...........8 3.2 FR: Calculate the SNR of the satellite..................................8 3.2.1 DR: Software Radio Interface..................................9 3.3 FR: Scoring Software ranks opportunities with 80% error [29] (in predicted SNR)............9 3.3.1 DR: Scoring Software models attenuation due to various causes................9 3.3.2 DR: Scoring Software models noise from the Sun (with respect to degrees from Sun).....9 3.3.3 DR: The software model shall grab data for it’s attenuation model locally and remotely....9 3.4 FR: Point system along an orbit path commanded by a manual input with 1◦ pointing accuracy....9 3.4.1 DR: The pointing system must have a slew rate of at least 1.2 deg/s..............9 3.4.2 DR: The system shall run on 120V, 60Hz power.........................9 4 Key Design Options Considered 10 4.1 Antenna Selection............................................. 10 4.1.1 Frequency Selection....................................... 10 4.1.2 Antenna Design.......................................... 11 4.2 Ground Station Design.......................................... 18 4.2.1 Central Processing Unit (CPU).................................. 18 4.2.2 Data Storage (No Trade Study).................................. 19 4.2.3 Software Defined Radio (SDR)................................. 21 4.3 Antenna Rotor Assembly Selection.................................... 21 4.4 Scoring Software Data Acquisition.................................... 23 4.4.1 Data through remote access (the internet)............................ 23 4.4.2 Data through local sensors.................................... 23 4.4.3 Summary............................................. 23 5 Trade Study Process and Results 23 5.1 Antenna Selection............................................. 23 5.1.1 Frequency Selection....................................... 23 5.1.2 Antenna Design.......................................... 26 5.2 Ground Station Design.......................................... 29 5.2.1 Central Processing Unit (CPU).................................. 29 5.2.2 Radio System........................................... 30 5.3 Antenna Rotor Assembly Selection.................................... 31 5.3.1 Trade Study Metrics....................................... 31 5.3.2 Trade Study Quantification.................................... 32 5.3.3 Justification............................................ 32 5.4 Scoring Software Data Acquisition.................................... 33 5.4.1 Trade Study Metrics....................................... 34 5.4.2 Trade Study Quantification.................................... 34 5.4.3 Justification............................................ 35 09/30/19 2 of 38 CDD University of Colorado Boulder 6 Selection of Baseline Design 36 6.1 Frequency Selection............................................ 36 6.2 Antenna Design.............................................. 36 6.3 Central Processing Unit (CPU)...................................... 36 6.4 Software Defined Radio (SDR)...................................... 36 6.5 Antenna Rotor Assembly......................................... 36 6.6 Scoring Software Data Acquisition.................................... 36 09/30/19 3 of 38 CDD University of Colorado Boulder 1. Nomenclature LEO Low-Earth Orbit MEO Medium-Earth Orbit GEO Geostationary Orbit CPU Central Processing Unit SSA Space Situational Awareness RF Radio Frequency LNB Low-Nose Board-cast Amplifies LNA Low-Nose Amplifies S NR Signal-to-Noise Ratio HPBW Half-Power Beam Width T BD To Be Determine RAM Random Access Memory COTS Commercial Off the Shelf USB Universal Serial Bus S DR Software Defined Radio IS S International Space Station 09/30/19 4 of 38 CDD University of Colorado Boulder 2. Project Description 2.1. Purpose For this project we will design and build a passive Radio Frequency (RF) satellite observation test-bed. We will use this to develop and test prediction software which will rank potential satellite observation opportunities. RF is a section of the electromagnetic spectrum containing electromagnetic waves with frequencies ranging from 20 kHz to 200 GHZ. The RF band is commonly used for communication and data transfer between satellites and ground stations. Ever since the first satellite, Sputnik, was launched into orbit, space has demanded our attention. Peaceful devel- opment of space will always be important, but there is no doubt that it has recently become a new theatre for military conflicts. With the advent of high-performance satellites, it is now possible to perform reconnaissance, communica- tion, and other tactical operations from space [1]. With astronautics technology becoming more accessible, countries across the world now possess these capabilities. Although radar has been quite capable of tracking these satellites in the past, current satellites may possess radar warning receivers designed to thwart this [2]. The fact that satellites operated by foreign powers are capable of evading ground surveillance using active radar highlights the importance of using a passive system for satellite tracking. Passive RF is currently being used in radar warning receivers, passive radar, and anti-radiation missiles, among a few other devices. Detecting the signal of an actively transmitting target is not a new concept [3]. Since satellites must transmit data back to Earth, they are guaranteed to expose their position. This is why passive RF can be used to find their location reliably. For this project, a set of satellites will be observed in their orbits to be tracked and scored based on their position and ability to be observed. One important factor for developing the prediction algorithm/software is the accuracy of a passive RF observation in various positions and orbits in space, such as a satellite being closer to the horizon, a satellite being in front of sun, a satellite in low-earth orbit, etc. It will consider observation opportunities across a set of possible satellites at different times. The prediction algorithm/software itself will take the signal-to-noise (SNR) and other factors to calculate the Figure of Merit for our prediction. This test-bed and prediction algorithm/software will set the foundation for current satellite tracking ground stations to incorporate passive RF into their observation schedules. 2.2. Concept of Operations PRATT9 enhances Space Situation Awareness (SSA) by observing satellites using the RF frequency signals they emit, as well as predicting when and where observations with a passive RF system should be made. This objective requires a ground station, antennas, a predictive software package, a CPU, and data storage. Before receiving any signals, the CPU with our software installed will compute and score the quality of a potential observation commanded by user input and rank it according to SNR. The antenna will then be powered, and it will track the known orbit of the satellite to make SNR observations. The observed SNR will be compared to the predicted SNR and will be sent to storage. Figure 1 reiterates the points made above. 09/30/19 5 of 38 CDD University of Colorado Boulder Figure 1. Concept of Operations 2.3. Functional Block Diagram The functional block diagram in Figure2 shows the main components necessary for PRATT9 to function. A Power Source is required to power the ground station and the CPU/Data Storage. The Power Regulator will be responsible for distributing power to the rest of the components within the ground station. The Central Processor in the ground station commands the Signal Strength Detector to obtain the SNR of the selected frequency once the satellite is within view and scoring has finished. The Antenna unit block consists of the physical