CubeSatSim Glossary

Here's a handy glossary for the various technical terms and acronyms associated with the CubeSatSim.

AFSK – Audio Frequency Shift Keying.

Antenna - A device that converts an electrical signal into a radio wave, or a radio wave into a radio signal.

Amp – Short hand for Ampere, which is the SI base unit of electrical current.

Amateur Radio - Is a popular technical hobby and volunteer public service that uses designated radio frequencies for non-commercial exchange of messages, wireless experimentation, self-training, and emergency communications. The CubeSatSim transmits telemetry on frequencies within the Amateur Radio bands.

AMSAT - The Radio Amateur Satellite Corporation. AMSAT is a worldwide group of Amateur Radio operators who share an active interest in building, launching and then communicating with each other through non-commercial Amateur Radio satellites. There are different AMSAT organizations around the world.

APRS - Automatic Packet Reporting System. APRS is an Amateur Radio-based system for real time digital communications of information that includes GPS coordinates. APRS data can be displayed on a map.

Arduino– A small single board computer. The Arduino Integrated Development Environment (IDE) is used to compile software used in the Raspberry Pi Pico for the CubeSatSim project.

Beacon - Is the satellite's signal that signifies its presence to the world and can be tracked by almost any ground station or Amateur Radio operator. Generally, the signal in beacon primarily has the call sign of the satellite and may also have health data or telemetry data.

bps - The data transmission rate in Bits Per Second (bps).

BPSK- Binary Phase-Shift Keying. A digital modulation scheme that conveys data by changing, or modulating, two different phases of a reference signal.

BME280 – A sensor used to measure relative humidity, barometric pressure and ambient temperature. The BME280 sensor uses the I2C communications interface bus in the CubeSatSim.

Bus - A conductor, or group of conductors, that serve as a common connection for two or more circuits.

Calibration - The process of converting the numerical measurement of a sensor to a known value. After calibration, a sensor gives more accurate readings.

Callsign - A combination of letters and numbers used to identify a radio station. Used by amateur radio operators and also commercial radio and TV transmitters.

Command and Control - Satellite Command and Control (C2C) messages are used to connect, usually over radio, with a satellite and upload commands, settings, schedule operations and experiments, and other functions.

CPU - The Central Processing Unit (CPU) is the "brains" of a computer that executes instructions and controls input and output. Also just known as a processor.

CubeSat - Is a small satellite with a form factor of 10 cm cubed. A 1U CubeSat has a mass of no more than 2 kg, and often use commercial off-the-shelf (COTS) components for their electronics and structure.

CubeSatSim - The AMSAT CubeSat Simulator is a tool for education and demonstrations. It can be used in a classroom or training setting to introduce the basics of nanosatellites, or it can be used to teach STEM (Science Technology Engineering and Math) concepts, or it can be a stepping stone in a project to build and launch an actual CubeSat into space.

Current - Electrical current is the flow of charged particles, usually electrons, measured in the units of Amperes or Amps or milli Amps.

CW - Continuous Wave. AKA Morse Code. The very first digital mode of communication.

Demodulation – Is the process of extracting information from a transmitted signal.

Diode - Is an electrical element that only allows current to flow in one direction.

Direwolf - A popular open source computer software program used to decode APRS packet and DTMF signals, among others.

Downlink - Radio communication from a satellite to a ground station. Uplink is radio communication in the other direction.

Drivers - software installed on a computer to allow a device to be accessed by software on the computer. For example, an RTL-SDR radio dongle needs to have drivers installed on a computer to be used.

DTMF - Dual Tone Multi Frequency (DTMF) tones are used over the radio or network to send digits or letters. They have been used over telephone networks in the past. In the CubeSatSim, they can be used for Command and Control signals.

Eye Diagram – A display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input (y-axis), while the data rate is used to trigger the horizontal sweep (x-axis). Eye diagrams are displayed and utilized by the FoxTelm software when the CubeSatSim is transmitting in the FSK or BPSK mode.

FFT - Fast Fourier Transform (FFT) is a mathematical method to calculate and display a radio spectrum in a graphical way.

FIAB - Fox-in-a-Box. A small, easily-deployed Fox satellite telemetry receiver (ground station) that utilizes a Raspberry Pi and an SDR dongle. FIAB can be used as the Ground Station for the CubeSatSim. A Raspberry Pi image file is available for download or purchase pre-installed on a SD card from AMSAT.

Fox-1 - The Series of five 1U CubeSats identified by a letter (A - E) launched into Low Earth Orbit by AMSAT. The FoxTelem software decodes the telemetry transmitted by these satellites.

FoxTelem - A software program included with the Fox-In-a-Box ground station image file, used to decode Fox-1 FSK and BPSK CubeSatSim telemetry.

FSK - Frequency Shift Keying. This is the digital modulation technique in which the frequency of the carrier signal varies according to the digital signal changes. FSK is a type of frequency modulation.

FUNcube - A 1U CubeSat launched into space by AMSAT-UK also known as AO-73 that transmits telemetry in BPSK 1200 bps.

GPIO – General Purpose Input Output. In the context of the CubeSatSim, this is the 40-pin header used on the Raspberry Pi Zero and Raspberry Pi 4. The GPIO pins on the Raspberry Pi Pico are along the outside edge of the Pico’s printed circuit board. These GPIO pins are the physical interface between the Raspberry Pi and the CubeSatSim sensors and peripheral devices. Ground station – Used to communicate and command satellites in space. (See AMSAT Journal Vol 42, No. 4 for a detailed description of the CubeSatSim ground station).

gyroscope - A gyroscope or just a gyro is a device that measures rotation rate. The MPU6050 sensor in the CubeSatSim has a gyroscope.

HAB – High Altitude Balloon. High altitude ballooning is a hobby that allows hobbyist to explore earth’s upper atmosphere utilizing customized payloads.

Ham Radio – A slang term for Amateur Radio.

HT - A Handy Talkie (HT) is a term for a portable battery powered radio ham radio transmitter and receiver that you can hold in your hand.

I2C - Inter Integrated Circuit bus. A synchronous, multi-master/multi-slave, single-ended, serial communication bus used to communicate between the Raspberry Pi Zero and various sensors in the CubeSatSim.

IDE - Integrated Development Environment. An IDE is a software application that helps programmers develop software code efficiently.

IHU – Internal Housekeeping Unit. Housekeeping data includes items like temperature, voltage and attitude.

Image File – Is a file that contains a complete copy of another drive or SD Card. Also known as a disk image. An image file containing common ground station software is available for the Raspberry Pi. The image can be downloaded and flash onto an SD Card for quickly setting up a CubeSatSim ground station.

IMU – Internal Measurement Unit. An IMU often contains an accelerometer and gyroscope.

INA219 – A sensor for measuring current and voltage. In the CubeSatSim, the INA219 sensors are connected to the Raspberry Pi Zero via the Pi’s I2C bus.

ISM Band - Portions of the radio spectrum reserved internationally for Industrial, Scientific, and Medical (ISM) purposes.

kHz - Kilo Hertz (kHz) is a radio frequency in thousands of cycles per second.

LED – Light Emitting Diode.

LEO – Low Earth Orbit. LEO is an orbit that is relatively close to Earth’s surface. It is communally considered an altitude of less than 1000 km above Earth.

MHz - Mega Hertz (MHz) is a radio frequency in millions of cycles per second.

Mode - A Mode can be defined as how something is done or how it happens. The CubeSatSim uses five different forms of modulation, or modes, to send information to the ground stations. These modes are CW, FSK, BPSK, APRS, and SSTV.

Modulation - Is the process of encoding information in a transmitted signal.

MPU6050 – Is an IMU sensor that combines a gyroscope and accelerometer and uses a standard I2C bus for data communication.

Nickel Metal Hydride - Is a type of rechargeable battery used in the CubeSatSim. Also written as NiMH, these batteries are safer to use than Lithium batteries.

Open Circuit - A open circuit (sometimes written as o/c or oc) is when nothing is connected to an electrical output. For example, the open circuit voltage of a solar panel is the maximum voltage that can be measured when nothing is connected between the plus and minus wires of the solar panel.

OSCAR – Orbiting Satellite Carrying Amateur Radio.

Packet - A small block of data transmitted together over a radio or computer network.

Payload - A payload is made up of scientific instruments and all the electronics that support a given mission. The CubeSatSim simulates a satellite payload and can be used as a high altitude balloon payload.

Phasor diagram - A graphical representation, plotted on a coordinate system, of the phase relationship of the two phases of a BPSK modulated signal sent from the CubeSatSim. It shows the transitions from one phase state to the other and is displayed when decoding BPSK in the FoxTelm software.

Pi Zero - A Pi Zero is one of the smallest Raspberry Pi Single Board Computers (SBC) that is used as the processor in the CubeSatSim.

Pitch - One the principle axes used in aviation and aerospace that refers to the up or down angle of the nose of an aircraft or spacecraft.

Potentiometer - A Potentiometer is a variable resistor who resistance can be changed by turning a screw or moving a slide. Also known as a Trimpot or just a Pot.

Power - Electrical Power is the rate of doing work or using energy, and is measured in Watts or milli Watts. Electrical power is calculated as the product of the Voltage and the Current.

PSU – Power Supply Unit. The battery board functions as the PSU in the CubeSatSim.

QSSTV - A software program included with the Fox-In-a-Box ground station image file, used to decode CubeSatSim Slow Scan TV pictures.

Raspberry Pi – Is a single-board computer made by the Raspberry Pi Foundation, a UK charity that aims to educate people in computing and create easier access to computing education. Two different form factors of the Raspberry Pi are used in the CubeSatSim (Raspberry Pi Zero and Raspberry Pi Pico).

RBF – Remove Before Flight. For the CubeSatSim, the RBF switch activates the CubeSatSim and allows operation using internal battery power.

Repeater - A radio repeater receives a radio signal on one frequency and retransmits the signal on a different repeater. A cross-band repeater receives on one radio band and retransmits on a different radio band.

RF – Radio Frequency.

Roll - One the principle axes used in aviation and aerospace that refers to the up or down angle of the wings of an aircraft or the rotation of spacecraft about its path of flight.

RSSI – Received Signal Strength Indicator.

RTL-SDR - A popular low cost SDR with a USB interface that plugs into a computer such as a Raspberry Pi or laptop to receive radio signals.

Telemetry - The process of recording and transmitting the readings of an instrument or sensor.

Transceiver - Is a combination of a radio transmitter and radio receiver.

Troubleshooting - Is the method of trying to determine the cause of a problem or anomaly or failure. Troubleshooting a problem with a satellite in space is usually done by a careful analysis of telemetry data.

SDR - Software Defined Radio. A SDR is a radio communication system that uses software for the modulation and demodulation of radio signals.

Sensor - A device which detects or measures a physical property and records, indicates, or otherwise responds to the physical property.

Short Circuit - A short circuit (sometimes written as s/c or sc) is a path of minimal resistance. For example, the short circuit current of a solar panel is the maximum current that can be measured when a wire is connected between the plus and minus wires of the solar panel.

SNR - Signal-To-Noise ratio. SNR is the ratio between the desired information or the power of a signal and the undesired signal or the power of the background noise.

Solar Panel - A device that coverts energy from sunlight into electrical energy to run a CubeSat or charge batteries.

SSTV - Slow Scan Television. SSTV is a way of sending pictures over a voice bandwidth channel using audio tones.

Uplink - Radio communication from a ground station to a satellite. Downlink is radio communication in the other direction.

UHF - Ultra-High Frequency. UHF radio frequencies range between 300 MHz and 3 GHz. The CubeSatSim transmits and receives in the UHF range of radio frequencies.

USB - The Universal Serial Bus (USB) interface common on computers for charging and data communications. There are different types of connectors including micro USB, USB-C, etc.

Volt - The SI unit of electromotive force, the difference of potential that would drive one ampere of current against one ohm resistance.

Waterfall display - Is a graphical representation of the signals across a frequency range, generally color- coded to indicate signal amplitude or strength, displayed over time.

Web SDR – A software program included with the Fox-In-a-Box ground station image file, can be used to decode CubeSatSim Packet telemetry.

Yaw - One the principle axes used in aviation and aerospace that refers to the left or right angle of the nose of an aircraft or spacecraft.