The Terms

| April 3, 2017

Often it helps you know your terms when getting into the hobby of FPV. Here we compiled all the head knowledge you’ll ever want.

Frequency – the radio signal sent by the transmitter (remote or camera) to the receiver (the drone or FPV screen). It is measured in Hertz (oscillations of the perpendicular fields per second). The most common frequencies in the market are 2.4Ghz (controls) and 5.8Ghz (video); other frequencies include 1.2Ghz, 1.3Ghz, and 433Mhz. Lower frequencies generally provide better long-distance performance and better penetration. Frequency is one of the first things to check to ensure compatibility between a transmitter and a receiver.

FPV – stands for First-person View. It is a method for controlling RC (radio controlled) vehicles. In a simple setup, a camera attached to the front of the vehicle sends a video feed to back to the pilot’s monitor or goggles. A more complex setup generally includes a camera on a remote controlled gimbal.

Telemetry – a process in which measurements are taken remotely (i.e. acceleration, pressure, etc…) and sent back to a ground station (i.e. FPV goggles, computer, etc..) for monitoring.

Video – the visual medium of motion picture. It’s the medium by which information is transmitted from the camera on the vehicle to the headset or monitor.

LCD – stands for Liquid Crystal Display. It is a display technology utilizing a grid of liquid crystals which make up pixels. Each pixel displays a different color to recreate the picture. Higher pixel count = higher resolution = clearer picture.

Goggles –  the FPV headset used to display the video transmission provided by the camera on the drone. Goggles are generally the preferred way of piloting drones.

Camera – the device on the drone that captures the video stream which is transmitted to pilot and allows him or her to control the vehicle.

Antennas – the electrical device that converts electrical power to radio waves and vice versa. They are tuned to specific radio frequencies depending on the application. Antennas come in different shapes: cloverleaf, skew planar wheel, windmill, and fan. These are typically found in the following pairs Cloverleaf (Tx) + Skew Planar Wheel (Rx) and Windmill (Tx) + Fan (Rx).

Cables – insulated wires used for transmitting electricity for the purpose of power transfer or telecommunication.

Frame – the rigid structure upon which all of the drone components are mounted. They are typically made out of plastic composites or carbon fiber, but metal and other materials are occasionally used depending on the purpose.

Carbon Fiber – a very strong, durable material used for many of the structure components. It is a lightweight plastic reinforced with carbon fibers. It is generally the preferred material for frames especially in the racing community.

Props – fan blades that convert rotational motion into thrust. They are typically defined by three basic measurements: diameter, pitch, and number of blades. Diameter is the length across the circle circumscribing the blades of the prop. Pitch is the distance (in inches) the prop would move in a single revolution moving through a solid.

ESC – stands for Electronic Speed Controller. It is the electronic component which varies the motor’s speed and direction by generating three-phase electronic power to drive brushless motors. It is connected to both a power source and the flight controller using the information from the controller to regulate the power to the motor.

Flight Controller – the brain of the drone. At a minimum, a flight controller takes the user input from the receiver and the stabilization data from the gyro and accelerometer to send calculated information to the ESCs which in turn drive the motors. More complicated setups include a barometer and GPS sensor for collecting altitude and positioning information which allow the drone to execute complex tasks such as hover and autonomous flying. Simple flight controllers are generally used for racing while the more complex setups are typically used for videography, mapping, delivery, etc…

OS – stands for operating system. On personal computers, Apple OSX and Microsoft Windows are two of the most common operating systems. The OS manages hardware and software system resources. For DIY racing and general purpose drones, OpenPilot, Cleanflight, and Betaflight consist of the primary OS’s. For DIY autonomous drones, Pixhawk, Ardupilot, and DJI Naza are three of the most popular Flight Controllers/OS’s.

Open Source – refers to materials in which the source design (technical documentation, code, etc…) is made available by the creator under a license that allows modifications or enhancements by anyone.

Gimbal – a pivoted support that allows an object to be rotated about an axis. In drones used for photography and cinematography, a 2 or 3-axis gimbal is attached to the drone to support the camera; it allows for visually complex aerial shots as the camera can move independently from the drone.

Yaw – is a movement/rotation around the yaw (vertical) axis. Typically manipulated by moving the left control stick horizontally.

Pitch – is a movement/rotation around the side-to-side (horizontal) axis. Typically manipulated by moving the right control stick vertically.

Roll – is a movement/rotation around the front-to-back (depth) axis. Typically manipulated by moving the right control stick horizontally.

Altitude – generally known as a height or depth measurement of an object relative to its surroundings.

 

DIY – stands for “Do It Yourself”. Both an ideology and community promoting designing, building, and tinkering.

Latency – the time delay between cause and effect. In FPV, a high latency video stream often leads to more frequent crashes.

Motor – an electrical machine that converts electricity into circular motion. Kv is one of the most common measurements for motors and possibly the most important to consider when building your drone. Kv is the motor velocity constant – it represents the number of rotations per volt applied. Lower Kv motors have more torque and can drive bigger props while higher Kv motors have less torque, but generally a higher top speed.

Battery – the power source of the drone. It is a device that contains electrochemical cells which allow it to store electricity in a portable form. Batteries are generally measured in number of cells (S), volts (V), milliamp hours (mAh), and discharge rate (C). The “S” number represents the number of cells in the battery. In the most common RC batteries – LiPos – there are 3.7 volts per cell. Batteries with higher cell count have more volts and can drive motors at higher RPMs. [Note: check the operating specs for the motors to avoid burning them out] Milliamps hours represent the capacity of the battery and higher numbers mean a bigger battery and generally longer flight time (up to a point). Lastly, the discharge rate represented by “C” represents the multiplier by which you can discharge the battery. A 20C battery can safely discharge at a rate 20 times more than the capacity of the battery. [Note: many batteries are labeled with two “C” numbers with the lower one representing safe continuous discharge and the higher one representing the safe burst discharge (few seconds max)]

*Tip: make sure the transmitter and receiver implement the same transmission protocol.

LiPo – the most common type of RC battery. They use a dry electrolyte polymer for storing electricity unlike their counterparts – Li-Ion which use a liquid based electrolyte solution.

 

Channels & Bands (VTX) – VTX stands for video transfer and often refers to the video transmitter attached to the camera on the vehicle. Most VTXs use specific frequency bands depending on the manufacture. For drones, the most common spectrum is 5.8 Ghz with bands A, B, E, F, and R. Each band contains 8 distinct channels; however, they are only spaced 20 Mhz apart which causes the channels to bleed into each other. For that reason, we often choose channels spaced 40Mhz apart which minimizes the bleed for most low power/short range flying. Make sure your receiver is compatible with your VTX – for example, Boscam receivers typically operate on bands A, B, E, and F while ImmersionRC receivers operate only on band F. R, or Raceband is fairly new and was created specifically with racing in mind.

 

DSSS  – stands for Direct-sequence Spread Spectrum. It is a signal modulation technique used by transmitters and receivers to prevent unauthorized takeovers. The remote’s transmitter and the vehicle’s receiver are paired to use the same pseudo noise code generator unknown by other devices. The information is then seamlessly transmitted between the remote and vehicle while remaining unintelligible by everything else.

 

PCM – stands for Pulse-code Modulation. Essentially, it is a way of converting an analog signal to a digital signal. The amplitude of the continuous signal is sampled at regular intervals creating a discrete representation of it; this can then be stored in memory and or manipulated by a processing unit.

 

PPM – stands for Pulse-position Modulation. It is a way of transmitting digital bits over an analog signal by transmitting a pulse in a possible time-shift. The process is repeated over the specified number of seconds.

 

DSM/DSM2/DSMX – protocols for 2.4 Ghz Spektrum RC transmitters and receivers. The protocols were created to decrease interference. DSM2 & DSMX are enhancements to the original DSM protocol using two channels instead of one. DSMX also provides channel hopping allowing more users to operate their vehicles over the same bandwidth with less interference.

*Tip: make sure the transmitter and receiver implement the same transmission protocol.

 

FASST – is Futaba’s 2.4 Ghz protocol for implementing Frequency Hopping Spread Spectrum. The transmitter and receiver are synced using the transmitter’s identification code and pseudo-randomly hop frequencies at a given time interval. One of the most sophisticated and robust protocols for data transmissions.

*Tip: make sure the transmitter and receiver implement the same transmission protocol.

 

Gyro – short for gyroscope. This device is used for measuring the vehicle’s orientation. Data is sent from the sensor to the flight controller which uses the info (along with other sensor data) to maintain aerodynamic stability. Vibrating, MEMS (Microelectromechanical Systems) gyros are the typical choice for multirotors and hobby RC.

 

Accelerometer – is a device that measures the vehicle’s acceleration. The data is sent from the sensor to the flight controller which uses the info (along with other sensor data) to maintain aerodynamic stability. They are also key components of inertial navigation systems. Like gyros, most accelerometers found in multirotors are vibrating MEMS (Microelectromechanical Systems).

 

AFHSS – stands for Adaptive Frequency-hopping Spread Spectrum. It attempts to reduce the chance of interference and thus improve performance by randomly skipping around the spectrum and navigating around “bad channels.”

 

Interference – typically refers to the collision of two or more electromagnetic waves that result in data being modified/corrupted during transmission. Commonly occurs when there are many pilots flying at once with small spacing between channels. Heavy interference can lead to a complete failure of VTX which will often lead to a hard crash.

*Flying Tip: Make sure to mitigate the chances of interference by following proper “flyer’s etiquette”.

 

S.Port – stands for Smart Port. It is a special port developed by FrSky that allow a variety of external sensors to be connected to the receiver and broadcast back to transmitter. Some flight controllers will also output telemetry data through the smart port.

*Buying Tip: make sure that your receiver model has a Smart Port before buying Smart Port sensors.

 

Firmware – is a type of software that controls and monitors a system. It is a set of instructions running directly on the hardware. ESCs and various peripherals can contain firmware, some of which can also be updated and or modified.

 

BEC – stands for Battery Eliminator Circuit. It is a circuit designed to deliver power to other components without the need for an additional battery. BECs can be built into ESCs allowing various peripherals to be powered without the need of an additional battery or connection to the PDB.

 

PDB – stands for Power Distribution Board. It is a helpful component that divides up the power from the battery into sub-circuits while greatly simplifying the wiring process. ESCs, the Flight Controller, Receiver, and other peripherals which require power are often wired to the PDB.

 

VCC – refers to plus line in an integrated circuit, power-supply cable.

 

ACCSTi – stands for Advanced Continuous Channel Shifting Technology. It is a technology created by FrSky that is yet another implementation of frequency-hopping.

 

Drone – A vague word most commonly referring to UAVs, or Unmanned Aerial Vehicles. In popular media drones are often portrayed as multirotors although drones can also encompass other remote controlled aerial vehicles such as planes and wings (i.e. Military Drone).
Multirotor – What is commonly known as a drone, a multirotor is an aerial vehicle held in the air by multiple motors with the thrust going in a downward direction of the aircraft. This enables the ability to hover steadily unlike other aircraft such as planes or wings. Multirotors range in name and style depending on the number of motors of the craft as well as its arrangement. Examples of common multirotors based on the number of motors are: Tricopter, Quadcopter, Hexacopter, and Octocopter. Within those classes, the arrangements can be altered to create other common multirotors such as: A-Tail, V-Tail, Y6, X8, and more.