FPV Quadcopter Basics

Published

April 23, 2017

Modified

May 3, 2023

Power Distribution Board

PDB (Power Distribution Board)
- Connects battery to the ESCs and the
- All positive & negative pads (terminals) are connected
Non carbon fiber frames may have the PDB build into the frame
Some PDBs may include a Voltage Regulator (BEC Battery Elimination Circuit)
Characteristics
- Current Rating needs to support the max total current consumed by the ESCs
- Number of Connectors for convenient soldering

Motor

ESC (Electric Speed Controller)
- Control the speed of the motor spin
- Connected to the FC
Weight
- Total weight of the vehicle, including payload (battery, HD cam)
- Frame size limits propeller size which limits motor size
Electric Power
- Measures in W (Watt)
- Voltage (V) * Current (A) (voltage multiplied by current)
Current Rating
- Maximum current motor can handle
- Measured in A (Ampere)
Thrust
- Measures in g (Gram)
- Higher thrust equates in higher top speed, and higher current drawn
- Full thrust needs to be supported by the batteries maximum discharge rate (C-Rating)
Torque (N.m)
- Measures Angular Force
- How much “push” the rotation shaft has
RPM Rounds Per Minute
- Measures Angular Speed
- How fast the motor rotates the propeller
- Response, how fast the motor changes RPM
Efficiency
- Thrust (g)/Power (W) (trust divided by power)
- Higher efficient, means less power consumed
- Power not transformed to trust dissipates as heat
Kv Number/Rating
- RPM per volt supplied to the motor
- Rating assumes no load on the motor, and constant voltage
- 1200kv * 3V = 3600rpm
Thrust to Weight Ratio
- 2:1 minimum
- 3:1, 4:1 normal
- up to 8:1 for race (more agility, harder to control)
4-digit number AABB, AA stator width, BB height

Brushed

Pro
- Low cost
- Simple control (no controller required for fixed speed)
- 2 control wires
Con
- Brushes wear off because of friction (stop conducting electricity)
- Speed/torque moderately flat (brush friction increases at higher speed)
- Poor heat dissipation (due to internal construction)
- Higher rotor inertia (less dynamic)
- Lower speed range (mechanical limits on the brushes)
- Brush arcing generates causes interference (EMI, noise)

Brushless

Pro
- More durable (due to absence of brushes)
- Speed/torque flat
- High efficiency (no voltage drops)
- High output power to size ratio
- Better heat dissipation
- High speed range
- Lower electric interference
Cons
- Higher cost
- Requires ESC (Electric Controller)

Propellers

Propellers
- 2CW (clockwise) & 2CCW (counter-clockwise)
- Differ in length (diameter), pitch, and number of blades
Shaft Power
- Motor input power to the propeller
- Expressed in W (Watt)
- Torque * Angular Velocity (rad/s)

Flight Controller

FC (Flight Controller)
- Primary function: control motors thrust corresponding to the pilots inputs
- Interface with sensors to maintain the aircraft flight state
- Configurable and programmable, to adjust multi-rotor behavior and flight characteristics
- Support different flight modes aka profiles, e.g. self-leveling mode
Sensors types:
- Gyro (Gyroscopes)
- Acc (Accelerometer)
- Barometer (barometric pressure sensor)
- Magnetometer (compass)
Firmware software race/acro flying:
- Cleanflight
- Betaflight
- Raceflight
Processor F1,F3,F4
Integrated Voltage Regulator
- Power the FC board directly from the battery
- Measures battery level
Integrated PDB (Power Distribution Board)
RX protocols

RC (Remote Control)

RC (Remote Control) Radio TX Transmitter (Controller)
- Controller sticks called Gimbal
- Mode controller configuration
- Mode 1: throttle on the right stick
- Mode 2 (most common): throttle on the left stick
- Mode 3/4 rarely used
All sticks self center with the exception of the throttle axis
RX Receiver build into the vehicle
Frequency, typically 2.4GHz, 1.3GHz used for long range
Frequency Hopping, aka channel hopping protocol
- Software continuously scans for the best frequency
- Switches channels automatically on radio interference
- From 2.4000 - 2.4835GHz
Binding is the process of connecting transmitter with a receiver
- TX/RX pairing requires compatible communication protocols
Model (profiles) memory, save multiple TX/RX pairings
Training with Buddy Mode linking two controllers
Firmware programs: Cleanflight

Receiver Protocols

Communication between radio receiver and the flight controller
Taranis (FrSky)
- ACCST (Advanced Continuous Channel Shifting Technology)
Spektrum
- DSM (Digital Spectrum Modulation)
- DSM2 uses 2 frequencies for data transmission
- DSSS (Direct Sequence Spread Spectrum), 2.4GHz modulation, frequency at power-on
- DSMX up to 60 frequencies for data transmission
- TEAR assignment for channels 1-4
Futaba
- FASST (Futaba Advanced Spread Spectrum Technology), supports telemetry
- FHSS & S-FHSS (Frequency-Hopping Spread Spectrum)
- AETR assignment for channel 1-4
OrangeRx (HobbyKing)
FlySky protocol & manufacturer
- IBUS, bidirectional digital serial protocol
Multi-Module multi protocol transmitter
- nrf24-multipro

Channels

Determines how many individual actions can be controlled
Channels 1-4 control flight
- Throttle motor power up/down
- Yaw rotating right/left (Rudder)
- Pitch lean forward/backward (Elevator)
- Roll lean left/right (Aileron)
AUX (auxiliary) channels for extra switches
- Used to change flight modes, trigger functions
- Recommended at leas 6 channels for quadcopter
- Arm switch on

Vendors

Transmitter

FlySky FS-I6 (~50Euro)
- Frequency: 2.4GHz, 6 channel
- Protocol: AFHDS 2A
Taranis Q X7 (>130Euro)
- Frequency: 2.4Ghz, 16 channels (XJT module)
- Antenna: 2dbi
- Protocol: FrSky (X,D series) (externel module)
- Firmware: OpenTx
- Telemetry: RSSI
- Connector: mini USB (firmware updates, simulators, OpenTX companion)
- RF module: JR type bay for external transmitter modules
- Aux: 6 switches (2 pots, 4x 3pos)
- Input: 6~15V
- Battery: Removable 6xAA battery tray, 2S/3S LiPo compatible (bay dimensions 92x59x17mm)
- Display: 128x64px backlight LCD
- Storage: 60 models (additional SD card slot)
Taranis X9D Plus (~250Euro)
Multiprotocol Transmitter Module [01]

Receivers

Furious Mini RX
- Compatible: FrSky Taranis, Taranis Plus, XJT module
- Size 17x24mm, weight: 2.4g (inc. antenna)
- SBUS without inversion, HUB telemetry
- 8 channels, single antenna
- Voltage: 4-6V

VTX (Video Transmitter)

FPV (First Person View) Video piloting by live streaming to video
Reads the video signal from the flight camera and transmits the stream down to ground
Transmission Power, aka power output: 25mW (used for indoor flight), 200mW, 600mW
- Power radiated through the transmitter
- More power may increase range, with the cost of increased noise on sidebands
- Regulation in Europe forbids transmission above 25mW
FPV transmitter/receiver require to work on compatible frequenzy/channel
5.8Ghz is the most common used transmission frequency for the video signal
Band
- F FS/IRC
- E Lumenier/DJI
- A Boscam A
- R Raceband
Channels: 32-40 channels
- Channels incrementally aligned with a band
- Channel chart lists supported channels of a VTX
- Multiple channels allow parallel signals on a single frequency
- Raceband optimum frequency distribution for up to 6 pilots
Channel Switching Mechanism
- DIP switches (require screwdriver, and channel chart)
- Digital switch with button (auto cycle channels) [often band at racing events]
- Programmable with infrared remote (often proprietary receiver)
Voltage Tolerance
- Check if the VTX supports the voltage of the battery
- Voltage Regulator (on the PDB) allows to provide lower voltage for the VTX if required
- LC Filter filters noise from the electricity (from the ESCs) to ensures smooth power supply for best FPV performance
VTX ground should not touch a carbon frame
- May overheat due to resistance
- Back feed noise
OSD On Screen Display
- Overlays flight information onto the video stream
- Enables the pilot to monitor the vehicle in real-time
- Flight data monitored: battery voltage, motor current, altitude, etc.
- RSSI indicator for radio signal strength

Antennas

Tuned to specific frequency, typically 5.8GHz
Antenna Polarization
- Linear & Circular, different radiation/emission patter (single plane vs. circular plane (corkscrew))
- Linear provides extra range, antennas need to be aligned to maximise the radiation pattern overlap (to prevent signal loss)
- Circular, better signal reception, reject multi-path signals
Directional & Omnidirectional Polarization
- Directional antennas increase range but reduce coverage (long narrow beam)
- Omnidirectional antennas increase coverage but reduce range (short wide beam)
Types of Antennas
- Duck/Dipole: Linear, omnidirectional
- Skew Planar: Circular, omnidirectional (4 lobs)
- Cloverleaf: Circular, omnidirectional (3 lobe)
- Array: Circular, omnidirectional
- Helical: Circular, directional
- Patch: Can be both circular or linear, directional
- Crosshair: Circular, directional
- Yagi: Linear, directional
Antenna Connector SMA (most popular), RP-SMA
Gain
- Alters the shape of the radiation pattern to gain extra range
- Measure of power in decibel (dB)
Diversity Receivers (dual receiver systems)
- Combine multiple antennas and receivers on the ground
- Monitor and dynamically select the receiver with the strongest signal

Camera

Most FPV cameras use analogue video, resolution TVL (TV lines)
Video Standards
- PAL 720x567@25fps
- NTSC 720x480@30fps
CMOS image sensor
- Rolling shutter (capture image pixel by pixel), vibrations may case negative effect on video stream
- Usually light and use less power CCD
CCD image sensor
- More expensive compared to CMOS sensors
- Global shutter (entire image captured at once)
- Large dynamic range to perform better in bright/dark conditions
Latency
- Delay introduced during processing of the image data
- Typical latency 140ms
Field of View
- Angel captured by the lens, focal length in millimeter
- Higher field of you allow to see more around (may distort boarder, or curve horizon)

References

Youtube…

https://www.youtube.com/@volaertus

Vendors…

Shops…

Germany…

--- title: FPV Quadcopter Basics catergories: - Hardware - Electronics date: 2017/04/23 date-modified: 2023/05/03 --- # Power Distribution Board * **PDB** (Power Distribution Board) - Connects battery to the ESCs and the - All positive & negative pads (terminals) are connected * Non carbon fiber frames may have the PDB build into the frame * Some PDBs may include a **Voltage Regulator** (BEC Battery Elimination Circuit) * Characteristics - **Current Rating** needs to support the max total current consumed by the ESCs - Number of **Connectors** for convenient soldering ## Motor * **ESC** (Electric Speed Controller) - Control the speed of the motor spin - Connected to the FC * **Weight** - Total weight of the vehicle, including payload (battery, HD cam) - Frame size limits propeller size which limits motor size * Electric **Power** - Measures in **W** (Watt) - `Voltage (V) * Current (A)` (voltage multiplied by current) * **Current Rating** - Maximum current motor can handle - Measured in **A** (Ampere) * **Thrust** - Measures in **g** (Gram) - Higher thrust equates in higher top speed, and higher current drawn - Full thrust needs to be supported by the batteries maximum discharge rate (C-Rating) * **Torque** (N.m) - Measures **Angular Force** - How much "push" the rotation shaft has * **RPM** Rounds Per Minute - Measures **Angular Speed** - How fast the motor rotates the propeller - **Response**, how fast the motor changes RPM * **Efficiency** - `Thrust (g)/Power (W)` (trust divided by power) - Higher efficient, means less power consumed - Power not transformed to trust dissipates as heat * **Kv** Number/Rating - RPM per volt supplied to the motor - Rating assumes no load on the motor, and constant voltage - `1200kv * 3V = 3600rpm` * **Thrust to Weight Ratio** - 2:1 minimum - 3:1, 4:1 normal - up to 8:1 for race (more agility, harder to control) * 4-digit number `AABB`, `AA` stator width, `BB` height ### Brushed * Pro - Low cost - Simple control (no controller required for fixed speed) - 2 control wires * Con - Brushes wear off because of friction (stop conducting electricity) - Speed/torque moderately flat (brush friction increases at higher speed) - Poor heat dissipation (due to internal construction) - Higher rotor inertia (less dynamic) - Lower speed range (mechanical limits on the brushes) - Brush arcing generates causes interference (EMI, noise) ### Brushless * Pro - More durable (due to absence of brushes) - Speed/torque flat - High efficiency (no voltage drops) - High output power to size ratio - Better heat dissipation - High speed range - Lower electric interference * Cons - Higher cost - Requires ESC (Electric Controller) ## Propellers * Propellers - 2CW (clockwise) & 2CCW (counter-clockwise) - Differ in length (diameter), pitch, and number of blades * **Shaft Power** - Motor input power to the propeller - Expressed in **W** (Watt) - `Torque * Angular Velocity (rad/s)` # Flight Controller * **FC** (Flight Controller) - Primary function: **control motors thrust** corresponding to the pilots inputs - **Interface with sensors** to maintain the aircraft flight state - Configurable and programmable, to adjust multi-rotor behavior and flight characteristics - Support different **flight modes** aka profiles, e.g. self-leveling mode * Sensors types: - **Gyro** (Gyroscopes) - **Acc** (Accelerometer) - Barometer (barometric pressure sensor) - Magnetometer (compass) * Firmware software race/acro flying: - Cleanflight - Betaflight - Raceflight * **Processor** F1,F3,F4 * Integrated **Voltage Regulator** - Power the FC board directly from the battery - Measures battery level * Integrated **PDB** (Power Distribution Board) * **RX** protocols # RC (Remote Control) * RC (Remote Control) Radio **TX** Transmitter (Controller) - Controller sticks called **Gimbal** - **Mode** controller configuration - Mode 1: throttle on the right stick - Mode 2 (most common): throttle on the left stick - Mode 3/4 rarely used * All sticks self center with the exception of the throttle axis * **RX** Receiver build into the vehicle * **Frequency**, typically **2.4GHz**, 1.3GHz used for long range * Frequency Hopping, aka **channel hopping protocol** - Software continuously scans for the best frequency - Switches channels automatically on radio interference - From 2.4000 - 2.4835GHz * **Binding** is the process of connecting transmitter with a receiver - TX/RX pairing requires compatible communication protocols * **Model** (profiles) memory, save multiple TX/RX pairings * Training with **Buddy Mode** linking two controllers * Firmware programs: Cleanflight ## Receiver Protocols * Communication between radio receiver and the flight controller * **Taranis** (FrSky) - ACCST (Advanced Continuous Channel Shifting Technology) * **Spektrum** - DSM (Digital Spectrum Modulation) - DSM2 uses 2 frequencies for data transmission - DSSS (Direct Sequence Spread Spectrum), 2.4GHz modulation, frequency at power-on - DSMX up to 60 frequencies for data transmission - TEAR assignment for channels 1-4 * **Futaba** - FASST (Futaba Advanced Spread Spectrum Technology), supports telemetry - FHSS & S-FHSS (Frequency-Hopping Spread Spectrum) - AETR assignment for channel 1-4 * OrangeRx (HobbyKing) * **FlySky** protocol & manufacturer - IBUS, bidirectional digital serial protocol * [Multi-Module](https://github.com/pascallanger/DIY-Multiprotocol-TX-Module) multi protocol transmitter - [nrf24-multipro](https://github.com/goebish/nrf24_multipro) ## Channels * Determines how many individual actions can be controlled * Channels 1-4 control flight - **Throttle** motor power up/down - **Yaw** rotating right/left (Rudder) - **Pitch** lean forward/backward (Elevator) - **Roll** lean left/right (Aileron) * **AUX** (auxiliary) channels for extra switches - Used to change flight modes, trigger functions - Recommended at leas **6 channels** for quadcopter - **Arm** switch on ## Vendors ### Transmitter * **FlySky FS-I6** (~50Euro) - Frequency: 2.4GHz, 6 channel - Protocol: AFHDS 2A * **Taranis Q X7** (>130Euro) - Frequency: 2.4Ghz, 16 channels (XJT module) - Antenna: 2dbi - Protocol: FrSky (X,D series) (externel module) - Firmware: OpenTx - Telemetry: RSSI - Connector: mini USB (firmware updates, simulators, OpenTX companion) - RF module: JR type bay for external transmitter modules - Aux: 6 switches (2 pots, 4x 3pos) - Input: 6~15V - Battery: Removable 6xAA battery tray, 2S/3S LiPo compatible (bay dimensions 92x59x17mm) - Display: 128x64px backlight LCD - Storage: 60 models (additional SD card slot) * **Taranis X9D Plus** (~250Euro) * **Multiprotocol Transmitter Module** [01] ### Receivers * **Furious Mini RX** - Compatible: FrSky Taranis, Taranis Plus, XJT module - Size 17x24mm, weight: 2.4g (inc. antenna) - SBUS without inversion, HUB telemetry - 8 channels, single antenna - Voltage: 4-6V # VTX (Video Transmitter) * **FPV** (First Person View) Video piloting by live streaming to video * _Reads the video signal from the flight camera and transmits the stream down to ground_ * **Transmission Power**, aka power output: 25mW (used for indoor flight), 200mW, 600mW - Power radiated through the transmitter - More power may increase range, with the cost of increased noise on sidebands - Regulation in Europe forbids transmission above 25mW * _FPV transmitter/receiver require to work on compatible frequenzy/channel_ * **5.8Ghz** is the most common used transmission frequency for the video signal * **Band** - **F** FS/IRC - **E** Lumenier/DJI - **A** Boscam A - **R** Raceband * **Channels**: 32-40 channels - Channels incrementally aligned with a band - **Channel chart** lists supported channels of a VTX - Multiple channels allow parallel signals on a single frequency - **Raceband** optimum frequency distribution for up to 6 pilots * **Channel Switching Mechanism** - DIP switches (require screwdriver, and channel chart) - Digital switch with button (auto cycle channels) [often band at racing events] - Programmable with infrared remote (often proprietary receiver) * **Voltage Tolerance** - _Check if the VTX supports the voltage of the battery_ - **Voltage Regulator** (on the PDB) allows to provide lower voltage for the VTX if required - **LC Filter** filters noise from the electricity (from the ESCs) to ensures smooth power supply for best FPV performance * VTX ground should not touch a carbon frame - May overheat due to resistance - Back feed noise * **OSD** On Screen Display - Overlays flight information onto the video stream - Enables the pilot to monitor the vehicle in real-time - Flight data monitored: battery voltage, motor current, altitude, etc. - **RSSI** indicator for radio signal strength ## Antennas * Tuned to specific frequency, typically 5.8GHz * Antenna **Polarization** - **Linear** & **Circular**, different radiation/emission patter (single plane vs. circular plane (corkscrew)) - Linear provides extra range, antennas need to be aligned to maximise the radiation pattern overlap (to prevent signal loss) - Circular, better signal reception, reject multi-path signals * Directional & Omnidirectional Polarization - Directional antennas increase range but reduce coverage (long narrow beam) - Omnidirectional antennas increase coverage but reduce range (short wide beam) * **Types of Antennas** - Duck/Dipole: Linear, omnidirectional - Skew Planar: Circular, omnidirectional (4 lobs) - Cloverleaf: Circular, omnidirectional (3 lobe) - Array: Circular, omnidirectional - Helical: Circular, directional - Patch: Can be both circular or linear, directional - Crosshair: Circular, directional - Yagi: Linear, directional * **Antenna Connector** SMA (most popular), RP-SMA * **Gain** - Alters the shape of the radiation pattern to gain extra range - Measure of power in **decibel** (dB) * **Diversity Receivers** (dual receiver systems) - Combine multiple antennas and receivers on the ground - Monitor and dynamically select the receiver with the strongest signal ## Camera * Most FPV cameras use analogue video, resolution **TVL** (TV lines) * Video Standards - **PAL** 720x567@25fps - **NTSC** 720x480@30fps * **CMOS** image sensor - Rolling shutter (capture image pixel by pixel), vibrations may case negative effect on video stream - Usually light and use less power CCD * **CCD** image sensor - More expensive compared to CMOS sensors - Global shutter (entire image captured at once) - Large dynamic range to perform better in bright/dark conditions * Latency - Delay introduced during processing of the image data - Typical latency 140ms * **Field of View** - Angel captured by the lens, focal length in millimeter - Higher field of you allow to see more around (may distort boarder, or curve horizon) # References Youtube... - <https://www.youtube.com/@volaertus> Vendors... - <https://betafpv.com> ...[amazon.de/store](https://www.amazon.de/stores//page/7E01A3EF-3B3E-4719-9AF6-2C035C34F638) - <https://geprc.com> Shops... - Germany... - <https://www.premium-modellbau.de> - <https://www.rctech.de> - <https://www.fpv24.com> :