Glossary
Every FPV term you keep hearing, explained.
Acro, BLHeli, CRSF, KV, RHCP, RPM Filtering — if you've seen it on a forum, it's defined here.
A
4 terms- Acro Mode
- Manual rate-based flight mode. Sticks command rotation rate, not angle — the quad keeps rotating until you center the sticks. The mode all FPV is flown in.
- Angle Mode
- Self-leveling auto mode where stick position commands a tilt angle. Used for stabilized cinematic shots and teaching beginners.
- AIO
- All-in-One board. FC + ESC on a single PCB, common in micros and whoops.
- Arm / Disarm
- Enabling or disabling motors. Always disarm before reaching for the drone.
B
4 terms- BEC
- Battery Eliminator Circuit. Steps down LiPo voltage to clean 5 V / 9 V / 12 V for cameras, VTX, RX.
- Betaflight
- Open-source flight firmware that runs on most FPV drones. Free GUI configurator.
- BLHeli / AM32
- Firmware that runs on ESCs to control motor commutation.
- BNF / PNP / RTF
- Bind-and-Fly (no radio), Plug-and-Play (no RX/radio), Ready-to-Fly (everything in the box).
C
4 terms- C-rating
- Continuous discharge rating of a LiPo. C × capacity (Ah) = max continuous amps.
- Cinewhoop
- Ducted 3" drone designed for smooth, indoor, around-people cinematic shots.
- Cobra
- Skyzone analog goggles line, popular budget-to-mid analog choice.
- CRSF
- Crossfire Serial Protocol. Low-latency RX-to-FC protocol used by ELRS and TBS Crossfire.
D
1 term- Dshot
- Digital signal protocol from FC to ESC. DShot300/600 are common today.
E
3 terms- EdgeTX
- Open-source firmware for FPV radio transmitters (forked from OpenTX).
- ELRS
- ExpressLRS. Open-source, low-latency, long-range RF link for FPV. 2.4 GHz or 900 MHz.
- ESC
- Electronic Speed Controller. Powers and commutates brushless motors.
F
4 terms- Failsafe
- What the quad does when it loses control link — typically motors-off and (with GPS) RTH.
- FC
- Flight Controller. The brain board with gyro, MCU, and Betaflight.
- FPV
- First Person View. Flying via real-time video feed from a camera onboard the drone.
- Freestyle
- Style of FPV emphasizing flow, tricks, dives — closest to skateboarding.
G
1 term- Gyro
- MEMS chip on the FC that measures rotation rates. ICM-42688-P is the modern standard.
H
1 term- HD / Digital
- Digital video systems: DJI O3, Walksnail Avatar, HDZero. Sharper than analog, slightly more latency.
I
1 term- ICM-42688-P
- Modern, quiet gyro chip used in most current FCs.
J
1 term- Jello
- Vertical rolling shutter wobble in video. Usually caused by vibration or warped props.
K
1 term- KV
- Motor RPM per volt with no load. 1750 KV × 22.2 V ≈ 38,850 RPM unloaded.
L
2 terms- LiPo
- Lithium Polymer battery. The standard FPV power source.
- Long Range
- FPV style focused on flying miles from launch with GPS, low-KV motors, and HD video.
M
3 terms- MicroSD
- Card slot on FCs and digital VTXs used for blackbox logs and onboard HD recording.
- Motor mount
- M3 hole pattern (typically 16×16 or 16×19) on the frame arms for motors.
- Multipath
- Reflected RF signal that arrives slightly delayed, causing video noise. RHCP antennas reject it.
O
1 term- OSD
- On-Screen Display. Overlays voltage, current, RSSI, etc. on your video.
P
5 terms- Pids
- Proportional, Integral, Derivative gains. Tunes how the FC corrects rotation errors.
- Pitch (prop)
- Theoretical forward distance per rotation. Higher = more speed, more current draw.
- Pit Mode
- Low-power VTX mode (~25 mW) used in the pits so others can fly without interference.
- Polarization
- Orientation of the RF wave. RHCP and LHCP must match between VTX and goggle antennas.
- Prop wash
- Turbulent air from the quad's own wake disturbing the gyro during quick stops.
R
6 terms- Rates
- How fast the quad rotates per stick deflection. Tuned per pilot taste in EdgeTX/Betaflight.
- RHCP / LHCP
- Right- and left-hand circular polarization. Pick one and stick with it for video.
- RPM Filtering
- Notch filters in Betaflight driven by real motor RPM from bi-directional DShot.
- RSSI / LQ
- Received Signal Strength / Link Quality. Two metrics for control-link health.
- RTH
- Return To Home. Auto-fly-back behavior triggered by failsafe (requires GPS).
- RX / TX
- Receiver (on the quad) and Transmitter (your radio in your hands).
S
2 terms- SBus / FPort
- Older FrSky serial RX protocols. CRSF/ELRS has largely replaced them.
- Stack
- FC + ESC bolted together with vibration-isolating standoffs.
T
1 term- True X / Stretched X
- Frame geometries. True X is symmetrical; stretched X has longer wheelbase forward/back for pitch character.
U
1 term- UART
- Universal Asynchronous Receiver/Transmitter. A serial port on the FC — RX, VTX telemetry, GPS each need one.
V
1 term- VTX
- Video Transmitter. Sends camera feed to your goggles.
W
1 term- Whoop
- Tiny ducted indoor drone (65 mm / 75 mm) for practicing inside.
X
1 term- XT60 / XT30
- LiPo battery connectors. XT60 for 4S+ 5" quads; XT30 for micros.