FPV Receiver Guide: Nano vs Diversity vs Gemini X Explained
CSKYUAV is a China-based drone and RC parts manufacturer with over 10 years of experience, shipping factory-direct to customers across Europe and Russia. Choosing an ExpressLRS receiver for your drone comes down to risk: a simple nano unit for park flying, an antenna-diversity or true-diversity model for racing and freestyle, and a Gemini Xrossband dual-band receiver when your radio supports Gem-X and you fly long range. PWM receivers with six or eight channels serve fixed-wing and servo-driven builds. This FPV receiver guide explains each tier using the factory specifications of the receivers we stock.
What Is ExpressLRS and Why Receiver Choice Matters?
ExpressLRS (ELRS) is an open-source radio link for hobby RC, known for sub-10 ms latency, packet rates from 25 to 1000 Hz and range that typically exceeds the video link. Because the protocol is open, any receiver works with any ELRS transmitter on the same band and firmware version — no vendor lock-in. The real differences live in the hardware: antenna layout, one versus two radio front-ends and single- versus dual-band operation decide how reliably that range survives real flying.
If you are still deciding between 2.4 GHz and 915 MHz for your country, read our 915 MHz vs 2.4 GHz ExpressLRS receivers guide first. Transmitter-side choices are covered in the FPV radio controller guide. Here we focus on the receiver itself.
The ExpressLRS Receiver Lineup at a Glance
Receivers in our range fall into four hardware tiers plus one special-purpose family. The table uses factory specifications.
| Receiver | Tier | Frequency | Size / weight | Output |
|---|---|---|---|---|
| XR2 Nano | Basic nano | 2.4 GHz | 16 × 12 mm / 0.8 g | CRSF (UART) |
| XR3 Nano | Antenna diversity | 2.4 or 900 MHz | 22 × 15 mm / 1.3 g | CRSF + UART |
| RP4TD | True diversity | 2.4 GHz | 23.7 × 16.3 mm / 1.4 g | CRSF + UART |
| XR4 | Gemini Xrossband | 2.4 GHz + 900 MHz | 22 × 18 mm / 1.7 g | CRSF + UART |
| ER6G / ER8G | PWM + diversity | 2.4 GHz | 42–60 mm long / 5–12 g | 6–8 × PWM + CRSF |
All listed models run the same open-source ELRS firmware, refresh up to 1000 Hz where supported, and expose telemetry over CRSF to your radio.
What Is Antenna Diversity in an ELRS Receiver?
Antenna diversity means the receiver has one radio front-end but two antennas, each with its own connector, and it switches to whichever antenna receives the stronger signal. In a drone, antennas placed in different orientations cope with frame shadowing: when carbon arms block one, the other usually still sees the transmitter.
The XR3 Nano antenna-diversity receiver is a compact example: 22 × 15 mm, 1.3 g, an ESP32-C3 with a Semtech LR1121 transceiver, two IPEX-1 antenna connectors with T-antennas, CRSF plus an extra UART port, and telemetry power up to 100 mW. Because diversity adds almost no weight, the XR3 is a popular default for small quads that want better link robustness without a bigger receiver.
True Diversity: Two Receivers in One Package
True diversity goes one step further: the receiver contains two complete radio circuits that listen simultaneously. This delivers not just antenna selection but genuinely independent RF paths. The RP4TD true-diversity receiver shows the design: dual SX1281 transceivers, two 65 mm 2.4 GHz T-antennas, up to 2 × 100 mW telemetry output, a wide 4.5–12 V input range and dual temperature-compensated oscillators (TCXO) that keep frequency stable in changing temperatures. The mini RP4TD-M version keeps the dual RF chain at about 1 g for weight-critical builds.
Which one do you need? Antenna diversity handles orientation and shadowing; true diversity adds protection against frequency drift and weak single-front-end sensitivity. Racers and freestyle pilots who fly through varied orientations and temperatures benefit most from true diversity.
Gemini X and Xrossband: Dual-Band Receivers Explained
The newest tier combines both redundancy ideas on different bands. ExpressLRS Gemini runs two identical antennas on the same frequency, while Gemini Xrossband (Gem-X) runs one antenna on 2.4 GHz and the other on Sub-G 900 MHz at the same time. The receiver keeps the link alive by switching between two physically different frequencies — the strongest form of anti-interference redundancy currently available in hobby radio.
The XR4 Gemini Xrossband receiver implements this with two LR1121 transceivers, dual-band T-antennas and independent RF circuits, and you can set it to Gemini single-band mode or Xrossband dual-band mode depending on your transmitter. Dual-band Xrossband support on the TX side (for example Gem-X radios) is required to unlock the full benefit. For pilots who mostly fly 2.4 GHz but want a radio-ready backup path, the DBR4 dual-band Xross Gemini receiver is the matching compact option.
PWM Receivers for Fixed-Wing, Rovers and Servo Builds
Not every aircraft runs a flight controller. Fixed-wing planes, gliders, rovers and camera rigs often plug servos straight into the receiver, which is what PWM channels are for. The ER6G offers six PWM channels plus CRSF serial output and battery-voltage detection, while the ER8G adds eight channels with 20 cm antennas and up to 100 mW telemetry — enough for a full-wing build. Both tolerate a wide supply range (3.5–8.4 V) and their telemetry power is adjustable from the transmitter LUA script.
For telemetry beyond voltage, ExpressLRS PWM receivers also speak CRSF to expansion sensors. The ERS-GPS sensor (32.8 × 25.5 mm, 13.35 g, 3.0–12 V) plugs into ER-series receivers and streams GPS position back to the radio, which matters for fixed-wing return-to-home workflows — more detail in our FPV GPS module guide.
A special case is the GR-01 receiver for DJI RS camera gimbals: it outputs the DJI RS Pro protocol so you can operate a RS-series gimbal directly from an ExpressLRS radio instead of the DJI controller, binding by powering the receiver three times and pressing BIND in the ELRS Lua script.
Antenna Placement and Replacement Pitfalls
Receiver hardware matters only if the antenna does its job. Keep antennas clear of carbon, batteries and video transmitters, and mount diversity antennas perpendicular so at least one stays clear at every attitude. When replacing a lost or broken antenna, use a genuine spare: the 4-piece replacement antenna set fits RP1, RP3, RP4TD and RP4TD-M receivers, but expect reduced range if a small whip antenna replaces the original T-antenna. Band-specific range expectations are covered in our long-range FPV antenna guide.
Frequently Asked Questions
What is the difference between antenna diversity and true diversity?
Antenna diversity uses one radio front-end that switches between two antennas to pick the stronger signal. True diversity contains two independent radio circuits that listen at the same time, which also protects against frequency drift. In our range the XR3 is the antenna-diversity model and the RP4TD is the true-diversity model.
Do I need a Gemini Xrossband receiver like the XR4?
Only if your transmitter supports Gemini or Gemini Xrossband mode. The XR4 can run single-band Gemini (two antennas on one frequency) or Xrossband (2.4 GHz plus 900 MHz at once) to match the radio. For a regular single-band ELRS transmitter a standard receiver is the right and cheaper choice.
Which receiver should I use for a fixed-wing plane without a flight controller?
Use a PWM receiver such as the ER6G (6 channels) or ER8G (8 channels). Servos plug directly into the outputs, serial CRSF is still available for a flight controller or telemetry sensor, and battery voltage is monitored and sent back to the radio.
Why is my receiver range suddenly short?
Check the antenna first — damage or an unplanned swap is the usual cause, and a small whip antenna in place of a T-antenna shortens range. Also confirm the antenna is clear of carbon and metal, that transmitter and receiver share a band and firmware generation, and that you stay within legal power limits.
Is 2.4 GHz or 900 MHz better for my receiver?
2.4 GHz gives lower latency and is legal almost everywhere; 900 MHz (Sub-G) penetrates obstacles better and suits long-range flights where regulation allows it. Our dedicated 915 MHz vs 2.4 GHz comparison walks through the full decision.
What is the lightest receiver for a 5-inch quad?
The XR2 Nano weighs 0.8 g with its integrated tower antenna and covers basic 2.4 GHz CRSF builds. If you want diversity on a small quad, the XR3 adds about 0.5 g and the mini RP4TD-M keeps true diversity at roughly 1 g with a dual RF chain.
Summary
Choosing an ExpressLRS receiver is about matching hardware redundancy to your flying risk: a light nano unit for casual flying, an antenna-diversity XR3 or true-diversity RP4TD for racing and freestyle, a Gemini Xrossband XR4 or DBR4 when your radio supports dual-band, and a PWM ER6G or ER8G for fixed-wing and servo-driven builds. Whatever you fly, keep antennas clear of carbon and electronics and use genuine spares. All receivers in this guide ship factory-direct from CSKYUAV with wholesale pricing and ODM/OEM support — contact us with your build details and we will confirm stock, firmware options and shipping to Europe or Russia within 24 hours.