Quick Answer
ELRS stands for ExpressLRS. It is an open-source radio-control link between the transmitter in your handset and the receiver in your drone. ELRS supports 2.4GHz and sub-GHz hardware, uses LoRa modulation, carries control plus telemetry, and is now the default choice we recommend for most new FPV setups.
What Is ExpressLRS?
ExpressLRS is the control link, not the video system. Your radio handset sends stick and switch commands through an ELRS transmitter; the ELRS receiver on the aircraft passes those commands to the flight controller, normally over CRSF. The return link carries telemetry such as link quality, receiver signal and battery data.
The project is open source and uses Semtech radio hardware with a compact over-the-air packet structure. Official ExpressLRS documentation lists two main families: 2.4GHz hardware with packet rates up to 1000Hz, and 900MHz hardware with packet rates up to 200Hz and better penetration. That distinction matters more than the brand printed on the receiver.
Our practical rule is simple: choose the band first, then make sure the transmitter and receiver support the same band and major firmware version. A 2.4GHz receiver cannot bind to an 868MHz-only transmitter merely because both carry the ELRS name.
Why ELRS Became the FPV Standard
Open hardware choice: RadioMaster, BetaFPV, Happymodel and other manufacturers build compatible equipment. You are not locked to one brand, provided the frequency band, firmware generation and hardware target match.
Useful performance choices: 2.4GHz offers the highest packet rates for racing and freestyle. Sub-GHz equipment trades packet rate for penetration and is aimed at specialist long-range use.
Small receivers: Modern 2.4GHz receivers fit tiny whoops as well as full-size quads. The Happymodel EP1 TCXO adds a temperature-compensated oscillator for better frequency stability without forcing a larger control-link ecosystem.
Active firmware: ExpressLRS 4.1 followed 4.0 with revised dynamic-power behaviour, handset bind-phrase management and fewer misleading “Telemetry Lost” announcements. We would choose ELRS for a new FPV radio unless an existing fleet gives you a strong reason to remain on another protocol.
2.4GHz vs 868/915MHz ELRS
| Band | Official maximum packet rate | Hardware rule | Our recommendation |
|---|---|---|---|
| 2.4GHz | Up to 1000Hz | Use a 2.4GHz transmitter and 2.4GHz receiver | Start here for whoops, racing, freestyle and ordinary long-range builds |
| Sub-GHz | Up to 200Hz | Use the correct regional domain and matching sub-GHz hardware | Choose it only when penetration or a dedicated long-range link matters more than maximum packet rate |
In the UK, sub-GHz ELRS equipment is normally sold as 868MHz hardware; 915MHz is associated with other regulatory domains. Do not copy a frequency-domain setting from a US tutorial. Use the legal domain and output limits for the country where you fly.
The BetaFPV ELRS Nano Receiver listing has separate 2.4GHz and 868MHz variants. They are choices, not one receiver that automatically changes band. For almost every first system we would buy 2.4GHz because the radios and receivers are easier to source and the performance margin is already substantial.
ELRS vs Crossfire: Which Should You Choose?
| Decision | ELRS | Crossfire |
|---|---|---|
| Ownership | Open-source project | Proprietary TBS ecosystem |
| Main hardware choices | 2.4GHz and sub-GHz from multiple manufacturers | Primarily sub-GHz TBS hardware |
| Best reason to choose it | Wide hardware choice, high 2.4GHz packet rates and no single-brand lock-in | You already own a reliable Crossfire fleet and do not want to re-equip it |
| Our pick for a new FPV setup | Yes, usually 2.4GHz | No, unless a specific project or existing fleet calls for it |
We would not replace a working Crossfire fleet merely to follow a trend. For a first radio or a clean-sheet build, however, ELRS gives a broader receiver choice and a clearer upgrade path across radio brands.
Which ExpressLRS Version Should You Use?
ExpressLRS 4.1.0 is the current stable release at the time of this update. It is compatible with other 4.x firmware, adds bind-phrase control from the handset, refines the statistical dynamic-power algorithm introduced in 4.0, and reduces “Telemetry Lost” call-outs that can otherwise sound like a control-link failure.
The important boundary is the major version. ExpressLRS 4.x will not connect to 3.x, 2.x or 1.x. Version 4.0 also removed support for STM32-based targets, including R9M and Ghost-derived hardware, so older equipment may need to remain on the maintained 3.x branch rather than being forced onto 4.x.
For new supported hardware, we would use the latest stable 4.x release. For an existing fleet, check every transmitter and receiver target before changing major version, update the whole fleet together, and keep a record of the firmware target used. See our ExpressLRS firmware update guide before you flash anything.
ELRS Transmitter vs Receiver: What You Need
| Part | Where it lives | What it does | What must match |
|---|---|---|---|
| ELRS transmitter (TX) | Built into the radio or fitted as an external module | Sends controls and receives telemetry | Receiver band and compatible major firmware |
| ELRS receiver (RX) | Installed in the drone, wing, car or boat | Passes controls to the flight controller and returns telemetry | Transmitter band and compatible major firmware |
| Flight-controller connection | Usually one UART on the aircraft | Carries CRSF serial data between receiver and FC | TX-to-RX and RX-to-TX wiring, plus Serial RX configuration |
For a first setup, choose the ELRS 2.4GHz variant of the RadioMaster Boxer or a dedicated ELRS radio such as the RadioMaster TX15. Do not assume every Boxer variant contains ELRS: the same product family is also sold with other internal RF modules.
Bind with a phrase: Set the same private binding phrase on the transmitter and receiver. Three rapid power cycles can trigger bind mode on many receivers, but we treat that as a recovery method, not the normal fleet-management plan.
Configure Betaflight: Wire receiver TX to flight-controller RX and receiver RX to flight-controller TX. Enable Serial RX on that UART, select the CRSF serial receiver provider, enable telemetry, then apply the ExpressLRS Link preset for your chosen packet rate.
Check before arming: Confirm channel movement, failsafe behaviour, link-quality display and antenna security with props removed. Browse our verified radio receivers and R/C transmitters after deciding which band you need.
Dynamic Power Explained
Dynamic power lets the transmitter raise output when link conditions worsen instead of running at the configured maximum all the time. ExpressLRS 4.0 introduced a statistical algorithm that models the signal-to-noise ratio needed for better than 99% link quality. Version 4.1 then lowered the power-down threshold so the system has more opportunities to reduce output again when conditions improve.
We recommend enabling dynamic power only after the basic link is proven. It cannot fix a damaged antenna, a mismatched frequency band or a receiver installed against carbon. Treat it as power management, not a substitute for correct hardware and antenna placement.
FAQ
What does ELRS stand for?
ELRS stands for ExpressLRS. The name combines "Express" (for fast packet rates and low latency) with "LRS" (Long Range System). ELRS is simply the abbreviation of ExpressLRS, both refer to the same open-source radio control protocol for FPV drones.
Is ELRS the same as LoRa?
No, but they are related. ELRS uses Semtech's LoRa modulation as its radio physical layer, but ELRS is a complete radio control protocol built on top of it. LoRa handles the RF modulation and spread-spectrum encoding; ELRS adds the packet structure, frequency hopping, telemetry, arming logic, and flight controller integration. Think of LoRa as the engine and ELRS as the complete vehicle built around it. The two technologies solve different jobs: LoRa is the radio modulation, whilst ELRS adds the control-link protocol, telemetry and flight-controller integration.
Should I upgrade from ELRS 3.x to 4.x?
For new supported hardware, use the latest stable 4.x release. Do not update one device in isolation: 4.x cannot connect to 3.x. Check hardware targets first because 4.0 removed STM32-based support, then update the transmitter and every receiver in the fleet together. Older unsupported hardware should remain on the maintained 3.x branch.
Is ELRS better than Crossfire?
For most pilots, yes. ELRS offers broad hardware choice and packet rates up to 1000Hz on 2.4GHz. Crossfire has a longer heritage and some pilots prefer its 868/915MHz performance for extreme range. Crossfire is more plug-and-play, whilst ELRS needs slightly more setup. For the majority of FPV pilots, ELRS provides better value.
What frequency is best for ELRS?
Choose 2.4GHz for most FPV drones. It supports packet rates up to 1000Hz and has the widest choice of small receivers. Sub-GHz ELRS tops out at 200Hz but offers better penetration, so reserve it for specialist long-range work. The transmitter and receiver must support the same band.
Do I need a licence to use ELRS?
UK use depends on the frequency, regulatory domain and transmitted power, not the ELRS name. Licence-exempt operation still has technical limits. Select the UK/EU domain, stay within the applicable Ofcom requirements, and do not copy 915MHz or high-power settings from US tutorials. Drone-registration duties are separate from radio-spectrum rules.
Can I use any ELRS receiver with any ELRS transmitter?
Not automatically. Different brands can interoperate, but the transmitter and receiver must support the same frequency band and compatible major firmware. A 2.4GHz-only transmitter will not bind to an 868MHz receiver, and 4.x will not connect to 3.x.
How do I update ELRS firmware?
Use the ExpressLRS Configurator desktop app to build and flash firmware. For receivers, the most common method is Betaflight Passthrough via USB. TX modules and receivers can also be updated over WiFi. Always match major firmware versions across all devices. See our full ELRS firmware update guide for step-by-step instructions.
What is a binding phrase in ELRS?
A binding phrase is a text string (minimum 8 characters) you set when flashing firmware to both your TX module and receiver. It acts as an anti-collision mechanism, seeding the frequency hopping pattern so your devices connect. All devices with the same binding phrase on the same frequency band will bind automatically. It is not for security or encryption.
Is ELRS 4.x compatible with 3.x receivers?
No. ELRS 4.x is not compatible with 3.x, 2.x or 1.x. Version 4.1 is compatible with other 4.x releases. Update the transmitter and receivers together, and verify that each hardware target supports 4.x before flashing.