Happymodel and BetaFPV ELRS receivers with TCXO

All ExpressLRS transmitters and receivers work on the certain frequency. Both devices must operate on the exact frequency in order to be able to talk to each other. The precision of the frequency is mostly dependable on the crystal oscillator (XO). This makes crystal oscillator the very important part in the ELRS hardware.

One of the most notorious problems with ExpressLRS hardware is that some manufacturers hardware have unacceptable high frequency error. And in the high or low temperatures it gets even worse. There is certain threshold of the frequency error for the link to work.  Up to 40 ppm error (=~100 kHz) frequency difference is considered still acceptable.

Detailed explanation about the Crystal Oscillator (XO) Frequency Error can be found on the expresslrs.org webpage: https://www.expresslrs.org/3.0/hardware/crystal-frequency-error/

BetaFPV SuperD receiver

BetaFPV SuperD receiver is the first ExpressLRS receiver with full dual diversity and temperature compensated crystal. Receiver has two SX1280 LoRa RF ICs, two PA/LNA amplifiers and two antenna connectors. Power amplifier provides 100mW for telemetry link.

Available @ BetaFPV: https://betafpv.com/products/superd-elrs-2-4g-diversity-receiver

Aliexpress: https://www.aliexpress.com/item/1005004938838056.html

Specifications
Item: BETAFPV SuperD ELRS 2.4G Diversity Receiver
MCU: ESP32 PICO D4, dual SX1280 (SX1281)
Antenna Connector: IPEX MHF 1/U.FL
RF Frequency: 2.4GHz (2400~2480MHz)
Telemetry Power: 20dBm (100mW)
Receiver Protocol: CRSF
Input Voltage: +5V DC @ “+” pad
PCB Size: 22mm*14mm
Weight: 1.1g excluding antenna
Crystal oscillator: high-quality TCXO

Happymodel TCXO EP1,EP2 and EP1 Dual receivers

Happymodel has also released their three EP1, EP2 and EP1 Dual ExpressLRS receivers with temperature compensated crystals (TCXO).

Available @

Banggood: https://www.banggood.com/HappyModel-EP1-Dual-or-EP1-RCXO-or-EP2-TCXO-…-1975740.html

Makerfire: https://shop.makerfire.com/…/happymodel-ep1-tcxo-and-ep2-tcxo-2-4ghz-expresslrs-receiver-elrs

Aliexpress: https://www.aliexpress.com/item/1005002459298315.html

EP1 TCXO Receiver
Type: ISM2.4GHz
ESP8285 MCU
SX1280(SX1281)IMLTRT RF Module
Omni directional antenna
Frequency Range: 2400 MHz to 2500 MHz
Receive refresh rate: 25HZ~500Hz
Working voltage: 5V
Weight: 0.41g (without antenna)
Dimension: 10mm*10mm*6mm
Peak gain: 2.23dB
Default Firmware out of factory: HappyModel_EP_2400_RX V2.2 version
Built-in a TCXO (temperature compensated crystal oscillator)

EP2 TCXO Receiver
Type: ISM2.4GHz
ESP8285 MCU
SX1280(SX1281)IMLTRT RF Module
SMD Ceramic antenna
Frequency Range: 2400 MHz to 2500 MHz
Receive refresh rate: 25HZ~500Hz
Working voltage: 5v
Weight: 0.44g
Dimension: 10mm*10mm*6mm
Peak gain: 3.7dB
Default Firmware out of factory: HappyModel_EP_2400_RX V2.2 version
Built-in a TCXO (temperature compensated crystal oscillator)

EP1 Dual TCXO Receiver
Type: ISM2.4GHz
ESP32 PICO D4, dual SX1280(SX1281)
Antenna connector: IPEX MHF 1/U.FL
RF Frequency: 2.4GHz (2400~2480MHz)
Telemetry power: >19dbm
Receiver protocol: CRSF
Input voltage: +5V DC @ “+” pad
PCB size: 19mm x 14mm
Weight: 1g (excluding antenna)
Built-in a TCXO (temperature compensated crystal oscillator)
Firmware: HappyModel EP1 Dual 2400 RX (starting from ExpressLRS V3.0)

Both manufacturers dual diversity receivers have multicolored LED for status indication. SuperD and EP1 Dual receiver RGB status indication is shown below.

RGB Color	Status	Description
Rainbow	Fade effect	Power on
Green	Quick flash	WIFI upgrading mode
Red	Quick flash	No RF chip detected
Orange	Double flash	Binding mode
Orange	Triple flash	Connected, but mismatched model-match configuration
Orange	Slow flash	Waiting for connection
	Solid on	Connected and color indicates packet rate (see below)

The RGB light color corresponding to the packet rate