ELRS-915M-TX High-Frequency Head 1W Low Phase Noise Performance

A low-power, high-signal-purity 915MHz ELRS protocol high-frequency head, centered on excellent low phase noise performance, specifically designed for professional wireless communication and high-precision control scenarios with stringent requirements for signal quality, spectral purity, and receiver sensitivity.

1. High-Precision Telemetry and Data Transmission: Used in applications such as scientific observation drones and payload data downlink, where extremely high signal fidelity is required.

2. Spectrum-Sensitive Systems: Maintains communication quality in dense spectral environments or scenarios with severe adjacent-channel interference.

3. Precision Timing and Synchronization Networks: Serves as a wireless clock synchronization or trigger signal transmission node for distributed systems.

4. Research and High-End Prototype Development: Provides a high-purity RF signal source for experiments in communication algorithm research and weak signal reception.

1. 1W Efficient Power and Ultra-Low Phase Noise: Ensures medium-to-short-range communication link budget while significantly reducing signal baseline noise, improving signal-to-noise ratio and receiver sensitivity, enabling longer effective communication range and stronger weak-signal capture capability.

2. High-Performance Architecture Based on ELRS Protocol: Inherits ELRS features such as high refresh rate, low latency, and strong anti-interference capabilities, while achieving spectral purity through optimized RF circuitry, ensuring stable and reliable connections in complex electromagnetic environments.

3. Enhances Overall System Communication Quality: Low phase noise directly reduces signal demodulation errors and lowers the bit error rate, particularly benefiting the stable operation of high-order modulation modes (e.g., LoRa long-range mode).

4. Professional-Grade RF Design: Utilizes low-noise amplifiers, high-performance oscillators, and optimized filtering design to ensure signal purity at the hardware level, meeting industrial measurement and research-grade application standards.

   Essential Parameter

   Frequency bands:

   915MHz (FCC) and 868MHz (EU)

   output power:

   0.5W/1W/2W/5W/10W (Default factory setting: 5W)

   Refresh rate:

   25Hz/50Hz/100Hz/200Hz

   Power consumption:

   8.4V,2.3A@10W,200Hz, 1:200

   Antenna connector:

   SMA

   USB port:

   Type-C

   Battery input voltage range:

   5-8.4V (2S)

   Built-in fan power supply:

   5V

   alloy heat dissipation fin, alloy cover

   Main control IC:

   ESP32+LR1121, with ESP8285 as the back-up chip

   Warning: Do not connect a power supply of 2S or higher than 8.4V to the ELRS-915M-TX high frequency head. Otherwise, it may cause permanent damage.
   Warning: Before powering on the ELRS-915M-TX high-frequency head, install the manufacturer's matching antenna. Failure to do so may damage the PA chip and reduce power output.

   The ELRS-915M-TX high-frequency head features a set of relay-compatible interfaces for user selection, with its base compatible with all Micro (also known as JR or SLIM) remote controls available on the market. The interface and design are shown in the figure below.

   Appearance and Heat Dissipation Structure

   Within the compact JR interface standard dimensions, the system integrates up to 10W of transmission power. To achieve stable performance at this extreme level, the design team redefined the high-frequency head's structural design. By combining an aluminum alloy fin heat sink, an efficient turbo fan, a metal casing, and a 10W RF PA chip with dedicated heat dissipation alloy, they created a product that integrates efficient heat dissipation, robust protection, and strong anti-interference capabilities. This ensures reliable performance for ultra-long-range navigation in harsh environments.

   Pre-Frequency Basic Configuration

   The ELRS-915M-TX high-frequency head is designed to receive only Crossfire Serial Data Protocol (CRSF) signals by default. The remote control's high-frequency interface must support CRSF signal output. Using the OpenTX remote control system as an example, this guide demonstrates how to configure the remote to output CRSF signals and control the ELRS high-frequency head with a LUA script.

   3.1 CRSF Protocol

   In the OpenTX system, select MODELSELECTION to access the MODELSETUP interface. Here, disable Internal RF (set to OFF), enable External RF, and set the output mode to CRSF, as shown in the figure below.

   

   Connect the ELRS-915M-TX high-frequency head correctly and configure the remote control as the CRSF output for the External RF head as described above.

   3.2 LUA Script Installation and Control (already Available)

   To adjust the power, refresh rate, and frequency of the ELRS high-frequency head, you need to use the OpenTX system's LUA script, as shown below.

   • Copy the official LUA script ELRS.lua to the remote control's SD card, located in the Scripts/Tools folder.
   • On the OpenTX system, press and hold either the SYS button (as found on RadioMaster T8 remote controls) or the MENU button (as used in Frsky Taranis devices).
   • Using the X9D remote control or similar devices, access the SD-HC CARD interface. In this interface, select the ELRS.lua script and execute it.
   • If the LUA script runs successfully, the interface will appear as shown below. (Default factory setting: 5W)
   
   • Using LUA scripts, you can configure parameters such as Rate (refresh rate), Ratio (feedback packet rate), and Power (output power). All LUA script functions are detailed in Table 1 below.
   Table 1 Script Description Table

   Name	Parameter name	Parameter description
   0:250	Data packet and bad packet ratio	Located in the upper right corner of the interface. It shows the number of data packets sent per second directly between the high-frequency head and the remote control, as well as the number of bad packets.
   Packet Rate	Packet rate	The higher the frequency, the shorter the data packet transmission interval of the high-frequency head, and the more precise the control.
   TelemRatio	Backhaul packet rate	For example, 1:64 means the high-frequency transmitter sends 64 data packets, and the receiver returns one.
   Power	Power	High frequency transmitter power
   RF Freq	Radio frequency	The current radio frequency used by the high-frequency head
   Bind	Binding	The high-frequency head is bound
   Wifi Update	WIFI update	Turn on WIFI for high-frequency head to update firmware

   Note: The official LUA script ELRS.lua can be downloaded from the ELRS support website (URLs are provided in the information section).

   4. Frequency Discrimination Method

   The ELRS high-frequency head uses the ExpressLRSV3.5.0 official protocol in its factory firmware and has no binding phrase configured. Therefore, the receiving end must also be V3.0.0 to V3.5.0 and has no binding phrase set.

   The frequency steps are as follows

   1. Step1: After the receiver is powered on, press the receiver button for a long time. The LED on the receiver will enter the double flash state, indicating that the receiver has entered the frequency matching mode
   2. Step2: Install the antenna on the high-frequency head, insert the remote control, and insert the external XT30 port battery (optional). Enter the Express LRS configuration interface, scroll down to find the Bind option, as shown in the figure below.
   
   3. Step3: After pressing the Bind button, the receiver enters a slow flash state and then a normal light state for about 2 seconds, indicating that the frequency reception is successful
   5. Power Settings

   The ELRS high-frequency head supports power outputs of 0.5W,1W,2W,5W, and 10W.

   The ELRS high-frequency hair transmitter power switching uses a LUA script. Select Power to switch directly between 0.5W,1W,2W,5W, and 10W. For details, see "LUA Script Control".

   
   

   Company Information

   Shenzhen Fengqing Instrument Co., Ltd.

   Crafted in China, Quality Forges Low-Altitude Security.
   Upholding a "customer-first" philosophy, Fengqing Instrument is committed to providing professional service throughout the entire product lifecycle:

   • Pre-sales Consultation: Customized solution designs and product recommendations based on client needs.
   • In-sales Support: Comprehensive technical support for installation, debugging, and operational training.
   • After-sales Service: Rapid-response system including remote support and on-site maintenance.