5W 915M-TX High-Frequency Head High-gain Design

5W 915M-TX High-Frequency Head High-gain design

A medium-power, high-gain, professional-grade 915MHz wireless data transmission high-frequency head. It achieves an excellent balance between transmission distance, signal stability, and penetration capability, serving as a cost-effective and reliable industrial-grade remote control and data communication solution.

1. Medium-to-Long Range Drone Applications: Suitable for industrial drones in inspection, mapping, and security, enabling reliable control and data transmission at distances of 5–10 kilometers.

2. Remote Control in Complex Environments: Used for controlling vehicle, boat, and robot models in obstructed outdoor environments such as buildings or forests.

3. Regional Wireless Data Transmission and Relay: Acts as a medium-power data uplink or relay unit for IoT nodes, sensor networks, or low-power wide-area networks.

4. Research and Prototype Development: Provides a stable and reliable 915MHz frequency band hardware platform for communication protocol validation and remote control system development.

1. 5W Optimized Power and High-Gain Design: Achieves an outstanding balance between power and efficiency. Combined with a high-gain antenna design, it ensures communication distance and signal quality while optimizing power consumption, heat dissipation, and device size.

2. Advantages of the 915MHz Gold Frequency Band: Compared to 2.4GHz, it offers longer propagation distance, stronger diffraction, and penetration capabilities, significantly improving connection reliability in non-line-of-sight and complex environments.

3. Integrated "High-Frequency Head" Design: Highly integrates RF power amplification, filtering circuits, and antenna interfaces, providing plug-and-play convenience and simplifying system integration while enhancing overall electromagnetic compatibility and reliability.

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

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.