Bidding Farewell to the "Metal Shielding Effect": MN54L's Penetration Power Ensures IIoT Device Connection Stability in Containers and Cabinets.

Introduction

This test aims to validate the signal penetration and connection capabilities of the MN54L-C15 Bluetooth module in an extreme Radio Frequency (RF) shielding environment. By installing the Device Under Test (DUT) inside the furthest end of a large metal shipping container and conducting connection tests within a parallel-container setting, we simulated severe conditions common in Industrial IoT (IIoT) applications where signals must penetrate metal structures, such as equipment cabinets, walls, or buildings.

1. Test Objectives

✅ Quickly verify the maximum effective communication range of the MN54L BLE module when communicating with external devices from inside a large metal container.

✅ Test the communication performance of the Chip Antenna version module at its optimal axial direction while penetrating the container.

2. Test Date & Environment

3. Equipment Required

4. Test Parameters

5. Test Procedure - MN52H-U40 (Master, +8 dBm)

5.1 Preparation and Connection Establishment

1. Equipment Setup: Confirmed that the SLAVE/PERIPHERAL (MN54L-C15) and the MASTER/CENTRAL (MN52H-U40) TX Power were both set to +8 dBm.

2. Transmission Rate: Set to 1M mode with 4 packets transmitted per second.

3. Starting Point: The SLAVE device was placed inside the furthest end of the 40-foot container, the container door was closed, and the antenna was oriented towards the MASTER's driver position.

4. Connection Check: The MASTER established an active connection and performed bidirectional packet transmission. Packet reception was verified via LED indicator lights on the module.

5.2 Distance Measurement and Data Logging

1. Incremental Test: The MASTER moved outwards along the LOS path in 10-meter increments (approx. 10 steps).

2. Monitoring: At each point, the connection status was monitored. Packet loss was identified by the LED indicators extinguishing or blinking irregularly. Continuous transmission/reception defined a valid connection.

3. Angle Test: At the distance where signal attenuation began, the impact of the SLAVE device's antenna rotation on the Packet Success Rate (PSR) was tested to confirm the signal pattern.

4. Maximum Range: Movement continued until significant packet loss occurred (e.g., LED blinking slowed down or stopped). Google Map and GPS were used to precisely record the disconnection distance and surrounding environment.

6. Test Procedure - iPhone 7 (Master, 0 dBm)

6.1 Preparation and Connection Establishment

1. Equipment Setup: Established an active connection between the iPhone 7 and the SLAVE, verifying packet reception via the LightBlue® interface.

2. Transmission Rate: Set to 1M mode with 4 packets transmitted per second.

3. Starting Point: The SLAVE device was placed inside the furthest end of the 40-foot container and the door was closed.

4. Connection Check: Connection status was monitored via the LightBlue® screen.

6.2 Distance Measurement and Data Logging

1. Incremental Test: The MASTER (iPhone 7) moved outwards along the LOS path in 10-meter increments.

2. Monitoring: At each point, connection quality was checked via the LightBlue® screen.

3. Maximum Range: Followed the same procedure as Section 5.2 (Step 4) to determine and log the maximum effective connection distance.

7. Test Results (Maximum Effective Connection Distance)

The table below shows the maximum distance at which the MN54L-C15 (PERIPHERAL) maintained a stable bidirectional connection after penetrating the container barrier:

Note: The aerial view is not a photo of the actual site.		Note: The aerial view is not a photo of the actual site.

8. Test Conclusions and Observations

1. Severe Signal Constraint: Compared to open-field test results, the connection range dropped drastically from hundreds of meters to tens of meters. This confirms the extreme attenuation effect of the multiple metal containers on the 2.4 GHz Bluetooth signal.

2. Pro-Grade vs. Consumer-Grade Performance Difference:

o MN54L (PERIPHERAL) paired with MN52H-U40 (MASTER) achieved 81.14m.

o MN54L (PERIPHERAL) paired with iPhone 7 (MASTER) achieved 59.87m.

o This result highlights that the professional-grade MN52H-U40 module, with its higher Tx power and superior receiver sensitivity, provided approximately 36% better connection performance when overcoming severe signal fading compared to the consumer-grade phone.

3. Conclusion: Despite the highly challenging RF environment, the MN54L-C15 module successfully penetrated multiple metal containers and maintained a stable connection, especially when paired with a professional Bluetooth MASTER module. This demonstrates that the MN54L possesses an adequate Link Budget and stable RF performance to meet the demands of industrial applications requiring communication through metal enclosures and multi-barrier scenarios.

★ Source: Arad Connectivity Co., Ltd.  / The content of this article has obtained the authorization for promotion, release and reprint from Arad Connectivity Co.,Ltd.

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