KB: RSL10 Measuring RF Free Field Distance with different TX power

**RSL10 Measuring RF Free Field Distance **


This application note describes how to measure the RF communication distance that can be achieved with the RSL10 Bluetooth® 5 radio SoC. It also provides some empirical measurements taken with an RSL10 board as an indication of achievable range in free field.

Hardware Requirements

To carry out the measurements you need:

Software Setup

  • Google Maps or another online map service
  • Follow the instructions in the RSL10 Getting Started Guide to install the RSL10 SDK and then:
    • Load the peripheral_server_UART sample project onto EVB_A
    • Load the central_client_UART sample project onto EVB_B
  • Install your preferred emulator software (such as Tera Term) for sending and receiving data

Figure 1. Equipment setup to measure the RSL10 communication distance

RF Free Field Distance Test

Configure the Tx power level in the app_init.c file of the peripheral_server_UART sample project for transmission.

  • The default value is 0 dBm.

/* Set radio output power of RF */


  • Connect EVB_A to Laptop_A and EVB_B to Laptop_B using USB cables.
  • Begin transmitting data from EVB_A .
  • The data being received by EVB_B can be monitored via the emulator software running on Laptop_B .

Now take the equipment out to an open area to measure the transmission distance. Place EVB_A and Laptop_A at a known starting location, and begin walking with EVB_B and Laptop_B until you reach a point where the communication is broken.

Distance Calculation

Once the field test is complete, the distance can be calculated using an online map service (such as Google Maps). Mark the location of your start point where EVB_A and Laptop_A were placed, and then mark the location at which the communication was broken.

  • The distance between the two points is the maximum transmission distance for the configured power level.

During tests conducted by ON Semiconductor, the following results were achieved for different levels of Tx power:

Table 1: Maximum transmission distances measured by ON Semiconductor**

Figure 2. ON Semiconductor distance measurement