Wi-Fi Non-Signaling Test

[中文]

The Wi-Fi Non-Signaling Test, also known as fixed frequency test, directly controls the device to transmit specific signals without establishing a data connection. It evaluates key RF performance metrics, such as transmit power, spectrum quality, and error rate, ensuring wireless communication quality in various scenarios.

Set Up Test Environment

The RF non-signaling test firmware environment mainly includes a PC, tester, a USB-to-UART board, a device under test (DUT), and a shield box.

../../_images/rf_non_signaling_setup.png

Test Environment Setup

  • PC is connected to the USB-to-UART board via USB and to the tester via an Ethernet cable. The PC needs to have the EspRFTestTool toolkit, tester control software, and the driver for the USB-to-UART board installed.

  • Tester is used to test the RF performance of the DUT in different modes. Typically, it is the WT-328/IQXel tester.

  • USB-to-UART board is used to communicate between the PC and the DUT.

  • Device under test (DUT) refers to a product designed based on the ESP32 chip or module. It is connected to the USB-to-UART board via UART and to the tester via an RF connection cable. The DUT is usually placed inside a shield box.

  • Shield Box is used to isolate external RF interference and ensure the stability of the test environment.

Note

  • The CHIP_EN pin of the DUT is pulled up by default. If it is not pulled up in the product design, you need to manually connect the CHIP_EN to the 3V3 pin.

  • Some serial communication boards have already swapped RXD and TXD internally, so there is no need to reverse the connection. Adjust the wiring according to the actual situation.

  • ESP32 has a power-on self-calibration feature. The RF connection cable must be connected to the tester before the DUT is powered on for testing.

Conduction Test

  • For modules without an onboard PCB antenna, the RF connection cable can be directly soldered to the antenna feed point of the module (as shown in the schematic diagram above).

  • For modules with an onboard PCB antenna, cut the trace that connects to the PCB antenna feed point and solder the RF connection cable. The RF cable’s shielding metal layer must be thoroughly soldered before connecting to the module’s GND. The GND soldering point can be either the shield cover or the exposed GND layer on the PCB (after removing the green solder mask). Besides, it should be as close to the feed point as possible.

../../_images/pcb_antenna_conducted_test.png

Soldering RF Connection Cable to Module with Onboard PCB Antenna

Flash Firmware

  1. Open EspRFTestTool.

  2. Set ChipType, COM, BaudRate, and click Open to open the COM port.

Note

Set BaudRate to 115200

  1. Flash ESP32 RF Non-Signaling Test Firmware to Flash via UART.

../../_images/nonsignaling_firmware_flash.png

ESPRFTestTool Configuration

  1. After the firmware flashing is completed, pull the boot pin high or leave it floating. The chip will enter the working mode after power-off restart.

Start Testing

Wi-Fi TX Performance Test

  • Test Mode:

    • TX packet: Packet transmission duty cycle less than 50%, used for TX performance tests

    • TX continues: Packet duty cycle close to 100%, used for certification tests;

    • TX tone: Used for single-carrier tests.

  • Wi-Fi Rate: Set Wi-Fi test rate

  • BandWidth: Set Wi-Fi test bandwidth

  • Channel: Set Wi-Fi test channel

  • Atteunuation (0.25 dB): Set power attenuation

    • 0 means no attenuation, which is the default value;

    • 2 means 0.5 dB attenuation;

    • 4 means 1 dB attenuation, and so on.

  • Duty Cycle: Set the packet duty cycle in TX packet tests. The default duty cycle is around 30%. Supported values: 10%, 50%, 90%.

  • Certification EN: Not enabled by default. Used only when verifying Power Limit function.

  • Certification Code: Not enabled by default. Used only when verifying Power Limit function.

After clicking start, the log window should print Wi-Fi transmission parameters similar to the following:

Wifi tx out: channel=1, rate=0x0, BK=0, length=50, delay=1200, packet_num=0

The above parameters indicate that Wi-Fi packet transmission is normal, and the transmission performance can be detected with tester at this time.

../../_images/esp_wifi_tx_on.png

Wi-Fi TX Performance Test

Wi-Fi RX Performance Test

  • Test Mode: Set to RX packet for RX performance tests.

  • Wi-Fi Rate: Set Wi-Fi test rate.

  • BandWidth: Set Wi-Fi test bandwidth.

  • Channel: Set Wi-Fi test channel.

After clicking start, the tester sends packets on the test channel. Click stop after completion. The log window should display packet RX information similar to the following:

Correct:1000 Desired:1000 RSSI:-614 noise:-960 gain:0 paral:0 para2:0 freq:0

Where:

  • Correct: The total number of packets received this time.

  • Desired: The number of packets received at the corresponding rate this time.

  • RSSI: Represents the average RSSI of the received Desired packets. For example, “RSSI: -614” means the RSSI value is -61.4.

Note

  • If Desired is 0, no packets were received from the tester. Please check the tester’s packet settings and packet file to ensure the packet RX link is normal;

  • If Desired is not 0 and Correct is greater than Desired, there is interference in the environment. Please retest in a shielded environment;

  • Other parameters in the packet RX information are only used for RD debug and have no actual meaning.

../../_images/esp_wifi_rx_on.png

Wi-Fi RX Performance Test

Appendix

This appendix is mainly used to explain the target output power of the chip’s Wi-Fi, which is used for RF debugging or test reference.

ESP32 Wi-Fi Target TX Power

Rate

ESP32 Wi-Fi Target Power (dBm)

11b 1M

19.5

11b 11M

19.5

11g 6M

18

11g 54M

14

HT20-11n MCS0

18

HT20-11n MCS7

13

HT40-11n MCS0

18

HT40-11n MCS7

13