“For conventional Wi-Fi products, the communication distance is generally within 100 meters. The ZM602 launched by Zhiyuan Electronics is a Wi-Fi module with a kilometer-level communication distance. How about its communication distance test in the actual environment? This article will take you to understand.

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For conventional Wi-Fi products, the communication distance is generally within 100 meters. The ZM602 launched by Zhiyuan Electronics is a Wi-Fi module with a kilometer-level communication distance. How about its communication distance test in the actual environment? This article will take you to understand.

Influencing factors of communication distance

In the previous article “How does wireless communication spread farther? “, we introduced three main factors that affect the communication distance in wireless communication: signal strength, minimum receiving sensitivity, and signal-to-noise ratio. Among them, the signal strength and the minimum receiving sensitivity are mainly affected by the performance parameters of the product, while the signal-to-noise ratio is mainly affected by the communication environment.

The radio frequency performance of the product is the basis for long-distance communication. ZM602 series Wi-Fi modules have excellent radio frequency performance. In 802.11b mode, the transmit power can reach up to 18dBm, the minimum receiving sensitivity can reach -98dBm, and the link budget can reach up to 116dB, making it possible to realize ultra-long-distance Wi-Fi communication .

Figure 1 Wireless communication and interference in the air

Device parameter configuration

ZM602 series module is a Wi-Fi+BLE IoT serial port transparent transmission module, mainly used in low-speed, long-distance application scenarios, supports Wi-Fi, BLE dual serial port data transmission, supports TCP/UDP/MQTT/HTTP And other common communication protocols, Wi-Fi supports Station mode (client) and SoftAP mode (hot spot).

In this communication distance test, we use two ZM602 modules and choose TCP communication mode for data transmission and reception. The parameter configuration is as follows:

ZM602A: SoftAP mode, TCP server (local address 172.16.1.1, local port 4000), 115200 baud rate;
ZM602B: Station mode, TCP client (remote address 172.16.1.1, remote port 4000), 115200 baud rate.
After the above simple configuration, the two modules establish a Wi-Fi connection to realize serial data transparent transmission.

Figure 2 Serial data transparent transmission

Communication distance test

The communication environment will greatly affect the communication effect, mainly due to the obstacles in the environment and the influence of signal interference. For this test, we chose an open environment on the lake to minimize the interference of obstacles and space signals. The choice of antenna can also greatly affect the communication effect. In order to achieve the best communication effect, we chose a rod antenna with a gain of 5dBi for this test, and the antenna is connected through the IPEX connector of ZM602.

We first place the ZM602A module with configured parameters on one end of the lake, power on and start, the module will work normally in SoftAP mode. Then we moved along the lake to a location 500 meters away and placed the ZM602B module. Power on ZM602B, the module works in Station mode, start Wi-Fi scanning, we can find the hotspot signal sent by ZM602A, and connect. After the Wi-Fi connection is successful, the serial port data transparent transmission can be realized between the two modules. At a distance of 500 meters, the communication effect test is as follows:

Figure 3 500-meter communication distance test results

The test results show that at a distance of 500 meters, the communication effect of ZM602 is good without any packet loss.

Then we moved to the opposite bank of the lake, at this time the distance between the two is about 850 meters. Perform the test in the same operation at this location, and the communication effect test is as follows:

Figure 4 Communication distance test results

The test results show that at a distance of 850 meters, ZM602 can still maintain a good communication effect without any packet loss.

Due to environmental constraints, we did not conduct a longer-distance communication effect test. From the test results, ZM602, with its excellent radio frequency performance, has a good communication effect at a communication distance of 850 meters in an open lake environment, and can completely realize kilometer-level Wi-Fi communication.

Figure 5 Diagram of communication environment