01 Wireless Transmission and Reception
1. Introduction
Yesterday, I tested this micro 433MHz receiving module, which can read the transmitted coding information through programming the microcontroller. I am now preparing to conduct outdoor tests with a battery and the transmitting module. The LED status on the receiving module will indicate whether the reception is normal. Both the transmitting and receiving modules use a 12V battery for stable power supply.
2. Test Results
1. Main Building Staircase Test
Carrying the transmitting and receiving modules, I walked down the stairs. First, I placed the transmitter on the left side of the staircase. Then, I held the receiver and moved to the right. During this process, I noticed the receiving signal light flickering, indicating an unstable signal. When I reached the right side of the staircase, approximately 50 meters away from the transmitting module, the reception signal was normal. Next, I walked towards the southern side of the road, which was about 100 meters away from the transmitting module. The receiving module displayed an unstable signal. It is understandable that the signal is unstable at long distances; in fact, there was already an unstable reception signal when I started from the transmitting module. I suspect two reasons: one is that the antenna of the receiving module is poor, and the other is that there is an issue with the signal decoding software.
2. Playground Test
I went to the playground for testing, where there is a more open area for testing. There were many students having physical education classes at the playground. I placed the test module on the ground and walked away with the receiving module. In fact, I did not walk far before I found that the receiving module’s signal was not very stable. The distance from the transmitting module placed on the ground was only about 20 meters. When the module was placed on the ground, it was basically unable to display the received signal. After picking it up, I could intermittently receive signals. This shows that height is important for both transmission and reception.
Next, I placed the transmitting module at a height to test whether it could improve the signal transmission distance. I placed the transmitting module on a wall about 2 meters above the ground. Then I walked towards the distance, and I could clearly feel that the signal was much more stable. Here, the distance from the transmitting module was about 30 meters, and although the receiving signal occasionally flickered, it was still very stable. Adjusting the receiving antenna can change the reception stability. Now I have reached the vicinity of the diagonal of the playground, about 150 meters from the transmitting module. At this point, the receiving signal has become very unstable. When placed on the ground, it can no longer receive the signal. I returned to the vicinity of the transmitting module. I could see that within 20 meters, the receiving signal was very stable. The testing at the playground ends here. Next, I will modify the microcontroller detection program to improve the stability of signal detection.
※ Conclusion ※
This article documents the outdoor testing process of the 433MHz high-power wireless transmission module. The receiving module displayed unstable reception signals. Next, I will adjust the receiving software to adapt to the signal demodulation process under weak signal conditions.