Frequency hopping is easy to understand. Frequency hopping is constantly changing the carrier frequency. The lora chip sx127x itself supports frequency hopping, it can set a period of time, which we will refer to as t1. After the sending end passes t1, the carrier frequency will switch to the next set value, and after t1, the carrier frequency will switch again. The receiving end must agree with the sending end on the law of frequency hopping, that is, maintain the same frequency hopping table and know which frequency to switch to next time.
At the beginning, the carrier frequency used by lora was 433mhz. After t1 time, it jumped to 435mhz, and then after t1, it jumped to 431mhz...and so on, it has been changing the transmission frequency. This is lora's frequency hopping.
Is there any rule to follow this frequency hopping frequency setting, how many mhz should I set next time? First of all, you have to determine what type of lora chip you are using. For example, the frequency range supported by sx1276 and 1278 is different. In theory, you can jump within the frequency range supported by lora chip. Which one to jump to next time All can be flexibly configured by the software. However, considering the actual situation, it is not recommended to set some frequency points. For example, each country has radio usage regulations. At some frequencies, it is not allowed to transmit radio signals, so the frequency points that are not allowed by the country should be avoided. It is also necessary to consider the matching of the antenna, which frequency range of the antenna you use can give full play to its advantages, etc.
Understand the concept of frequency hopping, so what is the role of frequency hopping?
Increase anti-jamming, for example, there is always data being transmitted in the 433mhz in the air. When you also use 433mhz, there is a greater possibility of interference. So frequency hopping can jump to, for example, the 435mhz frequency band to avoid conflicts with other people sending wireless frequencies
Some countries have regulations that the duration of a wireless signal sent on a channel (that is, a frequency point) cannot exceed a certain time. Generally speaking, you can't always occupy this frequency, so frequency hopping can play a role at this time.