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sandeepmistry / arduino-LoRa

An Arduino library for sending and receiving data using LoRa radios.
MIT License
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relation between Distance and (SF & BW & CR) #485

Open hoseinaghajari opened 3 years ago

hoseinaghajari commented 3 years ago

Hi there, what is exactly relation between Distance(between 2 module) and Values of SF & BW & CR?

I just know that I should increase SF and Tx Power when distance inceases.

IoTThinks commented 3 years ago

There is no such mathematical equation for the wireless world. However, they are surely related.

Local regulation limits the TX Power. Normally up to 25dBm depending on where you live.

morganrallen commented 3 years ago

Sure there are calculations that can be done. In the RF world a 'Link Budget' calculation is a standard practice to get an idea of Link-to-Link performance (including theoretical distance). SemTech even provides the 'LoRa Modem Calculator Tool' to give you a lot of detailed information. This article give a pretty good overview of understanding these kind of calculations but always understand that there will be a lot of variance between different setups. https://medium.com/home-wireless/testing-lora-radios-with-the-limesdr-mini-part-2-37fa481217ff

IoTThinks commented 3 years ago

There are some calculations. But not an exact caculation as wireless is not a perfect environment.

The calculation is only for a perfect no-obstacle environment.

IoTThinks commented 3 years ago

Can view more from this? https://youtu.be/jMFa3AiDbcI

Kongduino commented 3 years ago

As mentioned, there isn't an exact way to calculate the impact. However, as a rule of thumb, the higher the SF, and the lower the BW, and the slower, and longer range, the transmission will be. And vice versa.