I’m looking to build an application where I need to measure the distance between two devices that are about 100 meters apart inside a straight tube with line of sight with each other. Which module should I use and would I be able to measure such distances?
Hi redpanda,
What is the diameter of the straight tube? And are the tube walls reflective?
I am asking those questions because there might be some constructive or destructive interference over a 100m distance even for the LOS condition. It is called the Fresnel zone, and you may lose the link because of the destructive interference at some points.
The maximum range can be extended by adding an external LNA. Depending on the antenna design and environment, maximum distance performance may change. Therefore, we cannot guarantee that 100 m is achievable with your application or not.
TX power is also another important point to improve the maximum range. In the European region, the maximum allowable power limit is -31.3dBm/MHz which is 10dB higher than the other regions(-41.3dBm/MHz). I hope you can benefit from 10dB more power which allows you to improve the maximum range by approximately 3 times compared to other regions.
Kind regards,
Emre
Thanks for the reply Emre. The tube could vary between 0.5 and 2 meters in diameter and is not perfectly circular. I’m not sure if the walls are reflective but it’s relatively smooth and is not made of metallic materials. For my application, it is okay to lose the signal in some spots as long as I have coverage in over 90% of the entire distance range. My application is global, meaning it would need to work in EU and non-EU regions.
Hello panda,
I am not an expert on this field but read through quite a lot of stuff in this forum.
This link provides great info of what happens if you want to send data through a steel tube.
As you said, your tube probably isn’t reflective. Could it be tho, that there might be interference on the outer site of the tube? Dirt for example could still change your results.
My advice would be (if it’s possible) to buy a simple kit and try meassuring through different tubes with different sizes and distances. There are some comparably cheap modules that are fairly easily programmable as well (this one for example).
Kind regards
Fhilb 