# What does baud rate in SICK LMS do and how does it affect the frequency of the messages being published on the topic?

In SICK LMS range finder, what does baud rate do and how does it affect sampling rate, frequency of messages being published on /scan topic?

Let the detection angle be θ.

Anglular resolution be α.

Then, anglemin = −θ/2

anglemax = θ/2

angle_increment = α which is angular resolution between two beams. If the laser scan has frequency of β scans per second then in 1/β second, 1 scan will give g = (θ/α) + 1 beams.

Time increment can be calculated as t_increment = (1/β)/g

Now how does buad rate fit into above calculations?

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Baud rate does not affect those calculations at all. As @jayess explained in their answer, baud rate is the communication rate on the serial line between the SICK LMS and the PC. The higher the baud rate, the faster the devices communicate, which means there's more bandwidth. When two serial devices communicate, they must both be set to the same baud rate, or else the receiver won't be able to decode the signals it gets. The SICK LMS probably has the baud rate set by a configuration command, so you will have to match the baud rate in your node to whatever your SICK LMS is set to.

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A thorough explanation of what baud rate is, I believe, out of scope for this site (refer to this article or the Wikipedia entry instead). Basically, it's the number of symbols (voltages or whatever is being used) that the signal produces per second.

Without knowing what ROS package you're referring to, I can't give much more of an explanation except that it's essentially a measure of how much data is coming in per second. Also, I don't believe that it's used for any calculations, just for connecting with the sensor so you know how much data is coming in per second.

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