There are a lot of frequencies out there transmitting a lot of data. Some frequencies take more bandwidth than others to transmit, while others take more power. When you are trying to transmit your data, whether it's a radio signal or satellite signal, you need to make sure that you aren't getting a lot of interference and that you are able to broadcast within the speed and bandwidth that is appropriate for you. One way to do that is to use a data acquisition bandpass filter.
The bandpass filter can be a circuit in a receiver or transmitter, or it can be a separate device. The way that it works is that the data transmission goes through the filter. The filter is set so that it will only allow certain frequencies to go through and will block the other frequencies from going through. Think of it as if the frequencies were a bunch of people walking through a hallway wearing different colored shirts. Some are faster, some are slower, some need more energy to get to where they are going, some aren't as strong. At one end of the hallway, there is a gate with only one or two openings on it. Those openings are for people who are wearing turquoise and teal shirts, and only those people. Anyone else wearing a different color shirt would be blocked at the end of the hall and not be able to go anywhere. What are some reasons to use a bandpass filter?
If you have ever used an analogue radio where you had to turn the knob to find the right station, you can understand interference when it comes to various frequencies. If you aren't on just the right spot, you are going to pick up the signal from another frequency over top of the frequency that you want. That's what a bandpass filter is designed to help deal with. When the signal is getting transmitted, it will go through the filter, which is set to only allow one specific frequency out and will block all the others. That way, none of the frequencies around the desired frequency are going to go out at the same time, causing data to be corrupted and broadcast signals to be fuzzy.
Making sure that only the correct frequency gets broadcast is important. There are a lot of ways to limit that, but the easiest way is to use a bandpass filter.