olemus
filter, mis laseb läbi teatava sagedusvahemiku signaalid, muud aga tõkestab
= a device that passes frequencies within a certain range and rejects requencies outside that range

näiteid
https://www.youtube.com/watch?v=5rthqWznCMI
https://midopt.com/wp-content/filter_image/MidOpt_BP525_Trans_Graphic.png
http://www.rfwireless-world.com/images/rf-bandpass-filter-calculator.jpg

ülevaateid
https://en.wikipedia.org/wiki/Band-pass_filter
https://www.electronics-tutorials.ws/filter/filter_4.html
https://www.electronics-tutorials.ws/filter/filter_7.html