object oriented PHP expert (decode bytes based on my example)

I have a device that send data to my server via HTTP POST REQUEST each 10 seconds (i can't change or control the way it send data) so i created a php script ([login to view URL]) which see the data and write them into a file ([login to view URL]) but problem is coz in the body of HTTP REQUEST i see strange characters.(check [login to view URL]) - I contacted the company that created device and they send me a big script in OOP php ([login to view URL]) that decode this, also script has other features but i dont need them. - so what i need now is: can u check the [login to view URL] that they send me and then copy just the part of code which decode the body part of HTTP REQUEST u can search [login to view URL] so body part need to be decoded when in HTTP REQUEST HEADER is [request_code] => send_cmd_result so u need to fix [login to view URL] works with this (need to be procedural php not OOP)