JAkási diplomka
https://www.vutbr.cz/www_base/zav_prace_soubor_verejne.php?file_id=6142


použitelné 
http://www.telskol-pohoda.wz.cz/files/tsy/2.DIGITALNI_SPOJOVACI_POLE.pdf


PCM  G.711    https://www.itu.int/rec/T-REC-G.711 






 https://en.wikipedia.org/wiki/Time-division_multiplexing
Each voice time slot in the TDM frame is called a channel. In European systems, standard TDM frames contain 30 digital voice channels (E1), and in American systems (T1), they contain 24 channels. Both standards also contain extra bits (or bit time slots) for signaling and synchronization bits.[5]