Kwinkqubo yokuhanjiswa konxibelelwano lwedijithali, kukho iiseti ezimbini ze-digital optical transceiver, enye ibizwa ngokuba yi-"Plesiochronous Digital Hierarchy" (Plesiochronous Digital Hierarchy), ebizwa ngokuba yi-PDH optical transceiver; enye ibizwa ngokuba yi-“Synchronous Digital Hierarchy” (I-Synchronous Digital Hierarchy), ekubhekiselwa kuyo njenge-SDH yokubona i-transceiver.

Inkqubo esebenzisa uchungechunge lwedijithali lwe-plesiochronous (PDH) kukuseta iwashi echanekileyo kwi-node nganye yonxibelelwano lwedijithali, izibonakaliso zezi wotshi zonke zinezinga elilinganayo eliqhelekileyo. Nangona ukuchaneka kwewotshi nganye kuphezulu kakhulu, kusoloko kukho umahluko omncinane. Ukuze kuqinisekiswe umgangatho wonxibelelwano, umahluko phakathi kwezi wotshi kufuneka ungagqithi kuluhlu oluchaziweyo. Ke ngoko, le ndlela yongqamaniso ayilulo ungqamaniso oluyinyani ngokungqongqo, kungoko ibizwa ngokuba "yi-quasi-synchronous."

Kwixesha elidlulileyo lothungelwano lwezonxibelelwano, uninzi lwezixhobo ze-PDH ze-transceiver optical zazisetyenziswa, olu chungechunge lunokulungelelaniswa kakuhle kwi-traditional point-to-point yonxibelelwano.Ngophuhliso olukhawulezayo lonxibelelwano lwedijithali, kukho ukuhanjiswa okuthe ngqo kokuncinci kunye nokuncinci. , kwaye uninzi lwee-digital transmissions kufuneka zidluliselwe, ngoko ke, uchungechunge lwePDH alukwazi ukuhlangabezana neemfuno zophuhliso lwenkonzo yonxibelelwano lwangoku kunye nolawulo lwangoku lwenethiwekhi yonxibelelwano. I-SDH yinkqubo yothumelo eye yavela ukuhlangabezana nale mfuno intsha.