- shift ▁key ing ▁( PS K ) ▁to ▁spread ▁the ▁radi ated ▁power ▁over ▁a ▁wider ▁spectrum ▁( range ▁of ▁frequencies ) ▁than ▁normal ▁radio ▁transm issions . ▁This ▁reduces ▁sus cept ibility ▁to ▁noise , ▁jam ming , ▁and ▁inter ception . ▁In ▁J T ID S ▁Time ▁Division ▁Multiple ▁Access ▁( TD MA ) ▁( similar ▁to ▁cell ▁phone ▁technology ), ▁each ▁time ▁interval ▁( e . g ., ▁ 1 ▁second ) ▁is ▁divided ▁into ▁time ▁sl ots ▁( e . g . ▁ 1 2 8 ▁per ▁second ). ▁T ogether , ▁all ▁ 1 5 3 6 ▁time ▁sl ots ▁in ▁a ▁ 1 2 - second ▁interval ▁are ▁called ▁a ▁" frame ". ▁Each ▁time ▁slot ▁is ▁" bur sted " ▁( trans m itted ) ▁at ▁several ▁different ▁car rier ▁frequencies ▁sequ entially . ▁Within ▁each ▁slot , ▁the ▁phase ▁angle ▁of ▁the ▁transmission ▁burst ▁is ▁varied ▁to ▁provide ▁PS K . ▁Each ▁type ▁of ▁data ▁to ▁be ▁transm itted ▁is ▁assigned ▁a ▁slot ▁or ▁block ▁of ▁sl ots ▁( channel ) ▁to ▁manage ▁information ▁ex changes ▁among ▁user ▁participation ▁groups . ▁In ▁traditional ▁T D MA , ▁the ▁slot ▁frequencies ▁remain ▁fixed ▁from ▁second ▁to ▁second ▁( frame ▁to ▁frame ). ▁In ▁J T ID S ▁T D MA , ▁the ▁slot ▁frequencies ▁and / or ▁slot ▁assign ments ▁for ▁each ▁channel ▁do ▁not ▁remain ▁fixed ▁from ▁frame ▁to ▁frame ▁but ▁are ▁varied ▁in ▁a ▁pseudo - random ▁manner . ▁The ▁slot ▁assign ments