▁tank ers ▁while ▁loading ▁from ▁a ▁F P SO . ▁Both ▁will ▁have ▁a ▁G PS ▁receiver . ▁As ▁the ▁errors ▁are ▁the ▁same ▁for ▁the ▁both ▁of ▁them , ▁the ▁signal ▁does ▁not ▁need ▁to ▁be ▁corrected . ▁The ▁position ▁from ▁the ▁F P SO ▁is ▁transm itted ▁to ▁the ▁sh utt le ▁tank er , ▁so ▁a ▁range ▁and ▁bearing ▁can ▁be ▁calculated ▁and ▁fed ▁into ▁the ▁D P ▁system . ▁R AD ius ▁and ▁R ada Scan . ▁These ▁are ▁rad ar ▁based ▁system , ▁while ▁the ▁R AD ius ▁have ▁no ▁moving ▁parts , ▁the ▁R ada Scan ▁has ▁a ▁rot ating ▁anten na ▁under ▁the ▁d ome . ▁Gu id ance ▁Marine ▁has ▁improved ▁the ▁mini R ada Scan ▁with ▁the ▁R ada Scan ▁View ▁which ▁has ▁an ▁added ▁advantage ▁of ▁rad ar ▁back - sc atter . ▁This ▁en hanced ▁the ▁D PO ' s ▁situ ational ▁aw aren ess . ▁These ▁systems ▁usually ▁have ▁respond ers ▁which ▁are ▁active ▁targets ▁that ▁sends ▁the ▁signal ▁back ▁to ▁the ▁sensor ▁to ▁report ▁the ▁range ▁and ▁bearing . ▁The ▁range ▁is ▁typically ▁up ▁to ▁ 6 0 0 ▁meters . ▁In ert ial ▁navigation ▁is ▁used ▁in ▁combination ▁with ▁any ▁of ▁the ▁above ▁reference ▁systems , ▁but ▁typically ▁with ▁g n ss ▁( Global ▁Navigation ▁Sat ellite ▁System ) ▁and ▁H ydro ac oust ics ▁( U SB L , ▁L BL , ▁or ▁S BL ). ▁ ▁He ading ▁reference ▁systems ▁Gy ro comp ass es ▁are ▁normally