( ( Recognized ( as ( ( the ( world 's ) ) ( premier ( navigation ( satellite system ) ) ) ) ) ) ( , ( GPS ( ( ( ( operates ( via ( ( ( ( ( ( ( a constellation ) ( of ( ( 24 satellites ) ( -LRB- ( ( not ( including spares ) ) -RRB- ) ) ) ) ) , ) ( a ( ground ( control system ) ) ) ) , ) and ) ( thousands ( of terminals ) ) ) ) ) , ) ( to ( help ( ( ( ( locate and ) guide ) ( military ( and ( civilian users ) ) ) ) ( ( ( ( ( ( in ( the air ) ) , ) ( at sea ) ) , ) and ) ( on ( the ground ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (VBN Recognized) (PP (IN as) (NP (NP (DT the) (NN world) (POS 's)) (JJ premier) (NN navigation) (NN satellite) (NN system))))) (, ,) (NP (NNP GPS)) (VP (VBZ operates) (PP (IN via) (NP (NP (NP (DT a) (NN constellation)) (PP (IN of) (NP (NP (CD 24) (NNS satellites)) (PRN (-LRB- -LRB-) (PP (RB not) (VBG including) (NP (NNS spares))) (-RRB- -RRB-))))) (, ,) (NP (DT a) (NN ground) (NN control) (NN system)) (, ,) (CC and) (NP (NP (NNS thousands)) (PP (IN of) (NP (NNS terminals)))))) (, ,) (S (VP (TO to) (VP (NN help) (VB locate) (CC and) (VB guide) (NP (JJ military) (CC and) (JJ civilian) (NNS users)) (PP (PP (IN in) (NP (DT the) (NN air))) (, ,) (PP (IN at) (NP (NN sea))) (, ,) (CC and) (PP (IN on) (NP (DT the) (NN ground)))))))) (. .)))
Recognized as the world's premier navigation satellite system, GPS operates via a constellation of 24 satellites (not including spares), a ground control system, and thousands of terminals, to help locate and guide military and civilian users in the air, at sea, and on the ground.
(ROOT (S (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT the) (JJ worldwide) (JJ radio-navigation) (NN system)) (VP (VBN formed) (PP (IN from) (NP (NP (DT a) (NN constellation)) (PP (IN of) (NP (CD 24) (NNS satellites))))))))) (CC and) (S (NP (PRP$ their) (NN ground) (NNS stations)) (VP (VBP gps))) (. .)))