Ground Surveillance Radar (GSR) is best when used in the defense. Assuming the PMC is deployed in some hardened base of operations, GSR would be deployed inside the compound as an early warning against a possible attack. You couple GSR with random force protection patrols into the hinterland, mounted and dismounted. More than likely, any mounted and dismounted patrols would go out as a result of some indication from a GSR or an observation by an Air Asset.