It depends on the system, often times they’ll have additional guidance assistance, such as an infrared seeker or some inertial posturing system. SARH just means the main guidance is provided by a seeker picking up radar from a external emitter painting the target. As supposed to ARH (active radar homing) where the missile has its own emitter and detector. Most systems aren’t just one thing these days, for the sake of redundancy and error correction.