You will need to monitor the direction and angle of approach to gauge where to aim. You will also need to take into consideration doppler effect on approach and depart, as this will change the frequency up and down. You will likely need to aim your directional antenna (assuming you're using one) this way and that way until you get the sat too. Tuning into a beacon freq is usually easiest as that is typically always broadcasting in sunlight. Otherwise, if you're looking for packet transmissions and voice you may or may not hear something when aiming right at the sat. Good luck.