S.O.S signal using whistle blow

Whistle
Always carry a whistle. Fix a lanyard and hang it around your neck. Carry a second one in your Survival Kit, just in case one gets lost. Sacrifice aesthetics. You do not need a beautiful whistle, you need a whistle that is loud, shrill and can be heard over long distances. If you hear voices, whistle three bursts in short intervals, then continue with three long bursts and another 3 short bursts. Wait for a bit and repeat the three bursts again. If you do not hear anyone, whistle out the SOS signal. Keep doing this at regular intervals. This method is really good if you are injured and cannot walk. Rescuers might be close by, but cannot see you ... but they will hear you and come to you. Which is why you need to keeping repeating the whistling at regular intervals.

p/s: simple cue: 3 kali pendek, 3 kali panjang, 3 kali pendek.. alright?