เรือดำน้ำมีระบบ Anti-Frogman   ลองอ่านดู มีโซน่าหลายระบบที่ตรวจพบมนุษย์กบได้ : ตอบ จขกท ว่าตรวจเจอแน่ แม้ว่า หน่วยซีลจะใช้อุปกรณ์ดำน้ำแบบพิเศษ (Rebreather)  

https://en.wikipedia.org/wiki/Anti-frogman_techniques#Ultrasound_detection

[Spoil] คลิกเพื่อดูข้อความที่ซ่อนไว้
Ultrasound detection

Artificial intelligence and electronic neural networks and developments in ultrasound have made possible specialized diver-detector sonars.
Experience has showed that passive sonar (i.e. merely listening for underwater sounds) cannot detect everything; in particular it cannot easily detect rebreather divers and unequipped surface swimmers; and it can detect direction, but not distance unless readings from two or more listening stations can be correlated.

High-power low-frequency sonar commonly used for depth sounding and to detect large objects (including submarines) is not good at detecting small objects like divers, but the US Navy Diving Manual 24 says that it is hazardous to divers.[2]


Examples of  diver-detecting active sonar systems  are:

1.    Sonardyne SENTINEL diver detection sonar
2.    AN/WQX-2: >>>>>>>>>>>>>>>>>>>>>the US Navy uses it.
[Spoil] คลิกเพื่อดูข้อความที่ซ่อนไว้The AN/WQX-2 is a diver-detector sonar used in anti-frogman precautions. It is in service with the US Navy. It uses Kongsberg Mesotech components. It can detect divers up to 2400 feet (= nearly half a mile) away.
ระบบที่ใช้ในกองทัพเรือสหรัฐ สามารถตรวจเจอได้ในระยะไกลถึง 2400 ฟุต (เกือบครึ่งไมล์)

The AN/WQX-2 finds range and bearing of the detected target relative to the sonar. The C3D console developed by SPAWAR converts this to a GPS position. It has software to distinguish diver echoes from shoals of fish, marine mammals, debris, bubbles from boat wakes, etc.
ซอฟแวร์สามารถแยกเสียงสะท้อนของมนุษย์กบ ให้มีความแตกต่างจากเสียงจากฝูงปลา สัตว์พวกวาฬ โลมา ฯลฯ เศษวัสดุ พรายน้ำจากเรือ ฯลฯ

3.    AquaShield Diver Detection Sonar Designed to protect energy installations, ports and coastal facilities
4.    Cerberus (sonar): a blue egg-shaped device.
5.    CSDS-85 Omni Surveillance Sonar made by CTech
6.    DDS 9000 multibeam diver detection sonar: by Kongsberg Gruppen
7.    DDS-J diver-detection sonar designed to protect underwater oil pipelines: by Westminster International Ltd
8.    Harbour Surveillance Sonar by Marport C-Tech Ltd.
9.    Northstar Electronics
10.    NuvoSonic
11.    UPSS = Underwater Port Security System
12.    WESMAR Web System is a diver-detector sonar.
13.    Underwater Security Systems