假如我們能製作『水中派』，是否就有了探測『聲納』！

Sonar signal processing

Sonar systems are generally used underwater for range finding and detection. Active sonar emits an acoustic signal, or pulse of sound, into the water. The sound bounces off the target object and returns an “echo” to the sonar transducer. Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels. But passive sonar cannot measure the range of an object unless it is used in conjunction with other passive listening devices. Multiple passive sonar devices must be used for triangulation of a sound source. No matter whether active sonar or passive sonar, the information included in the reflected signal can not be used without technical signal processing. To extract the useful information from the mixed signal, some steps are taken to transfer the raw acoustic data.

 

得以一訪『美人魚』故鄉？

Mermaid

A mermaid is a legendary aquatic creature with the head and upper body of a female human and the tail of a fish.^[1] Mermaids appear in the folklore of many cultures worldwide, including the Near East, Europe, Africa and Asia. The first stories appeared in ancient Assyria, in which the goddess Atargatis transformed herself into a mermaid out of shame for accidentally killing her human lover. Mermaids are sometimes associated with perilous events such as floods, storms, shipwrecks and drownings. In other folk traditions (or sometimes within the same tradition), they can be benevolent or beneficent, bestowing boons or falling in love with humans.

The male equivalent of the mermaid is the merman, also a familiar figure in folklore and heraldry. Although traditions about and sightings of mermen are less common than those of mermaids, they are generally assumed to co-exist with their female counterparts.

Some of the attributes of mermaids may have been influenced by the Sirens of Greek mythology. Historical accounts of mermaids, such as those reported by Christopher Columbus during his exploration of the Caribbean, may have been inspired by manatees and similar aquatic mammals. While there is no evidence that mermaids exist outside folklore, reports of mermaid sightings continue to the present day, including 21st century examples from Israel and Zimbabwe.

Mermaids have been a popular subject of art and literature in recent centuries, such as in Hans Christian Andersen‘s well-known fairy tale “The Little Mermaid” (1836). They have subsequently been depicted in operas, paintings, books, films and comics.

 

那個 SoundDevice 的

Simultaneous Playback and Recording

To play back an array and record at the same time, use sounddevice.playrec():

myrecording = sd.playrec(myarray, fs, channels=2)

The number of output channels is obtained from myarray, but the number of input channels still has to be specified.

Again, default values can be used:

sd.default.samplerate = fs
sd.default.channels = 2
myrecording = sd.playrec(myarray)

In this case the number of output channels is still taken from myarray (which may or may not have 2 channels), but the number of input channels is taken from sounddevice.default.channels.

 

果真不是為此而設？？

邀人在陸上，先勤練眼力呦！！