Chapter 467 - Chapter 467: Chapter 291 Encyclopedia of Crime (1/2)

Chapter 467: Chapter 291 Encyclopedia of Crime

Buried something?

In the Criminal Investigation Brigade Office, He Song and Hu Daqiang were both startled, their gazes involuntarily falling upon Lin Chuan.

Lin Chuan, however, shook his head, “To be precise, there is a small gap in between; if it was completely buried in soil, it would not achieve the purpose of transmitting sound. Even if there were sounds, the waves would not be stable enough.”

He Song was the first to raise a question,

“Lin, your conjecture is reasonable and well-founded, but I want to ask, we have checked thoroughly, and we also used a detector just now, there was no metal response nor any electricity. Even if there is a small gap, how does it transmit sound out?”

This question had also stumped the two detectives.

It was an area they rarely touched upon.

Apart from some difficult and suspenseful cases, many cases only required the collection of evidence at the scene, determination of the motive for the crime, and then questioning the criminal suspects, alibis, checking surveillance footage, and finally making a judgment based on comprehensive materials to establish the suspect.

If it wasn’t the only suspect, they would break it down one by one.

It was not a difficult task.

With their experience in crime scene investigation and detection, they were all veteran detectives, excellent detectives.

But even Hu Daqiang had never delved into eavesdropping devices and sound propagation; it was entirely an area of ignorance for him.

Lin Chuan noted their reactions and then smiled, “Have you ever heard of a ‘golden lip’ eavesdropper?”

The three of them looked at each other and shook their heads.

Lin Chuan then went straight into the explanation, “This is a very special kind of eavesdropping device, once known as the king of eavesdroppers. It only needs an antenna, a small cylindrical body, a very thin diaphragm, and an outer shell to achieve the purpose of eavesdropping. The key is, it doesn’t need electricity.”

“What is its working principle?” Shen Qianqian asked curiously.

“You haven’t been an… cough!”

Lin Chuan paused, giving a slight cough, almost slipping up.

Immediately after, he took a sip of tea, “You haven’t come into much contact with agents or, to put it another way, you haven’t had many dealings with them, so you don’t know much about various eavesdropping devices.”

Shen Qianqian pursed her lips slightly, nodding a little.

It was the truth.

However, in her heart, she sneered, thinking that he was the only agent she had come into contact with!

But now was not the time for jokes. She gave Lin Chuan ample face, playing the role of a supportive audience to let Lin Chuan continue his educational lecture.

Lin Chuan was indeed a professional agent.

He had a thorough understanding of eavesdropping devices.

Under the knowledgeable gazes of the three, he explained, “The working principle of the ‘golden lip’ eavesdropper is based on the reception and conversion of electromagnetic waves. When radio waves are transmitted to the eavesdropper, it will convert these microwave beams into an electric current. This current passes through the membrane, varying with the vibrations of the sound waves, causing the shape of the membrane to change.”

“What happens next is that the deformation of the diaphragm changes the capacitance between the diaphragm and the container, thereby changing the resonant frequency of the capacitor.”

“Ultimately, this change in capacitance will create an electric field between the disc and the cylinder, which changes the potential of the cylinder. This change is then amplified and converted into an audible sound signal.”