Experts thought that underground optical cables can intrude on people's privacy.
already in 1999, the us army. UU. He was aware of the special ability of fiber optics to control the behavior of people.
So, How does underground fiber monitor people's footprints??
Research by experts suggests that from cars and pedestrians in the process of action, vibrations will occur. This vibration creates a unique signal within the cable.
Last spring, a group of researchers from the University of Pennsylvania in the USA. UU.
Developed an underground fiber optic cable for telecommunications.
The cable stretches two and a half miles long and researchers integrated it into a scientific monitoring device.
Depending on the device, They found that when COVID-19 hit last year, the flow of people on campus almost disappeared, which continued until June.
But at the time when human traffic began to decrease, car activity was increasing.
“It can be seen that people have little walking activity compared to their usual conditions, but the number of vehicles has almost returned to its normal levels before the epidemic”. “, Dijo Zhu Qiyuan, professor at the University of Pennsylvania Earthquake School.
Professor Zhu Qiyuan is the main thesis author of the journal Seismic Records.
Besides, was surprised to find a subtle signal pole identified by a fiber cable.
Fiber optic transmission acts on signal transmission by capturing optical pulses.
But when people or cars pass over the fiber, vibration causes interference and scatters part of the light towards the light source.
Researchers at the University of Pennsylvania measured the cable's vibrations by illuminating the laser with an optical fiber and calculating its propagation time.. The technology is called DAS.
You can say that the technology is an update of the seismometer, which can traditionally measure only one activity position.
Powered by DAS, can be found 2,000 sampling sites within a radius of 2.5 miles.
This makes a great contribution to the human study of earthquakes.