Information about bats and radars (less)

Radar is a magical electric appliance, which measures the distance of wave arrester from the round-trip time of electromagnetic wave. If you ask who invented radar? Fink's Radar Machinery says that "the invention of radar cannot be attributed to a scientist, but many radio engineers have worked hard to study and adjust it." During the war, 500 scientists and engineers from MIT devoted themselves to radar research. Strangely, in nature, you can find God's radar for an animal. In the issue of the British magazine Fenmian 1947 1 month, the scientist B. Vesey-Fitzgerald published an interesting article explaining to us how bats guide themselves to fly in the dark, no matter how dark or narrow, they will not hit the wall. What is the reason? How does it know that there are no obstacles ahead? 1940, two American biologists Griffin and Garangbao used a natural radar to prove that bats can avoid collisions, but sound waves replaced electromagnetic waves, which are completely similar in principle. The bat's mouth emits high-frequency sound waves, which are beyond human hearing range. Two scientists used a special electronic device to record the high-frequency sound waves emitted by bats during flight. This kind of sound wave will inevitably turn back when it hits the wall. Its eardrum can distinguish the distance of obstacles and fly in the right direction. Like radar, bats regularly emit sound waves at very short intervals. Each bat has its own natural frequency, so that bats can distinguish their own sounds without disturbing them. For this reason, when a bat flies, it often opens its mouth. If you shut its mouth tightly, it will lose its command function. If it blocks its ears, it will hit the wall and cannot fly. This interesting experiment revealed its secret.

"Real-time Radar" in Flight

Bats are good at flying in the air, and can do "aerobatics" such as turning around, braking suddenly and changing flight speed quickly. The white dog hiding in the cave,

In tree holes or cracks in eaves; Flying in the air at dusk and night, preying on mosquitoes, flies, moths and other insects. Bats prey on a large number of pests, which is beneficial to people and culpable of punishment.

For protection.

In summer, the female bat gives birth to a fully developed larva. The newborn baby is covered with fluff, and its claws are firmly hung on its mother's chest to suck milk.

Mom won't fall off when flying.

The wings used by bats to fly. The structure of wings is different from that of birds, which is composed of skin membranes connected between forelimbs, hind limbs and tails. The second forelimb,

The third, fourth and fifth fingers are particularly long and suitable for supporting the skin membrane; The first finger is very small and grows outside the skin membrane, and there are claws at the end of the finger. The hind legs are short, the feet protrude out of the skin membrane, and there are five toes.

There are claws on the toes. When resting, I often hang my body upside down in a cave or under the eaves with my claws. When crawling on trees or the ground, grasp rough objects with your index finger and feet.

Lean forward. Bat's skeleton is very light, with a protuberance on the sternum similar to the keel process of birds and muscles that affect the movement of its wings.

Bats have wide mouths and small sharp teeth, which are suitable for catching flying insects. Its vision is weak, but its hearing and touch are very sensitive. some

Experiments show that bats mainly rely on hearing to find insects. When a bat flies, it can produce ultrasonic waves in its throat and emit them through its mouth. while

When ultrasonic waves are reflected by insects or obstacles, bats can receive them with their ears and judge whether the detection target is insects or obstacles and the distance from it.

How far is it? People usually call this way of bat detecting targets "echolocation". The signals that bats send out when they seek food, orient and fly are made up of

Ultrasonic phoneme combination similar to language phonemes. After receiving the echo and analyzing its acoustic characteristics (such as amplitude, frequency and signal interval),

Before we decide what to do next.

Bats rely on echo ranging to locate, but only send out a simple sound signal, which is usually repeated by one or two phonemes according to certain rules.

From now on. When a bat is flying, the signal it sends out will be bounced by the object, forming echoes with different sound characteristics according to the nature of the object. Then there are bats

After analyzing the acoustic characteristics of echo, such as frequency, pitch and interval, bats determine the nature and position of objects.

Different parts of the bat brain can intercept different components of the echo signal. Some neurons in bat brain are sensitive to echo frequency, while others are sensitive to two.

The time interval between successive sounds is very sensitive. The cooperation of all parts of the brain enables bats to judge the characteristics of reflected objects. Bats use echolocation to capture.

The flexibility and accuracy of insects are amazing. According to statistics, bats can catch an insect in a few seconds and a dozen in a minute.

Insects. At the same time, bats also have amazing anti-interference ability, which can detect a special sound from the chaotic and noisy echoes, and then quickly

Analyze and distinguish this sound to distinguish whether the object reflecting sound waves is an insect or a stone, or more accurately judge whether it is an edible insect or an inedible insect.

Twenty thousand bats live in the same cave and will not interfere with each other because there are too many ultrasonic waves in space. Accuracy and resistance of echolocation in bats

Jamming ability has important reference value for people to study and improve the sensitivity and anti-jamming ability of radar.