Radio Frequency Interference意为（）。

A.4*3

B.7*3

C.1*3

D.MRP

A．between 3.4 GHz and 7 GHz

B．between 12 GHz and 14 GHz

C．between 14 GHz and 21 GHz

D．between 21 GHz and 27GHz

A.Finding the true nature of subatoraic particles.

B.Their work on very high frequency radio waves.

C.Laying the foundations of modern mathematics.

D.Their discovery of the laws of cause and effect.

A.英文全称为Radio Frequency Identification

B.是一种利用射频通信实现的接触式自动识别技术

C.具有体积小、容量大、寿命长、可重复使用等特点

D.可支持快速读写、非可视识别、移动识别、多目标识别、定位及长期跟踪管理

requency re.use in the network)？()

A.It increases the sensitivity of the mobile

B.It increases the number of mobiles with high C/I

C.The power consumption in the radio base station is reduced

D.It reduces the risk of MS receiver saturation

E.It reduces the number of mobiles with low C/I

Bluetooth

When you use computers, entertainment systems or telephones, the various pieces-and parts of the systems make up a community of electronic devices. These devices communicate with each other using a variety of wires, cables, radio signals and infrared light(红外线) beams, and an even greater variety of connectors and plugs.

The art of connecting things is becoming more and more complex every day. And Bluetooth has now become a new popular method of connecting devices that can streamline the process. A Bluetooth connection is wireless and automatic, and it takes small-area networking to the next level by removing the need for user intervention and keeping transmission power extremely low to save battery power.

Bluetooth Operation

Bluetooth networking transmits data via low-power radio waves. It communicates on a frequency of 2.45 gigahertz(千兆赫)(actually between 2.402 GHz and 2.480 GHz, to be exact). This frequency band has been set aside by international agreement for the use of industrial, scientific and medical devices(ISM).

A number of devices that you may already use take advantage of this same radio-frequency band. Baby monitors(微型监视器), garage-door openers and the newest generation of cordless phones all make use of frequencies in the ISM band.

One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about 1 milliwatt. By comparison, the most powerful cell phones can transmit a signal of 3 watts. The low power limits the range of a Bluetooth device to about 10 meters (32 feet), cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms.

Bluetooth can connect up to eight devices simultaneously. With all of those devices in the same 10-meter (32-foot) radius, you might think they'd interfere with one another, but it's un- likely. Bluetooth uses a technique called spread-spectrum(扩展频谱) frequency that makes it rare for more than one device to be transmitting on the same frequency at the same time. In this technique, a device will use 79 individual, randomly chosen frequencies within a designated range, changing from one to another on a regular basis. In the case of Bluetooth, the transmitters change frequencies 1,600 times every second, meaning that more devices can make full use of a limited slice of the radio spectrum. Since every Bluetooth transmitter uses spread-spectrum transmitting automatically, it's unlikely that two transmitters will be on the same frequency at the same time. This same technique minimizes the risk that portable phones or baby monitors will disrupt Bluetooth devices, since any interference on a particular frequency will last only a tiny fraction of a second.

Piconets(个人域网络)

Let's say you have a typical modern living room with the typical modern stuff inside. There's an entertainment system with a stereo, a DVD player, a satellite TV receiver and a television; there's also a cordless telephone and a personal computer. Each of these systems uses Bluetooth, and each forms its own piconet to talk between the main unit and peripheral(外围设备).

The cordless telephone has one Bluetooth transmitter in the base and another in the handset. The manufacturer has programmed each unit with an address that falls into a range of ad- dresses it has established for a particular type of device. When the base is first turned on, it sends radio signals asking for a response from any units with an address in a particular range. Since the handset has an address in the range, it responds, and a tiny network is formed. Now, even if one of these devices should receive a signal

A．Y

B．N

C．NG

Bluetooth

When you use computers, entertainment systems or telephones, the various pieces and parts of the systems make up a community of electronic devices. These devices communicate with each other using a variety of wires, cables, radio signals and infrared light(红外线) beams, and an even greater variety of connectors and plugs.

The art of connecting things is becoming more and more complex every day. And Bluetooth has now become a new popular method of connecting devices that can streamline the process. A Bluetooth connection is wireless and automatic, and it takes small-area networking to the next level by removing the need for user intervention and keeping transmission power extremely low to save battery power.

Bluetooth Operation

Bluetooth networking transmits data via 10w-power radio waves. It communicates on a frequency of 2.45 gigahertz(千兆赫)(actually between 2.402 GHz and 2.480 GHz, to be exact). This frequency band has been set aside by international agreement for the use of industrial, scientific and medical devices(ISM).

A number of devices that you may already use fake advantage of this same radio-frequency band. Baby monitors(微型监视器), garage-door openers and the newest generation of cordless phones all make use of frequencies in the ISM band.

One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about 1 milliwatt. By comparison, the most powerful cell phones can transmit a signal of 3 watts. The low power limits the range of a Bluetooth device to about 10 meters(32 feet), cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The Walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms.

Bluetooth can connect up to eight devices simultaneously. With all of those devices in the same 10-meter(32-foot) radius; you might think they'd interfere with one another, but it's unlikely. Bluetooth uses a technique called spread-spectrum.(扩展频谱) frequency that makes it rare for more than one device to be transmitting on the same frequency at the same time. In this technique, a device will use. 79 individual, randomly chosen frequencies within a designated range, changing from one-to another on a regular basis. In the case of Bluetooth. the transmitters change frequencies 1,600 times every second, meaning that more devices can make full use of a limited slice of the radio spectrum. Since every Bluetooth transmitter uses spread-spectrum transmitting automatically, it's unlikely that two transmitters will be on the same frequency at the same time. This same technique minimizes the risk that portable phones or baby monitors will disrupt Bluetooth devices, since any interference on a particular frequency will last only a tiny fraction of a second.

Piconets(个人域网络)

Let's say you have a typical modern living room with the typical modern Stuff inside. There's an entertainment system with a stereo, a DVD player, a satellite TV receiver and a television; there's also a cordless telephone and a-personal computer. Each of these systems uses Bluetooth, and each forms its own piconet to talk between the main unit and peripheral(外围设备).

The cordless telephone has one Bluetooth transmitter in the base and another in the handset. The manufacturer has programmed each unit with an address that falls into a range of addresses it has established for a particular type of device. When the base is first turned on, it sends radio signals asking for a response from any units with an address in a particular range. Since the handset has an address in the range, it responds, and a tiny network is formed. Now, even if one of these device

A．Y

B．N

C．NG

cancer. originally,because of a lawsuit that alleged such a link Network news programs ran their own tests of cell phones,reporting to the public that some cell phones exceed the maximum level of emitted radio frequency energy allowed by the US Federal Communications Commission.

In 2000.it was estimated that there were 92 million cell phone users in the United States and this number was growing by 1 million every month. More recently,the Cellar Telecommunications & Internet Association estimated that there were almost 170 million US cell phone users, and the seriousness of brain tumours, this is clearly a topic of wide concern.This report summarizes what we now know about the carcinogenicity of using cell phones.

Cell phones operate with radio frequencies.a form. of energy located on the electromagnetic spectrum between F M radio waves and the waves used in microwave ovens,radar;and satellite stations.Cell phones do not emit ionizing radiation,the type that damages DNA and is known to have the ability to cause cancer.

Cell phone technology works on a system of geographically separated zones called "cells" Each cell has its own "base station" that both receives and emits radio waves.When a call is placed from a cell phone,a signal is sent from the cell phone antenna to that cell's base station antenna.The base station responds to the cell phone signal by assigning the phone an available RF channel.When the RF channel is assigned,radio signals are simultaneously received and transmitted, allowing voice information to be carried between the cell phone and the base.The base station transfers the call to a switching centre.where the call can be transferred to a local telephone carrier or another cell phone.

6.There has existed argument about the link between cell phone and brain tumour.()

7.The rapid growing number of cell phone users has been a great concern in the US.()

8.The 3rd paragraph tries to prove that cell phones do not cause brain cancer.()

9.A switching centre is needed when we make a call through cell phone.()

10.The topic of the passage is about cell phone and cancer.()

听力原文： A team of scientists recently began a project to measure the effects of loud noises on sea animals. If the sounds don't harm the animals, then the researchers can go ahead with a plan to transmit sound waves through the Pacific Ocean to take the earth's temperature. Sound travels faster through warm water than cold water. By analyzing the speed of sound through the ocean over time, the scientists will be able to determine if cur planet is warming up. The experiment was nearly cancelled more than a year ago because environmental groups fear that the sound will confuse or harm sea-animals. So scientists are conducting tests on the animals first. The researchers lowered a loud speaker that emits low frequency sound about 1,000 meters beneath the ocean. Scientists at the site transmit sound waves into the ocean. Radio transmitters attached to some of the sea animals help the researchers keep track of the animals' movements. If sea-animals are distressed by the sounds, they would swim away from the speakers. So far, there aren't any signs that the animals are being harmed. Researchers at the site noticed that large numbers of sea-animals swim near the speaker whether it was turned on or off, but it is still too soon to know for sure, the scientists admit. The test will continue through September. "If all goes well," they say, "we can begin measuring temperature changes on our planet."

(33)

A．To determine whether the Earth's temperature is going up.

B．To study the behavior. of some sea animals.

C．To measure the depths of the ocean.

D．To measure the movement of the ocean.

A.INTR和NMI

B.INT和NMI

C.INTR和INTA

D.INTE和INET