调制解调器是什么样子
Modem is a device that can transmit data for long-range. The modem is a network device which is mainly used to access internet network but can be also used different special network access. The modem name is created with the conjunction of “Modulator” and “Demodulator” words which are two fundamental functions of a Modem.
Modem是一种可以远程传输数据的设备。 调制解调器是一种网络设备，主要用于访问Internet网络，但也可以用于不同的特殊网络访问。 调制解调器名称是由“调制器”和“解调器”两个词共同创建的，这两个词是调制解调器的两个基本功能。
调制解调器历史 (Modem History)
The first modem is used to multiplex lines in the 1920s for “News wire services”. Mass production of modems is started with the “SAGE” modems which are used for air-defense systems in 1958. Bell created a 103A dataset standard in 1962 which can work 300bit/s over a normal phone line. As a telecommunication company and monopoly, Bell created a lot of modems and created standards during the 1960s.In 1972 Vadiac introduced the VA3400 modem which can work full-duplex at 1,200bits/s over a phone network. The modern modem area starts in the early 1980s where speeds up to 18,432 bit/s were supported. Then 28.8k modems with 2400 baud rates are developed in 1994. Modems were mostly used for the internet connection and there were alternative ways to connect the internet. Last modems create with 33.6k and 56k speed later 1990s a.
第一个调制解调器用于多路复用1920年代的“新闻通讯服务”线路。 调制解调器的大规模生产始于1958年用于防空系统的“ SAGE”调制解调器。贝尔在1962年创建了103A数据集标准，该标准可以在普通电话线上以300bit / s的速度工作。 作为一家电信公司和垄断者，贝尔在1960年代创造了许多调制解调器并制定了标准。1972年，瓦迪亚克(Vadiac)推出了VA3400调制解调器，该调制解调器可以在电话网络上以1,200bits / s的速率进行全双工工作。 现代调制解调器领域始于1980年代初，支持的速度高达18432位/秒。 然后在1994年开发了具有2400波特率的28.8k调制解调器。调制解调器主要用于Internet连接，并且有替代方法可以连接Internet。 最后的调制解调器在1990年代后期以33.6k和56k的速度创建。
调制解调器如何工作？(How Modem Works?)
Modems work over analog phone lines in most of the cases. But computers and computer networks are completely digital. So the computer network data is digital and can not be transferred over the telephone lines by default. A modem that contains modulator and demodulator components translates digital data into analog signals which can be transferred over analog phone lines. Also modem can demodulate analog signals coming from the phone line into digital data. The internet connection is provided by the ISPs where the modem will connect to the ISP POP (Point Of Presence) point and the POP point has internet connection via fiber or cable.
在大多数情况下，调制解调器通过模拟电话线工作。 但是计算机和计算机网络是完全数字的。 因此，计算机网络数据是数字的，默认情况下无法通过电话线进行传输。 包含调制器和解调器组件的调制解调器将数字数据转换为可以通过模拟电话线传输的模拟信号。 调制解调器还可以将来自电话线的模拟信号解调为数字数据。 Internet连接由ISP提供，调制解调器将连接到ISP POP(存在点)点，并且POP点通过光纤或电缆具有Internet连接。
调制解调器类型(Modem Types)
There are different type of modems which are mainly related to the connection type and technology.
有不同类型的调制解调器，主要与连接类型和技术有关。
Cable Modem will use coaxial cables in order to transmit data. Coaxial cables are also used for antennas. The cable modem connection is the most reliable modem connection but creating the infrastructure is expensive for the ISP.
Cable Modem将使用同轴电缆来传输数据。 同轴电缆也用于天线。 电缆调制解调器连接是最可靠的调制解调器连接，但创建基础结构对于ISP来说是昂贵的。
DSL Modems are the most popular modem types in today’s world. DSL modems generally named as ADSL modems because the download speeds are higher than the upload speed. DSL modems use the telephone lines which is very widespread and cheap to operate for ISP.
DSL Modems是当今世界上最流行的调制解调器类型。 DSL调制解调器通常称为ADSL调制解调器，因为下载速度高于上载速度。 DSL调制解调器使用电话线，这对于ISP来说非常普遍且便宜。
Dial-up Modems are similar to the DSL Modems but they are the predecessor of the DSL Modems and provides low speeds. If the dial-up modem is connected the phone can not be used or while using a phone dial-up modem can not connect to the internet.
Dial-up Modems类似于DSL调制解调器，但它们是DSL调制解调器的前身，并且速度较慢。 如果连接了拨号调制解调器，则无法使用电话，或者在使用电话拨号调制解调器时，无法连接到Internet。
现代优势(Modem Advantages)
Modem became so popular during the 1990s and 2000s because of its huge advantages. Let’s list some of the most important advantages of the Modem.
由于其巨大的优势，调制解调器在1990年代和2000年代变得如此流行。 让我们列出调制解调器的一些最重要的优点。
- Modem connection and internet access are very cheap. 调制解调器连接和互联网访问非常便宜。
- Modems generally use phone lines that are already available. 调制解调器通常使用已经可用的电话线。
- The modem may provide high speeds with advanced modem types and good connections. 调制解调器可以通过高级调制解调器类型和良好的连接来提供高速。
- The modem is the most common connection type especially in rural areas. 调制解调器是最常见的连接类型，尤其是在农村地区。
如何选择调制解调器？ (How To Chose Modem?)
Modems are currently very cheap with mass production. If we need to buy a modem for using at home or at work we need to take care of the features and some metrics of the modem.
目前，随着批量生产，调制解调器非常便宜。 如果我们需要购买调制解调器在家中或工作中使用，则需要注意调制解调器的功能和某些指标。
Internet Infrastructure: First, we should check the currently available internet infrastructure. Mainly cable, dial-up, and ADSL connections are provided. We can use the following precedence if available.
Internet Infrastructure ：首先，我们应该检查当前可用的Internet基础结构。 主要提供电缆，拨号和ADSL连接。 如果可用，我们可以使用以下优先级。
- Cable Connection 电缆连接
- ADSL ConnectionADSL连接
- Dial-up Connection计算机)拨号连接
Modem Type : We will select the modem type according to the connection type. If the connection type is cable or coaxial we should select a cable modem that supports DOCSIS protocol. If it is an ADSL connection we should select an ADSL modem with proper ADSL versions like adsl+, adslv2.
Modem Type ：我们将根据连接类型选择调制解调器类型。 如果连接类型是电缆或同轴电缆，则应选择支持DOCSIS协议的电缆调制解调器。 如果是ADSL连接，则应选择具有正确的ADSL版本(例如adsl +，adslv2)的ADSL调制解调器。
Compatibility: For cable and ADSL modems the ethernet can be used to connect the internet but dial-up modems the dial-up modem should provide an interface like USB, PCI to connect the computer directly.
Compatibility ：对于电缆和ADSL调制解调器，可以使用以太网连接Internet，但拨号调制解调器拨号调制解调器应提供USB，PCI之类的接口以直接连接计算机。
Speed : Speed is another important factor where dial-up provides very low speeds. Adsl and cable connections provide higher speeds around 20-30 Mbps. Also in most cases the download and upload speed will be asymmetric which means download speed will be a lot higher than upload speed.
Speed ：速度是拨号提供非常低速度的另一个重要因素。 Adsl和电缆连接可提供约20-30 Mbps的更高速度。 同样在大多数情况下，下载和上传速度将是不对称的，这意味着下载速度将大大高于上传速度。
调制解调器与路由器 (Modem vs Router)
Even modem and router are different devices providing different services they can be used interchangeable because of the ADSL Routers functions. The router is mainly responsible for routing network or internet traffic between different networks. Modems generally provide the routing functions in order to reduce expense and operation const simply they can be called as “ADSL Modem”, “Router, “ADSL Router” interchangeably.
甚至调制解调器和路由器都是提供不同服务的不同设备，由于ADSL路由器的功能，它们可以互换使用。 路由器主要负责在不同网络之间路由网络或Internet通信。 调制解调器通常提供路由功能以减少费用和操作常量，它们可以互换地称为“ ADSL调制解调器”，“路由器”，“ ADSL路由器”。
调制解调器是什么样子