Wireless modem is a kind of computer hardware, it can translate computer digital signal into the analog signal transmitted over regular telephone lines, and the analog signal can be line another modem at the other end of the receiving, and translated into computer language can understand. This simple process completes the communication between two computers.
MODEM English is MODEM, which functions as an interpreter for analog signals and digital signals. There are two kinds of electronic signals, one is "analog signal" and one is "digital signal". The telephone lines we use are analog signals, and the PCS transmit digital signals. So when you want to connect your computer to the Internet via a phone line, you have to use a modem to "translate" two different signals. After connected to the Internet, when PC send information to the Internet, as a result of the telephone line transmission is analog signal, so have to use a modem to the "translation" digital signal into analog signals, can be transferred to the Internet, this process is called "modulation". When the PC to get information from the Internet, because of the information coming from the Internet through a telephone line are analog signals, so the PC want to read them, also must use the modem "translate", this process is called "demodulation. In general, it's called modulation demodulation
The average person's voice is 300-3400 hz frequency range, for the voice signal transmission in the ordinary telephone system, online the bandwidth of the assigned to it must be on the road, international standard take 4 KHZ for a (road occupied bandwidth. In the transmission process: speech signal to a 300-3400 hz frequency input, the sender's telephone transform the voice signal into analog signals, the analog signal through a frequency division multiplexer to change, can transmit multi-channel analog signal at the same time on line, later when they arrive in the receiving end after a XiePin process to restore it to its original frequency range of the analog signal, again by the receiving party telephone converts analog signals into sound signal. 
The information in the computer is composed of "0" and "1" to form a digital signal, while the transmission on the telephone line can only be analog electrical signal. Do not take any measures to use analog channel to transmit digital signals inevitably there will be a big mistake (distortion), therefore, in the ordinary telephone network to transmit data, it must to digital signal conversion to telephone network within the required when the original design of the audio spectrum (that is, 300 hz - 3400 hz).
Modulation is to control the carrier wave waveform with the baseband pulse, forming a signal suitable for the transmission of the line.
The demodulation is that when the modulated signal arrives at the receiving end, the analog signal that has been transformed by the modulator will remove the carrier and return to the original baseband digital signal.
A modem can also convert an audio signal into a higher frequency signal and convert a higher frequency signal into an audio signal. The other purpose of modulation is to facilitate line reuse so as to improve line utilization.
Based on the three main parameters of carrier signal, modulation can be divided into three kinds: amplitude modulation, frequency modulation and phase modulation.
The difference between a wireless modem and a wired modem
The cable cat's word is the average MODEM, which is Shared by telephone.
There are two kinds of wireless cat. One is to use the wireless card directly, which is to use mobile and unicom signals. Is a kind of telecom wireless MODEM, the current telecom wireless MODEM is primarily through telephone cable modems, and then to use the wireless network card in the computer, the use of the wireless MODEM range for 20 m or so commonly, mainly can be anywhere on the Internet at home.
If you're on a desktop, you can use a cable MODEM.
If it's a laptop, there's a cable MODEM that has a fixed Internet location. Can only at home, but also want to say in any room to use, although take computer go out once in a while, but to also can have the wireless signal, use the wireless MODEM will do the trick, in the home network, use someone outside of network). If you want to be able to surf the Internet anytime and anywhere, use mobile, unicom wireless Internet.