Modems
What does Modem stands for?
Modem is short for modulate, demodulate. It is a way to get a message from a PC across telephone lines to another PC. Your computer is digital and works with 0s and 1s, whereas the telephone is analog and works with waves. Thus you need to alter the form of the information in your computer generated message to enable it to be carried across the telephone lines.
How modems work?
The PC is considered a digital device. Thus everything about your computer and what you do with it, breaks down to a series of 0's and 1's. This comes about through a series of electronic switches which turn off and on. When the switch is off a 0 is created, when the switch is on a 1 is created. Thus when you type in the number 9, the switches have been programmed to see this as 00001001.
To pass a message between PC's using a modem, it must go through the telephone system. The telephone lines use an analog signal. This signal resembles your voice which has many tones and frequencies, ups and downs to it. It carries your voice in waves.
The modem is the bridge between the digital of your computer and the analog signal of the telephone lines. When you send a message via a modem from your PC the process is this:
- The message in your PC is in digital form therefore your PC has converted your message to a whole bunch of 0's and 1's. This message is sent to the modem which converts your digital message into the analog required by the phone system by modulating the frequency of the electronic wave.
- This encoding process puts the transmission into a mode compatible with the media of the telephone system which uses copper wire, microwave, fibre optic and satellite. The code is then transferred across this media. On reaching the PC the message is sent to, the analog signals are demodulated back into digital code through another modem and the message is received.
Buying a Modem
When deciding on a modem to buy, select a model that matches your computer and level of expertise. Modems can be purchased in three different forms, external, internal and as a PCMCIA card - commonly referred to as PC Card (used with laptops).
External Modems
If your expertise is minimal, you should purchase an external modem as it's the simplest to install.
External modems usually come with a panel of lights which display information about the current sessions (see the section titled 'The lights on your modem' further on), these can aid you in working out what problems are and how to fix them.
Many external modems also have a volume control which is great if you really don't want the whole household hearing you connection signals. The external modem can sit on top of your hard drive or on your desktop and is connected to your computer by a serial cable.
Internal Modem
Internal Modems tend to be cheaper since there is no case or power supply, no cables to knock loose or get in your way and you don't have to find somewhere to put it since it lives inside your computer
Installing an internal modem involves locating an unused IRQ interrupt and COM serial port in your computer and then simply configure your internal modem to use it.
Once you've got to this stage, take the outer case off your computer and install the card in a free expansion slot.
Wired vs Wireless Networking
Computer networks for the home and small business can be built using either wired or wireless technology. Wired Ethernet has been the traditional choice in homes, but Wi-Fi wireless technologies are gaining ground fast. Both wired and wireless can claim advantages over the other; both represent viable options for home and other local area networks (LANs).
Below we compare wired and wireless networking in five key areas:
- ease of installation
- total cost
- reliability
- performance
- security
About Wired LANs
Wired LANs use Ethernet cables and network adapters. Although two computers can be directly wired to each other using an Ethernet crossover cable, wired LANs generally also require central devices like hubs, switches, or routers to accommodate more computers.
For dial-up connections to the Internet, the computer hosting the modem must run Internet Connection Sharing or similar software to share the connection with all other computers on the LAN. Broadband routers allow easier sharing of cable modem or DSL Internet connections, plus they often include built-in firewall support.
Installation
Ethernet cables must be run from each computer to another computer or to the central device. It can be time-consuming and difficult to run cables under the floor or through walls, especially when computers sit in different rooms. Some newer homes are pre-wired with CAT5 cable, greatly simplifying the cabling process and minimizing unsightly cable runs.
The correct cabling configuration for a wired LAN varies depending on the mix of devices, the type of Internet connection, and whether internal or external modems are used. However, none of these options pose any more difficulty than, for example, wiring a home theater system.
After hardware installation, the remaining steps in configuring either wired or wireless LANs do not differ much. Both rely on standard Internet Protocol and network operating system configuration options. Laptops and other portable devices often enjoy greater mobility in wireless home network installations (at least for as long as their batteries allow).
Cost
Ethernet cables, hubs and switches are very inexpensive. Some connection sharing software packages, like ICS, are free; some cost a nominal fee. Broadband routers cost more, but these are optional components of a wired LAN, and their higher cost is offset by the benefit of easier installation and built-in security features.
Reliability
Ethernet cables, hubs and switches are extremely reliable, mainly because manufacturers have been continually improving Ethernet technology over several decades. Loose cables likely remain the single most common and annoying source of failure in a wired network. When installing a wired LAN or moving any of the components later, be sure to carefully check the cable connections.
Broadband routers have also suffered from some reliability problems in the past. Unlike other Ethernet gear, these products are relatively new, multi-function devices. Broadband routers have matured over the past several years and their reliability has improved greatly.
Performance
Wired LANs offer superior performance. Traditional Ethernet connections offer only 10 Mbps bandwidth, but 100 Mbps Fast Ethernet technology costs little more and is readily available. Although 100 Mbps represents a theoretical maximum performance never really achieved in practice, Fast Ethernet should be sufficient for home file sharing, gaming, and high-speed Internet access for many years into the future.
Wired LANs utilizing hubs can suffer performance slowdown if computers heavily utilize the network simultaneously. Use Ethernet switches instead of hubs to avoid this problem; a switch costs little more than a hub.
Security
For any wired LAN connected to the Internet, firewalls are the primary security consideration. Wired Ethernet hubs and switches do not support firewalls. However, firewall software products like ZoneAlarm can be installed on the computers themselves. Broadband routers offer equivalent firewall capability built into the device, configurable through its own software.
