ASSIGNMENT ON MODEM

INTRODUCTION OF MODEM

With the evolution of technology, world has contracted in to a small village. One single click on your computer can connect you to any part of the globe. All of this has been possible due to a small electronic device called Modem. In this information guide we will discuss in detail about modem, its types, history, working and other important things.

   What is a Modem?

Modem is an electronic device that converts computer's digital information into analog carrier signals and vice versa. Computers use modems to communicate with each other over a network. The word modem is derived from “modulator- demodulator" that defines the functions it performs.

How Modem Works?

Modems are computer hardware typically used to transmit digital data over a phone line. The working of modems can be easily understood from this. Modems always work in pair. The sending modem converts computer’s digital information into specific frequencies compatible with the
phone line, the process is called modulation. The receiving modem decodes the signal back into the digital information, the process is known as demodulation. In wireless modems, digital data is converted into radio signals and vice versa.

Origin Of Modems

The requirement of communication between distant computers led to the usage of phone line for data transmission. Since the phone lines were designed to carry analog information (voices) only and computers and its related network devices work in digital form, a interface was needed to bridge this gap, which could act as a converter between the two systems. The result came in the form of Modems. Initially modems were primarily used to communicate data between terminals and a host computer. Later their use was extended to communicate between end computers. It was around 1960 when modems came into existence. 1960s were the age of time-shared computers. A business would often buy computer time from a time-share facility and connect to it via a 300-bit-per-second (bps) modem. Now modems are used for different functions. Their applications include textual and voice mail systems, facsimiles, and they are integrated into cellular phones, pdas , and notebook computers enabling them to send data from anywhere. All these needs have increased the modem speed up to 28.8 kbps.

TYPES OF MODEM

  The classification of modems can be done on the basis of a number of criteria that includes line type, operation mode, synchronization, modulation, and range. Keeping aside all these types of modems, in this section we will discuss some of the most common and popularly used types of modems worldwide.

1. DSL (Digital Subscriber Line) Modem

DSL modems are the type of modems used to connect a PC to the Internet. These modems provide fast Internet access as they work on high-speed DSL connections that are considered much faster than dial-up Internet connections. The foremost advantage of DSL is its ability to use the phone line to make or receive calls while connected to the Internet. The traditional dial-up service can't provide this service without the use of a second phone line. DSL achieves this by adding a filter on the phone jacks in a
location that will have telephones connected to them. A DSL modem provides similar service to that provided by a dial-up modem, the only exception is the high speed. But this setup and technological make up of DSL modems differs from the dial up. Other major difference is that DSL modems are external modems and connects to a computer via a USB or Ethernet port, while the dial-up modems are usually installed inside computer terminals.

2.    ADSL (Asymmetric Digital Subscriber Line)

 Modem ADSL modem provides faster downloading (getting data) than uploading (sending data). These modems have significant advantages over the dial-up modems. Like dial up modem it also uses a standard telephone line but it does not tie up the line. Thus the telephone line can be used while accessing the Internet. ADSL service is like an "always on" connection that cannot be left connected indefinitely. ADSL modem is faster than a dial-up modem. Due to available bandwidth on the dedicated copper wire, ADSL modem can accommodate a telephone conversation. An ADSL modem needs ADSL service through an Internet Service Provider(ISP). It can't work with a dial-up account.

3.    SDSL (Symmetric Digital Subscriber Line) Modem

SDSL modems works on SDSL lines that provide equal bandwidth in both directions. Such types of modems are useful for those businesses which need to upload as well as download large files or programs to or from the Internet. These modems use voice traffic lanes to expand bandwidth, and therefore aborting the possibility of a conversation when the SDSL modem is connected. For this purpose a dedicated phone line is required.

4.   Cable Modem

Cable modems are the types of modems that uses cable TV wiring instead of the phone line to provide Internet connectivity. They provides bi-directional data communication via radio frequency channels on a cable television infrastructure. Cable modems mainly deliver broadband Internet access in the form of cable Internet taking the benefit of the high bandwidth of a cable television network. Cable modems work on the same principle as the DSL modem. One needs to have service from a cable TV provider for Internet connectivity and also some network cables . The frequencies used for data traffic and TV traffic do not interfere each other. Cable modems are commonly deployed in Europe, North and South America, and Australia.

5.    SatModem (Satellite Modem)

One of the least common types of cable modem is a satellite modem, or satmodem. It is a wireless modem converting digital data into radio waves to communicate with a satellite dish. This particular type of service is more expensive than other conventional types of Internet connectivity. Satellite modems can be of great help for businesses or people in rural areas that do not yet have DSL or cable service offerings. Internal Modem Internal modems are installed inside desktops or laptop computers , enabling the computer to communicate with other connected computers over a network. Internal modems are of two types, dial-up and

6.   WiFi. Dial up modem

operates over a telephone line and needs a network access phone number and log-on credentials to do the connection. A wi-fi modem can connect wirelessly and without credentials in certain cases.

7.    External Modem

All the modems initially used were external modems. They were in proprietary use for decades prior to 1981, which marks the release of the first affordable and practical modem for public use. External modems are useful in situations when no internal slots are available, or if the modem needs to be shared between computers that are not networked. An external modem connected to a desktop system can easily be disconnected and connected to different desktop or laptop. External modems for dial-up service are easy to setup and come with instructions. They are inexpensive and available at all places where computers are sold. These modems also include fax capability at the software level.

DIRECTLY CONNECTING YOUR      
           COMPUTER AND MODEM

     In the following instances it may be necessary to directly connect your computer into the modem that Shaw provided for your Internet service.

*  Your modem is online but you cannot connect via WiFi *  Your modem is online but you cannot obtain a working connection through your 3 rd party router (Linksys, D-Link, Netgear, etc), either by WiFi or through a wired Ether net connection to that router. *  When performing a speed test, a direct connection to your modem ensures the most reliable results and will simplify the process of troubleshooting the cause of slow Internet speeds (software, 3 rd party equipment, etc).

Setting up a Direct Connection

To directly connect your modem into your computer you will need access to your Shaw Internet modem and will need to use an Ethernet cable (was included with your Shaw Internet modem).

1. On the back of your modem, locate the port labeled either Ethernet or 1 or LAN1 and connect the Ethernet cable into this port. For reference, here is a photo of an Ethernet cable although the color of the cable can vary.

2. Connect the other end of this cable into the Ethernet port on your computer to establish a connection. For reference, please see the illustration below for a highlighted (red) view of a typical Ethernet port.

3. Disconnect the black power cable from the back of the modem.

4. Reboot your computer.

5. Reconnect the power cable into the back of the modem and allow a short period of time for the modem to come online.

6. Be sure to disable any wireless connections on your computer to ensure your only connection is sourced from this newly established Ethernet connection.

7. You may now test the connection to confirm proper operation.

WHAT FACTORS AFFECT MODEM SIGNAL STRENGTH AND SIGNAL QUALITY

The measure of a connection depends on both the Signal Strength and Signal Quality . RSSI is a measure of Signal Strength , while CINR, SINR, and Ec/Io are measures of Signal Quality for
various technologies. The values we report are specific to different technologies (e.g. LTE) and carriers (e.g. Verizon).

NOTE: The following values are approximations; they are solely CradlePoint’s interpretations. Each of these values will vary for different technologies and carriers: contact your carrier for more authoritative information. CradlePoint does not guarantee adequate performance, regardless of the Signal

1.   Strength and Signal Quality

An adequate connection depends on many different factors, including: Proximity to the cellular tower Tower load Physical barriers (mountains, buildings, trains, etc.) Competing signals Weather Signal going through a cellular repeater Signal Strength and Signal

2.    Quality numbers

do not incorporate all of the relevant factors. In particular, measurements of Signal Strength and Signal Quality for a specific moment do not reflect on the STABILITY of a connection, as these values will vary as conditions change.

3.   Signal Strength
RSSI = Received signal strength indicator (measured in dBm)
* Excellent above −65 (closer to 0 is better)
* Good −65 to −75
* Fair −75 to −85
* Poor below −85
4.   Signal Quality
Ec/Io (several technologies including HSPA+ and EVDO; measured in dB)
* Excellent above −2 (closer to 0 is better)
* Good −2 to −5
* Fair −5 to −10
* Poor below −10
5.   SINR = Signal to Interference plus Noise Ratio (LTE only; measured in dB)
* Excellent above 12.5
* Good 10 to 12.5
* Fair 7 to 10
* Poor below 7
6.  CINR = Carrier to Interference plus Noise Ratio (WiMAX only; measured in dB)
* Excellent above 22
* Good 16 to 22
* Fair 9 to 16
* Poor below 9
7.  Additional Disclaimers:

There is no black and white answer to what constitutes a successful connection. It is possible to disconnect with green values –or connect with red values – for several reasons, including:

A)    Modems may vary.

We support hundreds of modems, and not all of them have the same ranges of acceptable values. For example: in our experience the Pantech UML290 and Novatel 551L require minimum RSSI values of −64 for acceptable connections.

B)   You must factor in BOTH Signal Strength and Signal Quality. It is possible to have excellent RSSI but disconnect because of poor quality (and vice versa).

C)   Signal Strength and Signal Quality values do not hold constant. The variance of a signal is a significant factor in the success of a connection. A particular reading represents one moment, but these values may vary dramatically over time. A stable connection requires consistency. This is
a sample graph of RSSI values that shows how much the values jump (from http://radiomobile.pe1mew.nl/):

D)   Other factors: tower load, signal going through a repeater/booster, etc. Some factors that don’t show up in Signal Strength/Signal Quality values can greatly impact a connection.

THE BENEFITS OF A WIRELESS MODEM

Modern Internet users enjoy the freedom of accessing the network away from home and work. Whether it's through the use of a Wi-Fi hotspot in a cafe, grocery store, or public library, or through a phone or notebook that is able to access a mobile broadband network, wide availability to an Internet connection improves the ability to conduct business operations, check emails, and stay connected through
social networks. Wireless Internet access began primarily through the use of Wi-Fi hotspots, though the limited range of these access points quickly led to an increased use of wireless broadband. This allows for a broader range of access to the Internet, essentially enabling users to tap into the network anywhere they would be able to get phone reception with
their mobile carrier. Overview of Modems A modem is any device that is capable of receiving a signal
and transmitting it to other units. In terms of modern electronics, a wireless modem is a machine that is able to receive and transmit a network signal, like the Internet, without the use of cable connections. Understanding Wireless Modems It is worth understanding how devices access the Internet in order to choose products that will provide the fastest, most reliable, and least expensive service. Important distinctions exist between wireless broadband and Wi-Fi, as well as routers and wireless modems.
Wi-Fi Vs. Wireless Broadband A common point of confusion for wireless users involves the use of the terms "wireless broadband" and "Wi-Fi." Although they both connect a device to the Internet, they function in two different ways. With Wi-Fi, a landline cable connects a router to the Internet. The router then broadcasts a network hotspot that can be accessed by Wi-Fi enabled devices, such as laptops. The router can only transmit a signal within a certain range, however, and it is usually limited to the confines of a single building. Wireless broadband, on the other hand, is transmitted through the long-range frequencies used by mobile telephones. Unlike Wi-Fi, a portable device does not need to be within range of a hotspot to use wireless broadband. It receives its signal directly from a mobile carrier, not an intermediary device. The most common example of this is an Internet- enabled cell phone. Routers Vs. Wireless Modems Routers and wireless modems are also sometimes confused. The first thing to note is that a router, like those used in homes and cafes, contains a modem. It could technically be called a modem, though it is instead named for its ability to route network signals to multiple devices. A Wi-Fi router differs from a wireless modem because it uses a cable connection to receive its network signal. Confusion results from the fact that almost all routers are referred to as "wireless routers." Although they transmit their signal to wireless devices, most routers still require a cabled connection to the Internet.
That said, there are routers available that are truly wireless. These receive their network signals from
wireless broadband. While some fully wireless routers are designed for use in a home or office as
a replacement for those with a cable connection, there are also small, portable routers available.
If a device uses wireless broadband to send network signals to a single device, it is called a wireless
modem. If it transmits wireless broadband to multiple devices, it is a wireless router. It is also
technically not called a Wi-Fi router. Choosing a Wireless Modem In terms of application, a wireless modem will provide users with a much broader range of Internet access than Wi-Fi connections. While Wi-Fi routers are capable only of transmitting the Internet over a small range, wireless modems can be used almost anywhere there is cell phone reception. There are several types of wireless modems to choose from, and the choice between them depends on the needs of the user. The most common types of wireless modems include connect cards, USB sticks, Mi-Fi devices, and wireless routers. Cards Cards were one of the earliest forms of wireless modem connections. There are two types: PC data cards and
connect cards. These are available from mobile providers and can be used with a laptop, personal computer, or router. They are extremely small and easy to use. USB Sticks A USB stick is the fastest way to connect a laptop to the Internet with a wireless modem. Similar in size and shape to a USB flash drive, these sticks neatly fit into the USB port on a laptop. Use of sticks usually requires installation of special drivers and software on the computer. USB sticks are very portable and easily carried from point A to point B. Mobile Hotspots Wireless modems can be purchased that function like portable Internet hotspots. These products, like Novatel's Mi-Fi routers receive a wireless broadband network and transmit the signal to a defined range, similar to Wi-Fi hotspots. This enables use of all devices with Wi-Fi capability with a wireless broadband network, making them great for people who alternately use their PCs , smartphones , tablets , and other devices while moving around town. Wireless Routers Some routers are designed for home use, and they require no cables to receive or send the signal, relying instead on wireless broadband signals. When shopping for a true wireless router, be sure to investigate the product to determine if it uses a cable connection or wireless broadband for its network connection. Using Wireless Modems Although the use of wireless modems allows for access to the Internet almost anywhere, keep in mind that connection speeds may be slower than they would be through a wired line or Wi-Fi. Speed of wireless broadband connections are always improving, however, and some providers may be able to rival the speeds of standard cable Internet. Research various wireless providers' networks to determine which will provide the fastest connection times. Also, users who plan to use wireless broadband daily and for many hours at a time will find they are paying quite a bit more for the service than they would through a cable connection. Check to see how much providers charge to use their wireless broadband. Safety of Wireless Modems One major benefit of using a wireless modem is its increased security over Wi-Fi. While Wi-Fi connections have a host of safety concerns, including interception of sensitive documents and theft of credit card numbers and other personal information, wireless broadband is an inherently safer Internet connection. This is due to the encryption of the data through the wireless provider's network. Users of USB sticks or cards still need to be careful not to lose the devices, however, as they contain access credentials specific to their owner. Also, use of wireless broadband is still not as secure as a firewalled, cable connection to the Internet.