Linksys Media Hub NMH305

Storage is a crucial part of the digital lifestyle: We all need a place to put our stuff, and we need a way to access those files easily. Linksys has tried a few storage products in the past, but the Media Hub is its most ambitious effort. While it's not exactly a small business server that lets you set up user accounts – like the HP MediaSmart EX487 – and can't compete with the robust RAID and back-up options on Netgear ReadyNAS devices or those by Buffalo Technology, it has one glowing attribute: it's easy to use. Like most Apple products including the still viable Time Capsule, the Media Hub assumes you are not a certified Microsoft engineer or someone who carries USB key drives in your pocket 24x7. It's a smart product that eases you into the deeper features, with only a few caveats.

Setting up the Media Hub takes all of about three minutes. Connect one Ethernet cord to your router, turn it on, and you're done. Because the drive supports UPnP and works well with Windows, Apple iTunes, the Mac (thanks to Bonjour), and even Linux, you can expect to see the drive on your network without installing a driver or fussing with an IP address. Only when you do want to dive into the advanced features will you need the included setup CD or to access the drive's IP.

This NAS matches the styling of the new Linksys Multi-Room Home Audio gear – which is to say, it's gray and black and nothing too special compared to more elegantly designed network-attached storage devices. The difference between a media player you'd stick next to an HDTV, and this product, is that it will likely sit in a back closet somewhere. The Media Hub has two USB ports, one on the front and one on the back. There are very few buttons and lights. The NMH305 base model ships with one 500GB SATA drive and has one open bay. There's a power light and drive activity light – Linksys plans to release two additional models with higher capacities and an LCD screen that reports on drive status.

Performance on the Linksys Media Hub is just ho-hum – it's not going to set any speed records. About 6GB of MPEG-4 movie files took six minutes to transfer to the Media Hub, whereas the same transfer took 3 minutes to send to a home-built Windows Home Server and only 1 min 40 seconds to copy to the HP MediaSmart EX487 server. A 700MB collection of photos and documents took 50 seconds to write to the drive and 50 seconds to read, about 15 seconds longer than it took on the HP MediaSmart. The drive really showed some pokey behavior when we performed a full back-up of a desktop, which took about ten hours for about 200GB of data. The Media Hub has a gigabit Ethernet port, so it should be no slouch, but a real server adds some extra features to speed up disk copies.

source : reviews.digitaltrends.com

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Networking Topology

Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there.

Network topologies are categorized into the following basic types:

• bus
• ring
• star
• tree
• mesh

More complex networks can be built as hybrids of two or more of the above basic topologies.

Bus Topology

Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.

Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.

Ring Topology

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

To implement a ring network, one typically uses FDDI,SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.

Star Topology

Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch, and router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.

Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)

Tree Topology

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.

Mesh Topology

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.

A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.

Summary

Topologies remain an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.

source : compnetworking.about.com

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Simple Steps To Basic Wireless Hacking

The intent of this article is to show you information on basic wireless hacking along with just how important it is to secure your wireless Network. Please use this information wisely. I am not responsible for what you and your friends do with this information.

Today it is very easy to set up a wireless network. Basically plug in the router a few clicks on your computer and away you go. The average person can go to his or her local electronic store and pick up a wireless router for as cheap as 40 bucks. The Problem comes in when securing the network. A large amount of people don't take the time to learn how to, or care to set up security.. How much damage can some one do if they connect to a wireless network?

Well in this article I will show you just how easy it is to connect to one of these unsecured networks and what kind trouble can be caused. I am going to use just some built in tools of Windows.

How Simple is it to find a Unsecured Network?

In this example I am just using the windows wireless management tool. This will work fine if you are not on the move. If you are scanning for networks in a car or on your bike I would strongly recommend NetStumbler .

As you can see here just by looking at what networks are available close to my home, There is at least one unsecured network. I would be willing to bet you could go around your block and find at least one open network. I am going to use this Linksys network in my example.

So just how simple is it to connect to an Unsecurred network?
I just double clicked on the open linksys network.
It will warn you that you are connecting to a unsecure network.

Click Connect Anyways

Now I can start Browsing the Internet

What can some one do if they connect to unsecured network?

In this example this wireless network is still set at the default settings including the Administrator password. A simple search on http://www.routerpasswords.com you can find just about any wireless router Default password. SInce this is a linksys router the default password would be admin. Since most wireless routers are the default gateway, I will do a quick command in dos to find out what the default gateway is.

Click on start > Run

Type CMD and click ok

In the Dos window type ipconfig then hit enter

I look for the information under my wireless network card. The default gateway is 192.168.1.1 Type this in your Browser to connect to the router.

You will be prompted for a username and password.

Leave the username blank or type root

Since this is a linksys router I will use the password admin

To find out the default password for just about any router check out

http://www.routerpasswords.com/

If they did not change there router password you should be able to get in to the configuration pages of the router.

I am now connected to the router. This gives me complete access to see who is on the network. I can also do things such as set up security, open ports, and so much more.

How do you see who is connected to the network?

- Click on Status

- Click on Local Network

- Click on DHCP Client Table button

You should now see all computers that have been assigned an IP address by the router. Not all the computers on the network may not be connected at that time but a simple ping will let you know.

You could run a port scanner on each of these computer's IP address to find open ports such as ssh, telnet, termainal service and so on.

SInce we are able to configure the router we could open up ports and let any one on the internet have access to this network. We could also have a little fun by setting up wireless security on the network and locking out the owner of his or her's own network.

Lets say you could not get in to configure the router there still is a lot of trouble that can be caused just by being connected on the network. You could set up a Network packet capturing program such as Ethereal. Then use it to Scan for information such as username and passwords from websites they may login to.

You could also go out and cause some trouble on the web and it would trace back to there IP address.

At the Least you could enjoy the free internet. You get lost some where, get connected real quick and take advantage of google maps. Could come in handy in a pinch.

I hope this article got you thinking a little bit and if your wireless network is not secure, I hope this has convinced you to take the time to set it up.

source : www.mixeduperic.com

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Router Commands

In this section you will learn about the router commands, configurations, privileged mode commands, routing protocols, cisco labs and network configurations.

There are hundreds of basic and advance level commands of a router. It is not easy to remember all the commands. But some commands are frequently used and can be remembered with some practice. I have provided a list of the most commonly used commands based on their features and usage. You will find here some basic terminology of a router.

Routing: Routing is a process of moving the data (packets) through an inter network. Routing performs the two basic tasks. Define the paths for a packet and then forward the packets on the basis of defined paths. Routing can also be defined as the communication between two or more logically and physical networks and this communication (packet transfer) is brought by a router.

First of all you should remember the keyboard shortcuts of a router.

Keyboard Shortcuts
CTRL-N - show next command
CTRL-P - show previous command
SHIFT-CTRL-6 – Break

Configuring the Router

You will be able to learn the basic commands for configuring a router.
sh running-config - details the running configuration file (RAM)
sh startup-config - displays the configuration stored in NVRAM
setup - Will start the the automatic setup; the same as when you first boot the router
config t - use to execute configuration commands from the terminal
config mem - executes configuration commands stored in NVRAM; copies startup-config to running-config

config net - used to retrieve configuration info from a TFTP server
copy running-config startup-config - copies saved config in running config (RAM) to NVRAM or "write memory" for IOS under ver.11
copy startup-config running-config - copies from non-volatile (NVRAM) to current running config (RAM)
boot system flash - tells router which IOS file in flash to boot from
boot system tftp - tells router which IOS file on the tftp server to boot from
boot system rom - tell router to boot from ROM at next boot
copy flash tftp - Copies flash to tftp server
copy tftp flash - Restores flash from tftp server
copy run tftp - Copies the current running-config to tftp server
copy tftp run - Restores the running-config from tftp server

General Commands

Here is a list of the general commands. These are the basic level commands and most commonly used
no shutdown - (enables the interface)
reload - restarts the router
sh ver - Cisco IOS version, uptime of router, how the router started, where system was loaded from, the interfaces the POST found, and the configuration register
sh clock - shows date and time on router
sh history - shows the history of your commands
sh debug - shows all debugging that is currently enabled
no debug all - turns off all debugging
sh users - shows users connected to router
sh protocols - shows which protocols are configured
banner motd # Your customized message here # - Set/change banner
hostname - use to configure the hostname of the router
clear counters - clear interface counters

Privileged Mode commands of a router

Learn how to work in the privileged mode of a router.
enable - get to privileged mode
disable - get to user mode
enable password - sets privileged mode password
enable secret - sets encrypted privileged mode password
Setting Passwords on router
Here you will be able to learn how to set the password on a router.
enable secret - set encrypted password for privileged access
enable password - set password for privileged access (used when there is no enable secret and when using older software)
Setting the password for console access:
(config)#line console 0
(config-line)#login
(config-line)#password
Set password for virtual terminal (telnet) access (password must be set to access router through telnet):
(config)#line vty 0 4
(config-line)#login
(config-line)#password
Set password for auxiliary (modem) access:
(config)#line aux 0
(config-line)#login
(config-line)#password

Router Processes & Statistics

By these command you can see the statistics and different processes of the router.
sh processes - shows active processes running on router
sh process cpu - shows cpu statistics
sh mem - shows memory statistics
sh flash - describes the flash memory and displays the size of files and the amount of free flash memory
sh buffers - displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Buffers
sh stacks - shows reason for last reboot, monitors the stack use of processes and interrupts routines

IP Commands

Here is a list of the IP Commands
Configure IP on an interface:
int serial 0
ip address 157.89.1.3 255.255.0.0
int eth 0
ip address 2008.1.1.4 255.255.255.0

Other IP Commands:

sh ip route - view ip routing table
ip route [administrative_distance] - configure a static IP route
ip route 0.0.0.0 0.0.0.0 - sets default gateway
ip classless - use with static routing to allow packets destined for unrecognized subnets to use the best possible route
sh arp - view arp cache; shows MAC address of connected routers
ip address 2.2.2.2 255.255.255.0 secondary - configure a 2nd ip address on an interface
sh ip protocol

CDP Commands (Cisco Discovery Protocol uses layer 2 multicast over a SNAP-capable link to send data):

sh cdp neighbor - shows directly connected neighbors
sh cdp int - shows which interfaces are running CDP
sh cdp int eth 0/0 - show CDP info for specific interface
sh cdp entry - shows CDP neighbor detail
cdp timer 120 - change how often CDP info is sent (default cdp timer is 60)
cp holdtime 240 - how long to wait before removing a CDP neighbor (default CDP holdtime is 180)
sh cdp run - shows if CDP turned on
no cdp run - turns off CDP for entire router (global config)
no cdp enable - turns off CDP on specific interface

IPX Commands

Enable IPX on router:
ipx routing
Configure IPX + IPX-RIP on an int:
int ser 0
ipx network 4A

Other Commands:

sh ipx route - shows IPX routing table
sh ipx int e0 - shows ipx address on int
sh ipx servers - shows SAP table
sh ipx traffic - view traffic statistics
debug ipx routing activity - debugs IPS RIP packets
debug ipx sap - debugs SAP packets

Routing Protocols

RIP, IGPR and OSPF are the routing protocols and here is a list of the commands for the working on the routing protocols.
Configure RIP:
router rip
network 157.89.0.0
network 208.1.1.0
Other RIP Commands:
debug ip rip - view RIP debugging info
Configure IGRP:
router IGRP 200
network 157.89.0.0
network 208.1.1.0
Other IGRP Commands:
debug ip igrp events - view IGRP debugging info
debug ip igrp transactions - view IGRP debugging info
Access Lists
Here is a list of the Access list command of a router.
sh ip int ser 0 - use to view which IP access lists are applies to which int
sh ipx int ser 0 - use to view which IPX access lists are applies to which int
sh appletalk int ser 0 - use to view which AppleTalk access lists are applies to which int
View access lists:
sh access-lists
sh ip access-lists
sh ipx access-lists
sh appletalk access-lists
Apply standard IP access list to int eth 0:
access-list 1 deny 200.1.1.0 0.0.0.255
access-list 1 permit any
int eth 0
ip access-group 1 in
Apply Extended IP access list to int eth 0:
access-list 100 deny tcp host 1.1.1.1 host 2.2.2.2 eq 23
access-list 100 deny tcp 3.3.3.0 0.0.0.255 any eq 80
int eth 0
ip access-group 100 out
Apply Standard IPX access list to int eth 0:
access-list 800 deny 7a 8000
access-list 800 permit -1
int eth 0
ipx access-group 800 out
Apply Standard IPX access list to int eth 0:
access-list 900 deny sap any 3378 -1
access-list 900 permit sap any all -1
int eth 0
ipx access-group 900 out

WAN Configurations Commands

Networking over WAN is the main functionality of a router. The most common use of a router is for the WAN connectivity. Here is a list of the commands for the different methods of the WAN connectivity.

PPP Configuration

Point to point protocol is a method for the WAN connectivity and you will find here some commands of PPP.
encapsulation pppppp authentication
ppp chap hostname
ppp pap sent-username
sh int ser 0 - use to view encapsulation on the interface

Frame-Relay Configuration

One of the methods for the WAN connectivity is the Frame Relay. Find here some basic commands for the WAN connectivity through Frame Relay.
encapsulation frame-relay ietf - use IETF when setting up a frame-relay network between a Ciscorouter and a non-Cisco router
frame-relay lmi-type ansi - LMI types are Cisco, ANSI, Q933A; Cisco is the default; LMI type is auto-sensed in IOS v11.2 and up
frame-relay map ip 3.3.3.3 100 broadcast - if inverse ARP won't work, map Other IP to Your DLCI # (local)
keep alive 10 - use to set keep alive
sh int ser 0 - use to show DLCI, LMI, and encapsulation info
sh frame-relay pvc - shows the configured DLCI's; shows PVC traffic stats
sh frame-relay map - shows route mapssh frame-relay lmi - shows LMI info

Miscellaneous Commands

In the last but not least here is a list of the some miscellaneous and useful commands
sh controller t1 - shows status of T1 lines
sh controller serial 1 - use to determine if DCE or DTE device
(config-if)#clock rate 6400 - set clock on DCE (bits per second)
(config-if)#bandwidth 64 - set bandwidth (kilobits)

source : www.networktutorials.info

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Windows 7 Security

By : Sonny Discini
Right now, Windows 7 looks very much like Windows Vista because enhancements to the appearance and feel aspects of the operating system typically come late in the development process. Lucky for us, much of the awaited security functionality has already made its way into the beta build and we're going to look at some of the new changes for Windows 7.

Old friends, new twists

Returning from Windows Vista are Kernel Patch Protection, Service Hardening, Data Execution Prevention, Address Space Layout Randomization, and Mandatory Integrity Levels

Windows XP SP2 gave us the Security Center. Windows 7 discards this and in its place is an Action Center that incorporates alerts from 10 existing Windows features: Security Center; Problem, Reports, and Solutions, Windows Defender; Windows Update; Diagnostics; Network Access Protection; Backup and Restore; Recovery; and User Account Control.

In Windows 7, users can adjust consent prompt behavior using a slider control, if they have administrative privileges. Microsoft says they'll still be protected against malicious software, even if they never see another alert. While this may or may not be true, users have been conditioned to see alerts whenever something is happening. Without them, perhaps a false sense of security will develop on the part of the end user.

Windows Filtering Platform

Windows 7 introduces something called the Windows Filtering Platform (WFP). The idea is that third parties can take advantage of aspects of the Microsoft Windows Firewall in their own products. Microsoft says "third-party products also can selectively turn parts of the Windows Firewall on or off, enabling you to choose which software firewall you want to use and have it coexist with Windows Firewall."

While this sounds nice on paper, I can't see a vendor teaming their product with the Windows firewall. Smart money says they'll just use their own and ignore the Microsoft solution.

One nice thing to note about Windows 7 is that it makes it easier to configure that all-important home network. When users hit network problems, they curse the firewall and they're often right to. Windows 7 addresses the problem by taking over home network setup and making sure the firewall doesn't interfere.

We also see that scrollbars were removed in the configuration settings screen, as has the Software Explorer feature, and real-time protection in Windows 7 has been improved to reduce the impact on overall system performance. A welcome change from the bloat of Vista.

An inclusive BitLocker

Vista sailed in along with a fleet of new security features, among them BitLocker, a whole-disk encryption tool designed to protect your data even after an attacker makes off with your laptop. BitLocker utilizes a chip called a Trusted Protection Module (TPM). The Vista TPM transparently decrypts the drive once you've authenticated yourself with a password or smart card. A laptop thief can't break into the locked drive, even after booting to a different OS or moving the drive to another computer.

BitLocker drive encryption also supports removable storage devices, such as flash memory drives and portable hard drives has been added in Windows 7. This means that users can keep sensitive data on all of their USB storage devices as well as the physical drives on the host mentioned above.

As a side note to Bitlocker, using groups, you can ban writing to any removable drive that isn't BitLocker-protected. It's a very useful tool against the very real problem known as podslurping. With this policy in place, employees can still bring in the virus-of-the-month on an unprotected drive, but they can't take away an unprotected copy of the personnel database. It's also helpful to know that BitLocker to Go also allows users to securely share data with other users who have not yet deployed Windows 7.

That said, the testing I performed proved otherwise. I could not get this to work so I went to Microsoft and they confirmed that this is an issue in the beta build but will be fixed before final GA release.

Biometrics, System Restore and AppLocker

Biometrics enhancements include easier reader configurations, allowing users to manage the fingerprint data stored on the computer and control how they log on to Windows 7. And System Restore includes a list of programs that will be removed or added, providing users with more useful information before they choose which restore point to use. Restore points are also available in backups, providing a larger list to choose from, over a longer period of time.

I've seen more problems caused by System Restore than solved by it; I'm not a big fan. Still, users often resort to it when trying to clean up a real or imagined malware problem. In Windows 7, you'll at least have a clear idea of what collateral damage may result, as it lists all programs and drivers that would be removed or brought back by invoking a particular System Restore point. It's way better than guessing at the right restore point and hoping for the best, which is what you have to do now.

Another enhancement is AppLocker, accessed through Local Security Policy. It's a way to control which programs users can and can't use, and it's a lot more flexible than Vista's Software Restriction Policies. Still, it's not for the average user. Most IT shops should be pleased with this enhancement. I can see it being tailored to just about any corporate need.

Virtually all the changes in the security area are simply tweaking and improving on existing Vista features. But then, that's what Windows 7 is all about, right? While the enhancements seen thus far in the beta are nice, they aren't stunning.

I hope to see even more improvements before Windows 7 hits the streets.

source : www.enterpriseitplanet.com

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Save your computers from Spyware

The best defense against spyware and other unwanted technologies is to prevent them from getting on your computer in the first place. Awareness is the best approach to protect yourself online, so staying up-to-date on current threats and safe surfing practices is essential. Here are some steps you can take to stay safe while still getting the most from the Internet and software programs.

Keep security on your computer up to date.

• Update security patches:

Many malicious spyware developers exploit known security holes in essential software, such as operating systems and browsers. Update essential software frequently. Automate the process if your vendor offers the option.

• Security and privacy settings in Internet browsers:

Many Internet browsers have security and privacy settings that you can adjust to determine how much—or how little—information you are willing to accept from a Web site. Check the documentation or help file on your Internet browser to determine how to adjust these settings to appropriate levels. See GetNetWise.org for detailed instructions.

Download programs only from Web sites you trust.

• If you are not sure whether to trust a program you are considering downloading, ask a knowledgeable friend or enter the name of the program into your favorite search engine to see if anyone else has reported that it contains spyware or other potentially unwanted technologies.
• Look carefully at the address of the site you are visiting to make sure it is not an obvious spoof.
• Be particularly suspicious of programs you see advertised on unrelated Web sites. If a maker of a screensaver, “smiley” inserter, or other program heavily promotes its purportedly-free product, the product may include extra software you do not want.

Beware the fine print: Read all security warnings, license agreements, privacy statements, and “opt-in” notices with any software you download.

• Whenever you install something on your computer, make sure you carefully read all disclosures, including the license agreement and privacy statement. Sometimes important information such as aggressive installs or the inclusion of unwanted software in a given software installation is documented, but it may be found only in the EULA. The fine print may be the only place consumers can find notice of potentially unwanted technologies. Unfortunately, careful consumers must read all the fine print.
• When given the choice of opting into something, make sure you understand fully to what you are agreeing.
• If you have doubts about the legitimacy of the software, do not install it, or go to a trusted source to find more information about the software. To be safe, you should never install software if you are uncertain about it.

Don’t be tricked into clicking: You don’t have to click “OK,” “Agree,” or “Cancel” to close a window.

• If you want to close a window or dialog box, consider the options provided by your operating system or Web browser, such as closing the window with the ‘x’ mark in the upper corner or typing Alt+F4 in Microsoft Windows.
• Pay attention when closing windows; some dialog boxes may have a prominent statement that says, “Click here to close window,” then in less prominent text adds, “and install software.”

Be especially careful with certain types of “free” programs.

• Many file sharing applications are bundled with other, potentially unwanted software.
• Similarly, screen savers, cursor enhancements, wallpaper bundles, “smiley” inserters and any other software promoted aggressively often include extra software you did not request and aren’t expecting. Be sure you clearly understand all of the software packaged with those programs.

Use available tools to detect and delete spyware.

• There are a number of security tools available from a variety of vendors that can help you identify spyware, stop the installation of it on your PC, and/or remove it.
• Anti-spyware and Anti-virus software:

There are a number of programs (available both free and for a fee) from reputable vendors that can help detect spyware, prevent spyware from being installed on your PC, and/or remove spyware if it is installed. (Some programs can be removed through “Add/Remove programs” or other standard operating system features.) Note that some software that claims to be an anti-spyware tool is actually adware or other potentially unwanted software in disguise. For this reason, you should read reviews to be sure any anti-spyware software you download is from a reputable publisher.

• Personal firewall:

Installing and using a firewall provides a helpful defense against remote installation of spyware by hackers.

We encourage you to learn more about how to protect yourself from spyware by visiting the US federal government OnGuard OnLine Web site at http://www.onguardonline.gov.
source :www.antispywarecoalition.org

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MAKE OMNI ANTENNA

Introduction

Most of the designs on the web for 2.4 GHz omni antenna seem to involve brass tubing and lmr-400 cable, none of which are readily available to me. I then found a coax only design for 444Mhz that was based on the same idea. The only reasonable cable I could get my hands on was RG-213 from Maplin. By scaling the 444Mhz design up to 2.4 Ghz and using RG-213 I thought I'd have a go. In order to get about 6db gain from the antenna, it would need 8 sectors, with a 1/4 wave section at the top and a fly-lead with N-connector at the bottom. It should take about 2-3 hours to build an antenna using this design, but don't worry if it takes longer, you will get quicker, especially as you only need to make the jig once.


Most of the designs either had toroid magnets or a decoupler on the fly-lead of the antenna. However the location of the decoupler seems different in each design, and some designs quoted a decoupler length of 1/4 wavelength, others were !/4 wavelength times the velocity factor of the decoupler tube (brass tube quoted at 0.95). I've tried most locations and can report that without proper testing kit I can see no difference in the Signal to Noise ratio between having a decoupler and not. I decided to not bother as it simplified the design. If anyone knows a good reason why you must have a decoupler then I would love to know (especially if you know where it should be exactly). If you want to add a decoupler, please do, I found using 15mm or 22mm copper tube and a 15mm or 22mm end stop made a good design, just needing to be soldered together to get the right length, and a hole drilled in the end of the end stop to fit the cable.


Each sector of the antenna needs to be a 1/2 wavelength long multiplied by the velocity factor of the cable. The velocity factor of RG-213 is 0.66 . If you decide to use different cable (such as LMR-400) then you need to get the velocity factor of that cable (which will be different), and recalculate all the dimensions.

V * C 0.66 * 299792458
1/2 wavelength = ------ = ---------------- = 0.0405m = 40.5mm
2 * F 2 * 2441000000

V = Velocity Factor of RG213 = 0.66
C = speed of light = 299792458
F = Frequency of Signal = 2441000000 (middle of 2.4ghz range)

The 1/4 wave element is not adjusted by the Velocity factor, as it is in the open, so works out at just 31mm long giving a total antenna length of 355mm + fly-lead. (Thanks to Oscar for correcting me of this.)
Getting the parts

All of the parts are available cheaply from either Maplin and any diy shop.

* 1m RG-213U cable (available by the meter from Maplin). This is enough for 2 antenna. Buy more for whatever flylead length you want.
* N connectors, Depending on what you want to connect to , use either male or female connectors, and inline or bulkhead. Remember inline connectors need to fit 10mm diameter RG-213 cable
* 20mm pvc conduit (available from any diy store) Has a 20mm inside diameter, and 22mm outside.
* 22mm pipe clips (depending on how you want to mount the antenna), pipe clips make it easy to mount and unmount, or use the proper conduit brackets (but they seem a little expensive).

You don't need any special tools

* mm rule for measuring !
* junior hacksaw
* stanley knife
* pliers
* standard soldering iron (don't need a heavy duty one) and solder
* off cuts of wood to make a jig to aid soldering
* bench or vice to hold cable while you cut it

Cut the pieces

After much trial and error, I found that the neatest way to cut the cable is actually with a junior hacksaw. It gives a much cleaner finish than wirecutters. Each sector consists of a short length of RG-213 cable, with the central core sticking out each end.



When building the antenna, the exact length of each piece of RG-213 is not that important, it is the overall length of each sector that counts. I found that cutting the cable to 37mm with 6mm of core sticking out each end, gets enough overlap to easily solder the segments together. If you allow 1mm for the width of the hacksaw when cutting the sectors apart, it means you need 37 +6 +6 +1 = 50mm of cable for each sector making 8sectors + 1/4wave section come to 420 mm of cable for the antenna + cable for the fly lead.

The best way to cut each sector is to make the cuts where each end of the sheathed section of the sector will be, before making the cut between each sector. The picture below shows the top 3 sections of the antenna, and the 1/4 wave section, showing the order that the cuts should be made.



The best way to make the cuts is to mark them out on the cable first. When sawing the cable it has a tendancy to deform and bend, so lightly sawing round the outside sheath first, but not cutting through, helps give a guide to the cutting for real. I use the junior hacksaw to gently saw round the cable sheath to make the mark for each section.

The first mark will be at 31mm from the end, which is for the 1/4 wave section at the top. Once you have made the mark, it is time to cut round the cable. You want to cut through the sheath, shielding, and just into the central insulation, but not into the central copper wires. You may need to practice a bit first, but you should be able to feel as you cut through the shielding into the central insulation. By leaving plenty of sheathed section either side of the cuts, the shielding stays in place when being cut.



Now with pliers, gently twist off the end 31mm of sheath & shielding

This should leave the cenral insulator exposed. Using the stanley knife score round through the central insulator, but not too hard, or you will cut the central cable. Now twist off the insulation. You should be able to see the twist in the central cable through the insulation, which will show you which way to twist off the insulation, resulting in the central core twisting more tightly.


The next mark is 37mm down (68mm from end of the cable) and is the cut for other end of the sheathed section of the top sector. The next mark is 13mm down (consists of 6mm core from each sector and 1mm for cut between sectors) (81mm from end) and is the top of the sheathed section of the second sector. The next mark is 37mm down, then 13mm, then 37mm, and so on and so forth until you have each of the sheathed sections marked out.

You can now start making the cuts, remembering to only cut through the sheath, shielding and just into the central insulation. First make the cut at 37mm down, then the next cut a further 13mm down. You may find that some of the shielding pulls out when you make this cut, as the 13mm length of sheath cannot hold the shielding tight enough. Don't worry, it doesn't matter.



Now you are ready to cut off the top sector from the cable. You want to cut through the whole cable at the mid point of the two cuts you have just made, that is about 43.5 mm from the end of the sheath, or 74.5 mm from the end of the cable. See position 4 in the diagram above. Just saw carefully the whole way through the cable.

Now you can pull off the sheath and shielding from the each end.


Now score round the insulation as you did before, being careful not to cut the central cable

Now carry on making cuts 37mm down from the end of the sheath, and then 13mm further down (50mm from the end of the sheath), and then cut through the cable in the middle of the two cuts. Another sector made. You will need eight sectors in total. Make the same cuts as usual for the eighth sector as it will make top of the flylead as well. Now you have all eight sectors you need to check round the end of each sector to make sure that none of the shielding is touching the central cable, as odd strands can get left.

Now you need to make a gentle V shaped cut with the stanley knife, at each end of the sectors, to expose the shielding, which is where the central core of the next sector will be soldered.


Make sure that the V cuts at each end of the sector line up, othwise, when you come to solder the antenna together, the whole thing will be twisted all around. Once you have all eight sectors finished, its time to put them together.
Build a Jig
If you do not have a handy helper to hold the sectors together, then you will find it easier to make a small jig from offcuts of wood, to hold the sectors together as you solder them. The clamps on the right hand side of the picture need to be no more than 30mm long. The base board of the jig, needs to extend out to the right long enough to take the whole length of the completed antenna, as it will need to support it during the soldering, as the antenna is not rigid enough to support itself.


Don't make the clamps too tight, as you need to be able to easily lift the cable out after it has been soldered.


When you are readly to solder the sectors together, you need to take care , that each sector is correctly spaced. The overall length of each sector needs to be 40.5mm , measure from one end of the shielding of the sector you are adding, to the same end on the next sector, and slide the sectors together/apart until the distance is 40.5 mm. Try to get it as accurate as you can, as it affects the direction the antenna transmits in if you get it wrong. There should be a small 3mm gap between the sheaths of each sector.





Once you have soldered each sector together, lift it up, turn it over, and move it down the clamp ready for the next sector. This results in a nice straight antenna. When soldering, remember to heat both the shielding and core so that the solder runs smoothly and fixes them together.

Once complete, test the cable with either a bulb and battery or a multimeter. The center of the fly lead should form a circuit to the 1/4 wave section, and the shield of the flylead to the shield of the top section. Now test that there are no crossed connections, by ensuring there is no circuit between the center of the flylead and the shielding of the top sector, and no circuit between the 1/4 wave section and the shielding of the flylead.

Now fix the N connector of your choice onto the end of the fly lead. The type of connector you use depends on what you want to connect to. I use inline connectors, but you could use any connector you like. Slide the antenna into a length of conduiting. It should be a snug fit, you may need to gently ease it in. Now find an old soft drink bottle top, and pop it on the top end of the antenna. Voila one complete antenna ! Securing the antenna in the conduit is best left until you are ready to mount it somewhere. You can cut 5cm slots in the bottom if the conduit, and use a jubilee clamp to grip the flylead, or drill a hole through the conduit and use a cable tie to hold the fly lead, or use a bulkhead mount connector on a botle cap, and glue it to the bottom of the conduit, or glue the flylead in place. It's up to you.
Testing

I will assume you are connecting the antenna to a wireless card in a laptop, and connecting to an accesspoint somewhere. You will need to a signal to noise meter to examine the signal strength. Most wifi cards come with software that does this. Now its time to test that the antenna actually works. This can be harder than it sounds, as unless you can remove the existing aerial from the card or ap, you can't tell it is using your new homebrew antenna. Well wrapping the existing antenna completely in 6-8 layers of tinfoil, has a dramatic reduction on signal strength, now connect the antenna, and the signal should go back up. Remember that omni antenna send out the signal horizontally, so don't test it from the room below your access point. Hopefully you should see that your new antenna actually works. There are three ways to test the gain of the new antenna

* Use spectrum analyser in a professional radio lab
* compare the gain of your new antenna, to the gain of a known antenna (Not the pcmcia card)
* Carry out an empirical range test with your new antenna

If you have access to a spectrum analyser I'd love to know your findings. If you have an existing omni or yagi antenna, then you can compare the snr readings between the two antenna. Remember to do the test outside, as bouncing the signal off walls can really give odd results. Try to stand as far away from the antenna as possible when doing the test, as even moving near it can change the results a lot. Position the two antenna in the same place for the test. Don't try and compare the snr of your new antenna to that of the wireless card in your laptop, as just by turning the laptop round, or lifting it up, or holding it, can dramatically change the snr. Try it and see what I mean. If you don't have another antenna, then wander down your street until you are out of range. Now wander back towards your AP, and wait for the laptop to chime that it has made a connection. Note how far from home you are. Try it again, with the laptop connected to the new antenna. Remember to keep the antenna vertical. I found carrying them in a bag with the antenna poking out the top works well. Try not to hold the antenna, as this will change the snr. You should now be able to pick up your AP about twice as far away, assuming there are no new massive obstacles.

If you have a go at making this antenna, and get it working, drop me an email (address at bottom of page) and let me know how you found building it, whether you've found a simpler way, and ... be honest ... how long it took.

source : wireless.gumph.org

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Top review of HSDPA Modem

Here discuss about review HSDPA modem that may be tested that technology. This review I got from the people who already used. From here we can see what the feature, or the bad of HSDPA modem. I hope this review can be helping you to use HSDPA modem.

The Sierra Wireless AirCard 881U

At first glimpse, the AirCard 881U from Sierra Wireless is a beast of a gadget. Big, ugly, and surprisingly heavy, the USB modem isn't nearly as stylish as the other modems.
Similarly annoying is the install process. If you're a Windows user, it's easy -- simply pop the disc into your machine and follow the screen prompts. But if you're a Mac user, it's much more difficult. To install it on my Mac OS X 10.4 MacBook, I had to go to the Sierra Wireless Web page's support section and download the correct software for my operating system. Once that download was complete, I was finally able to install the software, restart my computer, and connect to AT&T's 3G network.

The AirCard 881U's software was delightfully easy to use and far more bearable than the ridiculous install. To connect to the 3G network, you need only to open the program and click the Connect button. In a matter of seconds, the modem is up and running and you're free to surf.
I was pleasantly surprised with the speed I experienced while browsing the Web. Simple pages like Google (NSDQ: GOOG).com opened in just a few seconds with 3G connectivity and more complex Web sites like ESPN.com opened about twice as fast as my EDGE-connected cell phone, but about 10 seconds slower than my Wi-Fi connection. All in all, I was getting about 1.0 Mbps on the downlink and roughly 375 kbps up.
Although 3G connectivity with the AirCard 881U was a great experience, it suffers from the same limitations that all USB modems do: it's governed by the data coverage that wireless carriers provide. And unless you live in a big city or around a densely populated area, don't expect 3G wherever you go. In fact, I quickly found myself surfing at EDGE speeds when I ventured away from the metro area.
The Sierra Wireless AirCard 881U is a generally lackluster USB modem that's bloated, too heavy, and more of an eyesore than anything else. And although connecting to 3G was delightfully easy and the price tag -- free after mail-in rebate -- is attractive, AT&T's $60 per month data plan and the AirCard 881U's aforementioned issues should make you think twice before picking it up.
source: www.informationweek.com

Sierra Wireless 875U HSDPA USB Modem

by:Sascha Segan
Blaze across the virtual globe with the Sierra AirCard 875U, the fastest, most flexible way to connect your laptop PC to AT&T's high-speed network and to dozens of other computer systems in foreign lands. High-speed wireless connection solutions are available from three major carriers, in four different forms. You can get them from Sprint, Verizon, or AT&T, and they come either as chips embedded in laptops, as PC Cards, ExpressCards, or USB dongles.
USB dongles such as the AirCard 875U are less compact than the other options, but they're a lot more flexible. Since pretty much every PC has a USB port, it's easy to move them between computers. The 875U's SIM card slot is also relatively easy to access under its front cover. This lets you move your SIM between the dongle and your phone more readily than you could with a card.
About the size of an old-school pager, the 875U has a USB jack that pops out of the modem's body on an easy-to-release latch. Plugged into your laptop, it sits upright like a periscope, with unobtrusive green power and signal lights. There's an easy-to-access external antenna port covered by a little rubber plug on the side.
The 875U operates with AT&T's standard LaptopConnect plans. One option costs $69.99 per month for unlimited use in the U.S., and the other will set you back $139.99 per month for unlimited U.S. data plus 100MB of data overseas, with additional overseas MB $5 each. Those prices are on a par with what's offered by Sprint and Verizon.
AT&T's network, meanwhile, has come a long way since I first looked at it last year. AT&T uses HSDPA technology, which also works in dozens of countries overseas, including most of Western Europe. Over the past year, AT&T has extended its network to most major U.S. cities and metro areas. The current HSDPA spec allows for 3.6-Mbps downloads and 384-Kbps uploads, in theory.
In reality, we got average speeds of just over a megabit for downloads on the 875U, with download speeds peaking at 1.63 Mbps. Uploads averaged 275 Kbps, but with a strong signal frequently hovered around 350 Kbps. That's broadband speed, although if you're used to wired or Wi-Fi broadband, you'll still feel that Web pages load slowly because of the average 240-millisecond latency on network requests. The 875U supports the 850, 1800, 1900, and 2100-MHz bands, so you'll be able to get access in Buffalo or Berlin, provided you're on the right service plan.
When the 875U isn't in 3G range, it drops down to AT&T's EDGE network, which offers speeds of around 80 to 120 Kbps down. I generally don't recommend EDGE cards for laptop users for a different reason—EDGE transmissions tend to make some laptop speakers buzz annoyingly. If you're traveling primarily through EDGE country, I'd recommend tethering a phone to your laptop via Bluetooth instead.
The 875U proved faster than the competing AirCard 875 PC Card and Option GT MAX 3.6 Express in head-to-head download tests. It's also faster than older models such as the AirCard 860. The competition was tight. Of 35 downloads, the 875U was the fastest on 15 of them; the ExpressCard was faster on 14 tries. Differences in signal strength between the 875U and the Option ExpressCard were negligible.
Rather, it's the AirCard's flexibility I like. As a USB device, it's easy to plug and unplug at will, and the SIM card slot is easier to extract cards from than on the ExpressCard. Better still, the 875U is compatible with Microsoft Windows XP, Vista, and Mac OS 10.4.9, though its driver isn't integrated into the Mac OS. You have to download a "Sierra AirCard Watcher" application from Sierra's Web site.
source: www.pcmag.com

Huawei E272

he E272 enables uplink speeds of up to 2Mbps and download rates of 7.2 Mbps. Within HSPA network, the device will facilitate fast internet browsing, instant access and the uninterrupted ability both to upload and download data. Combining cutting edge technologies with sleek design, customers can look forward to enjoying high-speed wireless access, both at home and on the go. The plug-and-play featured devices are compatible with Windows (Vista and XP) and Mac OSX, whether run on a PC, laptop or handheld device.

Benefits:
Boost your efficiency with 14 times faster download speeds than standard 3G.
Work more effectively with 22 times faster upload speeds than standard 3G.
Plug and go with any laptop or desktop, including Macs.
Enjoy seamless coverage at home and roaming abroad.
Connect with speeds of up to 7.2Mbps.

Specification:

* The USB Modem works with all laptops including Macs. It can also be used with any PC.

Microsoft Windows requirements:
* Standard USB interface
* Microsoft Windows 2000, XP or Vista
* Microsoft Internet Explorer 5.5 or higher
* At least 50MB free disk space and 128MB RAM

Apple Mac requirements:
* Standard USB interface
* Optimised for Power PC based Macs and Intel based Macs
* Mac OS X Panther 10.3.9 or higher

Technical Specification:
* 3G (UMTS/HSDPA/HSUPA) Frequency supported 2100Mhz
* EDGE/GPRS Frequency supported 900,1800 and 1900Mhz
* Support for USA/Canada :Yes For GPRS/EDGE at 1900MHz

Auto switch frequency: YES
WLAN network supported: NO
Apple Mac compatible: Yes , with special VMC software for Mac OS

source : hkoffer.com

Huawei E220 USB Modem

Been using Huawei E220 for around 1 month, I could say that this modem does its function well. No issue related to hardware. The installation process completed with auto-run in Windows Operating System, no need any installation CD, just plug the modem to any USB port and it will prompt you to start the software installation.
The connection is stable, however it depends on your network provider as well. in my home area, around Pangkalan Jati, Kalimalang. It could run very well for nights and days, without any need of reconnection.
This modem was launched back in 2006. Maximum speed is 3.6 Mbps, you could set this modem to use 3G only signal, or 3G prefered if you are not sure you will get a good reception of 3G signal.
Bought it for Rp.1.450.000 in a store at ITC Kuningan Jakarta, I am surprise to see this modem sold for Rp.1.250.000 at a small computer store in Palembang .
I use this modem along with Telkomsel Flash Unlimited Package which has virtually unlimited capacity but with limited maximum speed of 256Kbps (up to 3Gb per-month, before the speed is reduced to 64Kbps).
Connection of max 256Kbps is quite decent for me, allows me to check web mail, update anti virus, connect to my company VPN - Virtual Private Network, and do some downloads (never yet try to download big files though). However because the speed limitation of Telkom Flash unlimited package, I have never test the maximum speed of this modem.
I have tested this modem along with Telkomsel Flash in area of Kalimalang Jakarta (HSDPA connection - Very Good), Kuningan Jakarta (HSDPA connection - Very Good), Plaju - Palembang (HSDPA connection - not to good, some re-connection needed, sometime could not connect), Tuban - East Java (EDGE connection, but stable).
The whole body of this modem is plastics. There is no lock on the SIM card port, so you need to be careful not to drop this modem to the floor. It might spit out your SIM Card. Also don’t step on it, I believe it will break a part.
If you are a mobile person who need a notebook computer to work and be online, or you need a HSDPA modem which you could use on your home PC and notebook computer; and you just can’t rely on with your HSDPA smartphone for some reasons, I recommends Huawei E220.
source :myweathertop.wordpress.com

NOVATEL OVATION MC930D/MC950D

Nowadays, Internet connectivity ranks high in our hectic everyday schedules, regardless of the fact that we have places to visit, people to meet, and things to get done. It’s not surprising that we’re practically as dependent on the Internet as we are on electricity. Thus, we need absolute on-the-road mobility with universal connectivity. Today we’re going to review Novatel’s Ovation MC950D HSPA mobile broadband USB modem.
The Ovation MC950D is a 3G modem based on the latest HSUPA, HSDPA, and UMTS technologies. HSUPA stands for High-Speed Uplink Packet Access, HSDPA stands for High-Speed Downlink Packet Access, and UMTS represents Universal Mobile Telecommunications System technology. These are key technologies of 3G, which offers the most cutting-edge high performance data access speeds.

resumably, the Ovation MC950D and its younger sister, the MC930D, are the world’s smallest modems. This is possible thanks to their latest innovative design, which is similar to the USB stick form factor standards. It fits comfortably in a pocket. And most importantly, backwards compatibility isn’t neglected because the modem can switch back to quad-band GPRS/EDGE 2G technologies when tri-band UMTS 3G signals aren’t reachable.
The modem supports up to 7.2mbps downlink data access speeds and 2.1mbps uplink. The aforementioned are architectural limitations by design because these speeds are 100% dependent on carriers and network operators. This gadget doesn’t bring you the Internet “for free;” you need to sign up with a carrier for a plan or account in your area, and then you receive an UMTS HSUPA/HSDPA compatible SIM card.
Novatel Wireless optimized this modem for North America, Europe, and Japan, but technically worldwide support is possible as long as there is the necessary network coverage on the supported bands. It is platform independent so it works fine on Microsoft Windows, MAC OSX, UNIX, and Linux operating systems.
There are lots of network partners that are selling the Ovation MC950D modem. More often than not, these partners are network operators and, therefore, you can also sign up with them right away. For this review, the modem was acquired through Vodafone so it sports the “Vodafone” logo instead of Novatel Wireless. The red SIM card is also from Vodafone.
Nevertheless, we can’t continue before examining its price. The Ovation MC950D is available for around £159.80, €210, and US$320 at the time of writing. Sure, it’s not a bargain, but you need to pay the price for innovation and universal connectivity. Additionally, the plans can go up to €30 per month, but mostly this depends on features - whether it’s unlimited or not, your area, how the network looks there, etc.
source : www.devhardware.com

Sierra Wireless' Compass 597

Unlike its older brother, the AirCard 881U, the Sierra Wireless Compass 597 is an attractive addition to any computer. Better yet, the company's smallest USB modem offers a fully equipped device that easily outshines other Sierra Wireless products and competes admirably with the Novatel USB727. And with a beautiful black finish and an attractive light on the end to tell you it's in use, you won't be put off by this modem's looks.
The Compass 597's installation on my MacBook was quick and easy. In a matter of seconds, I popped the modem into my computer, installed the software, restarted my computer, and connected toSprint (NYSE: S)'s Mobile Broadband Network without a hiccup. Much like the Novatel USB727, the installation process was seamless. But no disc was required to install the software. Instead, the Compass 597 has all drivers and software already installed on it, which speeds and simplifies installation.
While connected to Sprint's Mobile Broadband Network, Google loaded quickly and detailed sites like ESPN popped up at an adequate, but noticeably slower speed than the load times I witnessed on Verizon's BroadbandAccess and AT&T's 3G network. According to Speedtest.net, I achieved speeds of about 875 kbps down and 300 kbps up.
The Compass 597 uses Sprint's SmartView software, which is easily the best package on the market and much better than the tools I used on the other modems. Aside from GPS tracking and the ability to search points of interest in your area, the tool also allows you to test upload and download times, get an updated view of Sprint's Broadband coverage map, manage your Sprint account, and access the company's Digital Lounge service.
Sprint's Digital Lounge allows you to buy anything from screensavers for your phone, to music, TV, and games. Even though most of the content is too expensive to justify a purchase, it's nice to have the option.
The Sierra Wireless Compass 597 is a fine USB modem that won't take up too much room in your pocket, nor look too foolish hanging off the side of your computer. And with a fantastic software package, it's not a bad idea to pick this one up -- if you don't mind spending $100 (after rebate) for the modem plus $60 per month for 5 GB of data.
source : www.informationweek.com


VODAFONE HUAWEI E172


Vodafone has partnered with Chinese telecoms equipment maker Huawei to create a USB 3G modem the size of a flash drive, but still capable of accessing HSUPA mobile data networks.

The mobile broadband USB modem stick, the Huawei E172, is Vodafone's smallest ever plug-and-play device and significantly smaller than any previous data card or 3G modem it has offered. It is compatible with Windows (Vista and XP) as well as Mac OS X.

Vodafone will offer the stick alongside its existing, E220 USB modem which was released last year. "They are exactly the same inside," said Vodafone spokeswoman Bryony Clow. "It's just that the E172 has a smaller form factor. We are looking to sell both as the different forms will appeal to different people. We'll be pushing the stick, but the modem will be available as well."

The E172 supports uplink speeds of up to 1.44Mb/sec and download rates of 7.2 Mb/sec, which they claim is theoretically 14 times the speed of standard 3G. However, the 7.2Mb service is currently only supported within Central London and at certain UK airports. This will increase as Vodafone continues the rollout of HSUPA to the rest of its 3G network.

"Vodafone was the first to improve download speeds with HSPDA, the first to increase upload speeds with HSPUA. And now we're pushing the boundaries of usability even further with a compact modem design," said Kyle Whitehill, enterprise director at Vodafone.

The mobile broadband market is getting more competitive, with network operators cutting prices and adding value to service plans to entice both consumer and business customers. Last week IT PRO reported that Carphone Warehouse and mobile network 3 had joined forces to offer a £35-a-month bundle comprising a mobile broadband service, bundled text messages and a Dell laptop.
source :www.itpro.co.uk

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