Lecture 3(b) :Wireless Networking(Unguided Media)


 The three broad categories of wireless media are:
1.       Radiowave - 10 Khz to 1 Ghz. It is broken into many bands including AM, FM, and VHF bands.
 The Federal communications Commission (FCC) regulates the assignment of these frequencies.
                   Frequencies for unregulated use are:
                  902-928Mhz - Cordless phones, remote controls.
                  2.4 Ghz
                  5.72-5.85 Ghz
2.       Microwave
               Terrestrial - Used to link networks over long distances but the two microwave towers must
                       have a line of sight between them. The frequency is usually 4-6GHz or 21-23GHz. Speed
                       is often 1-10Mbps. The signal is normally encrypted for privacy.
              Satellite - A satellite orbits at 22,300 miles above the earth which is an altitude that will
                   cause it to stay in a fixed position relative to the rotation of the earth. This is called a
     geosynchronous orbit. A station on the ground will send and receive signals from the
                   satellite. The signal can have propagation delays between 0.5 and 5 seconds due to the
    distances involved. The transmission frequency is normally 11-14GHz with a transmission
    speed in the range of 1-10Mbps.
3.       Infared - Infared is just below the visible range of light between 100Ghz and 1000Thz. A light
                     emitting diode (LED) or laser is used to transmit the signal. The signal cannot travel through
                    objects. Light may interfere with the signal.

Comments

Post a Comment

Popular posts from this blog

Lecture 4: Network Cabling and Tools

Image
3 Types of Ethernet cable are used in Networking 1-Straight through Cable 2-Cross Over Cable 3-Roll over cable Straight through cable, Cross over Cables are used for data transfer While Rollover cable is used to configure routers / switches / network devices. To remember which type of cable you should use, follow these tips:  To connect two serial interfaces of 2 routers we use serial cable .   To specify when we use crossover cable or straight-through cable, we should remember: Group 1: Router, Host, Server Group 2: Hub, Switch One device in group 1 + One device in group 2: use straight-through cable Two devices in the same group: use crossover cable For example: we use straight-through cable to connect switch to router, switch to host, hub to host, hub to server… and we use crossover cable to connect switch to switch, switch to hub, router to router, host to host HOW TO MAKE A NETWORK CABLE: 1. Unroll the required length of network cable and add a little extr...
Read more

Lecture 6(b): Subnetting Examples

Image
Before Going to Subnetting Examples put attention on below Slide it will help to solve exam Question: Subnetting Class C: Subnetting Class B: Subnetting Class A:  Note:According to Cisco in Subnetting First and Last Subnet is not Valid because 1st subnet contain Network Address of IP whom we go to Subnet in Last subnet Contain Broadcast Address,Practically we used that subnets otherwise it will wastage of IP's.Normally in exam question may be mention that 1st/last subnet included or excluded. Be Prepare for Quiz.In Next Post i Will explain VLSM and Route Summarization.
Read more

The CPU was previously shutdown due to thermal event overheating service the unit right now

Check you system fans are spinning on start up (and they don't stop). Put your computer in the coolest place available, preferably somewhere with air conditioning, and be sure there is space around the box for sufficient airflow. Open the box and remove any dust that has accumulated, particularly on the heat sink and fan(s) blades by using air blower. Blades can get very dirty over time without regular maintenance. The next step would be to remove the heat sink from the CPU (when the computer is off!), Apply silver thermal paste to the cpu and reattach the heatsink and fan. This would improve heat transfer. Determine the temperature of your processor in BIOS or third party tool,normal range from 60-65 ° C for the Pentium 4 While Maximum temperature for the processor is 95 c (Celsius). Processor Overheating Create Following Problems: Reduction of CPU life-span; Random freezes; Random restarts and Shutdown; Eventually the CPU can get burned. Note:Temperature Varies accordin...
Read more