There are a variety of devices that are included within a network, such as firewalls, routers, memory, switches, VoIP, modules, and wireless products. All of this hardware comes with a price tag that can add up to be quite expensive. There are some employers that would prefer to buy only new network equipment because of the guarantee that comes with them. Other employers want to purchase used Cisco network equipment in order to save some money. Although you or your company may be convinced that new equipment is the way to go, there are some reasons to buy refurbished equipment for your network.

1. Purchasing used network equipment can often save fifty to ninety percent of what purchasing new would cost. It is often more cost effective for owners to purchase used Cisco equipment for their small businesses.

2. Resellers of used Cisco equipment typically have better customer service which gives you the chance to talk to them when necessary without having to pay extra for technical support.

3. Popular Cisco network equipment resellers will often provide warranties for their used equipment that are competitive with a manufacturer warranty.

4. Cisco equipment that is new will instantly become used once the box is opened. You could research the equipment to determine how many different companies have used it before you. You may be purchasing a piece of equipment that is just an open box piece of equipment and has actually never been used.

5. Dealers that sell refurbished network equipment test the hardware before they sell it. This will give you the peace of mind knowing the equipment works and will save you some headaches when you first install and use it.

6. Purchasing used Cisco network equipment is good for the environment as well. These types of electronic equipment can leak hazardous materials that they contain and can be harmful to the environment.

7. Purchasing refurbished equipment for your network is practical. Your boss will be pleased by your effort to save money and will give you the praise you deserve.

8. In order to ensure that you have all of the best products that you need for your network, dealers will often offer other used products you can choose from.

9. You can purchase GBICs that are compatible with the manufacturer’s product but at a lower cost.

10. Money that is saved by purchasing refurbished equipment can be used to help raise employee morale and therefore productivity by giving them a bonus.

There are a number of reasons to purchase used network equipment, but these are the top buy used Cisco tips that can help you make the best decision.

The simple basic application of any communication satellite, whether it is low earth orbital or geosynchronous, involves transmission of information from an originating Earth station to the satellite concerned, which is termed as “up-linking,” followed by re-transmission of the same information to the designated Earth station. This re-transmission is termed as “down-linking.” The downlink of the information may be to one particular Earth station or broadcasted over a selected number of Earth stations, situated at a larger area. In order to perform this up-linking and down-linking, the satellite has a receiver and a receive antenna, a transmitter and a transmit antenna, just like a set of walkie-talkie, which has a receiver and a transmitter with an antenna, though, in here, the “receive” and “transmit” are done through the same antenna. Satellites need antennas separately for its two functions of receive and transmit. Additionally, the satellite has electronic switches. This is used to logically switch the uplink signals, down-linking it to the appropriate Earth stations. It has an electronic black-box to determine the destination or destinations of the signals being down-linked to the Earth Stations. There is that ever important electrical power in a satellite required in keeping alive the electronic circuitry. The exact component structure of a satellite may differ from one to the other, depending on its actual application, but the basic component requirements remain the same.

The electrical power needed by satellites for receiving and transmitting signals greatly depend upon its orbital path, that is, whether it is a low Earth or geosynchronous orbital satellite. Electrical power requirement mostly depend upon the height of the satellite above the Earth. The higher it is, a satellite would need that much power for its basic operation in receiving and transmitting signals On basis of this, a geosynchronous satellite, being at an altitude of 22,300 miles, would require much more electrical power than the low earth orbiting satellite, which is situated at only a few hundred miles from Earth. In theory, a geosynchronous satellite would need 10,000 times the electrical power than the low Earth orbiting satellite. This is an awful lot of power and the satellite is designed in a way to work out a compromise, without losing the application reliability.

A satellite is usually powered from a battery or a solar energy system. In some of the communication satellites, a combination of battery and solar power energy is used, with the batteries supplying power to the electronics circuitry in the satellite, with a change over to solar energy during sunlight cycle, when the batteries are left on charging. The battery is turned on during solar eclipses, when the solar panels become inactive.

The main difference between the satellites in different orbital path is the antenna. This antenna design sets the optimum power requirement of a satellite. There are basically many designs available for an antenna. Some direct their radiation to one particular direction and there are others which are omni-directional, radiating all around. This principle is carried further by a communication satellite. If you consider the height at which the satellite is orbiting, even a large area on this Earth will be a mere spot of an area from that height. With the earth stations located in a comparatively small area, a properly designed antenna will beam its signals within that constricted area and not in any other direction. With a bigger antenna dish diameter, the area of radiation decreases in relation to certain design parameters.

One of the parameter in such a design is called “gain” of an antenna. This gain tells us how much more power would be required to beam the signals on one square mile of an area, with the transmitter power evenly distributed (isotropic distribution) over all directions within that area. This is one of the primary design criteria, which goes into the requirement of less electrical power required for a geosynchronous satellite, compared to what it would, in theory.

The larger difference in the antenna system of a geosynchronous satellite and the low earth satellite is that, the antenna should always look at the Earth. While it is fairly easy for the geosynchronous satellite, being stationary relative to the Earth’s rotation, the low Earth orbit satellites zoom past any point on the Earth every 5 to 10 minutes. In this case it becomes difficult to maintain the antenna orientation, as required.

The Earth station is a moving target, when looked at from the low Earth orbiting satellite and some sort of tracking system must be incorporated in the design, so that the antenna tracks the Earth station as passes that spot in its orbital path. The other alternative is to make such a design, such that the antenna can beam at a wider angle covering a wider area of the Earth, so that the receiver or transmitter is always within the reach of the reception and transmission of the signals. In doing so, the gain of the antenna reduces and to maintain the right gain, a lot more power would be required for the transmitter to provide such signal transmission.

Where do we get that power? One may wonder why the transmitters are not designed that way to provide thousands of watts of power. It is simply that it is not possible to make that kind of power available in a spacecraft. The on-board power is generated either by the series of batteries on the craft or by the huge solar panels, mounted on the satellites. These solar panels have numerous solar cells which generate the electrical energy required from the sunlight, while charging the batteries during sun-light periods. During the time when it is dark, the power generation is switched on to the batteries.. These solar cells are similar to the ones that you find in you calculator. There is a limit of how much these solar panels can generate. This limitation sets the limit of how much power can be generated in a satellite system. In practice, in some of the satellites, these solar panels generate few thousands of watts of electrical power. It is just not conceivable in providing that high power transmitters on-board the satellites as is desired.

The batteries on board are deployed, when the Earth passes in between the satellite and the Sun, when the solar panels do not get the sunlight required to produce the electrical energy. Therefore, the batteries have to remain in good charged condition in order to take over the energy generation when required.

The satellite receives and transmits the signals in two different frequencies. In here we find the application of transponders in a satellite system. A transponder is a component of a satellite system that receives the signals from Earth stations and transmits it back to the designated Earth station or stations. The uplink of any signal from Earth station is done using a “dish” antenna pointing towards the satellite. This signal is sent to one of the transponders on board. The transponder amplifies this signal, shifts it to a different frequency and transmits back to Earth. This shift of frequency, from the received signal to the transmit signal, is to avoid any interference between the receiver, and transmitter frequencies. A downlink dish like antenna at the earth station, looking at the satellite, captures this signal from the transponder which is then processed. Satellites can downlink the signals received, to many Earth stations at any given moment. The system has the advantage of having the ability to uplink and then downlink to multiple earth stations thousands of miles apart and, with multiple satellites relaying the signals, it can easily cover the whole world.

We need all Emergency services, First Responders and Military to have reserve back-ups communication devices immediately available stored in Nano Boses, Lead Boxes or a Box made of dense material which will protect them from EMP Electro Magnetic Energy Pulse Weapons. Additionally any time a small hand held device such as a laptop, cell phone, handy talkie, two way radio, etc is not being used they too should be stored in the boxes. Aircraft hangers, which house new and latest technology aircraft should be lined with these materials. People at home in their houses should have a safe, perhaps with an inner lining of these materials to park their electronics at night. Back up hard drives for important financial institutions, government operations, emergency services, military operations should be stored in rooms, which are underground and lined with these materials.

Electronic Attack, EA, will be a bigger component of warfare in the future. Disrupting the enemy goes back as far as the theories of Sun Tzu in the Art of War and there is nothing more disruptive in our present period than a complete elimination of all electronic devices in our civilization. War planners today call it a major component in the Fog of War, where your enemy does not know what is going on. Increasing the uncertainty of events is part of warfare strategy and it is no secret to anyone who studies the game of war. When communication lines are down and you cannot get damage assessment reports, you cannot make decisions relevant to continue the fight, this causes hesitation and aides your enemy. You can bet that the United States uses these tactics when we go to war and you can be sure as the new net centric style of warfare continues so to will our enemies find solace in EA.

Citizens who are interested in protecting their data or electronics should be able to buy such items as these boxes at Wal-Mart or Home Depot for $24.95 to fit a couple of laptops and four family cell phones. There is more and more talk about a detonation device launched high above our country or a suit case pulse detonation EMP bomb being deployed atop a building in a large city instantly frying all you electronics. This means your cars electronic brain, the gas pumps, credit card processing machines, refrigerator, microwave, municipal facilities, power lines; everything electronic. This means hospitals, schools, military, police, fire, hydro plants, airports, sewer treatment, potable water pumps; a dooms day scenario like the worst Y2K predictions. Saving your personal information is key. We know today that our military, government and many financial institutions have their important data stored underground in salt mines, yet most all facilities which run the flows of our civilization are kept out in the open in simple structures using mundane building materials which often cannot even survive a small Tornado, Hurricane, flood, fire or eco-terrorist. We need to be thinking here on ways to protect our electronics and protect them from EMP. Think about it.