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Why you use different frequency bands in satellite communication?
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Why FDMA is not sensitive to near- far problems?
A frequency-division multiple access system (FDMA) is much less sensitive to near-far problems than code-division multiple access systems (CDMA). A FDMA receiver must select signals from a desired transmitter tuned to one frequency, and block signals from transmitters tuned to other frequencies -- this is fairly easy and low-cost to do with standard bandpass filters, even when the near-far problem causes undesired transmitters to sound much louder than the desired transmitter, as long as adequate "guard bands" separate one transmitter from the next. A DSS CDMA receiver must select signals from a desired transmitter and block signals from other transmitters, even when they are all transmitting on the same frequencies at the same time -- this cannot be done with standard bandpass filters. The techniques DSS CDMA receivers use to select the desired signals are much more sensitive to near-far problems.
A project on communication facilities in disaster management now please help?
Communication is a major bottleneck in case of any major disaster particularly when the traditional network system already in force brake down. In order to strengthen communications, it has been decided that police network (POLNET) will also be used for disaster management. For this purpose POLNET communication facility will be extended to District Magistrates, Sub Divisional Magistrates as well as the Control Rooms.For emergency communication, mobile satellite based units which can be transported to the site of the disaster are being procured. A group was constituted to draw a comprehensive communication plan for disaster management and the report has since been received. This provides for a dedicated communication system for disaster management with built in redundancies.Amateur radio is a community of people that use radio transmitters and receivers to communicate with other Amateur radio operators. If you were to ask a dozen different amateurs what ham radio meant to them chances are you would get 12 different answers. Amateur radio operators are often called ham radio operators or simply "hams" and frequently the public is more familiar with this term than with the legal term Radio Amateur. The source of this nickname is for all practical purposes lost from the beginning.Amateur (HAM) Radio is truly a hobby but often one that makes a difference especially in emergency or disaster situations. It is an activity of Self Learning, Inter-Communication & Technical Investigation carried on between Amateur Radio Operators. Amateurs talk to local friends over the radio waves using a hand-held transceiver, communicating digitally with packet radio to exchange personal messages or vital information in an emergency, talking to other hams anywhere in the world, or engaging in contests with other Radio Amateurs over the airwaves there is something for everyone.There are over Lakh people all over the world who pursue this activity in their free timeWhat Hams do with amateur radioQRP - Communicating with "very low power" is a challenge that many hams enjoy. QRP is usually practiced on the HF bandsHF radio - Hams can talk to other hams in literally any part of the globe using HF radiosVHF (2 meters) or UHF (70 cm.) transceivers hams enjoy extremely reliable communications within their local community. You can extend your VHF range up to 50 miles or more by transmitting through a local repeater.DXing. DX means distance communication and with the right equipment worldwide communication on the HF bands (10 through 160 meters) is a regular possibility.Emergency and other volunteer services - Floods, landslides, earthquakes, Cyclones, Accidents (Rail / Road / Air). when ever `normal' communications go out, hams are ready to use their radios to provide emergency communication services to their communitiesTechnical experimenting. Hams come from all walks of life ranging from technicians to engineers, teachers to scientists, and students to retirees. For many of them the attraction to the hobby is to build their own equipment whether it is just a simple antenna, something as complex as a transmitter, or an interface between their radio and a computer.Contesting. Contesting is often called the "sport" of ham radio. Almost every all the time there is some form of amateur radio contest. Hams get on the air and compete to see who can make the most contacts in a limited period of time.Talk to an astronaut. Yes, it is really possible. Space stations do have ham radio equipment and licensed ham astronauts take the time to make contacts with amateurs on earth. Hams also have satellites where you can bounce a signal to communicate with other hams on earth.Use digital communication. Connect a computer to your radio and install some software and you can be communicating digitally over the air. Some of these digital modes can be more effective in marginal transmission conditions and some even sport error free transmission.Internet communication. Using some of the latest technologies hams can supplement a modest station with Internet connections. Using features such as URL or IRLP on a local repeater a ham in Toronto can talk to one in Vancouver or even Australia using a simple hand-held transceiverAmateur television - It's just like real television because it is real television.Slow Scan TV - Send pictures around the world for little or no cost.Contests - You can put your radio operating skills up against other hams and teams of hams.Satellite communications - Hams operate using their own satellites for world wide communication using Walkie-Talkies.... They are easy to use too.Ham RadioHam Radio is also know as Amateur radio.It is a community of people that use radio transmitters and receivers to communicate with other Amateur radio operators. If you were to ask a dozen different amateurs what ham radio meant to them chances are you would get 12 different answers. Amateur radio operators are often called ham radio operators or simply "hams" and frequently the public is more familiar with this term than with the legal term Radio Amateur. The source of this nickname is for all practical purposes lost from the beginningCommunication is a major bottleneck in case of any major disaster particularly when the traditional network system already in force brake down. In order to strengthen communications, it has been decided that police network (POLNET) will also be used for disaster management. For this purpose POLNET communication facility will be extended to District Magistrates, Sub Divisional Magistrates as well as the Control Rooms.For emergency communication, mobile satellite based units which can be transported to the site of the disaster are being procured. A group was constituted to draw a comprehensive communication plan for disaster management and the report has since been received. This provides for a dedicated communication system for disaster management with built in redundancies.Besides the satellite, communication and education can play a proactive role in mitigation through awareness about the types of disaster and as to how prevention measures can be taken up.There is also a Satellite based communication system called the Cyclone Warning Dissemination Systems (CWDS) for transmission of warnings. There are 250 such cyclone-warning sets installed in the cylone prone areas of east and west coast. The general public, the coastal residents and fishermen, are also warned through the Government mechinery and broadcast of warnings through AIR and Television.What agencies need to be involved ? PoliceFireAmbulanceHospitalsClinicsDoctorsRed CrossBlood BanksMarine operations (are there bodies of water?)Coast guardDepartment of transportationDepartments of environment (if there is clean-up involved)AirlinesRail companiesLocal transit companiesBus companies (in case of evacuation)Border services - if applicableThe use of satellite, computers, electronics, better communication facilities are going to make significant difference in disaster management. The data processing and computers are providing a useful tool in decision making in disaster.When the disaster strikes, power goes out, all modes of communication (Telephone etc.) becomes inoperable, lifts stop functioning, when drinking water becomes contaminated, when normal modes of transportation suddenly becomes impossible, when casualties start coming in groups that is not the time for planning but that is the time of acting.Communication facilities for disaster management system is most important act as it convey at the right time communication in disaster, it may handle disaster and helping to decrease it.Two type of information needs in disaster management Pre disaster information: Question arise that how to get pre disaster information? It is getting from the research and analysis department of the geography in the country.Post disaster information: After the disaster, our first job is to find out where and where it was occurs. What is the next step to help people?Now a days Satellite communication play a major role in disaster management communication. Communication facilities can be set up for rescue and relief operation purposes. That type of early warning system developed at the different area's by itself.Here are the disaster communication facilities: DCWDS Digital Cyclone Warning Dissemination System set at Delhi and other coast area. It is for the pre disaster information.The WLL - VSAT system is in terms of handsets which can be easily taken inside of the affected areas and sends information by direct audio communication.The MSS Type C reporting terminal developed for the sending short messages directly through satellite in remote area.AES-SNG is a system which can send video pictures of the affected area for online review from the control center.Tele medicine: It is one more step for the disaster management communication. In this system, on line help can be provided from the hospital and super specialty doctors. Only connect up link to laptop or PC and get the online information about cure."Pocket Guide on First Aid"The First Aid pocket guide should contain aid that needs to be given for fractures, poisoning, cuts and burns, heat and cold wave and other threats that are prevalent in that area. The content shared in the guide should be supported with adequate pictures so as to give a clear and elaborate understanding about the topic. Choose awareness campaign strategy for either senior citizens or illiterate people and prepare a brief write-up.You need to first arrange it, first the cover page should have a red cross, then it should have an index ( it is necessary) the cover page can be of light blue colour with a red crosses box picture.You can use the red red cross pictures that we have posted in the end of this article.It should include "DRABCD" : DangerResponseAirwayBreathingCompressions/CirculationDephibrilationBelow is the list of supplies you should have in your First Aid : Plastic bandagesTranspore tapeAlcohol prepsAdhesive bandagesMicropore tapeGauzeExtra large plasticbandagesIodine prep padsFingertip bandagesSterile padsAntiseptic towelettesKnuckle bandagesAntiseptic ointmentAmmonia inhalantSponge packsInstant ice packsSterile eye washElastic bandagesEye padsSafety pinsFirst aid creamBandage scissorsTweezersButterfly bandagesWater tight utilitybox for contentsBurn gel to treat burnsBurn bandagesAdhesive spotsExtra large stripsSurgical tapeSpongesPain relieverWhat is the aim of First Aid ?The key aims of first aid can be summarised in three key pointsPreserve life is the overriding aim of all medical care, including first aid, is to save livesPrevent further harm also sometimes called preventing the condition worsening, this covers both external factors, such as moving a patient away from a cause of harm, and applying first aid techniques to prevent worsening of the condition, such as applying pressure to stop a bleed becoming dangerous.Promote recovery - first aid also involves trying to start the recovery process from the illness or injury, and in some cases might involve completing a treatment, such as in the case of applying a plaster to a small wound.First aid training often also incorporates the prevention of initial injury and responder safety, as well as the treatment phases.When First Aid is Required ?Altitude sickness, which can begin in susceptible people at altitudes as low as 5,000 feet, can cause potentially fatal swelling of the brain or lungs.Anaphylaxis, a life-threatening condition in which the airway can become constricted and the patient may go into shock. The reaction can be caused by a systemic allergic reaction to allergens such as insect bites or peanuts. Anaphylaxis is initially treated with injection of epinephrine.Battlefield First aid - This protocol refers to treating shrapnel, gunshot wounds, burns, bone fractures, etc. as seen either in the 'traditional' battlefield setting or in an area subject to damage by large scale weaponry, such as a bomb blast or other terrorist activity.Bone fracture, a break in a bone initially treated by stabilizing the fracture with a splint.Burns, which can result in damage to tissues and loss of body fluids through the burn site.Choking, blockage of the airway which can quickly result in death due to lack of oxygen if the patient's trachea is not cleared, for example by the Heimlich Maneuver.Childbirth.Cramps in muscles due to lactic acid build up caused either by inadequate oxygenation of muscle or lack of water or salt.Joint dislocation.Diving disorders resulting from too much pressure.Near drowning or asphyxiation.Gastrointestinal bleeding.Gender-specific conditions, such as dysmenorrhea and testicular torsion.Heart attack, or inadequate blood flow to the blood vessels supplying the heart muscle.Heat stroke, also known as sunstroke or hyperthermia, which tends to occur during heavyexercise in high humidity, or with inadequate water, though it may occur spontaneously in some chronically ill persons. Sunstroke, especially when the victim has been unconscious, often causes major damage to body systems such as brain, kidney, liver, gastric tract. Unconsciousness for more than two hours usually leads to permanent disability. Emergency treatment involves rapid cooling of the patient.Heat syncope, another stage in the same process as heat stroke, occurs under similar conditions as heat stroke and is not distinguished from the latter by some authorities.Heavy bleeding, treated by applying pressure (manually and later with a pressure bandage) to the wound site and elevating the limb if possible.Hyperglycemia, or diabetic coma.Hypoglycemia, or insulin shock.Hypothermia, or Exposure, occurs when a person's core body temperature falls below 33.7°C (92.6°F). First aid for a mildly hypothermic patient includes rewarming, but rewarming a severely hypothermic person could result in a fatal arrhythmia, an irregular heart rhythm.Insect and animal bites and stings.Muscle strain.Poisoning, which can occur by injection, inhalation, absorption, or ingestion.Seizures, or a malfunction in the electrical activity in the brain. Three types of seizures include agrand mal (which usually features convulsions as well as temporary respiratory abnormalities, change in skin complexion, etc) and petit mal (which usually features twitching, rapid blinking, and/or fidgeting as well as altered consciousness and temporary respiratory abnormalities).Sprain, a temporary dislocation of a joint that immediately reduces automatically but may result in ligament damage.Stroke, a temporary loss of blood supply to the brain.Sucking chest wound, a life threatening hole in the chest which can cause the chest cavity to fill with air and prevent the lung from filling, treated by covering with an occlusive dressing to let air out but not in.Toothache, which can result in severe pain and loss of the tooth but is rarely life threatening, unless over time the infection spreads into the bone of the jaw and starts osteomyelitis.
How did people communicate in 1980s?
Letters, telegrams, phones, a limited amount of e-mail, bulletin boards, radio, television and lots of other methods of communication were available in the 1980s.
Why there is an difference in uplink and downlink frequencies in satellites?
It is much easier to build a satellite transponder using different frequencies for the two directions (frequency division duplex, FDD). A single frequency (time division duplex, TDD) satellite link is possible, but then all earth terminal must be carefully synchronized. The satellite transponder and the earth terminals would be more expensive, the whole network would be more complex and less reliable. There is also a historical reason. Frequency bands were allocated decades ago and changing them would be very difficult. FDD and TDD terminals cannot coexist in the same geographical area.
What do infrared and radio waves have in common?
They are just different frequency bands of the electromagnetic spectrum.
What are the various physical and wireless transmission media?
Physical Media Twisted-Pair Cable Coaxial Cable Fiber-Optic Cable Wireless Media Broadcast Radio Cellular Radio Microwaves Communication Satellite
What is the function of satellite communication?
The satellite is used to receive foreign broadcast from other network stations and send it home usersAnswerSatellite communication is a process where a radio signal is transmitted to a satellite above your horizon. That satellite rebroadcasts that signal, on a different frequency, either to a ground station, or to another satellite to be relayed further. It allows communications without any local infrastructure, such as wires, towers, or other equipment. All that is needed is a receiver/transmitter which operates in the correct frequency bands, and which has sufficient power and sensitivity to communicate with a satellite, and the satellites.Satellite communication allowed the boats in the Volvo Round the World Ocean sailboat race to communicate with the race headquarters, irregardless of where in the world the boats were.
Why do uhf and vhf relate to television broadcasts?
Early television broadcasts were transmitted on VHF (very high frequency) radio channels. They moved to UHF (ultra high frequency) and have remained on that band since. These bands are used for terrestrial broadcasts. Satellite broadcasts use even higher frequencies.
Are mocrowaves a type of infrared waves?
No. Mocrowaves and infrared waves are both different frequency bands of electromagnetic waves. X-rays and visible light are others.
What are two main bands of television wave frequencies?
Amplitude and frequency
What are the two main bands of television wave frequencies?
Amplitude and frequency
How can you listen and talk to police on your Ham radio in case of emergency?
With a standard Amateur license, you have no authorization to operate outside of the amateur frequency bands, and if you're using commercial type-accepted ham equipment, it won't operate outside of those bands anyway. Public Safety radio services don't operate in the amateur frequency bands. You can listen to them any time, with a 'scanner' that covers the police bands, but you can't talk to them. If you have a special license and different equipment, or if the local police want to acquire ham equipment to use in emergencies, then that's a different story.
Satellite Internet access providers typically use frequencies in the C- or bands?
ku-
What type of wave is used for radar?
It is microwaves that are used for radar. They are high frequency, short wavelength electromagnetic waves, and a number of different frequency ranges of these microwaves are used depending on the application. A link is provided to the Wikipedia article on radar and the different bands or ranges of frequencies that are used and their applications.
What type of electromagnetic wave is used for radar?
It is microwaves that are used for radar. They are high frequency, short wavelength electromagnetic waves, and a number of different frequency ranges of these microwaves are used depending on the application. A link is provided to the Wikipedia article on radar and the different bands or ranges of frequencies that are used and their applications.
