Experiments
PURPOSE/ BACKGROUND:
The satellite was started with a basketball-sized pack of technology known as Sputnik 1. It was the World’s first satellite launched on 4 October 1957 by the Soviet Union having weigh 183 pounds,it took around 98 minutes to orbit the Earth. The launch of the satellite was just a single event, it was the beginning of space era and steered new military, political, scientific and technological developments. A satellite is a body that moves around another body in a mathematically predictable path called an Orbit. A communication satellite is a microwave repeater satellite station in space. It helps in telecommunications, radio, television and also wide internet applications. The three basic components used in satellite communication: Uplink transmitter, Downlink receiver and Transponder
1) UPLINK TRANSMITTER:
In the uplink station, the signal has to be sent at a different frequency usually in the higher 1GHz band to avoid interference with link signal. Another function performed by the uplink station is to control highly internal function of the satellite. Uplinks are controlled so that transmitted microwave beam is extremely narrow in order not to interface with adjacent satellite.
2) TRANSPONDER:
Each satellite has a number of transponder witch access to a pair of receive/transmit antennas and associated electronics for each channel. For example, in Europe, the uplink sends a signal at a frequency of about 14 GHz. These are received downlink converted in the frequency of about 11/ 12 GHz and boosted by the high power amplifier for retransmission to earth. A separate transponder is used for each channel and is powered by solar panels with backup batteries for eclipse protection. The Uplink transmitter sends signals at an uplink frequency, which is higher than downlink frequency to avoid the interference.
3) DOWNLINK RECIEVER:
The medium used to transmit signal from the satellite to earth is microwave electromagnetic radiation, which is much higher in frequency normal broadcast TV signal in VHF / UHF bands. Microwave still exhibit a wave-like nature but inherit a tendency to serve attenuation by water vapours or any obstruction in the line of sight of the antenna. The transmitted microwave power is extremely weak by the time it reaches earth and unless the well-designed equipment is used and certain installation precaution are taken, the background noise can ruin the signal.
Infrastructure:
For performing the experiment the satellite trainer kit, connecting wires and power supply.
USP:
By performing the experiment students understands the basic concepts of satellite communication, how satellite revolves around the earth and the satellite transmits the signal from the earth through uplink frequency, which differs from downlink frequency. It also helps them to understand the application of wireless communication and Data communication.
