In TDMA, the time slots are available to the ground stations with full bandwidth. In FDMA, the frequency bands are available to the ground stations with continuous time availability. By combining these two multiple access...
Archive - December 2021
The uplink and downlink carriers of the satellite are required to be modulated by the signal to be transmitted. The modulation can be analog or digital. In the earlier satellites analog modulations were dominant and therefore...
The communications satellites are used to carry telephone, television and data signals. The television and telephone signals are normally analog. The satellite earth station transmits these signals on the same link by...
The orbits of satellite can be rotated around the earth through various paths. These paths are called orbits of the satellite. These orbits are used to cover the specific application areas. Orbits of Satellite When the satellite...
Fig shows the block diagram of satellite communication system. The satellite consists of transmitters as well as receivers. They are also called as transponders. The satellite receives signals from earth station transmitter...
Principle : The narrow beam of radio waves is aimed at particular part of space. The same channel is reused over the another narrow beam aimed at another part of the space. This division of space in different directions of base...
Because of the development in communications and computer fields, the applications involving multiple users are also growing. For example, a cellular telephone network involve large number of mobile subscribers which communicate...
In the direct sequence spread spectrum modulation, the pseudo-noise sequence of large bandwidth is multiplied with the narrowband data signal. Therefore the output signal is spreaded over the complete output bandwidth at every...
Here we will discuss three types of applications of direct sequence spread spectrum signals : antijamming of signals, low probability intercept and code division multiple access to allow multiple users. Antijamming with the help...
In the previous subsection we studied the baseband transmission of direct sequence spread spectrum modulated signal. For long distance transmission or transmission over a satellite channel, BPSK can be used. DS-SS BPSK...