Subsystems

Hybrid coupler is the coupler that distribute the signal at equal ratio.

QPSK is the abbreviation of Quadrature Phase-Shift Keying, which is the phase modulation method using four phases. The signal of QPSK can be represented as: \[s(t) = A\cos{(2\pi ft+\phi)}\] where \(A\) is the amplitude of carrier wave, \(f\) is the frequency of carrier wave and \(\phi\) is the phase which changes depending on the signals:

Antenna gain indicates the power radiated from antennas. This article explains the definition of gain and the difference of absolute gain and relative gain. Definition of gain Antenna gain is defined as the ratio of the power radiated from the antenna to the power from reference antenna. Reference antenna is usually isotropic antenna or half-wave

Noise Figure (NF) represents the performance of amplifier in receiver system. Noise figure is the ratio of input S/N to output S/N: \[f = \frac{S_{in}/N_{in}}{S_{out}/N_{out}}\] where \(f\) is the true value of noise figure. The strength of output signal can be obtained as the following equation: \[S_{out} = GS_{in}\] where \(G\) is the gain of

What is Receiver G/T? The ratio of gain of receiver antenna to system noise temperature is called receiver G/T. Receiver G/T describes the performance of receiver equipments. This article explain the meaning of Receiver G/T and relation to derivation of C/N. Carrier power \(C\) is given by: \[C = P_r = \frac{P_tG_tG_r}{(4\pi d/\lambda)^2}\] where \(P_t\)

What is link design? Link design is a process of determining specification of communication architectures to establish link between satellites and ground stations or satellites each other. Link design repeats determination of specification, calculate link budget and evaluation. This article explain link design. How to calculate link budget? Final goal of lInk design is to

What is Free Space Path Loss? Imaginary space where no matter exists is called free space. Free Space Path Loss (FSPL) is loss when electromagnetic wave pass through free space. When calculating link budget, there are losses because of atmosphere, rain, polarization, etc. FSPL is the biggest loss in various loss. Dervation of Free Space

Eb/N0 is the ratio of energy per bit to noise density. Eb/N0 is described below: \[\frac{E_b}{N_0} = \frac{C}{N_0}\frac{1}{B}\] where \(C/N_0\) is the carrier-to-noise ratio, \(B\) is the bit rate. Thus, Eb/N0 can be considered as the carrier-to-noise ratio divided by the bit rate.

Binary Phase-Shift Keying (BPSK) is one of the modulation methods of Phase-Shift Keying (PSK), which uses two phases. BPSK signal is descrived as below. \[s(t) = A\cos{(2\pi ft+\phi)}\] where \(A\) is amplitude of carrier wave, \(f\) is frequency of carrier wave. \(\phi\) is phase depending on signal, Using this equation, BPSK signal can be shown