Diplexer is the equipment that combines two signal into one and divide one signal into two. Diplexer is used for multi-band system (which handles different frequency). The inner structure is as follows. The diplexer has high pass filter (HPF) and low pass filter (LPF). The signals come from right side of the image are combined. […]
Directional coupler is the equipement that distribute the signal for some 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 \(P_t\)
Hill’s equations are equations that describe the relative motion of the chaser object to the target object in the rendezvous of spacecraft. In this article, the meaning and derivation of Hill’s equations and the derivation of the Clohessy-Wiltshire (C-W) solution are explained. What is Hill’s equations? Rendezvous is a maneuver that brings closer a spacecraft
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