Coherent detection is one of the method to demodulate the signal modulated by PSK. Coherent detection multiplies the signal by the carrier wave. The signal modulated by PSK can be written as: \[s(t) = A\cos{(2\pi ft+\phi)}\] where \(A\) is amplitutde, \(f\) is frequency, and \(\phi\) is the phase difference. Multiplying this signal by the carrier […]
Duplexer is the equipment that used when transmitter and receiver shares the same antenna. Duplexer allows signal to pass from transmitter to antenna, but does not allow the opposite direction. Also, the signal from antenna to receiver can pass, but the opposite direction not.
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 \(P_t\)
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