Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"Jerzy GARUS"

Determination of radio communication channel respond with help of pseudorandom sequence DOI:10.15199/13.2015.12.8

  Knowledge of a radio communications channel transfer function is essential in ensuring the correct reception of digital broadcasts. Classic determination of the channel impulse response using signals similar to the Dirac delta is extremely difficult. Therefore, there are noticed frequent cases of abandonment of determining the impulse response using high voltage EMD pulses because of the need to conduct separate studies on the methodology of measurements. For example, in the work [1] is proposed to find properties of the radio channel in time and frequency domains by tests with using a vector network analyzer. The measurement of the propagation channel impulse response plays a very important role both in improving and developing new radio communication systems. Properties of the transmission channel are dependent phenomena occurring in it and among them the presence of multipath propagation, caused primarily a reflection, deflection and dispersion of radio waves [1-5]. This propagation also depends on the terrain, the volatility of the formation, land development. Above factors make the channel characteristics are not stationary. As a result of these phenomena, any signal from the transmitter reach the receiver in the form of several components of different and time-varying attenuation and delay. The paper presents some results of experiments conducted in a real propagation environment. Radio communication channel A signal transmitted by the radio communication channel can be represented using formula [2]: (1) where: a(t) - an amplitude of the signal, φ(t) - a phase of the signal, f0 - carrier frequency, a~(t) = a(t) exp[ j (t)] - complex amplitude. For the multipath propagation the signal received is determined by [2]: (2) where: βn(t) - attenuation coefficient of the nth propagation path, τn(t) - propagation delay of the nth path. An important parameter describing the channel is so called channel cohe[...]

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