Дослідження Спотворень Сигналів При Інтерполяції У SDR Передавачах З Модуляцією QPSK

Abstract

Software-defined radio (SDR) allows using software to set or modify working radio frequency parameters: communication standard, frequency range, modulation type, output power, etc. An interpolator is an integral part of the transmitter, which increases the sampling frequency of the modulated signal. Interpolators are built on the basis of integrated cascaded integral-comb (CIC) non-multiplier filters. CIC interpolation filters have uneven amplitude-frequency characteristic (AFC), so the CIC compensator filter is turned on for its alignment. The eye-diagrams of signals with different interpolation coefficients are investigated in the paper. The quality of the signal in the transmitter can be evaluated by the eye-diagram. Interpolation is accompanied by the effect of amplifying the signal, reducing the time of increase in pulse, reducing the signal quality factor. The jitter in the transmitter decreases when the interpolation factor is a multiple of the sampling rate of the information sequence of symbols. If the signal quality factor is Q>7, the bit error rate has a BER<10 -9 value for practice.