Using multi-frequency coherent signal to measurement of frequency response of narrow-band LF and HF circuits

摘要

W artykule opisano metod? jednoczesnego pomiaru wielu s?abych sygna?ów okresowych. Cz?stotliwo?ci poszczególnych sygna?ów zosta?y tak wybrane, ?e ich pomiar jest dokonywany z wykorzystaniem detekcji synchronicznej (koherentnej). Opracowano specjalny odbiornik do pomiaru sygna?ów w.cz., wykorzystuj?cy demodulator I&Q oraz dwustopniow? detekcj? koherentn?. Dzi?ki wykorzystaniu wielocz?stotliwo?ciowej detekcji koherentnej uzyskano du?? czu?o?? odbiornika i du?a dynamik? pomiaru. Podano przyk?ad zastosowania opisanej metody do pomiaru charakterystyki cz?stotliwo?ciowej filtru kwarcowego o cz?stotliwo?ci ?rodkowej 30 MHz.%In this paper a method allowing simultaneous measurement of tested objects using many periodic signals and applied to a receiver of the authors' design has been described. Frequencies of the signals were chosen in such a way that the measurement executed is the coherent measurement of all used signals. The receiver was applied effectively to measurements of HF signals utilizing an I&Q demodulator and two-stage coherent detection. Good sensitivity of the receiver and high dynamic range of the measuring set-up were obtained due to the application of coherent detection. Multiple shortening of the required time of measurement was obtained due to simultaneous multi-signal measurement. An example demonstrating the usefulness of the technology of simultaneous coherent measurement of many signals has been described.