The Use of Multi-Frequency Coherent Signal to Measurement of Frequency Response of Narrow-Band Circuits

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 for testing HF narrow-band circuits has been described.