The Development Of Handy CATV Field Strength Meter

Followed with the fast development of cable TV, the requirement of handy field strength meter become more and more. Two projects to produce it are described in detail in this paper, which are analog intermediate frequency project and digital intermediate frequency.In the analog intermediate frequency project, the signal to be measured is converted to be a fixed intermediate frequency signal, which then is demodulated, logarithm amplified and detected to be a DC signal that can reflect the original signal strength. After passing the A/D Converter, it will be processed by Microcontroller in software. This paper describes the hardware and software to implement the project in detail and explains how the circuit characteristics influence the measurement error and how to processing the data .In the digital intermediate frequency project, the intermediate frequency signal is converted to digital signal directly into the DSP chip, then it is be processed by DFT. In this paper, the principle of the project is introduced, the hardware and software of it are analyzed and designed and the project is evaluated in the TMS320C5402DSK. It is proved that the digital project is better in the frequency resolution and amplitude accuracy .