Portable Frequency Spectrum Monitoring Equipment Based On FFT

With the growth of the people's living standard, the quality of television signals is required to be better and better. And how to monitor client television signal quality using the most convenient way becomes a question of common interest. As we are in the analogue television to digital television transition period, TV signals are in various modulations and types, conventional monitoring facilities have been unable to meet our needs. This paper presents a design method of a portable frequency spectrum monitor, adopting the architecture of software defined radio (SDR), which uses the software to achieve functions as much as possible to reduce the system dependence on hardware equipment. When the monitoring signal standard changes, we need only change the software to adapt to the new standard so that we can reduce the cost and shorten the development cycle.First of all, the paper introduces the structure and characteristics of generic frequency spectrum monitoring equipment, and then discusses some key technologies of the receiver of the system, such as the frequency conversion principle of tuner, sampling theory of signal, digital down-conversion, digital generator of signal, and so on. And finally, the paper proposes the design and implementation of frequency spectrum monitoring equipment based on FFT, taking MCU and DSP as its core hardware platform.Compared with the traditional spectrum monitoring equipment, the Frequency spectrum monitoring equipment based on FFT is compatible in monitoring all kinds of television signal system. It is able to analyze not only the spectrum of wireless analog and digital signal, but also the cable television signal. Another prominent advantage of the monitoring device is the high speed and unlimited storage capacity, and when input signal is analyzed in vector, the processing results can be stored in external Flash memory, which is the unreachable ability of the traditional equipment.