Abstract: It is important to grasp the spectrum’s state within a period of time in electronic reconnaissance of modern times. Digital phosphor technology (DPX) is a recent crucial innovation of real-time spectrum analysis technology. It can show the spectrum’s state of a period of time intuitively by images, highly enhance the capability of capturing and observing signals and is applied to radar reconnaissance appropriately. We have designed a DPX system. Signals are sampled directly in RF in this system in real time. The digitized data is sent though an FPGA that computes very fast spectral transforms of FFT, and the resulting frequency-domain waveforms are saved and accumulated to create the bitmaps. 65,535 FFT was continuously processed and accumulated to create a DPX image to display the state of real-time spectrum during about 100 ms. The image is 3D that is composed of pixels representing x, y, and z values for frequency amplitude, and hit count. The z values are displayed by different colors, and so we need pseudo-coloring coding for the DPX image. The traditional method of pseudo-color coding is mainly for the following 256 gray image, however, the DPX image in our system is high resolution of 0－65535. To improve the display of the DPX image, a new method of pseudo-coloring coding based on RGB tricolor which named “take bit from binary number” (TBFBN) was brought forward. This method has focused on the scope of 0-65535, coded every value, and overcome the lack of traditional method that coded within 0-255. To select the method and the parameter, several experiments ware carried through, and by contrast, the best display was chosen. The practical results have shown that the technology of DPX can show the sate of spectrum directly and the method of TBFBN has boosted up the effect of DPX display and improved the ability of observing and resolving.