Orban’s all-digital OPTIMOD-FM 5500 Audio Processor can help you achieve excellent audio quality in FM stereo broadcasting. Because all processing is performed by high-speed mathematical calculations within Freescale digital signal processing chips, the processing has cleanliness, quality, and stability over time and tempera- ture that is unmatched by analog processors. The 5500 can be used either as a full-featured multiband FM audio processor (including stereo encoder) or as an extremely high-quality stand-alone stereo encoder operating at 64 kHz to 512 kHz sample rates and offering lowpass filtering, overshoot limiting, composite limiting, and an ITU412 multiplex power controller. When used in the latter mode, the 5500 must be driven (usually via an STL) by a fullfeatured FM audio processor (like Orban’s 8500) that incorporates preemphasis- aware HF limiting and peak control. OPTIMOD-FM 5500 is descended from the industry-standard OPTIMOD-FM audio processors. Thousands of these processors are on the air all over the world. They have proven that the “OPTIMOD sound” attracts and keeps an audience even in the most competitive commercial environment. Because OPTIMOD-FM incorporates several audio processing innovations exclusive to Orban products, you should not assume that it should be operated in the same way as less sophisticated processors. If you do, you may get disappointing results.