The Blonde Tongue HE-12 and HE-4 are professional quality, modular headend systems, designed to maximize rack space. Each system begins with a rack chassis, either a horizontal 4 slot or a vertical 12 slot. The available slots can then be populated with a variety of modular components, including single width channelized audio/video modulators, a single width agile demodulators and single width agile micro modulators. (Note the demodulator can only be used in the vertical 12 slot chassis.) These modules are designed to work together to provide audio/video modulation and channel processing (modulator/demodulator).