This allows the 5700i to prevent clipping in a playback device’s analog signal path by predicting and controlling the analog peak level following the playback device’s reconstruction filter to an accuracy of better than 0.5 dB. The 5700i/HD implements “true peak” control in its HD processing chain by oversampling the HD peak limiter’s sidechain at 256 kHz. The Digital Radio processing chain offers an ITU-R BS.1770-3 Loudness Meter and Safety Limiter for use in countries that enforce a BS.1770 loudness limit on digital radio broadcasts. The stereo encoder’s stereo sub-channel modulator can operate in normal double sideband mode and in an experimental compatible single sideband mode that is offered to enable users to compare and assess the two modes. The composite limiter is a unique, “you can only do this in DSP” process that beats composite clippers by preserving stereo imaging while fully protecting the stereo pilot tone, RDS/RBDS, and subcarriers.
The 5700i has an internal, DSP-based stereo encoder (with a patented “half-cosine interpolation” composite limiter operating at 512 kHz sample rate) to generate the pilot tone stereo baseband signal and control its peak level. The 5700i prevents aliasing distortion in subsequent stereo encoders or transmission links by providing bandwidth limiting and overshoot compensated 15 kHz low-pass filters ahead of the 5700i’s audio outputs and stereo encoder. The stereo encoder has two outputs with independent level controls, each capable of driving 75Ω in parallel with 47,000pF (100ft / 30m of coaxial cable).īy integrating the stereo encoder with the audio processing, the 5700i eliminates the overshoot problems that waste valuable modulation in traditional external encoders. The 5700i achieves extremely tight peak control at all its outputs - analog, AES3 (for both the analog FM and HD channels), and composite baseband. The 5700i provides pre-emphasis limiting for the internationally used pre-emphasis curves of 50µs and 75µs. It can be configured to interface ideally with any commonly found transmission system in the world, analog or digital. The 5700i provides universal transmitter protection and audio processing for FM broadcast. The LEDs show all metering functions of the processing structure (Two-Band or Five-Band) in use.
Navigation is by dedicated buttons, soft buttons (whose functions are context-sensitive), and a large rotary knob. An LCD and full-time LED meters make setup, adjustment and programming of OPTIMOD 5700i easy - you can always see the metering while you are adjusting the processor.