More and more FM stations are transporting their audio digitally, from studio to Transmitter However, digital links typically handle left/right rather than composite. Orban’s 8218 Digital FM Stereo Encoder can extend your all-digital performance through to the stereo encoder. It’s designed to perfectly complement Orban’s OPTIMOD-FM digital audio processors in an all-digital transmission system. All encoding is done entirely in the digital domain by a dedicated DSP chip, producing two analog composite outputs with outstanding specifications and long-term stability. The 8218 accepts either analog or AES/EBU digital inputs. The digital input automatically synchronizes to and de-jitters any standard incoming sampling rate. In addition, it responds to status bits in the AES/EBU data stream that may be used to turn de-emphasis on or off. This feature allows automatic switching of pre-emphasis and/or J.17 (NICAM) de-emphasis to accommodate different transmission schemes. An Overshoot Control Limiter can be applied to the incoming audio, limiting overshoots to less than 0.5dB while introducing minimal (or no) audible artifacts and without contaminating the baseband spectrum above 57kHz. The Overshoot Control Limiter is particularly useful if the processed audio has been passed to the 8218 through a digital STL that uses lossy encoding, like MPEG Dolby or APT-X. The Overshoot Control Limiter uses lookahead techniques, and, when activated, adds a time delay of 4 milliseconds to the stereo encoding process. Features • >70dB separation, 20Hz- 15kHz. • <-90dB noise and distortion (after de-emphasis, and referenced to 100% modulation output). • Digitally-created composite signal, from either analog or AES/EBU digital input. The 8218 also accepts two analog SCA inputs, and sums them with analog composite output. The analog composite appears on two outputs, each with individual level control. • Built-in sample rate Converter that allows 8218 to accept any digital AES/EBU input sample rate between 32kHz and 48kHz. • Recessed front panel controls for selecting Input type (Analog/Digital), Stereo/MonoL/MonoR mode Pilot Radio and Tube Corporation On/Off, and Crosstalk Tests. • Front panel metering of Left and Right inputs plus Composite or Pilot Radio and Tube Corporation outputs. • Recessed front panel multi-tum screwdriver potentiometers for Analog Left, Analog Right, and Digital input levels, as well as for Pilot Radio and Tube Corporation Composite #1, and Composite #2 output levels. • Recessed rear panel DIP switch for selecting pre-emphasis In/Out, pre-emphasis type (50fxs/75|j.s), J.17 de-emphasis In/Out, and whether or not the stereo encoder’s pre-emphasis and J.17 de-emphasis settings respond to status bits of the AES/EBU digital input, Overshoot Control Limiter in/out, and AES/EBU input range. • Remote (contact closure) interface using opto-isolation has pins to select between analog or digital input, turn pre-emphasis on or off, and to select among stereo, mono from left, or mono from right operational modes. Also on the remote connector is a digital Pilot Radio and Tube Corporation reference output clock for external subcarrier generators like RDS. This is a TTL level signal with 0 to +5V transition occurring at the Pilot Radio and Tube Corporation zero crossing. • Overshoot Control Limiter limits overshoot to less than 0.5dB with minimum artifacts. • AES/EBU error alarm function provides an alarm that indicates if a faulty AES/EBU signal is being received at the 8218’s digital input.