Features

User-Friendly Interface

A large (quarter-VGA) active-matrix color liquid crystal display (LCD) makes setup, adjustment and programming of the 8500 easy. Navigation is by a miniature joystick, two dedicated buttons, and a large rotary knob. The LCD shows all metering functions of the processing structure in use.
Use the Locate joystick to navigate through a menu that lets you recall a preset, modify processing (at three levels of expertise), or to access the system's setup controls.

Absolute Control of Peak Modulation

The 8500 provides universal transmitter protection and audio processing for FM broadcast. It can be configured to interface ideally with any commonly found transmission system in the world, analog or digital.
The 8500 provides preemphasis limiting for the internationally used preemphasis curves of 50 µs and 75 µs. Its preemphasis control is seldom audibly apparent, producing a clean, open sound with subjective brightness matching the original program.
The 8500 achieves extremely tight peak control at all its outputs—analog, AES3 (x2), and composite baseband.
The stereo encoder has two outputs with independent level controls, each capable of driving 37Ω in parallel with 47,000pF, (100ft / 30m of coaxial cable).
By integrating the stereo encoder with the audio processing, the 8500 eliminates the overshoot problems that waste valuable modulation in traditional external encoders.
The 8500 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 8500's audio outputs and stereo encoder.
The 8500 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 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.

Flexible Configuration

OPTIMOD-FM 8500 is supplied with analog and AES3 digital inputs and outputs. The digital input and the two digital outputs are equipped with sample-rate converters and can operate at 32 kHz, 44.1 kHz, 48 kHz, 88.1 kHz, and 96 kHz sample rates. The preemphasis status and output levels are separately adjustable for the analog and digital outputs. Each output can emit the analog FM processed signal, the digital radio processed signal, or the low-delay monitor signal.
An AES11 sync input allows you to synchronize the output sample rate of either (or both) AES3 outputs to this input. You can also synchronize the outputs to the AES3 digital input or to 8500's internal clock. The sync source of each AES3 output is independently selectable.
A defeatable delay line can delay the FM analog processing output up to 16.2 seconds. Delay can be trimmed in intervals of one sample of 64 kHz to match the analog and digital paths in the HD Radio system, eliminating the need to use the delay built into the HD Radio exciter and permitting the 8500's internal stereo encoder and composite limiter to drive the analog FM exciter.
The analog inputs are transformerless, balanced 10k instrumentation amplifier circuits, and the analog outputs are transformerless balanced, and floating (with 50Ω impedance) to ensure highest transparency and accurate pulse response.
The 8500 has two independent composite baseband outputs with digitally programmable output levels. Robust line drivers enable them to drive 100 feet of RG-59 coaxial cable without audible performance degradation.
The 8500's two subcarrier inputs are mixed with the output of the 8500's stereo encoder before application to the composite output connectors. One input can be re-jumpered to provide a 19 kHz pilot reference output. Both inputs have internal level trims to accommodate subcarrier generators with output levels as low as 220 mV.
The 8500 precisely controls the audio bandwidth of its analog FM processing to 17 kHz. This prevents significant overshoots in uncompressed digital links operating at a 44.1 kHz-sample rate (or higher) and prevents interference to the pilot tone and RDS (or RBDS) subcarrier. The bandwidth of the 8500's digital radio output is adjustable in 1 kHz increments between 15 kHz and 20 kHz.
The 8500 has a defeatable multiplex power limiter that controls the multiplex power to ITU-R BS412 standards. An adjustable threshold allows a station to achieve maximum legal multiplex power even if the downstream transmission system introduces peak overshoots into the 8500-processed signal. Because this limiter closes a feedback loop around the audio processing, it allows the user to adjust the processor's subjective setup controls freely without violating BS412 limits, regardless of program material. The multiplex power limiter acts on all outputs (not just the composite output). It reduces clipper drive when it reduces power, simultaneously reducing clipping distortion.
All input, output, and power connections are rigorously RFI-suppressed to Orban's traditional exacting standards, ensuring trouble-free installation.
The 8500 is designed and certified to meet all applicable international safety and emissions standards.

Adaptability through Multiple Audio Processing Structures

A processing structure is a program that operates as a complete audio processing system. Only one processing structure can be on-air at a time, although all are active simultaneously to permit mute-free switching between them. The 8500 realizes its processing structures as a series of high-speed mathematical computations made by Digital Signal Processing (DSP) chips.
The 8500 features four processing structures: Five-Band (or "Multiband") for a consistent, "processed" sound with 17 ms delay (typical), free from undesirable side effects, Low-Latency Five-Band (12 ms delay), Ultra-Low-Latency Five-Band (3 ms delay), and Two-Band (17 or 22 ms delay) for a transparent sound that preserves the frequency balance of the original program material. A special Two-Band preset creates a no-compromise "Protect" function that is functionally similar to the "Protect" structures in earlier Orban digital processors.
The 8500 can increase the density and loudness of the program material by multiband compression, limiting, and clipping, which impove the consistency of the station's sound and increasing loudness and definition remarkably, without producing unpleasant side effects.
The 8500 rides gain over an adjustable range of up to 25 dB, compressing dynamic range and compensating for both operator gain-riding errors and gain inconsistencies in automated systems.
The 8500's Two-Band processing structure can be made phase-linear to maximize audible transparency.

Controllable

The 8500 can be remote-controlled by 5-12V pulses applied to eight programmable, optically isolated GPI (general-purpose interface) ports.
The 8500 is equipped with a serial port to interface to an IBM-compatible computer running Orban's PC Remote software. The connection can be either direct or through an external modem.
The 8500 has a second serial port that allows the user to set up security and communications parameters through a simple ASCII terminal program running on any PC. It also permits simple ASCII strings to trigger preset recall, facilitating interface to automation systems that can emit such strings through an RS232 serial port.
The 8500 can be connected through its built-in 100 Mbps Ethernet port to a TCP/IP network.
A Bypass Test Mode can be invoked locally or by remote control to permit broadcast system test and alignment or "proof of performance" tests.
The 8500's software can be upgraded remotely or locally through the 8500's serial or Ethernet port.
8500 PC Remote software is a graphical application that runs under Windows 2000 and XP. It communicates with a given 8500 via TCP/IP over modem, direct serial, and Ethernet connections. You can configure PC Remote to switch between many 8500s via a convenient organizer that supports giving any 8500 an alias name and grouping multiple 8500s into folders. Clicking an 8500's icon causes PC Remote to connect to that 8500 through an Ethernet network, or initiates a Windows Dial-Up or Direct Cable Connection if appropriate. The PC Remote software allows the user to access all 8500 features and allows the user to archive and restore presets, automation lists, and system setups (containing I/O levels, digital word lengths, GPI functional assignments, etc.).
The 8500 Audio Processor contains a built-in lineup tone generator, facilitating quick and accurate level setting in any system.
The 8500 Audio Processor contains a versatile real-time clock, which allows automation of various events (including recalling presets) at preprogrammed times. To maintain accuracy, this clock can be synchronized automatically via the Internet to a reference time source.

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