Optimod-FM 8700: Overview
In the toughest competitive environment ever, a winning strategy includes OPTIMOD-FM 8700.
OPTIMOD-FM 8700 is Orban’s flagship processor. Featuring versatile five-band and two-band processing for both analogue FM transmission and digital media, the 8700 provides the industry’s most consistent sound, track-to-track and source-to-source. This consistency allows you to create a sonic signature for your station with the assurance that your signature will stay locked in, uniquely branding your sound.
The 8700 builds on 8600 V4’s outstanding reliability and industry-leading sound quality. It adds Ravenna audio-over-IP connectivity (100% AES67 compliant) and a hot-swappable, dual-redundant power supply with automatic failover. A digital MPX output using a 192 kHz AES3 connection is now standard, as are two digitized SCA inputs. A new program-adaptive subharmonic synthesizer ensures punchy bass, even with older program material. An important feature is a phase skew corrector/multipath mitigator that ensures crisp reception when receivers blend to mono and minimizes energy in the stereo subchannel without compromising separation. The phase skew corrector uses a proprietary multidimensional processing algorithm that can simultaneously correct multiple phase problems, like a combination of analogue tape gap skew and comb filtering caused by multiple-microphone pickup of a single instrument in the original recording session.
Orban’s exclusive MX peak limiter technology decreases distortion while increasing transient punch and high frequency power handling capacity. Compared to the 8500’s limiter, the MX limiter typically provides 2.5 to 3 dB more power at high frequencies, which minimizes audible HF loss caused by pre-emphasis limiting. Drums and percussion cut through the mix. Highs are airy. “Problem material” that used to cause audible distortion is handled cleanly.
The 8700’s main goal is to make FM analogue broadcasts more competitive with the cleanliness, punch, and open high frequencies of the digital media against which FM analogue transmissions now battle. The FM loudness wars represent 20th-century thinking; in the 21st century, the new competition is digital media. Thanks to its crisp, punchy sound, the 8700 helps level the playing field between analogue FM and its ever more aggressive digital-only competitors.
The 8700 offers 8500-style processing presets too. Because the input/output delay of the MX peak limiter is too long to permit talent to monitor off-air on headphones, 8500-style is useful for remotes and outside broadcasts where off-air headphone monitoring is desired and the 8700’s low-delay monitor output cannot be brought to the talent.
In addition to subharmonic synthesis and phase skew correction , the 8700 provides stereo enhancement, HF enhancement, equalization, AGC, multiband compression, low-IM peak limiting, stereo encoding, and composite limiting — everything that even the most competitive major market station needs to stand out on the dial.
Processing for digital media like DAB+, netcasts and HD Radio™ is supplied standard. The FM and digital media processing paths split after the 8700’s stereo enhancer and AGC. There are two equalizers, multiband compressors and peak limiters, allowing the analogue FM and digital media processing to be optimized separately. The bottom line? Processing that optimizes the sound of your FM channel while punching remarkably crisp, clean, CD-like audio through to your digital channel audience.
More than 20 excellent sounding, format specific factory presets get you started. You’ll find all of your favorite 8500 presets, plus “MX” presets designed by Bob Orban to exploit the exciting possibilities inherent in the 8700’s MX peak limiter technology. Although the factory presets are fully competent “out of the box,” you can customize them with easy one-knob LESS- MORE control or with more than 60 advanced controls whose versatility will satisfy even the most finicky on-air sound designer.
If you choose to use the 8700’s superb DSP-based stereo encoder and composite limiter, be assured that they deliver an FM analogue signal that is always immaculately clean and perfectly peak limited, with full spectral protection of subcarriers and RDS/RBDS regardless of the amount of composite limiting.
A full-featured RDS/RBDS generator that supports dynamic PS is standard.
The 8700 includes ITU-R BS.1770-3 loudness meters and loudness controllers for use in countries that enforce a BS.1770 loudness limit on FM radio broadcasts. There are independent loudness meters and loudness controllers for the FM and digital radio processing chains.
For our European customers, a second-generation ITU BS.412 multiplex power controller yields the best possible coverage while flawlessly complying with the standard. You can adjust it to maximize loudness within the constraints of the BS 412 standard or to produce less gain change at the expense of slightly lower loudness. The 8700 applies MPX power gain reduction after the clippers so that the texture of the processing can include more “clipper sound” when desired. Regardless of how you adjust the multiplex power controller, you can be sure that you will always meet the BS 412 requirements flawlessly.
A loop-through connection is provided to enable a ratings encoder (such as Arbitron®) to be inserted between the output of the audio processing and the input to the stereo encoder. You can insert either after the AGC (allowing one ratings encoder to be used for both the FM analogue and HD processing chains) or just before the stereo encoder (driving the ratings encoder with the highest possible audio level).
Silence sense on the various inputs allows automatic failover between inputs, as specified by the user. The silence sense detectors can drive the 8700’s tally outputs and send SNMP traps/alerts.
An intuitive joystick, knob and button navigation system and a bright, active-matrix colour LCD makes it easy to set up and program the 8700 from its front panel.
Ethernet connectivity is standard, as is an easy to use PC remote control application that runs on Windows 2000, XP, Vista, 7 and 8 and that can control many 8700s on a TCP/IP network. In addition, programmable contact-closure (GPI) control plus ACSII terminal control via the 8700's RS232 serial and Ethernet ports and give you total freedom to interface the 8700 with your facility's remote control infrastructure, whatever it might be. The simple, ASCII-based API can be used to allow custom third-party applications (including automation systems) to recall presets, view status and set the controls.
The SNMP (Simple Network Management Protocol) features allow you to monitor your Optimod's status and to send Alarm notifications via your Optimod's Ethernet connection to your network.
Optimod-FM 8700 Digital MPX provides a digital composite output using a 192 kHz AES3 connection. This output appears on a male XLR-type connector on the breakout cable supplied with the Optimod. This output is fully compatible with and interoperable with the de-facto industry standard digital connection being implemented by transmitter manufacturers and others.
Several processor manufacturers and transmitter manufacturers have already implemented a system that uses the left channel of the AES3 signal to pass the FM stereo part of the composite baseband, leaving the right channel available. The original implementation does not allow the entire 99 kHz composite MPX signal to be digitized into a single bitstream. The Nyquist frequency of 192 kHz is 96 kHz, and practical anti-aliasing filters limit the flat passband to a frequency significantly lower than Nyquist. Hence, any subcarriers above about 80 kHz (in particular, 92 kHz SCAs) must be injected and digitized separately.
Orban’s implementation is a 100% backward-compatible superset of the original left-channel-only system and can be used with all such hardware, although its full benefits can only be enjoyed if the hardware receiving the signal is designed to take advantage of it. Orban’s system removes the bandwidth limitation while using the same AES3 192 kHz transport as the original system. We sample at 384 kHz and multiplex the samples in an even-odd sequence between the left and right channels of a 192 kHz AES3 link. Thanks to its 384 kHz sample rate, this system has sufficient bandwidth to pass the entire FM baseband (up to 99 kHz) without aliasing. The link uses straightforward 192 kHz stereo AES hardware, and relies on the fact that the AES3 standard allows the left and right channels to be sample-locked and time-synchronized with each other both to prevent both phase cancellation in a mono mixdown and widening of the stereo image.
A wordclock/sync reference input appears on a female BNC jack at the end of the breakout cable that connects to the digital composite connector. It accepts a 1x 5V p-p squarewave wordclock signal at 32, 44.1, 48, 88.2, or 96 kHz, or a 10 MHz sinewave or squarewave signal, 0.5 to 5 V peak. 10 MHz is a common output frequency produced by GPS and rubidium frequency standards. You can configure the 8700 Digital MPX to lock its 19 kHz pilot tone and output sample frequency to this input. The digital MPX hardware also provides two new SCA inputs on BNC jacks. These are digitized at 384 kHz sample rate using 16-bit converters and can only feed the digital composite output. (If you need to use both the digital and analogue composite outputs, you must split the outputs of your SCA generators with Y cables so that each generator output drives one digitized SCA input and one non-digitized SCA input.)
“Multipath Mitigator” Left/Right Phase Skew Correction
The phase skew corrector maximizes the quality of a mono mixdown or blend that might occur in a receiver. At higher frequencies (where audible comb filtering of the mono sum is most likely to occur), the corrector removes phase differences between the left and right channels, converting the HF signal into “intensity stereo” while preserving phase differences at lower frequencies where these differences are important for psychoacoustic “envelopment.”
By removing phase shifts between the left and right channels, the process minimizes the amount of energy in the stereo subchannel, which consequently minimizes multipath distortion without compromising stereo separation. It can allow more stereo enhancement to occur for a given amount of multipath distortion. The process also minimizes the amount of peak overshoot during SSB/VSB operation of the stereo encoder, thus minimizing the amount of composite limiting needed to constrain peak modulation to 100.
This process can not only correct problems due to phase skew between the left and right channels of an analogue recording due to head gap misalignment, it can also correct comb filtering caused by spaced microphones feeding the left and right channels, which can occur on drum kits and other sources that have been multi-miced.