Jitterbug's jitter management and audio clock reclamation can make some cheap cables sound great, and great cables sound even better.
AES audio stage distribution now works. IOL's Jitterbug® board level product manages digital audio jitter by reducing it to inaudible levels through clock waveform reclamation. Jitterbug also boosts the digital signal, enabling further transmission distances. Outputs can be configured to either mirror or duplicate outbound channels, the latter enabling channel redundancy.
Correcting even the best cable's faults delivers the highest quality digital audio signal.
For information regarding a ready-to-deploy Jitterbug system for stage or structure use, contact us for a referral to IOL's Jitterbug product partners.
Jitter is the inaccuracy in the clock timing of digital data, and it is a pervasive problem with digital audio. As digital audio systems take the stage and the studio, issues with jitter become commonplace and problematic.
FIG. 1. Falling edge, digital audio waveform.
For more information on audio clock waveform attenuation, download IOL App Note Audio Clock Waveform, 17 May 2014 (PDF).
A long cable run to the stage may still need to be routed hundreds of feet further stage left and stage right. AES bitstreams in such cable lengths will include line-induced jitter; even minimal capacitance in a cable has been shown to inject abundant jitter into the digital audio data stream. Cables skew digital audio signals primarily by attenuating the highest frequencies.
Many factors impact the quality of the digital audio signal cable transmission. All cables, even the highest quality, are subject to their changing environments. EMI/RFI ingress and egress affects all cable assemblies.
As a digital signal travels down a cable and across numerous mating connectors of dubious quality, typically built in low-cost manufacturing zones by the lowest bidder, the capacitance, resistance, velocity of propagation, EMI, and inductance of these elements degrade, alter and otherwise modulate the shape of the transmitted square waveform. This manifests itself in a rounding off of the rise and fall times, as well as making the amplitude of the wave smaller, all of which creates significant difficulty for the receiving device to reliably detect the original data.
Excessive jitter can prevent a signal from being resolved at all.
Other factors impact the quality of the digital transmission. A particular venue's infrastructure and electrical/electronic environment. Abused rental equipment. Old cables that have been twisted and flexed repeatedly. Low-cost or legacy equipment not featuring the latest and greatest high performance DAC's and filters. A nearly endless list.
Jitter is not vastly different from phase noise. While phase noise exists in the frequency domain, jitter is defined in the time domain. DACs and ADCs extract the clock from the audio bit stream in order to control the conversion process. Permanent amplitude modulation caused by jitter creates timing errors in the clock signal, preventing data conversions from occurring with the required precision.
Since jitter is dissonant distortion, it will be more audible than harmonic distortion. Embedded clocks, such as clocking over ADAT or AES, typically suffer more jitter than word clocks. In order to properly manage and mitigate jitter to deliver a crisp, clean audio signal, clock recovery is needed.
No need to isolate source-clock jitter problems from cable-related jitter problems; Jitterbug seamlessly solves jitter issues automatically.
SIMPLIFIED BLOCK DIAGRAM
FIG. 2. Jitterbug power & signal operations. Six 4 channel boards can be daisy-chained together.
IOL's printed circuit board, Jitterbug®, supports AES3, IEC60958, S/PDIF & EIAJ CP1201 interface standards. Jitterbug directly accepts a cable run of AES digital audio, reclocks the audio data stream, mitigates jitter & boosts the digital audio signal for further transmission distances. Outbound audio is biphase-encoded and driven back on to the cable. Each Jitterbug board features 4 channels of superb sonic quality AES digital audio. Six boards can be daisy-chained together using the onboard connectors to create a 24 channel system (Mirror mode), fitting into a 1U enclosure.
Jitterbug operates in two distinct, jumper-selectable IO modes:
Mirror mode (default), where Ch1 IN is routed to Ch1 OUT (4ch IN/4ch OUT);
Dup mode, where Ch1 IN is duplicated on Ch1 & Ch2 OUT, and Ch3 IN is duplicated on Ch3 & Ch4 OUT (2ch IN/4ch OUT).
In Mirror mode, a 12/12ch system requires 3 PCBs; in Dup mode, a 12/24ch system requires 6 PCBs.
FIG. 3. Jitterbug's multi-mode operation options. Digital audio stream represented by 1's & 0's. All functional settings labeled in PCB artwork.
Jitterbug's Dup mode delivers a reliable, high-quality channel duplicator, perfect for building redundant systems. Each channel is replicated and boosted for re-routing in new and existing wiring installations and applications as diverse as broadcasting, studio, theatre, stadiums, houses of worship and conference centers.
The board can also be configured to support S/PDIF audio. Selectable audio inputs and outputs include 100ohm AES twisted pair or 75ohm coax. These impedances could also be mixed, if necessary; e.g., 75ohm IN, 110ohm OUT. The system supports audio up to 192kHz, 24bits, and features automatic frequency sampling detection at 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz & 192kHz. Each channel's receiver meets the AES3 specified minimum 200mV peak-to-peak input level for a clock recovery circuit, eliminating the need for an external line receiver. Each channel's transmitter provides an RS422 output, which meets the AES3 requirements for a balanced line driver.
Jitterbug is a board level product, including a complete reference design for our qualified Assembly Partners.
FIG. 4. Jitterbug prototype with jumper selections: 110ohm I/O; chassis ground; Mirror mode. All functional settings labeled in PCB artwork.
The board's dimensions are 2" x 6", meaning 6 boards to build a 24 channel system require a space of approximately 12", not including power supply and any physical I/O.
Many system designs can use an inexpensive wall-mounted power adapter to feed Jitterbug.
FIG. 5. Jitterbug top silk screen. All functional settings labeled in PCB artwork.
For information regarding ready-to-deploy 4 to 48 channel Jitterbug systems for stage, broadcast or structure use, contact us for a referral to IOL's Jitterbug product partners.
IOL is more than simply a connector vendor or bulk cable supplier. We continue to build our portfolio of interconnect electronics that enable our partners to offer private-labeled, synergistic products that generate significant revenue and profits.
Please contact us for a referral on Jitterbug full system availability and supply.
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