G E N E R A L I N F O R M A T I O N
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WheatNet-IP
/ Aug 2011
Generic “audio” cable such as Belden 8451 may be used for interconnecting
AES3 digital audio devices but only for distances of less than about 25 feet.
The actual cable length that will work satisfactorily in an installation is pri-
marily determined by the error correction and jitter tolerance of the AES3
receiver device and the cable used.
The impedance of most ‘analog’ cables ranges from 40 ohms to 70 ohms and represents a
large impedance mismatch from the nominal 110 ohms required in the AES3 standard. Such
mismatch will result in signal reflections, causing bit errors at the AES3 receiver. The higher
capacitance of generic analog cables also slows down the rise time of the digital data signals,
impairing the ability of the AES3 receiver to accurately detect digital signal transitions. This
may result in increased jitter.
Energizing
Assuming the WheatNet-IP is correctly rackmounted, you may now energize
it. There is no power switch. The AC line input voltage is permitted to be be-
tween 90 and 260VAC, 50 or 60Hz. Power consumption is under 100VA.
Aggressive AC input filtering is utilized at the AC input of the WheatNet-IP;
however, it is always advisable to use external surge protection and/or an uninter-
ruptible power supply (UPS), especially where AC power quality is questionable,
such as at a remote transmitter site.
Power conditioning, surge suppression, and even power backup devices are wise
investments when using sensitive modern electronic devices that use an internal
computer.
Use of a UPS (uninterruptible power supply) is a good idea and will protect the
WheatNet-IP from short duration power interruptions which may cause it to reboot.
During boot up, audio is interrupted for approximately 40 seconds.
A Word About Nomenclature
Throughout this manual references are made to “BLADEs,” “sources,” “des-
tinations,” and other terms whose meanings may not be instantly understood by
everyone. Let’s take a moment to clarify some terms.
1. BLADE. In the WheatNet-IP system a “BLADE” is taken to mean an indi-
vidual member of a WheatNet-IP system; any device that has a unique BLADE ID. It
commonly refers to an individual input/output rackmount unit, but a more complete
definition would include any network connected PC running a WheatNet-IP driver
as well, including Automation servers and even the Program Director’s PC if they
are running the WheatNet-IP driver to listen to audio streams. Conversely, any PC
that is running the WheatNet-IP Navigator GUI program or using a browser for
interfacing to the built in web servers on BLADEs is not a BLADE itself. Only those
devices that can transmit and/or receive WheatNet-IP audio streams are “BLADEs.”
2. Source. A source is any audio signal in the WheatNet-IP system that is uniquely
generated. Any WheatNet-IP signal that is created by accepting and packetizing an
input is a source, as is any signal generated within the system. Source signals may be
audio, logic, or both. A logic source might be a logic port triggered by an external
switch. We generally avoid using the term “input” to describe WheatNet-IP signals
because the term can be misleading. One would easily understand that an external
