C NTI AG 2005

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Titelfolie
Pro Audio Workshop Digital Audio Measurements
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Contact Details
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IdentifyingSignals
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Identifying signals
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Identifying signals
Multichannel Interfaces ADAT, TDIF, MADI
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Identifying signals
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Identifying signals
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Identifying signals
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Identifying signals
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The AES3Frame
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
The error correction of a CD player is able to
reconstruct many faults without any loss - so the
audio data is 100 identical to the original
data. But there can also be faults (due to
scratches on the CD) where the error correction
is not able to reconstruct the audio data 100,
so the played audio data is not identical to the
original audio material. In this case the CD
player should mark each faulty audio sample with
the validity bit set to "1".
MP3
ACC
Compressed audio data (e.g. MP3, ACC, Dolby
Digital) can also be transmitted using digital
audio interfaces. Such data is not useful for
direct D/A conversion. Setting the validity bit
indicates this.
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
The parity bit enables a receiver to find faulty
transmissions (e.g. due to disturbances of the
signal on the cable). Principle The transmitter
sets the parity in a manner, so that the count of
"1" - bits in a subframe is an even number. The
receiver checks this rule and reports a "parity
error" if the count of "1" - bits is not an even
number.
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The AES3 Frame
The transmitted data is a continuous stream of
"0 bits and "1"-bits like 100010110101110110110..
. The header (preamble) marks the beginning of a
new frame or subframe inside this bit stream.
There are three different preables
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The AES3 Frame
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The AES3 Frame
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The AES3 Frame
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Checking A to D converters
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Checking A to D converters
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Checking A to D converters
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Checking A to D converters
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Checking A to D converters
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ADAT ADAT Sync
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ADAT ADAT Sync
Interface Types Type I ? 20 Bit Type II ? 24
Bit Up to 48kHz (8 Channel)
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ADAT ADAT Sync
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ADAT ADAT Sync

• Two 48kHz channels are used to get one 96kHz
  channel. This mode is called (all names stand for
  the same)
• Single Channel double frequency mode (1C2f
  Mode)
• Double wire mode
• S-Mux Mode

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ADAT ADAT Sync

• Adat Sync is used to distribute wordclock and
  time code signals as well as Midi data (for
  machine control).
• All lines are galvanically isolated (current loop
  as used for Midi interfaces)

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The TDIFInterface
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TDIF Interface
Outpus
Inputs

• 8 bidirectional audio channels
• DB 25 connector
• 24Bit / 48kHz
• Max. cable length 8m
• One twisted pair transmitts two audio channels

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TDIF Interface
All lines are unbalanced and have a level of 2.5V
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TDIF Interface
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TDIF Interface
Tascam offers a TDIF to ADAT converter. With this
converter the audio signal (resolution, bit
defectives, ...) as well as the sampling
frequency can be tested with the Digilyzer DL1.
For testing other parameters like indicated
sample frequency, indicated preemhasis, ... use a
multimeter or oscilloscope (and this
documentation)
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Fine
Thank you for visiting the Pro Audio Workshop
For further info and downloads please
visit www.nt-instruments.com/digilyzer