2-5
Basic Operation
When digital clock is selected, any loss of lock detected in the incoming digital
audio, or reception of non-audio data will cause the digital input to be muted. An
error message will be displayed if this occurs. The PCM 90 will repeatedly try to
establish lock. If a valid signal is detected, the PCM 90 will unmute and resume
passing audio. The PCM 90 will always generate a valid wordclock at its digital
output, even if no clock is detected at the input. The frequency of the generated
wordclock will match the most recent operating sample rate.
The following types of errors are detected when the PCM 90 is set to Dig:
No Lock:
The PCM 90, at some point, lost lock to the incoming digital
audio signal. Digital audio input is muted.
Out of Range:
The sampling rate of the incoming audio signal is outside of
acceptable tolerance limits of +4%. Digital audio input is
muted.
Non Audio:
Indicates transmission of non-audio data, such as from a CD
ROM. Digital audio input is muted.
CRC:
The error is reported, but incoming audio is accepted.
Dig In Status
Pressing Load/
✱
from Input Source will display the current digital input status.
This status display is continuously updated, acting as a real-time monitor of the
PCM 90 digital input. This display is active even when the PCM 90 is set to
Internal clock. Note that in the case of an AES Pro format signal, "Emphasis"
means either CCITT or 50/15µs emphasis.
If valid digital audio is detected, the display will show the external clock rate and
format information, along with the status of the Emphasis bit(s) in the incoming
audio signal. If the PCM 90 has lost lock, the display message will indicate "No
Lock" and parenthetically show the internal clock rate now in use.
Error Log
The following errors are continuously logged and are available for review by
pressing Load/
✱
from the Dig In Status display and using ADJUST to scroll
through the error list.
Validity:
A Validity error indicates that the Validity bit was set in a frame
of incoming data and that the data attached to it may be
corrupted. This bit may also be sent when the transmitting device
is paused.
Confidence:
The PCM 90 is detecting excessive jitter or noise on the digital
audio line. No data has been corrupted, but corrective action
should be taken.
SlipSample:
Indicates that a single sample is misaligned with the window
defined by the Input Source. This may occur when an external
master changes sample rate, or when it is just powering up, but
should not occur in normal operation. (This type of error is
reported for reference only, as the PCM 90 does not accept
digital data when using its own internal clock.)
Upon loss of lock, or reception of non-
audio data, the PCM 90 will mute the
digital input and display the following
messages when Input Source or Dig
In Status is selected:
Input Source
Dig In Status
Not Locked
No Lock (Int 44.1)
Out of Range
No Lock (Int 44.1)
Non Audio: 44.1
Non Audio: 44.1
Audio
✱
Dig In Status
0.0 Prf 44.1 Emp:Yes
Audio
✱
Dig In Status
0.0 NoLock (Int:44.1)
When the PCM 90 loses lock, it will mute the digital input.
Summary of Contents for PCM 90
Page 1: ...User Guide Digital Reverberator PCM 90...
Page 3: ...User Guide Digital Reverberator PCM 90...
Page 11: ...1 1 Product Overview 1 Product Overview Block Diagram...
Page 84: ...Lexicon 3 24 PCM 90 User Guide...
Page 112: ...4 28 PCM 90 User Guide Lexicon...
Page 122: ...5 10 PCM 90 User Guide Lexicon...
Page 129: ...Lexicon Part 070 10399 Rev 1...
