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SR1 Operation Manual 82
© 2014 Stanford Research Systems
Digital Audio Input Sampling Rate
Generator
Fs Digital Audio Input Sampling Rate (ISR) is set to the Digital Audio Output Sampling Rate
(OSR)
Measured
Fs ISR is set to the value measured by SR1.
Status Bits The sample rate embedded in the digital audio channel status is used as the ISR.
User
Reference The ISR is set to a fixed user-entered value.
Digital Input Signal Controls
The embedded digital audio signal may be AC or DC coupled. AC coupling inserts a DC blocking filter
into the signal path with a pole at ~4 Hz.
The Deemphasis control is included for future expansion and is not implemented in the current version
of SR1.
Input Resolution may be set between 8 and 24 bits. The input data is truncated to the selected value.
Digital Audio Status Panel
The Digital Audio Status Panel at the bottom indicates the current status of the received digital audio
signal. It consists of 6 indicators, each of which glows green when the corresponding status condition is
"good" and red when the status condition changes to "bad." The 6 status conditions detected are:
Status
Condition Meaning
CRC For AES/EBU digital audio streams an 8-bit CRC code is generated from the
received channel status bits in each block and compared to the value stored in the
last byte of the channel status block. A red indicator indicates a CRC mismatch.
Lock Green Indicates that the digital audio receiver is locked to an input data stream. Red
indicates no lock.
Validity Red indicates that the validity bit has been set in one of the received sub-frames
Confidence This indicator glows red when either the Unlock or Bi-phase error is detected.
Coding Bi-phase error. A valid digital audio signal remains at the same amplitude for no
longer than two Unit Intervals (UIs) (Except during preambles). A red indicator
indicates that this condition has been violated.
Parity Each digital audio subframe contains a parity bit which summarizes the parity of the
remainder of the bits in the subframe. A red parity indicator means that the received
parity bit does not match the parity computed in the remainder of the subframe.
Carrier Status Tab