Nevion AV-HD-XMUX - Manual (Page 7)

AV-HD-XMUX (-T/R) / AV-SD-XMUX (-T/R) Rev. L
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1.2 Signal flow
Video may be presented on the optical or electrical inputs. The module will switch to the
other input if the module can not lock to a signal. The video is re-clocked and transformed to
parallel video. The parallel video goes into a line buffer which is used to de-glitch the video
when switched on the correct line. No errors are flagged or produced when the video is
switched on the appropriate switching line. All ancillary data, including embedded audio is
extracted from the video signal. All the packed data is sent to the group router. The de-
embedded audio is sent to the stereo audio cross-point router.
The AES audio inputs are initially connected directly to the audio router. Sample rate
converters are inserted if there are sample slips and the signal is not a data signal. The
sample rate converters may be disabled with DIP switch 1.7.
The audio processing is performed on the stereo router outputs.
Four of the router outputs are connected to the four stereo delay lines. The outputs of the
delay lines are connected to four inputs of the stereo audio router.
The audio signal is delayed by a few samples during de-embedding, re-packeting the audio
and audio processing. Signals that pass through the stereo audio router will be delayed by a
small number of samples. The group router outputs from the de-embedders do not introduce
any additional delay as the audio does not require unpacking and re-packing.
The embedder core embeds either re-packeted audio from the stereo router or the existing
de-embedded audio as configured in the group router.
The embedded audio packets are inserted into the video signal together with the control
packets and any other packets that were present in the original video signal. The video is
serialized and output through the cable and laser drivers. The AES audio signals are taken
from the outputs of the audio router.
1.3 Data signal
The data signal is transported using the User bits in one of the embedded audio streams.
De- embedded data is output on the RS485 output and data received at the R422 input is
embedded into the output video. The configuration sets the audio source containing the data
signal to de-embed, the data format to be received on the backplane connector and which
output signal to embed data into.
1.4 Video reference
The input video always has the highest priority. The output video and audio will always be
synchronous to this signal.
AES input 1 will be used as a reference for the internal video generator as long as the
sample rate converter is not active. ( FPGA firmware 1.56 and greater. Contact Support for
upgrade)
The internal generator will run at a frequency close to the last valid signal.