CatonCaster HD422 User Manual
Appendix E – CatonCaster HD422 Audio Explanation
Downmix Audio Setup
There are two primary modes of audio down mix operation for the CatonCaster HD422 receiver/decoders.
These settings only affect the signal if the digital output is set to PCM. It will also affect those embedded
audio channels that are set to a PCM down mix. There are no gain changes or decoding if the digital or
embedded outputs are set to Pass-through. The preset modes are Monitor (the default setting) and
Transmission.
The first preset, Transmission, allows no changes by the customer. Transmission is intended to provide a
limited dynamic range signal to drive a set top box or a transmitter. The Transmission mode does respond to
dialog normalization data. It provides a gain boost of 11 dB and has compression to prevent the signal from
overdriving a modulator. The 11dB gain boost is applied to the analog outputs, AES digital outputs set to
PCM, and any embedded outputs set to PCM. It will not affect the gain of digital outputs or embedded
outputs set to Pass-Through. It is intended to provide a similar audio level as a broadcast TV station signal
through an RF modulator. The down mix includes the center and surrounds channels if they are present, and
is represented as Lt/Rt. (left total, right total)
The second preset is Monitor. It has moderate processing, no gain boost and its down mix involves left and
right channels only (Lo/Ro). The mode setting is Line as the default, but may be changed to RF, Custom 0 or
Custom 1. In Line mode, the Dolby Dialog Normalization data is followed along with moderate processing.
The default down mix setting for Monitor is Lo/Ro. The down mix may be changed to Lt/Rt or Lt/Rt/auto. Lt/Rt
auto follows the embedded data in the stream if the producer has a preferred down mix. It will switch
automatically between Lo/Ro and Lt/Rt depending on the data in the stream. If no mode is specified, the
down mix will be Lt/Rt. In addition, the Dual Mono modes of operation may be selected. They will only have
an effect if the stream is encoded as Dual Mono. Dual Left or Dual Right applies that signal to both left and
right channels of the digital service, left and right channels of the analog outputs, and left and right channels
of any embedded stream set to PCM. Selecting RF as the compression setting will add 11 dB of gain and the
same processing as the Transmission mode to the analog outputs, AES digital outputs set to PCM, and any
embedded outputs set to PCM.
There is an additional selection at the bottom of the Dolby setup pull-down menu. This allows selection
between Professional Mode and Consumer Mode. In Professional Mode the built-in latency value is 32 ms
for all formats. In Consumer Mode, this latency varies depending on the format. If you wish to monitor using
a consumer receiver, you should choose Consumer Mode. The output sampling rate will always be 48 kHz,
even in consumer. The Consumer/Pro identification bit will be set to Consumer. Normal operation in the air
chain will use the Professional setting. This setting affects both Dolby Digital (AC-3) and Dolby Digital Plus.
If you want to run with no processing, choose Custom 1, Lo/Ro, and Dynamic Range disabled. This will still
allow gain changes called for in the Dolby metadata via Dial- Norm settings in the stream.
Audio Output Settings
The digital audio services may be set to PCM (AES) or Pass-through (AES data) as an output. This applies
to all available sources. The PCM setting will decode and automatically down mix an AC-3 or Dolby Digital
Plus stream to two channels of AES audio. Pass-through simply passes thru the Dolby AC-3 data in an AES
stream to be decoded by an external decoder such as the Dolby 568. Be aware the Dolby DP-568 is a
professional decoder and always has a decoding latency of 32 msec. The older Dolby DP-564 has both
professional and consumer modes of operation. If it identifies the Pro/Consumer ID bit as Professional, the
latency will always be 32 msec. If it identifies the Pro/Consumer bit as Consumer, the latency will vary
according to the format. Check the DP-564 manual for the actual latency values for Consumer mode. The
analog channels can be assigned to any of the digital sources. The analog gain may be adjusted for the
desired level. The gain setting does not affect the level of either the embedded audio or the digital services. A
setting of +4 dBu provides an output of +4 dBu for a digital signal level of -20 dBFS. To check the audio
output level, place the audio setup in Custom1 mode, down mix set to Lo/Ro, and the Dynamic Range
disabled. This will remove any signal processing in the down mix. Set the digital service output being
measured to PCM. A test stream of -20dBFS will output from the digital services as -20dBFS. If the analog
channels are set to a gain setting of +4 dBu, the output should be +4 dBu plus or minus 0.5 dBu. The analog
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