User's Manual

RFX-RMT Issue 1.1 Page 15 of 38
• Audio Analog to Digital Converter, 48 kHz, 24 bit. Four high impedance Analog
inputs. The channels are first buffered by a variable gain stage to cater for either
Mic or Line level inputs. A switchable 20dB stage is also included to cater for low
level Mic inputs. The audio channels are then converted into digital signals and
passed to the MPEG2 Encoder.
• Audio SDI de-embedder. Extracts digital audio from the SDI stream
• MPEG2 Encoder. Compresses the video and audio. The encoder uses a suite of
MPEG2 compliant compression techniques, where the data bit rate is reduced
by processing over multiple picture frames. The absolute picture ( Intra frame) is
interleaved with pictures that are created using difference data ( Predicted
frame) with Bi-directionally predicted frames (4:2:2 Only) in conjunction with
motion compensation; thus low data rates down to 4 Mbps, can be achieved.
The encoder includes special modes which are optimized for low delay
(latency).
The encoding parameters are loaded into the encoder at power up. These are
selected from one of the ‘preset’ encoder memories. See 0 and Appendix B
• ASI routing.
As an alternative to the internal MPEG encoder an external ASI data stream
may be used. The ASI input to the front panel is converted to parallel, and
automatically selected for 188/204/byte mode inputs, the signal is then
configured for the modulator input format and routed direct to the transport
stream output, bypassing the MPEG2 coder.
• DC Power Supplies
Switching DC/DC converters are used to generate the various supplies from the
incoming 9-18V battery supply. These include 2.5, 3.3V, 5V, 8V and +/-5V
supplies.
There are no field replaceable parts on the Encoder board. If a fault occurs with the board
contact RF Central for technical assistance.