Equipment Description
Page 4-10
Instruction Manual: evolution 5000 E5500 Mobile Contribution Encoder
ST.TM.E10033.3
Serial Digital Video Input Error Detection and Handling
The serial digital video input supports error detection and handling (EDH),
which is an error checking method for serial transmitters and receivers.
EDH is fully defined in the specification SMPTE RP 165-1994, ‘Error
Detection Checkwords and Status Flags for Use in Bit Serial Digital
Interfaces for Television’.
To check the serial link, three sets of flags are generated at the
transmitter and subsequently regenerated at the receiver (i.e. the
Encoder) to confirm the link is error free. The sets of flags generated are:
•
Full field flags, which are based on the regeneration of a cyclic
redundancy check (CRC) checkword calculated over the full field of
samples
•
Active picture flags, which are based on the regeneration of a CRC
checkword calculated over the active picture
•
Ancillary data checksum flags, which are based on calculating a
checksum for all the ancillary data packets within a field.
Errors detected by the MCE in the serial digital interface are reported as
‘SDI …’ errors on the front panel display. Refer to Annex C, Error
Messages, for a list and description of these error messages.
Multiplexing and Scrambling Functions
The Multiplexer receives packet streams from the Video Compression
Module, Audio Encoders and Data Input Module. In addition, the Host
Processor generates Service Information (SI) packets which are also fed to
the Multiplexer. The Multiplexer generates a transport stream from these
packet sources, and inserts NULL packets in the transport stream if no
data is available.
The transport stream is fed to the S8489 RAS Scrambling Module which
implements the proprietary Remote Authorisation System (RAS 1). This
provides an elementary form of security designed simply to prevent open
access to the transmitted service. RAS 1 supports two methods of key
entry: SNG key mode and fixed link mode.
In SNG key mode, a seven digit key is entered via the front panel controls.
If the receiver is in tracking mode, one key is entered which is
programmed into both the encoder and the receiver. If the receiver is in
independent mode, two keys have to be entered, one for the encoder and
one for the receiver.
In fixed link mode, an eight digit key is assigned by TANDBERG Television
and pre-programmed into the encoder and the receiver.
Scrambling is implemented on the PIDs listed in Table 4.1, and can be
switched on and off under user control
