HD9084 HDTV Caption Encoder Manual
Page 6-4 TROUBLESHOOTING
6.3. ANSWERS TO FREQUENTLY ASKED QUESTIONS
6.3.1. Can the HD9084 correct “illegal” captions?
Yes. The HD9084 reads each CDP, buffers the data on a per-service level, and rebuilds new CDPs on
the output. It can also look at the incoming CEA-608 in the CDPs and translate into comparable CEA-
708. Due mostly to these two features, it can fix numerous caption problems such as:
• Bits marked as "reserved" not at levels specified by standard
• Sequence counter discontinuities
• Header signaling optional sections that are not actually present in the CDP
• CDPs on wrong field or both fields of interlaced video (should only appear on first field of each
frame)
• CDPs wrong length for the video standard
• Wrong amount of CEA-608 data in CDPs (always want 120/1.001 characters per second of 608
data regardless of video frame rate)
• Poor CEA-608 to CEA-708 translation (corrected by ignoring upstream CEA-708 and re-
translating from CEA-608)
• Multiple CCPs per CDP (not an error but some equipment doesn't like this)
• CCP split across multiple CDPs (not an error but some equipment doesn't like this)
• relocate CDPs to specified line
• Do not pass data from CDPs that are likely corrupted (ie:critical or fatal errors)
When many of these problems are encountered by the HD9084, it will indicate this by displaying a fault
message on the front panel and illuminating the FAULT LED. Refer to section 3.9 for descriptions of the
fault messages.
6.3.2. Which Serial Port Should I Connect To?
The HD9084 rear panel has three serial ports, labeled A, B and C. Any serial port may be used for
typical captioning functions, since they all support the same Control-A serial protocol. All three serial
ports are configured from the factory for RS-232 communications, and the pinout is compatible with an
off-the-shelf null-modem cable. Ports A, B, and C are all configurable to support both RS-232 and RS-
422 communications.
If possible, keep Port A configured for RS-232 and do not connect equipment to it unless both ports B
and C are already in use. If the firmware requires upgrade in the future, as described in section 5.2 you
must connect a PC to Port A to load the firmware onto the HD9084.
If you wish to connect to an ATSC encoder, you must use Port B. Only Port B supports SMPTE-333
and Grand Alliance protocols used by these devices. Refer to section 3.6 for configuring Port B to use
these communication protocols.
6.3.3. There is No SD-SDI Video Present on the SD-SDI Output
The HD9084 includes a SD-SDI video bypass relay to ensure that SD-SDI video is passed, even when
the unit is powered-down. Make sure that your SD-SDI source is connected to the BNC connector
marked SD-SDI PGM IN, and the primary SD-SDI video output is connected to the BNC connector
marked SD-SDI BYPASS PGM OUT. If you still see no video, try the following:
1. Unplug the power from the Closed Caption Encoder.
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