Interpreting Console Messages

If you have a console, these are messages you may see:

There may also be messages from the system that are unrelated to the satellite ingest process, for example disk error or full disk.

New Image

At the beginning of each new image, a line similar to the following appears on the console.

New image   gvar.1997.113.205414.INDX Names:ALL CONUS

The gvar.1997.113.205414.INDX portion of this message is an index file name. Refer to the GVAR Index File Naming Convention for the complete description. Thus, gvar.1997.113.205414 is interpreted as follows:

*Field*	*Definition*
gvar	is the satellite signal type (GVAR)
1997	is the year when the image started
113	is the day of the year the image started
20	is the UTC hour the image started
54	is the minute the image started
14	is the second the image started
INDX	is the index file extension

The Names:ALL CONUS portion of the message above describes the ADDE dataset descriptors where the new index file is listed. In this example, gvar.1997.113.205414.INDX is listed in the descriptor files named ALL and CONUS.

Bit Slip

When the SDI software detects the start of a new GVAR data block, it reads the block length information from the block's header to compute the beginning of the next block. If the next block does not start at the predicted location, the current block contains more or less bits than its header indicated. A message appears on the console indicating the time and the words bit slip. You can expect to see some bit slips, and this may result in the loss of some data.

An increase in the number of bit slip errors may indicate a:

deteriorating signal
antenna positioning errors
degradation of antenna chain electronics
cable problem

Error

If the next block's synchronization code can't be located, the entire data block is lost and a message labeled as error appears on the console. This will result in the loss of data.

No Sync

The no sync message indicates that the ingestor is not seeing a sync pattern in the data stream. This is normal during housekeeping periods, but if it continues at other times, it could indicate any of the following:

poor termination of the signal; if you have a "Y"d signal (e.g., you split the clock and data signal from the bit syncs many times over) it will affect the termination of the signal; SDI's have a 75 ohm terminator built-in, and if you Y off an additional set of clock and data signals from the bit sync's output, you'll only get 37.5 ohm termination, etc.
the signal is NRZ-L format versus NRZ-S would prevent the SDI from recognizing the sync pattern; SDIs require NRZ-L format
the clock and data cables are reversed, resulting in a no-sync error
satellite problems (e.g., no data is being sent)
antenna postioning errors, or any of the above listed problems for bit slips could also give the no-sync errors

CRC Error

A new image is started when the priority frame start time changes within a block 0 that has a valid CRC code. A new image will not start if the CRC code is invalid (because of noisy data, etc.), causing the new image's data to be pasted on the end of the previous image. If the CRCs continue to be invalid, a new image is started after five consecutive block 0s with a new priority frame start time are received, regardless of the CRC status. When an image is started while the CRC is bad, the console displays the message:

CRC not valid.

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