Ultech Corporation DV2000, User Manual, Page: 24 / 45

24 ULTECH DV2000 User’s Manual
4.9 EDH Error Detecting and Handling Status Menu
A recommended practice exists that allows you to detect serial digital transmission errors as
well as errors in digital video equipment. The practice is known as SMPTE RP 165 Error
Detection and Handling System. The DV2000 fully supports this recommended practice by
providing two EDH processors: one to detect
errors in upstream equipment, and one to
recompute checksums for the benefit of
downstream equipment. The system works by
computing and transmitting checksums
separately for full field data, for active picture
data, and for ancillary data. The DV2000
computes the checksum for the incoming data
and compares it against the transmitted
checksum. If they deviate then an error flag is
set in the EDH Status Menu. A flag is set
according to the nature of the error.
The following is an explanation of possible
errors:
EDH Error Detected Here
If the incoming checkword does not match the calculated checkword, the EDH flag
is set.
EDA Error Detected Already
If the incoming EDH flag is set and the EDA flag has not been set, the EDH flag will
be cleared and the EDA flag will be set. However, if the incoming checkword is
invalid then the outgoing EDA flag will be set according to the incoming EDA flag
only.
IDH Internal Device Error Detected Here
These flags would normally be set by the DV2000 to detect internal failures. The
current DV2000 software version does not set these flags.
IDA Internal Device Error Detected Already
This flag is passed from input to output by the DV2000. The DV2000 ignores this
flag, although you can view the flag in the EDS Status Menu.
UES Unknown Error Status
This flag is passed from input to output by the DV2000. The DV2000 ignores this
flag, although you can view the flag in the EDS Status Menu. This bit is also set if
the incoming data does not have an error data packet. This informs downstream SDI
devices that the data being sent by the DV2000 has not been checked for errors.
Other menu items:
Packet Checksum This is the latest full field checksum. The checksum, together with the
error flags may be refreshed by selecting “Update Error Status”.
Error Count Counts the number of fields that had errors. This counter will accumu-
late errors until you reset it by selecting “Clear Errors and Error
Counter”, or until a count of 2 million is reached.