7 Operation on xDSL accesses
57
ARGUS 152
SNR margin
Signal-to-noise ratio margin in dB. The SNR margin is a
measure of how much additional noise the transmission can
stand and still maintain a bit error rate (BER) of 10
-7
. This value
is considered a reserve against interference signals.
Rule of thumb: The SNR margin in downstream should -
doubled - be at least equal to or greater than the SNR margin in
upstream.
Inpulse noise prot.
INP describes the quality of the protection against pulse
interference. The number of consecutive DMT symbols that can
be completely distorted without causing errors in higher layers.
Interleave delay
The delay (in ms) due to interleaving of data blocks.
FEC
Forward error correction
Number of transmission errors corrected using the checkbytes
of a codeword.
f (far):
Errors that the DSLAM detects and passes to
ARGUS.
n (near):
Errors that ARGUS detects in the transmitted
blocks.
CRC
Cyclic redundancy check
The checksum of the superframes transmitted by the remote
station does not agree with the locally calculated figure.
Possible cause: line interference.
f (far):
Errors that the DSLAM detects and passes to
ARGUS.
n (near):
Errors that ARGUS detects in the transmitted
blocks.
HEC
Header error checksum
Number of ATM cells with incorrect header checksums.
f (far):
Errors that DSLAM detects and passes to ARGUS.
n (near):
Errors that ARGUS detects in the transmitted
blocks.
ES
Errored seconds
Number of seconds containing one or more erroneous sync
words and/or one or more CRC anomalies.
SES
Severely errored seconds
Number of seconds containing one or more erroneous sync
words or at least 50 CRC anomalies.
LOSS
Loss of signal seconds
Shows the number of LOS errors in one second.
