ZyXEL Communications ZyXEL PLA-407 User Manual page 53

Table 11 Link Information (continued)
LABEL
Avg. Source PB CRC
Error Rate
Avg. Destination PB
CRC Error Rate
Avg. Bits/Carrier
Avg. SNR/Carrier
PLA-407 User's Guide
DESCRIPTION
This field displays the average CRC (Cyclic Redundancy Check)
error rate of transmission from the source device (as shown in
the screen) received by destination Powerline device.
A Cyclic Redundancy Check (CRC) is used as a checksum to
detect alteration of data during transmission. The CRC error
check is performed after Forward Error Correction. If the error
rate after FEC error correction is still high, then this indicates a
lot of noise at all frequencies on this section of your Powerline
network. Data transmission rates are reduced if there is a lot of
noise on the line.
A Cyclic Redundancy Check (CRC) is used as a checksum to
detect alteration of data during transmission. This field displays
the average CRC (Cyclic Redundancy Check) error rate of
transmission from the destination Powerline device to the source
device (as shown in the screen).
The CRC error check is performed after Forward Error
Correction. If the error rate after FEC error correction is still
high, then this indicates a lot of noise at all frequencies on this
section of your Powerline network. Data transmission rates are
reduced if there is a lot of noise on the line.
This field displays the average number of bits transferred over
the connection measured in Mbps. This represents the physical
rate of data transmission (the PHY rate) which includes not only
the files sent on your Powerline, but also line overhead required
to manage your network, such as error correction bits.
The PHY rate is the clearest indicator of the quality of your line.
• If the PHY rate is close to the HomePlug AV maximum data
transfer rate, then the quality of this section of the line is
very high, with very little attenuation.
• If the PHY rate varies between the maximum level and a
lower level (such as 60 Mbps), there is noise on this section
of your Powerline. Attenuation is not a factor.
• If the PHY rate is steady at a lower level (such as 80 Mbps),
this is caused by attenuation and not noise on this section of
your Powerline.
This field displays the average Signal to Noise Ratio (SNR)
measured in dB. Use this to check the amount of noise on this
part of your Powerline network. The higher the number the
better the connection quality.
Noise on your Powerline network is usually caused by household
appliances running on your Powerline network. The motor of a
refrigerator can create electrical interference. A cell/mobile
phone recharger which rapidly alternates between on and off
can also generate noise. Poor cable quality and installation can
also cause noise. To identify causes of noise on your network,
disconnect an appliance connected on this part of your
Powerline network and observe whether this reduces the Signal-
to-Noise ratio.
Chapter 6 The OS X Configuration Utility
53