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