Test/SELT Noise Floor Result Help

The Loop Noise Floor table provides a set of noise measurements.

Noise Floor Results

Tone

The noise mesurement consists of an array of values, one per sub-carrier. A 'sub-carrier' is also known as a 'tone' or a 'bin'.

Frequency (kHz)

The tones are spaced at 4.3125 KHz, so there are 512 tones from 0 Hz to 2208 KHz, which is the bandwidth of ADSL2+. For a particular SELT implementation, the chip used to measure noise may not support all of the tones.

Noise (dBm/Hz)

This object provides the inband noise of all of the sub-carriers on this line. It is an array of 16-bit signed integers stored in big-endian format. For example, string position 0 is the most-significant octet of the first noise value, and string position 1 is the least-significant byte of the first noise value. Each value is a signed 16-bit 2's complement number scaled as least-significant bit = 1/10 dBm/Hz. e.g. an integer value of 35 represents 3.5 dBm/Hz. If the measurement is invalid it will read as full-scale negative (0x8000).

 

January 22, 2011