Description: The Virtual Noise of upsteam. This is a string of 16 pairs of values in the following structure: Octets 0+1 - Index of 1st sub-carrier used in the context of a first breakpoint. Octet 2 - The PSD reduction for the sub-carrier indicated in octets 0 and 1. Octets 3-5 - Same, for a 2nd breakpoint. Octets 6-8 - Same, for a 3rd breakpoint. This architecture continues until octets 45-47, which are associated with a 16th breakpoint. Each subcarrier index is an unsigned number in the range 0 and (NSCds - 1). Each PSD reduction value is in the range 0 (0dBm/Hz) to 255 (127.5dBm/Hz) with steps of 0.5dBm/Hz.