nd T-TSC Showing Points Introducing Error These points indicate the following errors: 1. Timestamping noise (error) in the PTP slave port. Timestamping noise (such as granularity) in the PTP master port (only the T-BC can have a master port). Obviously, this is a point where any noise introduced by the T-BC is transferred directly to downstream clocks. 3. Noise introduced within the time clock itself (for example, due to system issues such as noise in the hardware signals). Any phase wander from the network that is introduced by the recovered physical frequency (such as SyncE). It is important to note that the recovered frequency would have been passed through a low-pass filter before being fed to the time clock. 5. Noise (such as wander) introduced by the local oscillator. 6. Noise introduced in the 1PPS output, which could be due to the hardware design of the clock (such as path delays or skewed rise times in the 1PPS signal). The clock TE is a combination of all the mentioned possibilities, and the various performance limits (measured at the output ports) become a test of these specific points. For a T-BC, the performance is measured at the 1PPS interface, the PTP interface, and at any frequency outputs (such as SyncE). For a T-TSC, the 1PPS and frequency output interfaces are the only options because a T-TSC has no PTP master port. Noise Generation The noise generation of a clock is the noise (normally phase wander) that is measured at the output of the clock when supplied with an error-free (or ideal) reference at the input. Figure 9-25 illustrates this scenario for a T-BC and a T-TSC and indicates the points (shown as dots) that can introduce er- ror within the T-BC/T-TSC. T-BC/T-TSC Noise @ PTP Time & (for T-BC only) (error free) phase slave master recovery Local Noise @ 1PPS oscillator Frequency (wander free) Frequency recovery Figure 9-25 Noise Generation Inside a T-BC and T-TSC The PTP and 1PPS signals will both output the cumulative phase and time noise generated from the different components within th