G.8273.4) Noise Type Class A Class B +50 ns +20 ns 200 ns (peak-to-peak) For further study Source: ITU-T G.8273.4, Table 8-1 Noise Tolerance and Transfer G.8273.4 specifies that the T-BC-P/T-TSC-P must be capable of tolerating input noise with the fol- lowing specifications: max/pktSelected2wayTE < 1100 ns, with a selection window of 200 S and selection percentage of 0.25%. Refer to the section "Parameters for Timing Performance" earlier in this chapter for more details on pktSelected2wayTE and other parameters of packet selection. The maximum value is used in the unassisted case because the TE is expected to be within the end-to-end timing budget of 1100-ns phase requirement from the mobile scenario-see "Chapter 10. Mobile Timing Requirements". This value is then used as the G.8271.2 network limit (meaning that the error at the end of the timing chain must be within this value to ensure that the requirements for the mobile use case are met). And the clock at the end of the timing chain must be able to tolerate it as input. As with the T-TSC-A case, for PTS networks when the T-TSC-P is external to the end applica- tion and where the end application limit is 1500 ns, the T-TSC-P is also expected to maintain max|TEL below 1350 ns at its 1PPS output. This allows for a 150-ns budget for the end applic- ation (see following section on budgeting). The metric max|TEL means that a low-pass filter with a bandwidth of 0.1 Hz is applied to the TE measurement samples from the 1PPS output prior to evaluating the max|TE|. The limits for noise transfer of a T-BC-P/T-TSC-P focuses primarily on the maximum noise that the clock can transfer from the input PTP timing signal to the output at the 1PPS and PTP master port. This noise transfer is calculated and specified in terms of phase gain. According to the recommend- ation, the phase gain should be smaller than 0.1 dB (1.1%). Transient Response For T-BC-P/T-TSC-P the transient is defined as any one of the following events: 1. The loss of the input PTP timing signal for a short per