imit of maximum tolerable input jitter and in terms of UI versus jitter frequency for various bit rates. wander Timing variations at frequencies below 10Hz are referred to as wander, and are typically caused by changes in phase and propaga- output of an add/drop multiplexer. Tributary output jitter (e.g. at tion delay (e.g. through satellites or long cables subject to tempera- DS-1 or DS-3) is measured while a SONET/SDH tester forces a ture changes). Wander is sometimes classified as long term (24 specified sequence of pointer movements. These are described in hours, i.e. daily temperature changes) or short term (15 minutes), the latest version of Bellcore TA-NWT-000253 and is being dis- these definitions being taken from ANSI T1.403. cussed further (1991) in ANSI IT1X1.6. To fully specify the jitter performance of a piece of equipment, we When equipment meets the jitter specifications at a hierarchical need to measure the input jitter tolerance, the jitter level at the interface, it should be possible to interconnect network sections output and also the jitter transfer function or the degree to which without causing bit errors. Error performance measurements 61/7 Table 61.4 Parameter values for input jitter and wander tolerance (G.823) Peak-to-peak amplitude unit interval Frequency Pseudo random Digit rate kbit/s test signal 1.15 (18us) 600Hz 20kHz 211 1 X 10-5 Hz (Rec. 0.152) 36.9 (18us) 2.4kHz 18kHz 100kHz 215 1 X 10 Hz (Rec. 0.151) 152 (18us) 400Hz 400kHz 215 1 X 10 Hz (Rec. 0.151) 34368 618.6 100Hz 10kHz 800kHz 223 1 (18us) (Rec. 0.151) 139264 2506.6 0.075 200Hz 500Hz 10kHz 3500kHz 223 1 (18us) (Rec. 0.151) 61.3 Error performance measurements discussed in Section 61.3.6, some in service measurements are more representative than others of the actual error performance of the 61.3.1 traffic signal. Furthermore, some are applicable to the path meas- Lines, paths and sections urement provided the parameters are not reset at an intermediate network interface. Others are only useful at the line or section level. Di