Why is there a selection of filters for the WFM601M jitter measurement?
The WFM601M includes the two filters specified in SMPTE 259M: 10 Hz and 1 kHz. It also includes two additional filters, 10 kHz and 100 kHz. These allow extra band limiting choices, useful for investigating jitter problems. For sophisticated users, these filter choices can be used to better match the alignment jitter measurement to the specific receiver chipset in use. For example, the Sony chip has a clock recovery bandwidth of about 500 kHz, so the 100 kHz filter gives the most appropriate alignment jitter number. If a GVG receiver is set to 50 kHz, then the 10 kHz filter would be the best choice. The added filter choices, especially the 10 kHz, also help prevent obsolescence should the 1 kHz standard be revised.
