VM700T * VMTB Upgraded VM700A

Features

• Automatic Measurement of H-Sync Frequency Offset Error and Drift-rate Characteristics
• Frequency Normalizing Allows Referencing to a Studio Timing Source
• Peak Hold Functions with User-definable Measurement Limits
• No Special Test Signals Required
• Measures Both NTSC and PAL Video
• Use Together with Existing SONET and SDH Test Systems to Aid in Total Network Timing Verification for Video Transport

Applications

• In Service Testing For Jitter in SONET/SDH Networks
• Measure H-sync Timing Wander Characteristic of Video Signal

Sync Timing Wander Measurement

Option 22 is a new VM700T and VMTB Upgraded VM700A video measurement application designed to measure H-Sync timing wander characteristics (also referred to as "Frequency offset and drift") of a video signal that has been transported over a SONET or SDH digital distribution network. Sync timing wander is a common, but often misunderstood and thus undiagnosed, problem with contribution quality video that has been transported over SONET or SDH distribution networks. Contribution quality video transport requires a higher level of network timing control than does voice or data transport. Option 22 provides a simple and efficient method for the verification of H-Sync frequency timing stability for contribution quality video applications.

Frequency Offset

Frequency Offset is the measurement of the absolute frequency error of the horizontal synchronizing pulse. Frequency Offset is a frequency accuracy measurement. Therefore, the measurement should be periodically normalized to a stable frequency reference by using the "Zero Offset" softkey function. For example, a video source of known accuracy, such as an SPG (possibly locked to Rb or Ce clock), can be applied to the VM700T source B input. This source is then measured with the Frequency Offset application. Next, the "Zero Offset" soft-key is touched, calibrating the display to channel B (SPG of known accuracy). Accurate frequency measurements to within 100 ppb on channel A or C can now be made. Display limit markers indicate peak Frequency Offset in ppm and Hz @ Fsc over the past 17 seconds. Default limit markers of ±2.8 ppm (±10 Hz) for NTSC and ±.226 ppm (±.1 Hz) for PAL may be reprogrammed to any value.

Drift-rate

The constantly updated Drift-rate application calculates the rate of frequency drift of the horizontal synchronizing pulse frequency. The rate of H-Sync frequency drift has the greatest effect on studio quality recording and post-processing equipment and is therefore of primary concern for users of such equipment.

Drift-rate limit markers of ±.028 ppm/sec (±0.1 Hz/sec) for NTSC and ±0.0226 ppm/sec (±0.1 Hz/sec) for PAL are clearly marked and can be quickly reprogrammed to any value. As in the Frequency Offset, measurement display markers indicate the Drift-rate peaks over the past 17 seconds with readout in ppm/sec and Hz/sec @ Fsc.

Specifications