OmniTek OTR 1001, User Manual

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OmniTek OTR 1001 User Guide, v3.1 N-7
Using Dedicated Test Sequences
Where there is no AV_ISD option, AV delay is measured using a dedicated Test sequence.
In this case, the Analyzer software analyses the input video signal, looking for the first frame in
the sequence (identified by the binary code). When this is detected, an internal timer counts the
time delay befre the audio pulse associated with this first frame is detected. The system
automatically detects whether the audio pulse is early or late with respect to the video, and
displays the results accordingly.
The delay that is determined is shown in the AV Relative Timing View.
Figure N-7: AV Relative Timing View
This shows two ‘meters’, the upper one showing the difference in timing relative to the video of
the audio in the first channel in the selected channel pair and the lower one showing this for the
second channel in this channel pair. The ends of the meter represent 1 field.
With the test sequences supplied, it is possible to measure the delay introduced in either PCM
audio or Dolby-E encoded audio, but it should be noted that Dolby-E transmission delays can
only be determined where the OTR includes the AUDIO_DOLBY_E option and where the
system used to generate the test sequence supports RVF files (or the test sequence has been
played out once on such as system and recorded for playback either from a videotape machine or
a video file server).
The test sequence is generated remotely from the analyser, allowing A/V delays in satellite,
cable, or terrestrial broadcast links to be measured.
The delay range that the system is capable of measuring is:
50Hz Systems 60Hz Systems
Audio early with respect to video: 0 ~ 5760 ms 0 ~ 4800 ms
Video early with respect to audio: 0 ~ 1920 ms 0 ~ 1600 ms.
The relative time delay measurement is typically expressed in milliseconds, and the accuracy is
better than 1 ms.