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OmniTek XR User Guide, Software Release 2.3 Page 113
Relative A/V Delay Testing
When determining the relative delay between the transmission of the audio and video
components of the signal, the OmniTek A/V Delay Test Sequence is installed remotely to
the video analyzer, which means that it is possible to measure A/V delays in satellite,
cable, or terrestrial broadcast links.
OmniTek Delay
Measurement System
RVF source
(e.g. OmniTek LAB)
Transmission Path
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 using an OmniTek TQ or an OmniTek XR that includes
the Advanced Audio and Dolby-E options.
In this mode, 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 before the audio input pulse 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 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.
Measurement using the Dolby-E (RVF-based) test sequence
1. The delay test sequence must be played out either from an OmniTek LAB system that
incorporates the Generator module or from a videotape machine or a video file server.
The steps used to play out this sequence are described on page 111.
2. Set the source routing such that the analyzer input is connected to the serial input. The
test sequence video should then be present in the Mini-Pic window while the audio
should be visible by displaying the Embedded PPMs
3. Use the Embedded PPMs display to identify which channel pair has the Dolby-E
information on it (usually pair 2).
4. Call up the Delay Measurement window, for example by clicking on its icon in the main
(Window) toolbar.
5. Use the Dolby-E Delay option in this window’s Options menu to ensure
that the Dolby-E Relative Delay is displayed, and the Dolby-E Audio
option in the same menu to select the audio channel containing the
Dolby-E data.