OmniTek 2.3 Relative A/V Delay Testing, Measurement using the Dolby-E RVF-based test sequence

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.

Transmission Path

RVF source

(e.g. OmniTek LAB)

OmniTek Delay

Measurement System

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.

OmniTek XR User Guide, Software Release 2.3 Page 113