Locking To External S/Pdif Sync Inputs; Locking To External Optical Sync Inputs; Video Sync; Video Levels - Apogee AD-1000 Operating Manual

The SAMPLE RATE Selector should be in the 6 o'clock – straight down – position. In this sync source mode, the
AD-1000 normally outputs the same frequency as the S/PDIF signal connected to the Sync Input. Two other
positions of the SAMPLE RATE Selector provide the unique ability to increase the input sampling rate by a 1.001
ratio.
Optical Sync Input
The optical sync source comes in via the optical cable input connector located on the rear panel. If the power
switch is in the NORM position, then this sync input acts in the same way as the S/PDIF or AES inputs do. If the
AD-1000 is selected to ADAT then the incoming signal is expected to be from an ADAT optical output. ADAT
input is only possible if the special AD1K-PRT option is installed. The SAMPLE RATE Selector should be in the
6 o'clock position. In this sync source mode, the AD-1000 normally outputs the same frequency as the ADAT
signal connected to the Optical Input. Two other positions of the SAMPLE RATE Selector provide the unique
ability to increase the input sampling rate by a 1.001 ratio.
Selecting an External Video Sync Source
A video signal is often used as a reference for locking a number of different pieces of audio and/or video equip-
ment together. The video signal is usually a very accurate sync reference and conveniently ties sound to picture.
The AD-1000's video sync source input is very flexible and can generate all the various sync output requirements
including many of the 0.1% (1.0x) derivatives.
In video applications it is important to match sound and picture. If sound and picture are not synchronized they
will drift depending on the differences between the two timing references. Timing accuracy is measured in parts
per million (PPM) difference from the ideal. Accuracy for various sources can be gauged by the time it takes for
two devices to drift one frame out of sync. The approximate times below assume worst-case conditions (one
reference fast, the other slow) and a frame period of 33 milliseconds.
Timing Accuracy vs. Drift
Common Timing Accuracy Standards: NTSC sync generators hold to 3 ppm

Video Levels

A video signal contains picture information in a sequence of thin lines and additional timing information to syn-
chronize (SYNC) the lines into a complete picture. The total video signal is represented as 1 volt peak-to-peak
(pk-pk) when driving into a 75 load. The picture part uses 0.7V pk-pk and the sync uses the remaining 0.3V pk-
pk. If the video signal is to be used just for sync purposes, a black picture can be used which consists of only
the 0.3V pk-pk part. Video sync information can also be distributed as a 4 volts pk-pk signal into 75
and 2 volts pk-pk into 75
In the AD-1000, the three different video standards supported are NTSC (525line/59.94 Hz), PAL (625line/50
Hz), and monochrome NTSC (525line/60 Hz). In each of these standards the input can be video, black video or
the higher level sync.
AD-1000 Operating Manual
1 ppm =
10 ppm =
100 ppm =
PAL sync generators hold to 1 ppm
AES/EBU digital audio holds to 10 ppm
Consumer digital audio typically holds to 50 ppm,
but can vary as much as 1200 ppm
for PAL.
4.6 hours (approximate)
25.25 minutes (approximate)
2.5 minutes (approximate)
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for NTSC