Ensemble Designs BrightEye 57 3G/HD/SD/Analog Test Signal and Sync Pulse Generator - Manual (Page 6)

www.ensembledesigns.com BrightEye 57
TM BrightEye 57 3G/HD/SD/Analog Test Signal and Sync Pulse Generator User Guide
Page 6
Tri Level Sync
Tri Level Sync offers improved timing accuracy over traditional Bi-Level Sync. The analog output of a
standard sync generator is Bi-Level Sync. The timing reference is the 50% point of the leading edge.
The relative timing of this point shifts with changes in gain, DC reference, and frequency response.
The timing reference in Tri Level Sync is also at the 50% point of the sync pulse, but because this pulse
has both the positive and negative excursions, this point is the same as the DC ground reference. This
symmetry makes the signal virtually immune to time shift from gain, DC and response errors. The zero
point never drifts. The zero crossing is easy to detect every time which ensures timing accuracy.
The Tri Level Sync Generator block is configured in the BrightEye Control application to one of four HD
formats (1080i, 1080p, 720p, or 1080sF). The Tri Level Sync output frame rate can be selected between
23.98/50/59.94, the most commonly used family of frame rates, and 24/30/60, reserved for use with
special applications such as film.
The BrightEye 57 will apply the selected TLS frame rates to specific formats and line rates as shown in
the table below.
Frame Rate 23.98/50/59.94 Hz 24/30/60 Hz
Line Rate NTSC PAL NTSC PAL
1080i 59.94 50 60 50
720p 59.94 50 60 50
1080p 23.98 25 24 25
1080sF 23.98 25 24 25
Tone Generator Locked to Master Clock or External Reference
The Tone Generator is also locked to the master clock or the external reference, so the 48 kHz AES
output will be synchronous to the video outputs. In NTSC there are exactly 8008 audio samples in
every five video frames. There will be exactly 1920 audio samples in every PAL video frame.
Configurable Tone Generator
The Tone Generator can be configured for silence, a continuous tone, or an interrupted tone which is
coordinated with the Cyclops moving element. The Tone Generator feeds the Analog Audio outputs
through a precision digital-to-analog converter. It feeds an AES formatter to produce a standard AES
output. And finally, it is fed to an embedder (audio inserter) so that it will also be a part of the SDI
outputs.
Internal Timecode Generator
The internal Timecode Generator feeds DVITC on the SDI outputs and VITC on the composite outputs.
Timecode can also be selected in LTC form on the programmable Aux 1, Aux 2, and Aux 3 outputs.