Grass-valley 7600REF Manuel d'utilisateur télécharger pdf (Page 54)

54 7600 SD/HD/MHD-REF — Instruction Manual

Operation

tenance, or changes in local conditions in which the required signals have

been degraded such that time synchronization is lost.

Acquisition Process

With satisfactory reception, the acquisition process commences automati-

cally and takes around 15 minutes. An enhanced mode (Site Survey) is suit-

able for static installation and may be initiated from the Site Survey

selection on the GPS menu. A complete Site Survey can take around 2

hours. Once completed, it provides more accurate timing signals.

A 1 Pulse Per Second (1PPS) signal waveform is illustrated in

Figure 26. 1PPS Signal Waveform

The leading edge of the 6 ms wide, positive going pulse provides the timing

reference plane for locking external equipment.

Internally, this signal locks the 27MHz PLL Oscillator such that PAL output

signals are both frequency locked and phase locked. Any NTSC output

signals are frequency locked but cannot be phase locked.

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Grass-valley 7600REF Manuel d'utilisateur Page 54