Dolby Laboratories CP500 Specifications download pdf (Page 147)

D-3

Sample Rate Conversion

The sample rate of the data comming from the film is determined ultimately by the

projector speed. For correct operation of the CP500, all data must be at a fixed

sample rate. The Cat. No. 680 Bit Rate Converter Card performs this function.

Discussion of Changeover Technique

Projector changeover sensing is provided through the 9 pin female D-connector

"Motor Start" on the CP500 rear panel. In single projector applications, all

terminals may be left unconnected, and the CP500 will assume projector 1. If

reversion to analog tracks is desired, the motor start signal must be provided,

otherwise the CP500 will not revert to analog, as without a motor running, the

CP500 assumes no analog track is playing. The motor start signals are used to

signal the CP500 in advance of a changeover in order that the video front end can

switch to video from the incoming reel prior to the actual picture changeover. The

changeover to the incoming projector CCD signal will be made at a time after the

Motor Start signal equal to (8 seconds minus the fixed delay value.) Removal of

the Motor Start signal prior to video changeover resets the changeover timing,

allowing the operator to “jockey” the placement of film in the projector for

between 1.5 and 7 seconds, depending on delay setting, without initiating a

changeover. Verification of changeover is confirmed by the Changeover signal at

the actual instant of changeover. If no Motor Start signal is asserted, the video

input follows the changeover signal.

Auxiliary Data Channel

The Auxiliary data channel may be monitored using an RS-232 compatible device.

The data format is RS-232 standard 115,200 bits/second, 8 bit data, no parity, 1

start bit, 1 stop bit. Connection to the data channel is provided through the DB-9

female connector, "Serial Data", on the rear panel. The data channel supports RS-

232C signal levels. The connector is wired as DCE (Data Common Equipment)

with TXD (Transmit Data) on pin 2 and signal common on pin 5. Pins 4 and 6 are

shorted, as are pins 7 and 8, to allow direct connection to a standard PC serial port.

The connector case is wired to chassis ground.

Serial Data Connector

Pin assignments

1n.c.

2 Serial Data Out

3 Serial Data In

4 Connected to pin 6

5 Signal Ground

6 Connected to pin 4

7 Connected to pin 8

8 Connected to pin 7

9n.c.

1 2 ... 142 143 144 145 146 147 148 149 150 151 152 153 154

No comments

Dolby Laboratories CP500 Specifications Page 147