DVR systems DVR31xxH Series - Manual (Page 25)

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Audio transmission is similar to video transmission. Try to avoid interference, dry joint, loose
contact and it shall be away from high tension current.
Figure 3-3 Mini 1U Series
3.5.5 Audio Output
The audio output signal parameter is usually over 200mv 1KΩ (RCA). It can directly connect to
low impedance earphone, active sound box or amplifier-drive audio output device.
If the sound box and the pick-up cannot be separated spatially, it is easy to arouse squeaking. In
this case you can adopt the following measures:
 Use better sound pick-up with better directing property.
 Reduce the volume of the sound box.
 Using more sound-absorbing materials in decoration can reduce voice echo and improve
acoustics environment.
 Adjust the layout to reduce happening of the squeaking.
Please refer to Figure 3-4.
Figure 3-4 Mini 1U Series
3.6 RS485
When the DVR receives a camera control command, it transmits that command up the coaxial cable
to the PTZ device. RS485 is a single-direction protocol; the PTZ device can’t return any data to the