Audio Input; Audio Output; Connecting To Alarm Input And Output - Dahua Smart 1U User Manual

4.2.3 Audio Input

These series products audio input port adopt BNC port.
Due to high impedance of audio input, please use active sound pick-up.
Audio transmission is similar to video transmission. Try to avoid interference, dry joint, loose
contact and it shall be away from high tension current.

4.2.4 Audio Output

The audio output signal parameter is usually over 200mv 1KΩ (BNC or 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.


Connecting to Alarm Input and Output

4.3
Please read the followings before connecting.
Alarm input
Please make sure alarm input mode is grounding alarm input.

Grounding signal is needed for alarm input.

Alarm input needs the low level voltage signal.

Alarm input mode can be either NC (normal Open) or NO (Normal Close)

When you are connecting two DVRs or you are connecting one DVR and one other device,

please use a relay to separate them.
Alarm output
The alarm output port should not be connected to high power load directly (It shall be less than
1A) to avoid high current which may result in relay damage. Please use the contactor to realize
the connection between the alarm output port and the load.
How to connect PTZ decoder
Ensure the decoder has the same grounding with DVR, otherwise you may not control the

PTZ. Shielded twisted wire is recommended and the shielded layer is used to connect to
the grounding.
Avoid high voltage. Ensure proper wiring and some thunder protection measures.

For too long signal wires, 120Ω should be parallel connected between A, B lines on the far

end to reduce reflection and guarantee the signal quality.
"485 A, B" of DVR cannot parallel connect with "485 port" of other device.

The voltage between of A, B lines of the decoder should be less than 5V.

Connecting Basics 22