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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.
2.8 Alarm Input and Output Connection
There are two alarm input types for you to select: normal open (NO) and normal close (NC).
Alarm input
Alarm input supports grounding alarm input.
When the alarm device is connecting one DVR and one other device, please use a relay to
separate them.
Alarm output
The alarm output max load shall be less than 0.5A. It should not be connected to high power load
directly to avoid high current which may result in relay damage. P lease use the co contactor to
realize the connection between the alarm output port and the load.
PTZ connection
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.
Device A/B cable cannot parallel connect with the 485 port of other device.
The voltage between of A, B lines of the decoder should be less than 5V.
Make sure the front-end device has soundly earthed
Improper grounding may result in chip damage.
Alarm input type
NO (Normal open)/NC (Normal close).
2.8.1
Alarm Input and Output Details
Alarm input and output interface is shown as in Figure 2-13.
