CompuLan Center dba/Digital IDView Technologies
12000 Ford Road, Suite 110
, Dallas TX 75234
12
2.6.4 Audio Signal Input
Audio port is a BNC connection.
The input impedance is high so the tone arm must be active.
The audio signal line should be firm and away from the electro magnetic Interference and connected
credible which avoids false and joint welding and oxidation. The high voltage current should be avoided
especially.
2.6.5 Audio Signal Output
Commonly the output parameter of a DVR audio signal is greater than 200m
v 1KΩ(BNC) which can
connect a low impedance earphone and active sound box or other audio output equipments through a
power amplifier. If the sound box and the tone arm can not be isolated, howling phenomena often exists.
There are some methods to deal with the above phenomena:
1
、
Adopt a better directional tone arm.
2
、
Adjust the sound box volume to be under the threshold that produces the howling phenomena.
3
、
Use fitment materials that absorb the sound to reduce reflection of the sound.
4
、
Adjust the layout of the sound box and the tone arm.
2.7 Alarm Input And Output Connections
Before connecting the device, please pay attention to the follow situations:
1. Alarm input
A. Alarm input is a grounding alarm input.
B. Alarm input demand is the grounding voltage signal.
C. When the alarm is connected with two DVRs or connected with a DVR and other equipments, it
should be isolated by relay.
2.Alarm output
Alarm output can not be connected with a high-power load (no more than 1A).When forming the output
loop it must prevent the big current from relay damage. Use the contact isolator when there is a high-power
load.
3.PTZ decoder connections
A. The grounding of the PTZ decoder and DVR must be shared otherwise the common-mode voltage
will lead to the PTZ control failure. The shielded twisted pair is recommended.
B. Avoid the entrance of high voltage. Make the layout reasonably. Take precaution from the thunder.
C. In the ou
tlying end connect 120Ω resistance paralleled to reduce the inflection and ensure the
signal quality.
D. The 485 AB lines of the DVR can not connect with other 485 output equipments paralleled.
E. The voltage between the AB lines of the decoder must be less than 5V.