directly connected to low impedance headphones, powered speakers or drive other audio output devices
through an amplifier. If spatial isolation cannot be established between external speakers and pickups, it
could result in a whistling sound. In the event, you may:
1、 Use pickups with better directivity;
2、 Adjust speaker volume to the level below whistle threshold;
3、 Use sound-absorbing materials in the working environment to reduce sound reflection and
improve room acoustics;
4、 Adjust the layouts of pickups and speakers to reduce the occurrence of whistling.
Connections to PTZ
A. The PTZ decoder must share a common ground with the DVR or possible presence of
common-mode voltage may cause you to lose control of the PTZ.
We recommend shielded twisted pair cable with its overall shield being used for common
ground;
B. Prevent against high-voltage power surge. Wire cables must be able to protect equipment from
lightning
C. Connect a 120 Ohm resistor in parallel at the far-end to reduce reflection and guarantee the
signal quality;
D. The AB-wire connections of the DVR’s 485 cable cannot be combined with 485 cables from
other output devices;
E. AB line voltage of the decoder should be lower than 5V.
Ground Wires of front-end equipment
Incorrect grounding may result in chips being burned.
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