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2.5.4 Audio signal output

Commonly the output parameter of a DVR audio signal is greater than 200mv

1KΩ(BNC)whichcanconnectalowimpedanceearphoneandactivesoundbox

orotheraudiooutputequipmentsthroughapoweramplier.Ifthesoundboxand

thetonearmcannotbeisolated,ahowlingphenomenaisoftenexperienced.

Here are some methods to deal with this phenomena.

1).

Adopt a better directional tone arm.

2).Adjustthesoundboxvolumetobelowthethresholdthatproducesthe

howling phenomena.

3).Usetmentmaterialsthatabsorbthesoundtoreducethereectionofthe

sound.

4).Adjustthelayoutofthesoundboxandthetonearm.

2.6 Alarm input and output connections

1. Alarm input

A. Alarm input is grounding alarm input.

B. Alarm input demand is the grounding voltage signal.

C. When the alarm is connected with two DVRs or connected with DVR

  andotherequipments,itshouldbeisolatedbyrelay.

2. Alarm output

 Alarmoutputcannotbeconnectedwith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 earth for the PTZ decoder and DVR must be shared otherwise

  thecommon-modevoltagewillleadtothePTZcontrolfailure.Shielded

twisted pair is recommended.

B. Avoid high voltage. Take precaution against the thunder and lightning.

 C.Attheoutlyingendconnectaparallel120Ωresistancetoensurethe

signal quality.

D. The 485 AB lines of the DVR can not connected with other 485 output

equipment in parallel.

E. The voltage between the AB lines of the decoder must be less than 5V.

4. Front equipment grounding note

Bad earthing can lead to burnout of the chip.

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Lo-Call 1890 866 900

e-sales@cctvireland.ie

Qvis DVR series User Manual

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