About Audio Signals
Audio signals are not all the same. There are four different types of audio signals:
- Microphone (Mic) level
- Instrument level
- Line level
- Speaker level
This article will focus on the two forms commonly encountered around NVRs and surveillance equipment, Mic Level and Line level.
Mic level signals, those coming from a microphone, are the weakest. These signals are usually in the range of 0.001 to 0.01 volts. Devices in this range require a pre-amp to increase the signal to line level voltage.
Line level signals, from pre-amps, are stronger than mic level. These signals usually range from 0.3 to 1.2 volts. Consumer devices are on the lower end of that range, while professional devices tend to be on the higher end of the range.
Connecting a device sending mic level output to a line level input will leave you unable to hear anything. The voltage is too low for what the input requires. Likewise, if you connect a line level device to a mic level input the result is clipping and distorted sound that is too loud because it is providing too much voltage for the input. <br><br>
System Audio Connectors
The style of connector used does not necessarily tell you whether to expect line level or mic level signals.
The system board audio inputs on many ExacqVision systems include 3.5mm jacks for line level input and mic level input, as illustrated below. While the terminal inputs for Hybrid systems are line level only.
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Audio Devices in ExacqVision Software
ExacqVision IP NVRs will only have audio inputs and outputs on the system board. These connections are found on the same panel as the network ports, monitor outputs, and USB ports on the rear of the server.
Within the ExacqVision Desktop Client software, in Configuration mode, you will find these inputs by expanding the Server name from the navigation tree along the left-hand side. Then expand Configure System and the System Audio node. Click on the Audio Inputs/Outputs node under System Audio to find these devices.
ExacqVision Hybrid NVRs have additional hardware for analog audio/video inputs. Video connections are made by BNC connectors. Audio connections are made via terminal inputs. Some legacy systems could still be encountered that used with wiring harnesses in which both video and audio were connected via BNC.
On these Hybrid systems audio inputs are found in two locations within the Client software. The system board inputs are found, as noted above. The additional analog input terminals will be found by expanding the analog board node on the navigation tree. Modern ExacqVision systems list this as tDVRxxxx. Expanding this board on the navigation tree and clicking the Audio Inputs/Outputs node beneath it reveals the analog audio input terminals.
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