Camera connection
Possibilities for connecting cameras available in the registrar.
For analogue DVRs and digital NVRs (see "Type") in this case, everything is simple: the number of video channels corresponds to the largest number of incoming video signals that can be connected to the device. Such a signal can come both from a camera and from an intermediate device — for example, a quad that combines a picture from 4 cameras. But in hybrid HVRs, the meaning of this paragraph is more specific. For these recorders, this specifies the maximum number of inputs that the device can handle in AHD only mode (i.e., analogue cameras only, no IP cameras). Data on hybrid mode (AHD+IP), as well as for using only IP cameras, are given separately for such recorders (see below).
Numerous channels (
32 channels,
64 channels and even
128 channels) allows you to create an extensive video surveillance system based on the registrar without using additional equipment (for example, the same quads). On the other hand, this characteristic significantly affects the price, and for living conditions,
registrars for 4,
8 or
16 cameras are quite enough.
RCA audio input
The number of
RCA analogue audio inputs provided in the design of the registrar.
Inputs of this type are used to connect the audio signal from analogue cameras capable of capturing sound, as well as from separately made microphones. At the same time, the number of such inputs can correspond to the number of BNC video inputs, which allows each analogue camera to be supplemented with sound. However, there are models that have only one RCA input with several BNC inputs.
RCA audio output
The number of
RCA analogue audio outputs provided in the design of the registrar.
This type of output is used primarily for audio output when viewing footage, in addition to the BNC and/or VGA output. Therefore, there are few such connectors in modern registrars — one, less often two (one each for BNC and VGA).
USB 3.2 gen1
The number of
USB 3.2 gen1 ports in the design of the registrar. This interface is used to connect various peripheral devices: USB drives for copying files or updating firmware, keyboards, mice, etc.
Specifically, USB 3.2 gen1 is the successor to USB 2.0. It supports higher data transfer (up to 4.8Gbps) and higher power supply.
Alarm input
The number of alarm inputs provided in the design of the registrar.
Alarm inputs allow the recorder to respond to various events and signals from other elements of the security system. For example, a door opening sensor can be connected to such an input, and upon a signal from it, the registrar will turn on the camera above this door. This ensures the automation of the security system and makes it less dependent on the human factor.
Alarm output
The number of alarm outputs provided in the design of the registrar.
Alarm outputs are used to transmit signals from the recorder to other elements of the security system — an alarm siren, electronic locks, spotlights, etc. Thus, the system can automatically respond to events recorded by the registrar — for example, block the doors when moving in the frame.
RS-232
The presence of an
RS-232 service interface in the recorder (also known as a COM port). Through such a connector, it is usually possible to remotely control the device’s operating parameters from a computer or specialized equipment using appropriate software. Also, the RS-232 port can be used to update the recorder firmware.
Bandwidth
The maximum data stream in Mbit/s that the NVR is capable of processing when recording and displaying. The throughput parameter is specified as the maximum incoming/outgoing speed, or as the sum of incoming and outgoing streams (total throughput). It is calculated in such a way that the throughput exceeds the total flow of all IP cameras connected to the DVR, and another 25–30% is put in reserve for playing video or viewing it via network access.
Resolution (all channels)
The highest resolution in which the recorder can record video when a signal is received from all channels simultaneously. If cameras are not connected to some channels, the recording resolution may be higher (see “Maximum Resolution”).
Higher resolution has a positive effect on detail, but takes up more space and requires more computing power for processing, which accordingly affects the price of the registrar.
