Comparison Hikvision DS-7632NXI-K2 vs Hikvision DS-7604NXI-K1/4P

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.

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.

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.

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.

The number of SATA connectors provided in the design of the registrar.

SATA is the most popular modern interface for connecting internal drives. One connector allows you to connect one hard drive (or other internal media), that is, the number of such connectors is, in fact, the largest number of separate drives that can be installed inside the recorder at the same time. Basic versions can be equipped with one SATA connector or two. More advanced ones have 4 SATA connectors, and already models for serious objects have much greater connectivity.

The largest total storage capacity with which the recorder is able to work correctly. By default, it is indicated only for internal media with a SATA interface (see above), however, in some models, data is also provided separately for external devices connected via eSATA.

Note that the limit on the total capacity follows from the fact that each individual port has its own limit on the capacity of the drive. In this case, the maximum capacity is distributed equally between the ports. This should be taken into account when choosing drives for the registrar: for example, in a 32 TB model with 8 SATA connectors, the limit for each connector will be 32/8 = 4 TB. This means that installing two internal 8 TB disks in such a registrar will not work, although their total capacity will be less than the maximum.

The PoE (Power over Ethernet) technology itself allows you to transmit not only data, but also energy to power network devices via an Ethernet network cable. And the presence of PoE output(s) makes it possible to power such devices from the network connectors of the recorder. This eliminates the need to lay additional wires or use independent power supplies, which can be especially important for some equipment, such as external IP surveillance cameras. And when using so-called splitters - devices that separate the PoE cable signal into purely network data and supply power - using such outputs you can also power equipment that does not initially support PoE (the main thing is that their power characteristics match the capabilities of the switch).

As for PoE standards, they determine not just the overall power supply, but also compatibility with specific devices: the consumer must support the same standard as the recorder, otherwise normal operation will be impossible. Nowadays, including in switch connectors, you can find two types of such standards - active ( 802.3af, 802.3at, 802.3bt) and passive (one is called that). The main difference between these varieties is that active PoE provides for matching the power source and load in terms of voltage and power; passive PoE does not have such functions, and energy is supplied “as is”, without adjustments. Here is a more detailed description of speci...fic standards:

- 802.3af. The oldest active PoE power format in use today. Provides power output power up to 15 W (at the consumer input - up to 13 W), output voltage 44 - 57 V (input - 37 - 57 V) and power in a pair of supply wires up to 350 mA. Despite its “venerable age”, it still continues to be widely used; so there are still quite a lot of recorders that work only with 802.3af on sale (as of the end of 2021). However, it is worth considering that this standard covers 4 so-called power classes (from 0 to 3), differing in the maximum number of watts at the output and input. So when using 802.3af, it doesn't hurt to make sure that the output power is sufficient for the selected load.

- 802.3af/at. A combination of two standards at once - the 802.3af described above and the newer 802.3at. The latter allows you to supply power up to 30 W to the output (up to 25.5 W at the input of the powered device), uses a voltage of 50 - 57 V (42.5 - 57 V at the input), while the power in a pair of wires does not exceed 600 mA. This combination is relatively inexpensive, but it makes it possible to power a wide variety of external devices; so at the end of 2021, it is this type of PoE output that is most popular among recorders.

— 802.3af/at, bt. A combination of 802.3af/at described above with the 802.3bt standard (PoE++, PoE type 3 or type 4). 802.3bt is the newest of the PoE power formats; Unlike earlier ones, it uses not 2, but 4 power wires, which allows you to supply very significant power to external devices - up to 71 V (with 90 W at the power output). Such capabilities can be indispensable when supplying energy to equipment with high consumption - for example, external surveillance cameras, supplemented by heating systems. On the other hand, support for the 802.3bt standard significantly affects the cost of the recorder, and such a connection places special demands on the quality of the cables. In addition, you need to keep in mind that this standard also includes the UPoE format, created by Cisco and used in its equipment; and this standard (it is known as PoE type 3) has a more modest power - up to 60 W at the output (up to 51 W at the consumer input). And the general 802.3bt standard includes two power classes - class 8, in which maximum performance is achieved, and class 7, where 75 W is supplied to the output and about 62 W reaches the consumer. So if you plan to use 802.3bt equipment, when choosing a recorder from this category, you must make sure that the power supply is sufficient for the normal operation of the connected devices.

- Passive. As already mentioned, the key difference between passive PoE and the active standards described above is that in this case the power output produces a strictly fixed power, without any automatic adjustments or adjustments for a specific device. The main advantage of this standard is its low cost: its implementation is much cheaper than active PoE, so such ports can be found even in entry-level recorders. On the other hand, the aforementioned lack of auto-tuning makes it much more difficult to coordinate equipment with each other - especially in light of the fact that different devices can differ significantly in the output/consumed voltage and power (power). Because of this, when using passive PoE, you need to pay special attention to the compatibility of the source and load in these parameters. If there is no match, then in the best case (if the voltage/power at the output is lower than required) the power simply will not work, and in the worst case (if there is excess voltage/power) there is a high probability of overloads, overheating and even breakdowns with fires - and such troubles may not occur immediately, but after quite a considerable time. And you definitely cannot connect devices with active inputs to passive PoE outputs - for the same reasons.

Number of LAN ports (RJ45) with PoE support provided in the recorder design.

These connectors are intended for connecting IP cameras. And PoE technology makes it possible to supply power to such a camera directly via the connection cable, thus dispensing with a separate connection to an outlet and without batteries/accumulators. Of course, to use this technology, the camera connected to a similar port must also use it. Most often, the number of channels corresponds to the number of PoE outputs (this can be 4 outputs, 8 or even 16 ports). But there are always exceptions.

The total power that the NVR is capable of delivering to all PoE outputs.

See above for details on such exits; here we only recall that the general idea of PoE is to supply power over the same Ethernet cable that transmits data. The total power is given for models in which there are more than one such connectors; it allows you to estimate the total power consumption of all PoE devices that can be connected to the NVR at the same time.

There are two important things to keep in mind when choosing a specific value. First, when multiple ports operate, the energy is usually shared equally among them; at the same time, the total power of the registrar does not always correspond to the sum of the maximum powers of all PoE outputs. For example, a model with 8 ports of 30 W each may have a total figure of not 240 W (8 * 30 W), but only 100 W. In fact, this discrepancy means that with the simultaneous use of all connectors, each of them will be able to deliver not 30 W, but a maximum of 100/8 = 12.5 W. The second point is that the total power consumption of the load should ideally be no higher than 75% of the claimed total PoE power — this provides an additional guarantee in case of malfunctions.