An IP surveillance camera shoots video and broadcasts a video stream digitally using a network protocol that provides packet routing. Essentially, an IP camera is a surveillance camera plus a mini computer. It consists of a sensor, lens, central processor, processing processor, compression processor, and network interface.
How an IP camera works
The lens focuses the image on the sensor. The sensor converts the color into an electrical signal. The signal goes to the processor for color, brightness, and other processing. The video stream goes to the compressor. The compressor compresses the stream – the data is now ready to be sent to the network via an Ethernet controller.
Each IP camera has its own IP address transmitted with the connection and used to synchronize the camera with the recorder: With a command or a special program, the recorder uses the IP address of the camera and connects to it. Without an IP address, it is not possible to set up the equipment to work together or to access the IP camera from a mobile device.
Thanks to digital stuffing IP-camera functionality tends to infinity at the expense of variety of software, and data can be accessed from any remote place of the planet where there is internet.
What IP cameras are connected to
IP camera transmits the video stream to a recorder (server), PC (with appropriate software), in the cloud (SaaS solution, software as a service).
Several IP-cameras are connected to the recorder via a router, switch or each to a separate port (if available). A router or switch that supports the network protocol of dynamic node configuration automatically distributes addresses and other network settings.
IP camera – low power equipment. Powered by an adapter, PoE switch or DVR if it supports PoE. PoE – Power over Ethernet, supplying power via Ethernet network, over twisted pair simultaneously with data broadcasting.
Connecting IP-cameras to PC depends on the number: if one camera, connect to LAN-interface of network card, if a few, connect to LAN switch, and already to it – IP-cameras, then make a network connection with assigning each a new network address.
Data transmission mechanisms, network and protocols
IP cameras work with the TCP/IP protocol stack. TCP/IP is a networking model with four layers of data flow: application, transport, network, network access.
Distribution of protocols by layer:
Application – HTTP, RTSP, FTP, DNS, etc.
Transport – TCP, UDP, SCTP, DCCP, etc. (RIP, routing protocols such as OSPF, working on top of IP – part of the network layer).
Network – IP (auxiliary protocols, such as ICMP and IGMP, working on top of the network protocol, but belonging to the network layer, and ARP – an independent auxiliary protocol, working on top of the data link layer).
Network Access Layer – Ethernet, IEEE 802.11 WLAN, SLIP, Token Ring, ATM and MPLS, physical media and information coding principles, T1, E1.
Transport protocols
TCP – guaranteed protocol (in the first test the package went 150,000 km without losing a single bit of information), it uses commands to pre-establish a connection, then starts transmitting data; it keeps track of the data and their sequence, adjusts the translation speed so that the data are not transmitted more heavily than they can be received. Corrects errors – sends a double if a packet is lost, and corrects an error if two identical packets arrived at the same address.
RTP is a protocol for transmitting traffic in real time. It includes data synchronization and packet sequence correction.
UDP – is an alternative to TCP, but does not establish a preliminary connection, and immediately begins broadcasting. It does not watch for data reception and does not duplicate in case of lost packet retrieval. Less reliable, but faster.
In terms of speed and transmission of real-time traffic, it is preferable to RTP or UDP, but in problematic networks, TCP is indispensable, because it corrects errors and corrects failures.
Interoperability protocols
Devices from one vendor are compatible by default. IP cameras support application protocols for compatibility with devices from other manufacturers. Mainly RTSP and ONVIF.
RTSP is an application protocol for remote control of an IP camera, with a description of flow control commands. Provides solely control of IP cameras by a server. It has nothing to do with compression, packets, transport protocol definition. Data transmission as such is not part of RTSP – there is a standard real-time transport protocol for that. RTSP requests go separately from the stream – through a special port.
The Profile S specifications define:
Configuration of the network interface.
Discovery of devices using the WS-Discovery protocol.
Management of camera operation profiles.
Streaming configuration.
Event handling.
PTZ control.
Security (access, encryption).
IP camera with internal archive meets the requirements of the two specification profiles.
How the IP camera transmits its signal
There are three ways: wired, wireless and hybrid (two ways: wired and wireless).
Wired connection provides a stable and high-speed broadcast, but requires the installation of networks that are limited in length by the type of cable: 100 m for twisted pair, 500 m for coaxial, 100 km for fiber optic (not including repeaters or switches).
For wireless broadcasting, the IP camera is built in Wi-Fi module (most often) or 3G/4G module. Transmission range is limited and reduced due to physical obstacles in the direction of the router and electromagnetic interference.
IP cameras with hybrid data transmission use wired and wireless communication, providing increased reliability of the local network.
Ethernet: The IP camera’s transmission medium
The IP camera runs on an Ethernet network, a technology that connects devices into a local area network (LAN) for packetized data transmission. A video surveillance system based on IP cameras needs only the usual local office network that habitually connects computers.
Ethernet is described by the standards of the IEEE 802.3 group. The standards define frame formats and medium access control protocols at the data link layer of the model of interaction between devices with each other.
A brief list of network modifications to the standards (maximum segment length is specified)
- Over twisted pair:
Ethernet, 10 Mbps: 10BASE-T – Cat. 3 and higher, 10BASE-T – two twisted pair Cat. 3 or Cat. 5 (100 м).
Fast Ethernet, 100 Mbps: 100BASE-T – Cat. 3 and Cat. 5 (100 м).
Gigabit Ethernet, 1000 Mbps: 1000BASE-T – Cat. 5e (100 m).
Intermediate Ethernet standards, 2.5 Gbit/s and 5 Gbit/s, respectively: 2.5 GBASE-T and 5GBASE-T – Cat 5e and Cat 6 (100 m).
10 Gigabit Ethernet, 10 Gbit/s: 10GBASE-T – cat. 6 (55 m) and 6a (100 m).
IP camera network interface – RJ45
IP camera network connector
- Via coaxial cable at 10 Mbps: 10BASE5 – RG-58 (up to 185 m), 10BASE2 – RG-8 (500 m).
- Optical cable (single-mode – fiber with the core diameter 7 ~ 10 times the wavelength of the light passing through it, multi-mode – fiber with a larger core diameter, which conducts light rays due to the total internal reflection):
Ethernet, 10 Mbit/s: FOIRL – up to 1 km, 10BASE-FL – up to 2 km.
Fast Ethernet, 100 Mbit/s: 100BASE-FX – multimode fiber, 400 m/2 km (half duplex/duplex*), 100BASE-SX – multimode fiber, 2 km/10 km (half duplex/duplex), 100BASE-FX WDM – singlemode fiber (primary use – transceivers).
Gigabit Ethernet, 1000 Mbit/s: 1000BASE-SX – multimode fiber (500 m), 1000BASE-LX – multimode fiber (550 m), single-mode fiber (5 km), 1000BASE-LH – single-mode fiber (100 km).
10 Gigabit Ethernet, 10 Gbit/s: several standards, from 26 m to 40 km.
Faster Ethernet is not yet used in video surveillance systems.
*Duplex mode of data exchange – sending and receiving simultaneously on two communication channels, half-duplex – one channel at a time.
To broadcast over coaxial and fiber optic cable you need a signal extender for coaxial cable and SFP-module for fiber optic. Sometimes the fiber port is built into the IP camera, but in most cases the network is laid at the switch level with SFP ports.
Features of IP-Surveillance Cameras
The main difference and the first advantage of an IP-Surveillance Network Camera is the digital video signal from the light sensor to the server.