Comparing Analog vs IP PTZ Camera System
There are plenty of articles and videos covering the difference between analog and IP camera systems but few of them has specifically mentioned the factor of pan tilt zoom camera and how this particular feature has affected the performance of two systems.
In this article, we would be introducing the key difference between analog PTZ cameras and IP PTZ cameras, and why A LOT OF customers are still using analog system.
1. Video Connection Interface
Analog PTZ cameras use BNC interface to transmit video data. It would be connected to a BNC cable, and there are other names for the cable such as RG59 or Coaxial. The cables are recommended to be shielded to prevent from signal interference. There are available shielded BNC cables available in the market that can be obtained easily. The maximum video output for conventional analog PTZ cameras, limited by CVBS signal, is 700TVL which is equivalent to 960H (note this is an approximate value as analog image quality is measured by TV Line instead of megapixel).
Meanwhile, IP PTZ cameras use Ethernet for video transmission as well as control. It comes with a female RJ45 connector. IP cameras are generally available in a lot higher resolution starting from 720p to 4K.
It is also to be noted that BNC cables are susceptible to interference. In addition, the coaxial cable itself could be greatly affected by weather and temperature. Since it is thicker, it is not convenient for wiring in intensive monitoring projects comparing to Ethernet cable.
2. PTZ Control Interface
As briefly mentioned above, coaxial cable (BNC) can only transmit video signals. If the system needs to transmit control data, audio and other signals at the same time, it needs additional wiring.
Most analog PTZ uses RS485 interface to control PTZ of the camera over Pelco P/D protocol. The DVR/PTZ Controller(joystick) needs to support the corresponding protocol in order to communicate with the PTZ camera. Note a lot of analog PTZ manufacturers have stopped integrating Pelco P into their analog cameras and select the newer protocol Protocol D as the primary communication protocol.
You will find out two types of RS485 connectors that are applied in DVR, and PTZ Controller.
The RS485 cable is a twisted pair that could be either a telephone line or a pair from the Ethernet cable (each Ethernet cable has 4 twisted pairs).
Some of the PTZ cameras support coaxial control over AHD DVR, meaning you don’t need to run a separate RS485 cable to enable PTZ control. However, this would sometimes cause signal interference. For example, the camera might appear to have stripped lines (horizontal bars) on the monitor while performing pan tilt zoom actions.
IP PTZ cameras, instead, can transmit both videos and control signals through Ethernet cable so you don’t have to run additional lines just to enable PTZ control.
3. Power Input
One of the greatest advantage for IP PTZ camera is the ability to run the camera through PoE (power over Ethernet).
Power over Ethernet technology allows you to run one Ethernet cable and supply both power and data signal to the camera.
The key advantage of PoE is its stability against wireless IP cameras and the ease of running just one cable comparing to analog PTZ cameras, which you will need to run BNC, power and RS485.
For analog PTZ cameras, running DC12V is the only option for powering the camera. Note since analog PTZ cameras require a lot more power than analog bullet camera, there are many wrong practices in powering analog PTZ cameras that are widely seen.
- Using Balun RJ45 to DC connector + ethernet to power the camera. This would cause significant voltage drop.
- Using 3-in-1 cables, this would cause both voltage drop but also interference.
Powering analog PTZ cameras are critical and you often have to install AC power source nearby or use thick AWG cable as power line. Meanwhile, PoE also experiences a lot less voltage drop and is ideal for running long distance of transmission.
Analog PTZs are a lot more cost-effective comparing to IP cameras. However, the price of HD IP PTZ cameras have dropped significantly in the last few years. Moreover, network PTZ cameras have better intelligent expansion capacity than the analog system, and can get regular firmware upgrade maintenance from the manufacturer.
On the other hand, IP cameras have lower cost of maintenance and after-sales support as it can be viewed through desktop and is easy to schedule a remote help session with manufacturer. Meanwhile, the benefit of PoE (running one ethernet cable for everything) makes it easy for hardware replacement and troubleshooting.
5. Latency and Some Benefits for Analog System
Though IP network system appears to be dominated these days, there are still primarily 3 benefits for using Analog PTZ cameras over IP:
1) some properties have pre-installed conventional analog wiring so it would be relatively easy to take down the old camera and replace it with the new one.
2) analog PTZ has minimal video transmission latency comparing to IP network system because the transmission is point to point (camera to monitor). For latency dependent tasks, analog system might still be a cost-effective option as it is more close to “real-time” without the need of encoding/decoding.
3) security purpose is another thing that drives some end-users to keep using analog PTZ cameras because IP-based equipment tends to face various types of attack while connecting to the internet. There are of course measures to separate and secure the network for surveillance but getting an analog system would be a reasonable alternative.
6. The Application of Analog-HD
While analog-HD seems to be a great option for saving cost and getting high quality video, the main issue for the promotion of analog-HD system is compatibility.
There are many different types of analog-HD systems including HD-TVI, HD-CVI, HD-SDI and AHD. Obviously major manufacturers would like to promote their own analog-HD system so when analog-HD first releases, different types of protocols are not cross-compatible, meaning you cannot add an AHD camera to a HD-CVI DVR.
Moreover, each HD-CCTV technology develops quite fast and the evaluation of one technology available online at one time doesn’t represent its performance several month later. For example, AHD technology has limited channel configuration in 2016 and the problem was fixed several months later. Meanwhile, most so-called comparisons weigh heavily on one type of technology (usually the one they are selling).
Later around 2017, there are hybrid DVRs available that claims to support HD-TVI, HD-CVI and multiple types of AHD video formats. Those DVRs, as our engineers evaluated, are likely to cause interference issues and compatibility issues especially if you use coaxial mode for PTZ control.
The bottom line is if you would like to purchase an HD-CCTV or analog-HD PTZ camera, please remember to get the DVR and camera together from the same manufacturer, otherwise there is a likelihood that you would be experiencing a lot of trouble.