Support - Technical Article

Various Redundancies for Enhanced Reliability

In shaping the present and future of video surveillance, storage devices like DVRs and NVRs play a prominent role in any overall security system. Obviously, both are used to store large amounts of data and video; hence if a crash occurs – or either experiences disk / power failure – there are potentially huge negative consequences. This is why, at PACE, we place a tremendous amount of emphasis on the overall system reliability of both our DVR and NVR components.

Additionally, our R&D team continues to devote ourselves on the development of high quality customer-oriented products.

Our product platform offers both a primary operating system and a backup. In the event of a main system crash, the back-up system is automatically activated, allowing the DVR to continue recording.

To kill glare light at night -- PACE HLS (High Light Reversion) technology

conventional camera
Conventional Camera HLS Camera
   

Recent years, the camera's image performance during night /low light conditions has been greatly improved in video surveillance industry; nonetheless legibility under wider array of light frequencies is still a consistent impediment for the ever-demanding details detection.

A good example is the vehicle's detection during night, as the image (1) described, conventional camera's lens may suffer serious glare interferences while a vehicle enters the target field of view. Here, the vehicle's detail such as its license plate is not visible. To a certain extent, a small vehicle's headlight can easily outfight the whole surveillance system at this critical moment.

With continuous effort on image quality enhancement, PACE HLS (High Light Reversion) technology is developed to solve this issue. As the image (2) referred, HLS technology is able to decrease maximally the glare disturbance such as the vehicle's headlight, making the entire video surveillance system more vital during the night monitoring of moving vehicles, especially in terms of parking lot management, access controlling efficiency, intrusion detection etc.

As to date, PACE has HLS models in analog camera range to satisfy users' real needs. For more information, please visit PACE website at:

Five Ways to Distinguish a Critical Mobile DVR

Transportation is part of nearly everybody's daily life; people use vehicles for work and leisure travel, schools dispatch buses to pick up students and send them home, logistics companies use vehicles to deliver goods. We can say the very fabric of society - people and assets - are being transported from one place to another every minute of every day Securing them is obviously extremely important. A mobile DVR has one of its prime roles in helping to secure such situations, protecting people flow and assets and ensuring the safety of traffic environments.

Many customers confuse mobile DVRs with regular DVRs, Though the functionality of a general-purpose DVR and a mobile DVR may be similar, it is not a case of "one type fits all." The comparison is more like adapting a novel into a movie, where different uses create different possibilities. A mobile DVR is specifically designed for vehicles, such as buses, armored cars, subway trains, etc. A good quality mobile DVR can record for a continuous time without failure; it can withstand the frequent vibration and unstable power supply associated with vehicles, factors which are fatal to a regular DVR. It can provide evidence of traffic accidents and terrorist attacks while uploading alarm information to a control center in emergency situations. A good quality mobile DVR will also have a long life span and give stable performance, which helps customers to reduce maintenance costs.

The main difference between a regular DVR and a mobile DVR lies in the environments in which they are meant to be used. We give here five factors which define an appropriate mobile solution: power supply, anti-vibration mechanism, dust prevention and heat dissipation, solid interface and data transmission.

1)Power supply
As a mobile DVR can only be located on the vehicle, its power supply must be drawn from the vehicle as well. In vehicles, the voltage is currently 12V, 24V, 110V, and is not as stable as that of indoor locations, especially during engine start-up and braking when voltage can fall to 9V or less. This creates a very unstable power supply. Electronics are very sensitive to power surges and spikes, and equipment fails quickly if they are not handled properly. Additionally, the mobile DVR acts as a hub that stabilizes power for sensors and cameras. However, some manufacturers use low-quality power supplies to reduce costs, but this inevitably shortens the life span of their products. So, indentifying a mobile DVR with an excellent power supply is crucial. Here we list some international standards relating to power systems for your reference: ISO 7637-2: 2004, JASO D001-94, SAE-1455. Customers can refer to these standards when buying mobile DVRs.

2)Anti-vibration mechanism
Since vehicles are constantly in motion, vibration is inevitable. Constant vibration leads to mechanical failure if it is not considered during design. One of the factors that sets rival products apart is the materials used for anti-vibration mechanisms. Most manufacturers use rubber to contain vibration since use of rubber lowers production costs. However, it deteriorates over time. Generally, rubber guarantees performance in short time frames but is susceptible to heat and cold, which softens or hardens the rubber. Higher-end mobile DVRs use wire rope, which ensures performance regardless of external factors.

3)Dust prevention and heat dissipation
Mobile DVRs are generally installed in confined spaces and compartments. This exacerbates the problem of heat dissipation because mobile DVRs are required to operate for a long time in such a confined environment. The challenge here is twofold. If you try to fit fans to the DVR, you will inevitably leave an opening in the enclosure and make it more vulnerable to dust. For this reason, fans are not acceptable for mobile DVRs, and an alternative approach must be considered. Aluminum is the preferred material for enclosures as it allows heat to dissipate even when it is completely sealed in. Low-cost mobile DVRs may use aluminum alloys instead of pure aluminum to reduce costs, but they will prove incapable of handling dust and heat adequately.

4)Solid interface
Due to the constant vibration on and within vehicles, a solid interface which combines devices is crucial to ensure a continuous and stable running environment. A BNC interface is standard for regular DVRs but it is not suitable for mobile DVRs since the BNC interface can easily loosen due to frequent bumps. A high-end mobile DVR adopts a solid aviation specification interface, it can sustain vibration, ensuring continuous transmission of power, signals and other data without failure. However, some manufactures use a common aviation specification interface which is not eco-friendly and is not sufficiently solid; such interfaces can easily break down over time.

5)Data transmission
In the past, transmission was the weakest link for many mobile DVRs but this has changed due to advances in wireless technologies. Previously, innovation in mobile DVRs was slow as the limited transmission options constrained how manufacturers could add value for users. Even Wi-Fi was not as significant as some thought it would be due to its Bandwidth fluctuation. The availability of 3G networks has enabled a wide variety of new functions. For example, it was not previously practical to transmit data collected from the vehicle in real-time, such as video, location, brake signals, speed and inertial measurements. However, all of this can be achieved in a mobile DVR.

The above advantages and features have seen mobile DVRs being widely used in the transportation sector, Mobile DVRs are surely the best choice for mobile surveillance due to their professional design for use in vehicles. In view of traffic accidents, legal mandates have been formulated to strengthen surveillance protection. For this reason, the potential mobile surveillance market may become very large. Customers should be aware of the features of mobile DVRs, selecting appropriate solutions in different applications accordingly.

Hardware Compression System vs. Software Compression System

PC-based DVR systems have become the choice for surveillance system integrators and users due to their higher scalability, flexibility and ease of customization. However, choosing a hardware compression system or software compression system can make a big difference.

By PACE Digital Technology

PC-based DVR systems appeal to system integrators and users because of their unique flexibility and scalability. By adding more compression cards, the system can support more video channels, and desired functionality can be achieved by adding daughter boards. In addition, the provided SDK allows the DVR system to be customized to meet specific requirements. A PC-based DVR system captures surveillance video in real-time and saves it to your hard drive. To do this, it has to gather the signal, and compress it, and save it to a video file on your drive. Every card captures a certain number of frames per channel (for example, a 16-channel card that captures 100 frames per second in total, captures 6.25 per channel, whereas one that captures 400 fps, can capture 25 per channel). Then, the system must compress it and save it. Either using a software process, or the DVR card itselfdoesit.

It's important to note that a PC-based DVR system can be made using either a software compression card or a hardware compression card. As the name suggests a software compression system (SCS) uses the card to capture the signal, and software to compress it. It's your computer's CPU and RAM that do this work, which comes at a high cost of your system resources.

A hardware compression system (HCS) not only uses the card to capture the signal, but will also compress it. It will have one or more chipsets on the card that are responsible for capturing, compressing and saving the video to the hard drive.

Software Compression System

The biggest problem of software compression DVR system is CPU Loading. This means that your computer's CPU, already busy with other things, is being heavily used by the DVR system. This may not be a problem with DVR systems running at a lower frame rate, but with faster, real-time systems, where the processor has 400 4CIF images to compress every second, the CPU can quickly max out. Why is it a problem? There are several reasons.

First, not all frames are the same size, nor they do not all require the same amount of work to process, which means the workload varies constantly regardless of the compression codec being used. Also, the CPU is busy processing other things like GUI (graphic user interface) changes, playback functions, motion detection and network operation, to name just a few. With the CPU under such heavy use, several large frames in a row can cause serious problems.

With the normal operation of your PC you see this all the time. One process simply waits its turn at the CPU, so you'll see a window take extra long to redraw, or the screen will take longer to refresh. This is not normally a problem. But with DVR operation, such 'traffic jams' are bad news. At 400 frames per second (4CIF resolution), you computer gets overloaded pretty quickly and starts to drop frames. Frame drop means gaps or 'blips' in your recorded video and audio artifacts. You may not notice occasional drops, but if your CPU drops more than a few, you will see it. In severe cases these traffic jams can cause your computer to crash completely.

Because a hardware compression DVR system uses its own chips for compression, the load on the computer's CPU and RAM is a great deal lower; frame drops almost never occur on these systems.

Hardware Compression System

A hardware compression system has one or more chipsets on the card that are responsible for capturing, compressing and saving the video to the hard drive. This means it has good performance coupled with low PC CPU and RAM resource requirements . For this reason a hardware compression DVR system is far more stable than software compression DVR system.

And because hardware compression cards usually use high performance chipsets to compress frames, the compression process will not be affected or interrupted by other programs. It brings more fluid video image to customers.

Meanwhile, with a low CPU occupancy rate, hardware compression system can easily accomplish additional functions by using spare system resources of computer, such as intelligent analysis, license plate recognition and so on. Network connection performance can be better as well, in particular fast transmit speed and multi-channel simultaneous connection.

Hardware compression systems can also easily support up to 64 channels in one PC with real time monitoring and real time recording (every channel is 25fps in PAL or 30fps in NTSC). Most software compression system supports only 16 channels.