November 14, 2011
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.