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, and logistics companies use vehicles to deliver goods. The very fabric of society – people and assets – is 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 and the flow and assets and ensuring the safety of the traffic environment.
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 continuously without failure. It can withstand the frequent vibration and unstable power supply associated with vehicles ? factors which prove fatal to a regular DVR. It can provide evidence of traffic accidents and terrorist attacks while uploading alarm information to a control centre 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. There are five factors which define an appropriate mobile solution: power supply, anti-vibration mechanism, dust prevention and heat dissipation, solid interface and data transmission.
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 or110V, and is not as stable as that of indoor locations, especially during engine start-up and braking, times when voltage can fall to 9V or less. This creates a very unstable power supply. Electronic equipment are very sensitive to power surges and spikes, and fail quickly if they are not handled properly. Additionally, the mobile DVR acts as a hub that stabilises power for sensors and cameras. 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. International standards relevant to power systems are ISO 7637-2: 2004, JASO D001-94 and SAE-1455. Customers should refer to these standards when buying mobile DVRs.
Since vehicles are constantly in motion, vibration is inevitable. Constant vibration leads to mechanical failure if this factor is not considered during design. One factor that sets rival products apart is the material used for the anti-vibration mechanism. Most manufacturers use rubber to contain vibration since use of rubber lowers production costs. However, it deteriorates over time. Generally rubber guarantees performance for a short time 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.
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. Trying to fit fans to the DVR inevitably leaves 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.
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.
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. But the availability of 3G networks has enabled a wide variety of new functions. For example, it was earlier not practical to transmit real-time data collected from the vehicles such as video, location, brake signals, speed and inertial measurements. However, all of this can now 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 rising traffic accidents there is a legal mandates to strengthen surveillance protection. For this reason, the potential market for mobile surveillance may become very large. Customers should be aware of the features of mobile DVRs, selecting appropriate solutions in different applications accordingly.Ashish Dhakan Chairman Prama Hikvision India Pvt Ltd