And, technically speaking, typical wireless data communication manages keystrokes, e-mail messages or reasonably sized files maxing out at 5 to 10 MB. But continuous streaming video recording in a digital evidence-gathering operation is unique and requires an average 100 MB or more storage capacity for each camera in use. Each patrol car takes at least 1 hour of MPEG1, MPEG2 or MPEG4 video per shift, and that file takes about 5 minutes to transfer from car to server. As more cars pull up to the police station or law enforcement facility, the amount of time required for downloading doubles with every new car.
Kustom Signals' wireless solution speeds the transfer process by relying on three to five APs from D-Link, a Fountain Valley, California manufacturer of computer networking equipment. The APs are mounted on each exterior wall of the police station and a similar access point is installed in each squad car equipped with an 80-GB disk drive for video storage. The D-Link APs, chosen for their rugged durability and resistance to heat, cold, dust, dirt and humidity, host an embedded Microsoft Windows XP-based program that initiates an FTP (file transfer protocol) session when the vehicle approaches headquarters.
According to Cigard, the officer drives his patrol vehicle up to the police station and into the wireless zone, then goes inside the building. By the time the officer returns to his vehicle, the file download is complete and the in-car disk drive is ready to store more video.
"The officer doesn't have to take anything out of the car. There's no removable hard drive or tape, and there's no need to run an Ethernet cable. Nobody has to do anything," Cigard says. "Productivity increases and the law enforcement agencies are able to gather unquestionable, untainted evidence automatically."
Video files transfer to back office servers into a database housed in 10-, 12- or 18-terabyte (TB) storage disks equipped with RAID for file backup, or in NAS storage enclosures. Officers can easily locate videos on this system to view, and burn DVDs to take evidence to court.Pros and cons
As with any new technology, there are both pros and cons to wireless video surveillance transfer solutions. The advantages include:
- Lower costs - One of the biggest advantages of wireless surveillance technology for law enforcement applications is the lower cost. Almost 80 percent of the expense of installing a wired system is associated with cabling and trenching. In many cases, city, state and federal grants are available to offset costs.
- Ease of installation - Eliminating the use of wiring will typically cut the installation time down to weeks instead of months for a traditional wired network.
- Portability - Today's network equipment, such as D-Link's APs, are light enough to carry.
- Self-healing - A wireless network will continue to operate even if one AP fails.
- Versatility - Wireless networks dramatically expand mobility and flexibility, with easy access to voice, video and data streams.
Possible disadvantages include:
- Lack of knowledge - Most law enforcement agencies need to rely on reliable wireless solution integrators to install their systems. However, with proper training, a wireless video network is very easy to operate and maintain.
- Insecure data - Despite widespread opinions to the contrary, today's technologically advanced wireless networks provide more than enough security for any application.
No matter how you slice it, the benefits far outweigh any potential disadvantages, and as a result many agencies are turning to wireless networking because it saves both money and time.
"The wireless camera system dramatically improves our ability to monitor certain areas of the city," says Tom Lawrence, deputy chief of the Dallas (Texas) Police Department.
"We can now provide our officers with critical, real-time information they can use to protect the public and themselves whenever an incident is detected."