Perimeter detection could be revolutionized by a new device that claims to positively identify human presence. Functioning as a buried electronic trip wire, SilentGuard uses unique disturbances in the earth’s electrical field to detect humans’ beating hearts.

“The earth has a naturally occurring electric field around it between the ground and the ionosphere, and at ground level it is 200-300 volts per meter,” explains Howard Sidman, president of DKL International Inc., Vienna Va., which developed the technology.

“A human has an electric field around 10,000 volts, so when the human brings its electric field into an area, it disturbs it dramatically, relatively speaking, and that’s what we’re detecting is that disturbance or perturbation,” he relates. “What we’ve found and patented is that disturbance is unique to humans and definable. It’s the electric field that humans emit that makes that disturbance which you then read.”

The module can operate for 100 linear meters, which is approximately 330 feet. As many as are needed can be run along a perimeter, Sidman asserts.

The two spikes indicate in data form when a human crosses the SilentGuard trip wire twice. The actual screen that will be seen by the control room operator will have a color bar change from green to red when a perimeter is breached and the segment where the breach occurred indicated. An audio alarm also will sound.

For an application currently being completed for Federal Prison Industries (FPI, trade name UNICOR), an agency of the U.S. Justice Department’s Bureau of Prisons, the modules are being connected to a network with a panel that displays a diagram of the facility being protected and shows where all the security modules are located.

If an alert occurs, an alarm sounds and the sector that is on alert flashes on the screen. The control room operator then can use remote video surveillance or other means to investigate the alarm.

“We expect that the false positive rate will be extremely low,” Sidman predicts. “Nothing is ever 100 percent, but we’re shooting to have it in the 98-99 percent accuracy range.”

Sidman thinks his product will have higher accuracy than buried cables that detect the vibration of a human footstep. Besides correctional facilities and courthouses, he thinks additional markets for the product could be military, airports, ports, chemical plants, gated communities, national borders and other homeland security installations. Use of the wire indoors concealed in walls or doorways is being developed.

The company will be working on integrating the system with existing graphical user interfaces (GUIs). He also sees the product’s eventual use as a temporary, mobile perimeter that could have an IP address and communicate with a laptop wirelessly.

Currently, the technology is being used in a handheld version that uses a patented selective polarization filter (SPF) to eliminate all but the unique ultra low frequency, non-uniform, electric field created by a beating human heart.

The handheld version can track a standing adult at a distance of 500 meters in the open, and at shorter ranges through concrete walls, steel bulkheads, brick, earthworks, plastics, heavy foliage, water, and other barriers, the company says. It is used in Asia and Europe for port security, mine safety and by law enforcement and search and rescue groups.

Sidman estimates the system will be available for production by summer. “We feel this system is going to take a long step toward eradicating false alarms,” he asserts. “We think that our system is going to make police respond to security alarms just like fire alarms are responded to by the fire departments.”

Video Terms Explained

Enlarge this picture The freeze frames of progressive scan video on the left do not blur as freeze frames from interlaced video on the right sometimes do.

What is the difference between “pictures per second,” “images per second” and “frames per second?”

All three terms basically refer to the same specification. In the digital imaging world, “pictures per second” (pps) and “images per second” (ips) are used interchangeably and typically refer to a JPEG image produced from a digital still camera in one second. This same usage was carried over to network cameras to define the video stream or video refresh rate.

More advanced MPEG-4 compression uses individual frames of different types to produce a video stream, so the term “frames per second” (fps) is now more widely accepted as an indication of video rate.

Photographers will typically use the term “image” more frequently. They take a good deal of self-contained, JPEG images, sometimes at a very fast rate, especially at a sports event. Individuals who work with network cameras talk about frames, because there are different types of frames that make up a video stream.

Also, it is worthwhile knowing what the difference is between a field and a frame. A video frame is a complete picture that is drawn onto the screen, either in progressive or interlaced fashion. A field is half of a full frame of interlaced video. In the network and digital world, we are typically not talking too much about fields, but refer to frames per second as video rate.

As for the difference between progressive and interlaced scanning, interlaced video means scan lines are even-numbered and pixel rows are refreshed 60 times a second followed by every odd-numbered row as well. An approximate frame rate of 30 times each second is then produced.

When you pause a digitally recorded video of an interlaced source, you can sometimes see those horizontal scan lines appear. This effect does not appear with progressive video because each pixel row is refreshed in numerical order (1, 2, 3, 4, 5, etc.) on the screen (or simultaneously), rather than interlaced (1, 3, 5, etc., followed by 2, 4, 6, etc.).

Enlarge this picture Power over Ethernet (PoE) is ideal for network video, because it saves the installation and material cost of a dedicated low voltage power cable.

Progressive scan video is great for viewing fine details and smooth motion. Today’s 720p and 1080p plasma displays produce high-resolution progressive video at the same frame rate as the video source. Either progressive or interlaced video rate can be represented in frames per second.

What is PoE (power over Ethernet), and what are the advantages and disadvantages of this technology?

Power over Ethernet (PoE) is ideal for network video, because it saves the installation and material cost of a dedicated low-voltage power cable. PoE devices such as network video cameras may be powered with up to 12W of low-voltage power at a distance compliant with Ethernet horizontal cabling distances (as specified by the Commercial Building Telecommunications Cabling Standard TIA/EIA-568A-5) which is usually 100m (330 ft.).

A PoE or 802.3af compliant power source injects power over two pairs of cables after it has been determined that a compatible 802.3af compliant receiving device has been connected to the other end of the Ethernet cable. It uses 48 VDC limited to 350 mA, providing a maximum of 12.95 W to each end node after cable loss.

The components of a typical PoE setup include network camera, Ethernet cables, patch cable, PoE midspan and network switch. The midspan is an 802.3af compliant power source equipment (PSE) that will typically be mounted above (or below) your network switch in the telecomm room.

A single port on the network switch connects to a port on the 802.3af compliant midspan adapter via a patch cable. Then, an Ethernet cable from this midspan port to the 802.3af compliant network camera (the power device) provides both the camera power and connects its video data stream.

PoE should not be confused with power injection systems that do not conform to the 802.3af standard. Eight actual PoE standards exist. If the 802.3af standard is not noted in the specifications, then the device is not compliant with standard PoE. — Contributed by Steve Surfaro, group manager, strategic technical liaison, Panasonic Security Systems, Secaucus, N.J.

‘Powerful’ Option for Supporting Video Systems

What Is a Mesh Network?

What is a mesh network and how does it work?

A mesh network is a type of network topology that involves multiple interconnects, usually wireless, between network nodes, enhancing the overall network throughput capacity. This type of communications system can be easily, efficiently and quickly deployed in a disaster area to cover as much area as possible.

Mesh networks are making their way into a number of key cities throughout the world, including Philadelphia and Las Vegas, and may be used for public Internet access or a city-wide video surveillance system for law enforcement, traffic and first responders.

In an urban deployment of a mesh network, there are wired base stations, fixed wireless relays and mobile nodes. The base stations act as routers or gateways between the Internet and the rest of the mesh.

The fixed wireless relays expand coverage and mobile nodes provide users with network accessibility and in many cases improve coverage. If the mobile nodes can act as relays, they not only expand coverage, but also improve performance. Not every mesh system permits this, and not every video surveillance or other security application can take advantage of this expansion. – Contributed by Steve Surfaro, group manager, strategic technical liaison, Panasonic Security Systems, Secaucus, N.J.

Network Camera? IP Camera? They’re nearly the Same

Are there any differences between an IP camera and a network camera, or is it just different terminology for the same thing?

They are essentially the same thing. However, “IP” is just one of many protocols used on a network. A network camera is a device that produces a video image and encodes it for streaming over a network. This device combines a lens, imager, DSP, processor and digital-to-analog converter in a single package. A network video camera will, at a minimum, include an Ethernet connection for the network.

A network camera uses “IP” or Internet Protocol to communicate with the network. Many cameras use file transfer protocol (FTP) to transfer video files associated with events as a separate communications method. Finally, most network cameras use network time protocol (NTP) to make sure their clocks are synced up with the network time. – Contributed by Steve Surfaro, group manager, strategic technical liaison, Panasonic Security Systems, Secaucus, N.J.