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Gear & Now: Wireless Video
Posted Apr 25, 2006 Print Version     Page 1of 1

Event videographers have long been saddled with a nightmare of unsightly connections and cables running along a gym floor, across the corporate boardroom, or up a church aisle.

Of course, with the right knowledge, equipment, and setting, wireless video can turn that nightmare into a dream come true! It can open up creative production opportunities and deliver technical solutions where none apparently existed.

It may sound easier than laying out and rolling back up miles of cable, but the learning curve can be steep. You may need expertise in RF engineering, a degree in regulatory law, and a valid helicopter license to enjoy all the benefits.

Like wireless audio systems, a standard wireless video system consists of transmitter, receiver, antenna, and power supply. Transmission distances vary depending on antenna selection (most operate in the 900MHz, 2.4GHz, and 5.8GHz ranges) and rated output power, usually described in milliwatts.

Analog vs. Digital

Analog systems are usually simplex, meaning they transmit in one direction only. Digital systems are available (and the price is dropping). Using spread-spectrum technology, they're often referred to as duplex or half-duplex, meaning that data moves in two directions (one at a time in a "half" system) and that it can be transmitted from point to point or from a single point to multiple points. These systems can also offer a camera-control link for pan/tilt/zoom, or to provide additional data security.

Analog transmissions can be live, real-time, and set up to maintain desired video resolutions (up to and including 500-plus lines). Several analog feeds can be located in the same area. Digital transmissions can be live, too, but they use a spread-spectrum technology that can result in dropped frames or loss of video quality, depending on how the system is configured. Improvements in digital transmission are coming, and the frame-rate issue will eventually be resolved.

With many of the products now on the market, a license is not required (such as for "FCC part 15" products). However, some systems do require a license to operate, depending on frequency, power output, or other factors. Some jurisdictions require that the user obtain a permit before conducting certain transmission activities (such as sending a signal across a state or federal highway).

FCC Issues

The Federal Communications Commission (FCC) is charged with regulating interstate and international communications by radio, television, wire, satellite, and cable. If a wireless system does not comply with FCC standards, the end user may incur fines.

As videographers well know, the FCC has set in place a drop-dead date for transition of analog-to-digital television transmission. As a result, part of the available wireless transmission bandwidth is being sold off, and existing analog transmitters are being "relocated."

The FCC mandated that most television broadcasters, fixed-link service users, and others replace and/or upgrade their 2GHz transmission facilities (with certain frequencies specified).

It appears that some ten channels will be reserved for licensed ENG and related activities (such as the wireless transmission of audio and video by broadcasters or their contracted independent service providers), but there is still some discussion and debate about the allocation of airwaves.

For example, the Association for Maximum Service Television, a leading industry advocate of advanced over-the-air digital television, broadcasting technology, and spectrum policy issues, has said the that current analyses of the RF and bandwidth allocations "drastically underestimate the interference that it . . . would cause to public, over-the-air transmission," and access.

Bandwidth and frequency issues duly noted, most wireless video systems need a clear line of sight between transmitter and receiver; certain signals will not go through concrete, steel, trees, or other obstructions without interruption or total loss.

Likewise, other signals around the same frequency can cause interference, especially with the 2.4GHz level. Cordless phones, wireless LAN/WANs, even microwave ovens can cause problems. Site checks with a spectrum analyzer, frequency locator, or demo system are a good idea in critical situations.

Types of Wireless Systems

From the babysitter-type setup to the high-end, high-def broadcast configuration, wireless video systems are available in a wide range of prices, features, and functions.

Home surveillance-type systems, of which there are several, operate in the 2.4GHz band. Most are priced around $200. Using standard RCA inputs, a video source can be connected to the transmitter, and signals are transmitted up to about 700' (clear line of sight). Power supplies and cables are included in the kit.

More professional setups, also in the 2.4GHz band, are available. A popular system known as the JonesCAM comes from Niche Concepts. Its TX/RX is a four-channel transmitter/receiver system that's rated up to one mile depending on the antenna configuration; it's priced at $275.

Its bigger brother, the TX/RX 2, is a higher-powered, 2GHz, 4/8-channel wireless system, with a 5GHz transmitting antenna, high-gain 14 dB fixed receiving antennas or a 14 dB handheld antenna equipped with a pistol grip, and a small color LCD screen for tracking purposes. The transmitter features composite video inputs and RCA audio, and operates on 12 V power supply. The receiver features corresponding video/line-level audio outputs.

The standard system does not require a license to operate (being an FCC Part 15 product); the Pro ($395) system is license-free for noncommercial use, but a license may be required otherwise.

Avalon RF offers a wide range of wireless video products, custom-configured depending on applications. Including UHF/VHF systems (which can penetrate walls or other such obstructions), microwave and FM products, its line up of transmitters and receivers offers options for VITC time code, two-way communications, and audio talkback features.

MicroTek Electronics' 5.8GHz wireless video and audio transmitter has ten user-selectable channels minimizing the chances for interference. Its MiniLink 5.8GHz system can be used with any color camera. It has a range of 1,000' with the standard antenna and a range of up to four miles with optional high-gain antenna. The ML58RX receiver is priced around $500; the ML58TX transmitter is about $800.

Laird Telemedia's new WaveShot AG system (replacing its LTM-WAVE) broadcasts a composite signal up to 300' away to any UHF ready monitor. The new system adds choice of up to eight frequency selections, RS170A compatibility, as well as audio transmission.

Described as a monitoring system, solid recording solutions are available. The LTM-WAVE-AG accepts composite video and line level audio. The transmitter runs on 9-12 V DC power. Laird's WaveShot video transmitter and receiver are priced at $525 (each).

Trango's new 5.8 system, called the FalconPLUS, offers up to seven-mile transmission (depending on antenna and power options) for audio (RCA in, stereo option) and video (BNC connections) rated at 460 lines horizontal/30 fps in the standard. The transmitter is designed for fixed-wall or pole-mounting; the seven-mile system is priced around $3,000.

Higher-end digital or broadcast systems, such as those from Nucomm, are often priced in the tens of thousands of dollars. Its CamPac microwave transmitter accepts component, composite, or SDI video (and two selectable audio channels) input, and converts it into a 4:2:2/4:2:0 MPEG-2 stream for transmission to receiver, decoder, and video recorder. It has selectable operating frequencies, user presets, and boats a signal delay of less than 100 milliseconds over a range of about a half mile. Strong specs, but the price—without receiver—is around $30K!

There are even higher-end systems, by the way: Nucomm's HD Channel Master system is used by major broadcasters—like New York City's WABC—in their news choppers. The Cineflex HiDEF aerial multi-band microwave system can also deliver a full-bandwidth 1080i signal.

Systems for Other Applications

While broadcast TV and professional videography are key drivers for wireless video technology, security, surveillance, and military users create a demand in this market as well.

Companies such as DTC Communications, for example, manufacture a wide range of what are called tactical video systems. All their kits are built to withstand the kind of rough treatment only a Special Ops, SWAT team—or wedding crew—can deliver!

DTC's DynaPIX SuperTRIAD diversity wireless camera system provides a 1,000' wireless video and stereo audio link from the "clip-on" SVTX-100 transmitter (which can mount between a standard A/B brick and the battery plate on the rear of a professional camera) to the receiver.

DTC offers specific frequencies and transmission capabilities in its products so as to provide signal strength that, according to DTC, is good for penetrating walls, beaming along long distance links, and serving over-the-horizon applications.

Avalon RF, by the way, also offers a wireless solution for more intimate settings—it comes with lapel camera with built-in microphone! Although designed for military and homeland security applications, I think the wedding videographer could find another use.

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