The fact that more and more U.S. troops are viewing video feeds directly from unmanned aircraft is highlighting what is either an issue of poor planning or fresh evidence of how hard it is to anticipate future needs.

The question is: Why wasn’t the Defense Department-mandated video waveform — the term for its recipe of signal strength and frequency — included in the library of waveforms drawn up under the government’s $37 billion effort to replace today’s patchwork of incompatible radios with fully compatible versions?

As it stands, the only way for users of the Joint Tactical Radio System (JTRS) to see video beamed over the Common Data Link waveform is to receive it on another device, such as a Rover or Video Scout computer, and feed the digital output into the JTRS network with a plug-in device. This means forces must carry two sets of equipment: a JTRS radio and a video receiver.

Opinions about the origins of the Common Data Link (CDL) conundrum generally fall into two camps, said Grant Palmer, vice president of communications systems at Cubic Defense Applications Inc.

One view is that the U.S. government’s JTRS program team did not consider the Common Data Link waveform simply because it was beyond the bandwidth specifications envisioned for JTRS radios when the Defense Department started the program in 1997. The thinking was that forces would need to be able to communicate through foliage, which meant ultra- and very-high-frequency signals up to about 2 gigahertz. The CDL waveform runs higher than that and can’t penetrate foliage. Most users also would need simple, omni-directional antennas rather than antennas that would have to be steered to stay locked onto video signal beamed by an aircraft for maximum range.

Others trace the problem to the state of computer technology in the 1990s. Even if planners had a crystal ball and could see that the wars in Iraq and Afghanistan would create an explosion in demand for video, incorporating CDL would have required racks of computers. Palmer is in that camp: “When the JTRS program started, [including CDL] wasn’t practical,” he said.

With that history behind them, government and industry technologists are now searching for solutions. America’s military labs have funded research and development to assess the feasibility of building single devices to receive the JTRS waveforms and the CDL form. It’s mostly a matter of smaller, lighter circuitry and antennas. “You’ll see prototypes [in 2010], including from us,” Palmer said.

At the moment, the research is separate from the JTRS program. At the JTRS program office in San Diego, spokesman Jeff Mercer said CDL hasn’t been considered by the JTRS team because it is a higher frequency waveform, above 2 gigahertz.

The JTRS radios are designed to be “software defined,” meaning users can reprogram them to receive other waveforms. The software-defined approach is akin to the operating system of a personal computer — Microsoft Windows, for example — with the waveform being the equivalent of an application, such as Word. The JTRS team has developed waveform standards to promote person-to-person or person-to-multiple-people communication. The waveforms fall into three general categories: new “transformational” networking waveforms, such as Wideband Networking Waveform; legacy waveforms like those used for satellite communications; and networking management waveforms.

The CDL waveform can’t simply be added to the library because the JTRS radios cannot physically receive signals above 2 gigahertz.

In addition to the hunt for a single device, the lack of a CDL capability in JTRS has sparked a fierce competition among U.S. companies to develop and sell lightweight, add-on equipment to tie video users into the JTRS network, or at least make the additional equipment smaller.

In the last few months, Palmer said, Cubic has unveiled CDL receivers and transmitters that are the size and weight of a paperback novel, compared with previous versions that were typewriter-sized. Reducing the size and weight to such a degree means that smaller remotely controlled or autonomously flying aircraft would be able to carry CDL electronics, although designers still have to work out some potential overheating issues with the CDL transceiver when the craft are stationary on the ground, Palmer said. Also, soldiers on the ground could plug a CDL unit into their JTRS radios to receive streaming video over a high-bandwidth connection, he said. With funding from the Air Force Research Laboratory, Cubic is working on both the plug-in CDL concept and on integrating CDL into the circuitry and software of new JTRS radios.

Cubic’s “mini CDL” transceiver, a 4-watt unit that transmits data at up to 45 megabits per second, is in its final test phase and has been flight-tested on remotely controlled aircraft such as the KillerBee, Aerosonde, Outlaw and Skylark II. It would send video to someone operating a Rover or Video Scout.

Elsewhere in the industry, Harris Corp. has developed a handheld video ISR receiver — a 2.8-pound device that receives tactical video feeds in the L, S and C bands. The RF-7800T ISR Video Receiver has connectors to plug the video into whatever display the soldier is using. Harris has also developed a multiband portable radio, which can be carried by the soldier on foot.

A team led by Lockheed Martin announced in December that it had completed critical design review for the Airborne, Maritime/Fixed Station (AMF) version of JTRS, which the company describes as a secure, Internet-like tactical network to provide forces with “unprecedented access” to voice, data and video communications. Because the network capabilities are defined digitally, and signal processing is handled by a programmable computer, the new AMF radios would communicate with legacy radios, waveforms and systems. Hardware upgrades would not be required as new radios are fielded.

AMF JTRS will utilize 10 waveforms in the JTRS library, said Mark Norris, Lockheed Martin’s director of the program.