Applied Technology: TANDBERG Television's Voyager Lite

TANDBERG Television's Voyager Lite

By Khalid Butt

Over the past four to five years, TANDBERG Television has worked to reduce the size of digital ENG solutions with each generation.

The most recent example is the Voyager Lite, an end-to-end wireless camera solution that refines the company’s developments in COFDM and MPEG-2 technology. As a result of its recent acquisition of AVS, TANDBERG Television was able for the first time to add RF systems and design expertise in-house to create a complete, non-collaborative transmission system.

The TANDBERG Television Voyager Lite at the Deutsche Touring Masters auto racing championships in Germany.

The system is comprised of a wireless backpack transmitter with MPEG-2 encoding, COFDM technology, RF upconversion and transmission; remote wireless camera control and two-way intercom; COFDM optimized receive antennas; downconversion; and a range of integrated receiver decoders for indoor and outdoor use. The lightweight solution weighs approximately four pounds. Professional cameras are generally fairly heavy pieces of equipment, so the size of the unit is particularly relevant when used for lengthy remote broadcast events! Adding additional weight by securing the unit onto the rear of a camera would tend to off-balance the camera, in addition to adding more weight onto the shoulder.

A camera operator brings it into the field to capture content, while another operator waits at the remote truck or central receive site with the IRD to receive the signal for transmission back to the studio. The system uses the same technology found within a typical TANDBERG Television headend system for broadcast networks.

The acquisition of AVS proved a major influence on the development of the system. Voyager Lite marks the first time the company has been able to produce an entire solution from the camera input into the transmitter through to the RF technology. This offers benefits including lower equipment costs and much faster reaction time to marketplace requirements.

The transmitter features “diversity antennas.” These antennas have been integrated into the fabric of the backpack solution to eliminate the need for a rod antenna. These integrated antennas are designed to be as effective as the rod antenna without being cumbersome in live coverage situations. Rod antennas are also generally more fragile and prone to accidental damage — not the sort of event you want during a live broadcast.

Furthermore, the transmitters and antennas are designed to radiate out and away from the operator’s body, without significantly reducing coverage. An omnidirectional rod antenna could potentially radiate directly into a user’s head.

The system also measures at least 100 times lower than the maximum figure stipulated in Specific Absorption Ratio (SAR) tests. Therefore, if a user carries it for several hours while covering a live event, radiation is not a concern.

Also, the backpack solution includes more than one antenna for additional diversity. If in certain circumstances (such as body shielding) the receiver at the remote truck or central receive site is unable to pick up a quality signal from one of the antennas, it will likely pick up a signal from the second antenna. This increases the coverage area.

Officially, the coverage area of the system is specified as a minimum of 450 feet from the camera operator to the reception site, but this is a conservative figure. In practice, with optimal setup and depending on the shooting environment, the distance can be much greater. For example, Mexico-based broadcaster Televisa was able to successfully transmit broadcast quality content back to a remote truck from a variety of distances (from 900 to 1200 feet or 2400 feet when the camera had line of sight of the receive truck) at the Winter Olympic Games in Salt Lake City, with no external transmit amplifiers or rod antennas.

The system has a software-selectable “low-delay mode” in addition to a standard-delay mode. In standard delay mode, delays between the transmitter camera input to the decoded output are typically between 0.5 to 0.75 seconds. In low-delay mode, the end-to-end delay for the system is two to three frames. Although the standard delay is sufficient for most applications, niche live broadcast applications such as multiple camera cutovers can potentially benefit from using this mode. However, when selected, all MPEG-based low-delay schemes will exhibit a “latency vs. picture quality” trade-off that will be application-dependent, for which the company can advise interested users. As much as an additional 1.5Mb to 2Mb is required to obtain identical standard-delay picture quality. For remote broadcasts, where quality is a must, this can potentially be a serious issue. Hence, the system retains the standard-delay mode as a software option.

The camera-agnostic openness of the backpack solution allows the backpack transmitter to operate with a wide range of professional or prosumer cameras with readily available video/audio interfaces. While the system can be integrated into a camera manufacturer’s interface, the open approach allows it to be interfaced with almost any camera for maximum interoperability. Likewise, it has an open output for further interoperability: Any MPEG-2/DVB-T receiver can decode the unit’s signals.

When audio is fed directly back to the remote truck from a wireless microphone and the video is fed back separately from the backpack solution, these two signals are usually out of sync. A simple way around this is an optional wireless microphone receiver/adapter adjusted to the transmitter. The microphone transmits content wirelessly to the transmitter, where the audio and video are sent to the truck in sync.

When used in the field, the system enables the camera operator to obtain high-quality coverage in difficult terrains and situations, and eliminates the heavy cables and additional personnel associated with a traditional remote crew.

Khalid Butt is a product manager for TANDBERG Television.

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