Digital television (DTV) in North America is based upon standards developed by the
Advanced Television Systems Committee (ATSC). ATSC technology allows broadcasters
to very efficiently deliver a combination of high definition (HDTV) and/or multiple standard
definition (SDTV) programs within a single channel frequency. In addition to HDTV and multi-casting, the advantages of digital broadcasting when compared with analog include reduced energy consumption thanks to improved signal coverage and smaller transmitter requirements, crystal clear pictures, the ability to broadcast data services, and many more.

Axcera is a leading manufacturer of analog and digital transmitters with state of the art designs and world-class quality manufacturing. Axcera's total DTV solutions consist
of completely integrated transmission systems including Axcera transmitters and site controllers, along with DTV encoders, multiplexers, transmission line and antennas,
power conditioning, battery backup systems, security systems, and even climate controlled environmental enclosures. Strong relationships with multiple manufacturers and industry partners for each system component allow Axcera to provide a true best-of-breed solution
for each service provider's individual needs.

A wide range of DTV products are available for both VHF and UHF frequency bands and at power levels ranging from a few watts to tens of kilowatts.

In many ways a DTV transmission system is very similar to an analog system. The key differences lie in the signal processing, modulation and output RF filtering. While component requirements can vary based upon the needs of each individual broadcaster, the block diagram below provides a visual representation of a "typical" digital transmission system.

In this illustration, standard analog video and audio signals are fed into the encoder, then modulated, upconverted, amplified and broadcast through the antenna. Here is a description of each component in the signal path:

• DTV Encoder - This is where the standard analog signal is converted and compressed into a digital bit stream, known as MPEG-2. This ensures that the signal is compatible with digital television sets. Encoders are available for both standard definition and high definition programming.
• Multiplexer - The multiplexer takes the multiple MPEG-2 streams and converts them into a single transport stream that can be fed directly into the modulator. Many multiplexers can handle a range of inputs, allowing a multiple program types (i.e. HD, SD, etc.) to be combined without degrading signal quality.
• ATSC Modulator - The modulator performs multiple functions. It accepts the digital transport stream and processes it to create the ATSC-compliant RF broadcast signal. It also provides the ability to digitally pre-correct this signal to compensate for any distortions that are introduced by the downstream power amplifiers and output filtering. Modulators are available with either fixed correction, which is set up manually, or adaptive pre-correction, which analyzes the signal and automatically pre-corrects for optimal performance.
• Upconverter and Power Amplifiers - This portion of the transmitter is the same as an analog transmitter. Simply put, the upconverter accepts the modulator output and places it on the desired UHF or VHF broadcast channel. The signal is then fed into the power amplifiers, which provide the necessary level of amplification to meet the stationÕs licensed power level.
• FCC Mask Filter - The final step in processing the signal is to ensure that any power that falls outside of the licensed channel frequency does not exceed the limits set by the FCC. There are two different mask requirements defined for operation under Part 74 of the FCC rules, which governs LPTV and translator operation. These are ÒsimpleÓ and ÒstringentÓ masks. The simple mask allows the use of a lower cost filter, but in some cases will limit the licensed power for a given station. The use of a more expensive ÒstringentÓ mask filter may allow for higher licensed power levels and larger broadcast coverage areas. Your FCC consultant can help you to choose the right option for your station.

For many community broadcasters and translator operators, an economical alternative to a new transmitter can be to convert their existing analog transmitters to digital operation. This can be a reasonably straightforward upgrade, depending upon the age and configuration of the analog transmitter to be converted.

In most cases, a transmitter can be converted by replacing the modulator and the output filter with DTV compatible components. Because transmitters operating under FCC Part 74 rules require type certification, the upgrade itself must either be type certificated for use with the transmitter model being upgraded, or a proof of performance must be done and kept on file at the transmitter site to demonstrate that the upgraded transmitter is in conformance with FCC rules. For this reason, it is recommended that such upgrades be performed by factory-trained technicians.

A modern, high quality analog transmitter will typically be capable of operating at approximately 40% to 50% of the rated analog power. For example, a 1kW peak visual plus 10% aural analog transmitter should provide approximately 400W to 500W of DTV output power. In most cases, this will be more than enough power to allow a station to meet its licensed DTV power level.

Axcera offers a complete line of digital transmitters and upgrade packages as well as complete integration and support services. Digital transmitter offerings include the Innovator™ CX and Innovator™ LX low power transmitters and translators, the Innovator™ HX medium and high power transmitters and Visionary™ series high power IOT transmitters.

Axcera also offers digital retrofit kits to convert analog transmitters and translators from any manufacturer. Exciter retrofit options include the fully adaptive Axciter™ Intelligent ATSC Modulator with available DTVision integrated signal analysis system, as well as the economical broadcast-quality DM8-R ATSC modulator and DR8A-R remodulator/exciter.

For more information on digital transmitters, translators or DTV conversion packages,
please contact our knowlegeable sales staff

Designed specifically for DTV translator operators and community broadcasters, the new Innovator CX is available at power levels up to 50W ATSC

The low to medium power Innovator LX can be configured as a transmitter, translator or booster

The DR8A-R is a broadcast quality ATSC receiver/modulator designed to convert nearly any analog translator or transmitter into a regenerative DTV translator.

The Axciter™ digital television modulator is the most advanced ATSC exciter available today.

World-class support from a world-class organization. Axcera's support team is dedicated to you, the customer and is available 24 hours a day, 7 days a week, 365 days a year.