The new Axciter(tm) digital television modulator is the most advanced ATSC exciter available today. Building on the field proven hardware platform of Axcera's digital exciter family, the Axciter offers terrestrial broadcasters the most flexible solution available. Because it operates using 100% digital signal processing, the Axciter can evolve as broadcast requirements change, helping to protect your investment for many years to come.

This unit utilizes a patented VSB modulation technique, which makes it possible to generate a virtually perfect 8VSB IF signal. Since the Axciter is a completely reprogrammable digital television exciter, it can be easily upgraded in the field with new software versions through the convenient front panel USB port. Critical parameters can conveniently be set and quieried directly on the color LCD screen or through an interface to a personal computer.

The DSP circuitry also handles frequency offsets allowing an unlimited number of user selectable offsets. In addition, asynchronous resampling techniques compensate for errors in the SMPTE-310M input sample rate, ensuring the best possible signal generation.

The companion converter accepts the standard 44MHz IF output of the digital VSB modulator and produces on-channel RF for any TV channel. the upconverter, which is based on proven frequency-agile dual-conversion technology using low noise PLL sources, requires no fixed channel filter in its signal path. This allows any channel to be selected directly from the front panel display with no tuning or hardware changes required, enabling a single broadband transmitter to back up multiple channels. This also simplifies spare parts stock as the hardware is the same for all channels.

Both the upconverter and the 8VSB modulator can be locked to an external 10 MHz reference for synchronization or precise frequency offest control. Non-volatile operation is achieved through flash-RAM (random access memory), which instantaneously stores all digital settings for the entire exciter-modulator system. This ensures that in case of power loss, the system will return to the previously selected settings when power is restored, saving time by eliminating the need to re-enter operating parameters.

Standard with all Axciters, our exclusive Axcera Adaptive Correction Technology (AXACT(tm))provides dynamic digital pre-correction that automatically tracks and corrects for distortions, both linear and non-linear, in the complete transmitter system. All adaptive operations are performed in the high-speed processor, which is capable of equalizing a complete transmitter system in just sixty seconds, and completng a full ystem optimization in about two minutes.

the continuous, real-time, non-linear component of AXACT is by far the most critical element of the correction system. Since the majority of linear distortions are caused by factors external to the transmission system, ATSC set-top boxes are designed to correct for large amounts of linear distortions. However, since DTV receivers cannot correct for non-linear distortions, this must be handled in the transmitter system or coverage will be affected in the fringe areas.

To obtain the necessary data, AXACT continuously samples the transmitter system output, both before and after the mask filter, through a down converter integral to the upconverter tray. The modulator processes the data and the necessary digital pre-correction is applied to the modulator output signal, resulting in consistent transmitter system performance, independent of environmental changes.

The Axciter also performs over fifteen safety tests upon each adaptive correction run to confirm that the new correction values are appropriate before applying them to the on-air signal. This ensures that the signal will not be negatively affefted by a failure of an RF component in the sample path, such as an RF coupler, connector, relay or cable.

Available on all Axciters is Axcera's exclusive DTVision (tm) digital signal analysis and test system. Designed to replace expensive DTV test equipment at a fraction of the price, this system samples the transmitter output and measures critical transmitter performance parameters. The information is then displayed in high-resolution graphical format on the modulator's full VGA front panel display - no external PC is required.

available performance parameters include digital SNR, error vector magnitude (EVM), eye diagram, graphs of adaptive equalizer performance and RF spectrum, constellation diagram, and more.

Every Axciter employs dual processors to ensure on-air reliability. The low-level control computer is a simple, highly reliable processor that is dedicated to running the modulator hardware, thereby generating the ATSC signal. This processor uses a highly reliable real-time operating system based on uC/OS for the mission critical 8VSB signal generation.

A second computer is dedicated to providing the adaptive processing, user interface, diagnostics and graphics, using the very stable and reliable Linux operating system. This high performance computer handles the processor intensive functions of performing all adaptive correction and processing the data for the optional DTVision signal analysis measurement and display, all without negatively affecting the critical on-air signal path. In the unlikely event of a failure of this computer, the Axciter remains on the air with a fully corrected ATSC signal. The Linux computer may even be rebooted with no interruption of the on-air signal, and the Axciter is capable of a cold start without the Linux computer. The net result is an extremely high level of on-air reliability.

The Linux computer also allows simple field upgrade to new operating modes, such as DTx slave, EVSB, Watermark, or other yet to be adopted ATSC enhancements, as they become available. Upgrades are handled by simply inserting a USB flash drive containing the upgraded software into any of the three USB interfaces, located on the Axciter front and rear panels, and executing the upgrade through the front panel GUI.

Continuing Axcera's leadership position in Distributed Transmission Technology, any Axciter can be easily field configured for slave mode operation, allowing DTx single frequency operation. DTx can allow a broadcaster to target population centers with much smaller transmitters than would be required for a typical single transmitter architecture. With a well designed system, DTx results in improved coverage throughout the licensed contour, lower overall power consumption, and inherent system redundancy.

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.