Minggu, 27 Mei 2012
Axciter Digital ATSC Exciter-Modulator
The Axciter adaptive 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. The Axciter supports ATSC, ATSC Mobile DTV and Distributed Transmission System (DTS) slave mode. 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. The Axciter is also a perfect candidate to retrofit existing transmitters, regardless of transmitter manufacturer; making any transmitter DTS and ATSC Mobile DTV compatible.
The Axciter utilizes a patented VSB modulation technique, which makes it possible to generate a virtually perfect 8-VSB IF signal. Since the Axciter is a completely reprogrammable digital television exciter, it can be easily upgraded in the field with new software versions. Critical parameters can conveniently be set and queried directly on the color LCD screen or via a remote or local interface to a personal computer.
The DSP circuitry also handles frequency offsets allowing any 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 upconverter/downconverter accepts the standard 44MHz IF output of the digital VSB modulator and produces on-channel RF for any TV channel. The upconverter section, 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. The downconverter section converts the output signal samples back to IF for adaptive signal processing
Both the upconverter/downconverter and Axciter 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 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.