DTV Exciter
with integrated 8-VSB Modulator

Keyfeatures/Benefits

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Itelco proudly present its DTV Exciter for high quality, error free digital signal broadcasting fully compliant with the ATSC (Advanced Television Standards Commettee) 8-VSB (Vestigial Sideband) DTV specifications (Document A/53).

The exciter converts the 19.39Mbps serial data bit stream, carrying video, audio, and data information, into a 1Watt rms 8-VSB RF signal in either VHF or UHF. Itelco� s know-how in RF systems and expertise in digital signal processing ensure the optimal integration of digital and analog technologies.

The exciter input is a 19.39Mbps serial data stream (transport layer) which is comprised of 188-byte MPEG-2 data packets. The data packets are composed of one sync byte and 187bytes of data that provide a 19.39Mbps data rate payload. The integrated modulator provides frame synchronization, randomization of the input data, forward error correction processing by means of Reed-Solomon coding, Interleaving, Trellis Coding which formats the data packets into data frames for transmission, binary data segments sync and data field sync insertion, modulation of a single carrier with VSB shaping and Baseband to IF conversion. The modulator output 8-VSB signal is then upconverted to the VHF or UHF channel frequency and amplified to the final RF power.

VSB Channel Occupancy

DTV EXCITER BLOCK DIAGRAM


The exciter has been designed with extensive use of re-programmable devices making the equipment easy to reconfigure. Adjustments due to modifications of standard specifications or specific customer requirements can be accomplished without replacing any part. No custom parts are used but only off-the-shelf components from leading companies in the market. The Itelco ultra-reliable design integrates advanced monitoring facilities protecting the entire exciter against overloads and failures. Due to the effective self diagnostic capability each card is able to indicate its own fault status. This results in great ease of troubleshooting and minimizes the requirement for the training of personnel, thus reducing repair costs.The Itelco DTV Exciter is easy to operate. LEDs on the front panel of the plug-in cards provide an instant readout of the operating status, e.g. fault conditions and corrections bypass modes. The need for routine adjustments and alignments is eliminated due to the digital processing scheme. The exciter incorporates an internal microprocessor-based control unit which allows commands, configuration settings and major parameter monitoring.

VSB Data frame

 Settings are stored in a non-volatile memory. The conveniently located remote control interface provides both relay contact and a RS232 serial interface. The exciter features compact dimensions. All plug-in cards, including the 8-VSB modulator, are housed in a 19 inch 4HE chassis. This chassis occupies the same rack space as a traditional analog exciter, allowing easy upgrade from NTSC or PAL to DTV service.ISO9001 certification assures the quality of Itelco transmitters in every step from design to production and customer support.


TECHNICAL CHARACTERISTICS

Modulation 8-level Vestigial Sideband Modulation (8-VSB)
Digital Mixing Digital I/Q modulation (preventing phase and amplitude unbalance)
Modulator Input
Parallel LVDS input and Asynchronous serial Interface (ASI) (Optional). (both conforming to DVB Doc. A010)
Input Data Rate 19.39 Mbps
Peak/Ave (99.9%) 6.3 dB
Channel Bandwidth 6.0 MHz
Excess Bandwidth 11.5%
Symbol Rate 10.762 Msymbol/Sec.
Bandwidth Efficiency 11.5%
Frequency Reference Interface for internal and external GPS receiver (optional)
Digital/Analog Converter 14-bit
Modulator Output 50 W SMA, analog IF 43.8 MHz reserved spectrum signal
Inner Code Rates 1/2; 2/3, 3/4, 5/6, 7/8 Punctured convolutional
IFFT Mode 2k, 8k
Guard Intervals 1/4, 1/8, 1/16, 1/32 of symbol duration
Frequency Stability with GPS receiver: 5x10 E-11 / long term; without GPS receiver: 1.5x10 E-7/year
Frequency Step 25 Hz
Test Signals (Facilities) Internal PRBS generator, ramp, packetized ramp
Monitoring Outputs Local Oscillator, IF output, RF output
Exciter Output 50 W  N, 1 W(rms), on channel band III or bands IV-V