UBS 250W DVB-T/T2, CCMB, DTMB, ATSC transmitter

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Bill Song@UBS

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Sep 20, 2012, 4:28:29 PM9/20/12
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Model: DTX2500U

Transmitter Features

 470 MHz - 860 MHz Broadband Transmitter/Repeater
 LDMOS Power Amplifier provides 250 Watt output POWER
• Support for ATSC, ATSC-M/H, DVB-T/H, ISDB-T/TB, CMMB and DTMB waveforms
 SFN and MFN support
 Adaptive Non-linear Pre-corrector
 Manual Linear and Non-linear Digital Pre-correctors
 Touch screen display for real time user interface
 Remote control and self monitoring via Ethernet and RS485 interfaces
 Built in web server accessible through Ethernet 
   connector with Internet Explorer
 Remotely manageable via SNMP
 GbE Transport Stream Input based on Pro-MPEG Forum CoP #3
 Occupying only 3 RU of standard 19” cabinet space


Transmitter Optional Features

 Integrated GPS Receiver
• 
Integrated DVB-S/S2 Receiver
• 
Integrated DVB-T/H Receiver 
• 
Integrated ISDB-T/TReceiver
• Adaptive Linear and Non-linear Digital Pre-correctors


UHF Transmitter Functional Overview

The DTX 2500U is a compact, solid-state transmitter, designed for digital terrestrial television broadcasting over a UHF frequency range of 470 MHz to 860 MHz.

Using the latest technology, the DTX 2500U converts an input transport stream (MPEG-2, CMMB Multiplex or ISDB-T/T
Multiplex) to a COFDM or 8VSB modulated RF signal. UBS has developed a Direct Digital Synthesis (DDS) process that allowing the Universal Modulator board to provide the amplifier portion of the transmitter with an RF signal. 

The modulator board RF output is amplified to a digital average out­put power level of 250 Watts by a highly efficient power amplifier, built using LD-MOS transistor technology. The power level stability at the transmitter’s RF output is maintained by an internal automatic level control loop. 

The PA employs its own microcontroller, which monitors the operation parameters of the PA, provides protection against abnormal operation conditions and communicates with the system controller.

The Adaptive Pre-corrector is a superior pre-distortion solution that com­pensates for RF Power Amplifier non-linearities including AM/AM and AM/PM distortion and protects against IMD and spectral regrowth while maximizing EVM performance. 


The manual Linear and Non-linear Digital Pre-correctors can also be used to maximize transmitter performance.
With the addition of an integrated DVB-S/S2 Receiver, DVB-T/H Receiver or ISDB-T/T
Receiver, the DTX 2500U can be configured as a terrestrial repeater. The input data stream is received and re-broadcast as a COFDM or 8VSB waveform.

The transmitter’s operational parameters are monitored and controlled by an embedded system controller that can be accessed from the front panel touch screen LCD or by using one of the remote control interfaces (Ethernet, SNMP, USB or RS232).

Optionally, the DTX 2500U RS232 interface can be dedicated for commu­nication with a 3rd party UPS. In this case, the transmitter is configured with an extra set of SNMP parameters and will actively monitor the UPS.

All of the transmitter’s components are enclosed in a standard 19” rack mount chassis, occupying only 3 “RU” of cabinet space. The transmitter is forced air cooled using two compact high performance fans, which are installed on the transmitter enclosure front panel.




The Universal Modulator 
receives the ASI or GbE (DVB-T/H mode only) transport stream, performs input data processing, generates a COFDM or 8VSB IF output and provides signal synchronization. The modulator also contains a pre-corrector module for both linear and non-linear output signal correction.

The Digital Upconverter with RF Output performs a direct digital upconversion from IF to the required RF channel frequency. The up­converter covers an entire UHF frequency range of 470 MHz to 860 MHz in steps of just 1 Hz.

The Power Amplifier (PA) is the final amplification stage for the transmitter’s output signal. The power amplifier is built using LD-MOS transistor technology, which provides high efficiency and excellent re­liability. The PA employs its own microcontroller, which monitors the operation parameters of the PA, provides protection against abnormal operation conditions and communicates with the system controller.

The Output Coupler measures the forward and reverse output power levels and reports data to the PA Controller.

The System Controller monitors and controls the entire transmitter system and also provides local and remote interfaces for all the com­mand and status functions.

The Linear and Non-linear Digital Pre-correctors are used to maxi­mize the performance of the transmitter in which the modulator is in­stalled.

The characteristics of the linear and non-linear pre-correction curves are set by means of an easy to use and highly intuitive graphical user inter­face: the UBS Corrector GUI software package (Windows compatible).

The DVB-S/S2 Receiver receives and demodulates a satellite signal and outputs an ASI transport stream.

The DVB-T/H Receiver receives and demodulates a terrestrial signal and outputs an ASI transport stream.

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