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General Discription

 

Digital TV Translator is a solution for ATSC Compliant digital transmit that receives RF signal from transmitter and re-transmits this signal after correcting signal distortion.

The design of the rack is very suitable for easy maintenance and service.
Each unit can be easily removed and checked. All internal cables are allocated in the proper raceways.
Moreover every units are continuously monitored in real time through suitable sensors and displays. A controller unit is connected to the Transcoder and the high power amplifier via a RS232C bus, in such a way that all the translator functions are kept under controller. Also it can provide remote control and monitoring of  translator using Ethernet and RS485. The translator is specially designed to be operated in dual drive configuration, shelf type doubling the Transcoders , the amplifier units and the band pass filters and controlling their operation through a proper automatic change over unit.

 

 

Feature

 

COOLING SYSTEM

The translator is air cooled with forced ventilation performed by high reliability built-in fan. A careful and proper design has been adopted in order to guarantee all the power devices to work safely even in very high temperature environment.

 

DYNAMIC AUTO PRECORRECTION

It performs the necessary pre-corrections to compensate linear/non-linearity introduced by the high power amplifier. It also compensate the group delay introduced by the output filter

 

CONTROLLER

The controller designed intelligently provide the management functionality all over the sub-units of translator via a RS232c port.

This unit is fitted with auxiliary communication ports to enable integration into local/remote supervision network. It includes the user’s interface, performs events logging and supervised the rest of the sub-assemblies units through internal bus. It performs translator switch-on/off, power out-on/off and command protections whenever necessary.

 

HIGH POWER AMPLIFIER built in Transcoder

The unit is consist of demodulator, modulator, up-converter and power amplifier.

The power amplifier use LDMOS device which operate in the efficient Class AB mode of amplifier. Built in power supply unit designed to be high efficient in terms of their over all power consumption by the use of switched-mode power supply. It is protected against over-power/temperature/current/voltage/drive, high-reflected power. A set of LEDs on the control display panel show the status of the amplifier circuit and power supply.

 

The modulator is a solution for ATSC compliant digital television that retimes the incoming data to fit the modulation and produces an RF carrier signal that has the VSB modulation on it. ATSC-compliant VSB Transcoder is a rugged, stand-alone rack-mountable. It is capable of modulator any terrestrial or cable channel carrying the VSB signal(2,4,8,8T,16). Also modulator applies programmable FIR filter coefficients required for VSB transmission as well as the adaptive filter correction for frequency response and time domain errors in the channel, the baseband signal in such a way to cancel out any nonlinear distortion that is caused by the intermediate or high power amplifiers.

 

A demodulator is designed to fulfill the most demanding requirements in terms of superior performance as well as operation and for the high quality broadcasting as same as transmitter.It receives RF signal from transmitter through antenna and demodulator to base band signal. Demodulated signal performs root-raised cosine filtering, synchronous detection, clock/packet/frame recovery, signal equalization after out of ATSC MPEG-transport packet(SMPTE310M)


 

 


BAND PASS FILTER

The translator is equipped with an input/ouput filter and a directional coupler at the final amplifier output. This filter attenuateds the harmonic and out of band radiation in addition to reducing the out of band noise power from the broadband amplifier. The directional coupler is used to sense the direct and reflected power for metering and protection purposed.

 

 

Operation Mode

 

Active-Reserve Type


Hot-Standby Type

 

 

 

 

■ Specification 

 

Translator Specification PTR020WA PTR100WA
Output Power 20W avg ±5% 100W avg ±5%
Out of Channel Emissions Better than ATSC Standards <-
Harmonics Rejection Better than 60dBc <-
Phase Noise Less than -107dBc@20KHz offset <-
Group Delay Less than ±25ns <-
Frequency Response Less than ±0.5dB@passband <-
TX SNR Better than ATSC Standards <-
Pilot Amplitude Error Less than ±0.5dB <-
Phase Error Less than ±5 deg <-
Amplitude Error Less than 1 dB <-
Output Frequency 470 ~ 860 MHz <-
Input Frequency VHF,UHF <-
Band Pass Filter
Insertion Loss 0.5dB or less(Center Frequency) <-
Handling Power 25W or less 140W or less
Impedance 50Ω <-
Connector N-Female, Rear <-
Return Loss 1dB or less <-
Attenuation Characteristics fc±6MHz 40dB or more  <-
fc±9MHz 70dB or more
Temperature -10 ~ 50℃ <-
Humidity(non-condensing) 90% <-
Dimension 2U 3U
High Power Amplifier    
Input Connector TNC Female <-
Output Connector N-Female <-
Cooling System Fan Cooling <-
RF Power Output 20W avg 100W avg
RF Power Input -10dBm <-
Power Supply Voltage AC220V <-
Frequency Response ±0.5dB or less(fc ±3MHz) <-
Input Frequency 470 ~ 860 MHz <-
Input Impedance 50Ω <-
Temperature Protection Auto switch off at 85℃ <-
Dimension 2U 3U
Transcoder(Exciter)  
Input Input Connector BNC Female, 50Ω <-
Frequency Band 470 ~ 860 MHz <-
Dynamic Range -75dBm ~ -10dBm(avg) <-
White Noise Threshold 15dB TOV,SER=2.5 Error/Sec,  BER = 3 Ⅹ 10E-6 <-
Modulation Mode 8VSB Trellis <-
Standards ATSC A53 document <-
Symbol Clock 10.762238MHz <-
Channel B.W 6MHz <-
Output Connector BNC Female, 50Ω <-
Frequency Band 470 ~ 860 MHz <-
Signal Level -10dBm, -15 ~ -5dBm adjustable <-
Frequency Stability 0.3ppm/3months <-
Auto Correction Auto/Manual Mode <-
Dimension Included in HPA 1 U
Transmitter Control Unit    
CPU 32 bit ARM <-
Remote Control RS-485, TCP/IP <-
LCD Display 2 Ⅹ 13 Character <-
Function TX Auto Change <-
RF input/ouput SNR Display <-
History Logging <-
Dimension 1 U <-