Digital up Gradation
Analog TV transmitter is ready to transit to digital TV transmitter. At present, when users buy TV transmitters, they naturally require the TV transmitters to be easily rebuilt into digital TV transmitters or the availability of analog and digital compatibility. Understanding this requirement, all Allink’s developed transmitters adopt combined amplification. As digital TV has no separated amplification, VHF transmitter power amplifier adopts MOSFET, and UHF transmitter power amplifier adopts LDMOS. When transmitter is changed from analog to digital, it is unnecessary to change power amplifier. Compared with analog TV transmitter, digital TV transmitter requires even higher frequency stability, higher system linearity and better system phase noise, all of which are realized through the exciter. Of course, modulation mode of analog TV broadcasting is totally different from that of digital TV broadcasting, which is also realized through the exciter. Therefore, digital TV broadcasting can be realized simply by changing the exciter of analog TV transmitter into that of digital TV transmitter. Changing either one of the dual exciters in the analog TV transmitter to a digital one can enable the same transmitter to broadcast analog and digital programs by time sharing, so as to realize gradual transition of analog TV broadcasting to digital TV broadcasting. Combined amplification, high linearity power amplifier etc. are advantageous to users and to successful transition to digital TV broadcasting.
Analog TV transmitter remote controlling system including hardware platform and software is used to monitor the main working parameters of transmitter, such as output power, reflect power, PA temperature, current, etc. The system will alarm and protect automatically against abnormal parameter, provide interface to facilitate the adjustment of working parameter and auto level control (ALC) function. All those functions are applicable for digital transmitter also. However certain parameter may request modification during the digitalization, but this modification can be performed simply by upgrading its software, and hardware platform remains the same.