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.
There are total 4 different standard systems for digital signal transferring. They are DVB-T system in Euro, Australian , Middle East and African countries, ATSC in USA, DTMB in China and ISDB-T in South America and Japan. Below is the details maps location of Digital TV standard in wordwide. For more details ,please refer to https://en.wikipedia.org/wiki/File:Digital_broadcast_standards.svg
In sourcing of FM transmitter, the most frequently asked question is ” i want to broadcast the FM radio signal in a area with 10km radius , could you tell me which model of FM transmitter we can use” . Strictly, the question is impossible to answer. The broadcasting distance is affected by so many factors. The height and gain of antenna, the quality of receiver electromagnetic environment will all affect the broadcasting radius, the below proposal is for reference only, it is the test result based on ideal using environments.
Below are the proposal:
3KM Radius: 30W FM TX + 1-Bay Antenna with 15meters Height.
6KM Radius: 100W FM TX + 1-Bay Antenna with 30meters Height.
10KM Radius: 300W FM TX + 2-Bay Antenna with 40meters Height.
20KM Radius: 500W FM TX + 4-Bay Antenna with 50meters Height.
or 1KW FM TX + 4-Bay Antenna with 30meters Height.
30KM Radius: 1KW FM TX + 6-Bay Antenna with 60meters Height.
or 1KW FM TX + 4-Bay Antenna with 100meters Height.
40KM Radius: 3KW FM TX + 6-Bay Antenna with 100meters Height.
or 5KW FM TX + 6-Bay Antenna with 80meters Height.
50KM Radius: 5KW FM TX + 8-Bay Antenna with 150meters Height.
or 10KW FM TX + 6-Bay Antenna with 120meters Height.
60KM Radius: 10KW FM TX + 8-Bay Antenna with 200meters Height.
70KM Radius: 10KW FM TX + 8-Bay Antenna with 300meters Height.
80KM Radius: 10KW FM TX + 8-Bay Antenna with 400meters Height.
90KM Radius: 10KW FM TX + 8-Bay Antenna with 500meters Height.