A DTV receiver is a set-top box that permits the reception of digital television. Its components are very similar to a desktop PC. The DTV receiver is a vital link in the chain of television system. The goal of a broadcasting system is to concentrate the hardware requirements at the source to simplify the receivers and makes it as inexpensive as possible.
It is usually connected to the TV set or incorporated in the TV set. The main features of a DTV receiver may be classified as follows:
The tuner in the box receives a digital signal from a cable, a satellite, or terrestrial network and isolates a particular channel. The signal is then forwarded to a demodulator and converted to binary format. Once in binary format, the demodulator will check for error and forward the binary signal to a demultiplexer that will extract audio, video, and data from the binary stream.Once the demultiplexer has finished with the signal, the decoders will transform the digital bits into a format suitable for viewing on the television set.
As the architecture of a DTV receiver can vary in function of the network operator or the set-box manufacturer, we have chosen to divide the physical components into the following categories:
All the main hardware components of the receiver are connected to the system board. Buses are used to carry the digital TV information between the hardware components.
The ATSC tuner module is available for accessing QAM-, OFDM, and QPSK-based networks. In addition to receiving inputs from digital networks, most tuners are also capable of tuning analog broadcasts. Tuners can be divided into three broad categories:
The function of the demodulator is to convert the analog signal to a digital bitstream. Then, it checks for errors and forward the bitstream to the demultiplexer.The modulator reverses the actions of a demodulator and its function is to deliver a signal to the return path tuner.
The technology used in DTV television is MPEG-2. The demultiplexer selects particular packets, decrypts, and forwards to a specific decoder.
A DTV receiver will normally contain three separate decoders for converting the digital bit-stream back into a format that can be heard and viewed by the subscriber.
A video decoder It transforms video packets into a sequence of pictures, which are displayed by the TV monitor.An audio decoder It decompresses the audio bit-stream. Different audio modes are usually supported by the DTV receiver: mono and dual channel, stereo, and joint stereo.A data decoder.
Graphics Processor
The main purpose of a graphics processor is to render a range of Internet file formats and proprietary interactive TV file formats.
The CPU, like in a desktop PC, is the brain of the DTV receiver. Functions provided by a CPU include:
As a computer, a DTV receiver needs memory to store and manipulates instructions. Most elements within the receiver require memory to perform various tasks: The graphics engine, video decoder...