Introduction

Astro is a subscription based direct broadcast satellite (DBS) or direct to home satellite television and radio service. this service is broadcast from the All Asia Broadcast Centre (ABC) located in Bukit Jalil, Kuala Lumpur. Astro is owned by MEASAT Broadcast Network Systems.

The History

The service was launched in 1996 following the launch of the MEASAT-1 satellite with an initial bouquet of 22 television and 8 radio channels. Currently, the service consists of 80 television, 17 radio, and 4 pay-per-view channels plus various interactive services. Astro's own news channel, Astro News, carries programming from the news channel Al Jazeera, available in dual language, Arabic and Malay.

* The first decoder was launch in 1996 by Philips Electronic using INS610 model.

*After 3 years, Astro launch the new model of decoder. It consist of two types of decoder like Philips and Nokia.

*After 5 years, Astro change again the decoder. It uses new model. The new model has a better performance.

What is Philips SAA7130HL

An alternative solution is the SAA7130HL decoder from Philips. Although I would consider this chip not an alternative but the newest electronic analogue. It is also a highly integrated low-cost single-chip solution that suits perfectly for capturing analog and digital broadcast. It transfers different types of multimedia data via the PCI bus. The analog signal is received by a 9bit ADC, decoded by multi-string combo-filters and scaled along horizontal and vertical axes. The decoded image is displayed in YUV and RGB formats. Analog audio signal is transferred via the connection cable to the system sound card.


Philips decoder exists in four different modifications today: 7130HL (basic or the simplest modification), 7133HL, 7134HL and 7135HL. The comparative table below is a pretty interesting thing to check out, that is why I decided to put it here:

I would like to draw your attention to the fact that NICAM digital encoding is implemented only in 7134HL and 7135HL modifications. So, I believe it makes sense to pay special attention to the TV-tuners built on the latest chip modifications, because stereo is always better than mono.

Now I would like to list the major specifications of the Philips SAA7130HL chip:
-NTSC/PAL/SECAM decoding;
-5 analog video-Ins: CVBS and S-Video;
-Video digitizing by two 9bit 27MHz ADC;
-Adaptive comb-filter for NTSC and PAL, which also works for non-standard signals;
-Automatic TV signal detector;
-Three-level detection of the copy protection system - Macrovision;
-Brightness, contrast, saturation and hue control;
-Universal bandwidth filter;
-Horizontal and vertical picture scalability including the enlargement and reduction of the picture size;
-Adaptive anti-alias filtering;
-Two types of alternative settings for active video image scaling;
-Playback in YUV and RGB modes;
-Gamma-correction, black stretching.
-Even by simply comparing the useful functions of the chips we can conclude that the solution from Philips is better suited for work with SECAM standard. In the long run it should result into better image quality in our case. The real tests will show though, how the things actually stand with the image quality. We will offer you captured TV images for all 6 TV-tuner models reviewed today, so that you could take a closer look and make your own conclusions about this or that card.

What is Conexant Fusion 878A

Fusion 878A seems to be one of the most widely spread decoders. It is a fully-fledged low-cost single-chip solution and is responsible for processing signals coming from the television and radio companies. Fusion 878A is a kind of link between the PCI bus and TV-tuner card. It ensures high bandwidth for multi-media streams of data and should work with some other PCI devices as a component of their electronics. Fusion 878A inherited all the goodies of Bt878 chip and added a few new functions of its own to the list. The decoder meets the requirements of the PC98/PC99 specification and complies with PCI 2.2 standard.
Fusion 878A chip is similar to Bt878 not only in terms of its software compatibility, but also on the hardware level (here I am talking about the same internal chip layout, which makes it much easier to replace the Bt878 with a Fusion 878A without redesigning the pinout and PCB layout). Fusion 878A can also be used in a wide range of digital products, which need to manage MPEG streams. The worlds moves to digital technologies with new broadcast standards, such as ATSC and COFDM, and television recording is actively involving MPEG compression. From this point of view, Fusion 878A can be also used as a PC hub managing numerous analog and digital video formats via the PCI connection.

Here are the major technical specifications of Fusion 878A:
-NTSC/PAL/SECAM decoding;
-Stereo decoding of the audio signals for TV and FM;
-Image capturing up to 768x576 pixels (PAL);
-Integrated module managing the data transfer via the PCI bus;
-HDTV/Audio/MPEG2 data transfer via the PCI bus;
-RF serial port (40Mbit/sec) for MPEG-streams transfer;
-RF parallel port (20Mbit/sec) for MPEG-streams transfer;
-CCIR656 interface (International Radio Communication Committee);
-Interface for processing Digital TV data from the television demodulator;
-Adjustable pixel density: 8, 16, 24 and 32 bit per pixel;
-Integrated color saturation filter (chroma) and signal brightness frequency divider (luma);
-Scalable image along X and Y axes;
-Receives digital audio data via the serial I2S port;
-PCI Rev. 2.2, PC 98/PC 99, WHQL certified;
-Allows audio-in for mono-signals.

The chip can be used in the following devices:
-PC TV;
-Digital television systems;
-Digital video-recorders;
-Digital videoconferencing systems;
-Freeze-frames capturing systems;
-Dynamic data capturing (subtitles, teletext, etc.).All above listed application fields for Fusion 878A show that it is a multi-fucntional chip, so you can see it not only inside a TV-tuner

How Does it Work?

The Satellite Dish
-When the signal reach to the viewer house, the satellite dish captured the signal. A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam.
-In some systems, the dish needs to pick up signals from two or more satellites at the same time. The satellites may be close enough together that a regular dish with a single horn can pick up signals from both.
-A new dish design uses two or more horns to pick up different satellite signals

The Receiver/Decoder
The receiver has four essential jobs :

-It scrambles the encrypted signal

-It takes the digital MPEG-2 or MPEG-4 signal and converts it into an analog format that a standard television can recognize.

-It extracts the individual channels from the larger satellite signal

-It keeps track of pay-per-view programs and periodically phones a computer at the provider's headquarters to communicate billing information

Receivers have a number of other features as well. They pick up a programming schedule signal from the provider and present this information in an onscreen programming guide.

The System

- It used expensive dishes to discover unique programming that wasn't necessarily intended for mass audiences.

-The dish and receiving equipment gave viewers the tools to pick up foreign stations, live feeds between different broadcast stations.

-The satellite was broadcast in C-band radio in the 3.7-gigahertz (GHz) to 6.4-GHz frequency range.

-Digital broadcast satellite transmits programming in the Ku frequency range (11.7 GHz to 14.5 GHz )

-The component is programming sources, broadcast center, satellites, dish and receiver.

Thomson Decoder Diagram

A decoder and decoding method are described, in which a syndrome is calculated from a codeword in a syndrome generator, an error polynomial is generated based upon the syndrome in an error polynomial generator, an error location is determined from the error polynomial in the error location generator, an error magnitude is calculated from the error polynomial in the error magnitude generator and the codeword is corrected by a error corrected codeword generator responsive to location and error magnitude. An intra-decoder block messaging scheme is described in which one or more components generate inactivity messages to signal an ability to process data corresponding to a next codeword. A dual Chien search block implementation is described in which Chien block is used to determine the number of errors corresponding to a specified codeword, separately from error location and magnitude calculations performed by the Chien/Forney block. An enhanced Chien search cell architecture is described which utilizes an additional Galois field adder to synchronize the codeword and error vector, thereby decreasing delay and expense corresponding to an error correcting block implemented with a LIFO register.

This patent application is related to simultaneously filed U.S. patent application Ser. No. 10/055,076, filed Jan. 23, 2002 entitled DUAL CHIEN SEARCH BLOCKS IN AN ERROR-CORRECTING DECODER; and U.S. patent application Ser. No. 10/055,470, filed Jan. 23, 2002 entitled CHIEN SEARCH CELL FOR AN ERROR-CORRECTING DECODER, both of which are incorporated herein by reference in their entireties.

Service and Technical Information

-The direct to home service is broadcast as high-power ku- band transmissions utilizing the transponders of the MEASAT satellite system.
-Reception of the service signals uses a fixed 60-cm diameter dish antenna.
-Ku-band signals can be affected by rain attenuation.
-The operators of Astro have employed a tailor-made system to boost power of the satellite delivery system to overcome this problem.

BCM3543 Block Diagram

BCM3543 is a highly integrated low-power solution combining the functionality of a complete ATSC-to-NTSC converter on a single chip. It provides superior ATSC signal reception and demodulation under both static and dynamic multipath conditions, with functionality targeted at National Telecommunications and Information Administration (NTIA) coupon-eligible converter box programs for analog switch off. The BCM3543 is compatible with an ATSC antenna design available exclusively from Broadcom. The BCM3543 exclusive antenna provides a high-performance indoor solution that only requires a single cable interface, eliminating difficult and costly outdoor installations. The antenna control is seamlessly integrated into the BCM3543 user interface, eliminating the need for consumers to manually adjust the antenna position in order to receive optimal signal reception. The BCM3543 has on-chip support to convert all ATSC A/53e standard- and high-definition inputs (including 60-Hz 720p, 1080i) to 480i output format, including 4:3 center cut-out letterbox of 16:9 transmitted images. The programmable graphics engine enables display of ATSC A/65C Program and System Information (PSIP). This all-silicon solution minimizes part count and provides ease of manufacturing. The comprehensive integration of ADCs and DACs simplifies system design and cost and has direct interfaces to all other system components including serial Flash (SPI), tuner (I2C), push buttons, and an Infrared (IR) demodulator. The terrestrial receiver directly samples 44-MHz centred tuner output with an ADC. It digitally resamples and demodulates the signal with recovered clock and carrier timing, filters and equalizes the data, and passes soft decisions to an ATSC A/53 and ITU-T J.83 Annexes A/B/C compatible decoder. A CEA/EIA-909 smart antenna interface is included on chip. A high-fidelity fixed 54-MHz crystal clock is used to clock in the 12-bit ADC. The BCM3543 has an MPEG-2 Digital Video Broadcasting (DVB)- compliant transport processor with advanced section filtering capability, MPEG-2 (MP@HL profile) video decoder, a Broadcast Television Systems Committee (BTSC) audio encoder, a Dolby AC3/MPEG-2 audio decoder, a pair of analog audio outputs (L-R), and a single NTSC video encoder with analog output. The BCM3543 incorporates a complete MIPS32®-based microprocessor subsystem, including caches with bridging-to-memory and a local bus, where external peripherals can be attached. Integrated peripherals include a universal asynchronous receiver/transmitter (UART), counter/timers, general-purpose input/output (GPIO), Infrared (IR) transmit (TX)/receive (RX), Broadcom Serial Control (BSC), and Serial Peripheral Interface (SPI) controllers.

Field of The Invention

An important function of any modern digital communications system is error control coding. Error control coding is the field of communications that deals with techniques for detecting and correcting errors in a digital system. Generally, error detecting/correcting schemes are utilized whenever it is desired to ensure that, during transmission or through storage of digital data, error is not introduced into the data, or in the alternative, if error is introduced into the data, that the introduced error is corrected. The ability to detect and/or correct data errors is accomplished by adding redundancy to the data. The inclusion of redundant bits in transmitted or stored data results in a coded signal or field comprised of more bits than the original uncoded signal or field.
One frequently used scheme for error detection/correction is through the use of so-called Reed-Solomon codes. Reed-Solomon codes are non-binary systematic cyclic linear block codes. Non-binary codes work with symbols that are comprised of several bits. Non-binary code, such as the Reed-Solomon code, are good at correcting burst errors because the correction by these codes is done on the symbol level. A systematic code, such as the Reed-Solomon code, generates codewords that contain the message symbols in unaltered form. The encoder applies a reversible mathematical function to the message symbols in order to generate the redundancy, or parity, symbols. The codeword is then formed by appending the parity symbols to the message symbols. The Reed-Solomon code is considered a cyclical code because a circular shift of any valid codeword also produces another valid codeword. Cyclic codes are popular because there exist efficient and inexpensive decoding techniques to implement them. Finally, the Reed-Solomon code is considered linear because the addition of any two valid codewords results in another valid codeword.
A typical Reed-Solomon decoder is comprised of the following major component blocks: (i) a syndrome generating block, (ii) an error polynomial block, (iii) an error location block, and (iv) an error magnitude block, (v) an error correcting block, and (vi) a delay block. The syndrome generating block is used to receive a codeword and generate a syndrome from the codeword. The syndrome is utilized to create an error polynomial in the error polynomial block. The error polynomial is passed onto the error location and error magnitude blocks, in which error locations and magnitudes for a codeword are respectively determined. An error vector is generated from the error location and magnitude. A delayed version of the received codeword is corrected by the error correcting block using the error vector corresponding to a specific codeword. The delay block is comprised of a memory to store the received codeword while the decoding process is performed to produce the error vector.Prior art decoders use these blocks to form a “delivery pipeline.” That is, the input to one block only depends on the output of a previous block and there is no feedback from one component block to a previous or subsequent block. Therefore, only one codeword at a time may be processed, and the next codeword to be processed isn't begun until the processing of the previous codeword is completed.

Inside The Decoder

Advantages and Disadvantages of Astro Decoder

Advantages

-The video quality is very good

-The sound is very clear and sharp

Disadvantages

-obstacles like trees or small buildings will reflect these

-the signal is often distorted even in viewing area

-the signal will be lost when heavy rain

Future Of Astro

- During high profile event, Astro add a Red Button interactive feature to some channels to provide a link to several different feeds from the event.
- It can enabling viewers to select between events or sporting matches that may be taking place simultaneously.