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.
Friday, October 17, 2008
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:
-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.
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:
-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:
-Digital television systems;
-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
Thursday, October 16, 2008
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
-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.
- 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.
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.
-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.