C/P
Which type of tuner to use has been questionned several times so I did some online research before making this guide hoping it will help poeple understand what are the diffrences between those tuners, Most of the text here is a copy/past from internet reliable sources:
Before we define each tuner keep in mind that DVB-S and DVB-S2 are satellite tunners, ATSC is OTA (Over The Air) tuner, and QAM is a cable tuner -havn't seen one integrated in a satellite receiver here in north America but they have them in europe and are known as DVB-C "cable" tuner (Where also ATSC is called DVB-T "terrestrial" tuner and DVB-S/DVB-S2 are obviousely called DVB-S "Satellite" tuner, They are not actually called but they do use DVB standards on all their braodcasts not too complicated like here in NA).
ATSC Tuner:
An ATSC (Advanced Television Systems Committee) tuner, often called an ATSC receiver or HDTV tuner is a type of television tuner that allows reception of digital television (DTV) HD and SD channels transmitted by television stations over the air in North America, parts of Central America and South Korea that use ATSC standards.
The ATSC standards were developed in the early 1990s by the Grand Alliance, a consortium of electronics and telecommunications companies that assembled to develop a specification for what is now known as HDTV. ATSC formats also include standard-definition formats, although initially only HDTV services were launched in the digital format. 2VSB, 4VSB, 8VSB or 16VSB can be used for modulating the signal however the FCC has always held that 8VSB (8-level Vestigial SideBand modulation) is the better modulation for use in U.S. digital television broadcasting, 8VSB modulation can transfer at a maximum rate of 19.39 Mbit/s, sufficient to carry several video and audio programs and metadata. ATSC signals are designed to use the same 6 MHz bandwidth as the old analog NTSC television channels. Once the digital video and audio signals have been compressed and multiplexed (ex: 8VSB), the transport stream can be modulated in different ways depending on the method of transmission VHF or UHF.
Such tuners may be integrated into a TV, Digital video recorder (DVR), Media player, Satellite receiver, USB box/PC card for computers or a set-top box that provides audio/video output connectors for old TV's commonly known as converter digital box or simply converter box, This type of tuner receives both bands UHF and VHF so an indoor or outdoor TV antenna is required in UHF, VHF or a combination of both, Check antennaweb.org for channels in your area and what antenna to use.
QAM Tuner:
QAM stands for Quadrature Amplitude Modulation, the format by which digital cable channels are encoded and transmitted via cable television providers. Although QAM uses the same 6 MHz bandwidth as ATSC, it carries about twice the data due to the lack of error correction; however, this requires a significantly cleaner signal path, such as distribution through hybrid fiber-coax digital cable.
Cable television stations can generally operate at a higher signal-to-noise ratio and can use 2-QAM, 4-QAM, 8-QAM, 16-QAM and so on all the way up to 4096-QAM but only 16-QAM, 64-QAM and 256-QAM are the most commonly used for cable services, 256-QAM as defined in SCTE can achieve a throughput of 38.78 Mbit/s, using the same 6 MHz channel.
No antenna is required for this type of tuner but a wallet is, as in the US there is a new regulation allows cable providers to encrypte the clear channels which most of them are locals, Before, cable companies were forced to provide those basic channels for free for poeple who cannot afford a subscription based service, they managed to get rid of that regulation by a new one.
Such tuners may be integrated into a TV (Will require cable card (PCMCIA type) if TV equiped with the slot even for clear channels), Digital video recorder (DVR), Media player, Satellite receiver, USB box/PC card for computers or a set-top box that is provided by the cable company to conncet to the TV.
DVB-S Tuner:
DVB-S is an abbreviation for Digital Video Broadcasting — Satellite; it is the original Digital Video Broadcasting Forward error correction and demodulation standard for Satellite Television and dates from 1994, in its first release, while development lasted from 1993 to 1997. The first application was commercially available in France via Canal+ enabling digitally broadcast satellite-delivered television to the public, Now it is used to serve every continent of the world. DVB-S is used in both Multiple Channel Per Carrier (MCPC) and Single channel per carrier modes for Broadcast Network feeds as well as for Direct Broadcast Satellite services like Sky (UK & Ireland) via Astra in Europe, Dish Network and Globecast in the U.S. and Bell TV in Canada.
DVB-S uses QPSK(aka 4PSK), 8PSK or 16-QAM. At the broadcasters decision, QPSK and 8PSK are the only versions regularly used
PSK is Phase-Shift Keying 4 and 8 are the number of phases, Q stands for Quadrature or Quaternary
While the actual DVB-S standard only specifies physical link characteristics and framing, the overlaid transport stream delivered by DVB-S is mandated as MPEG-2, known as MPEG-TS (Moving Picture Experts Group-Transport Stream)
DVB-S signal can be transmitted via a satellite or bird in diffrent bands, KU band (pay TV and FTA), C band (pay TV and FTA) and Ka band (DirecTV)
Such tuners may be integrated in a satellite receiver or an add on as a second tuner, USB box/PC card for computers.
DVB-S2 Tuner:
Digital Video Broadcasting - Satellite - Second Generation (DVB-S2) is a digital television broadcast standard that has been designed as a successor for the popular DVB-S system. It was developed in 2003 by the DVB Project, an international industry consortium, and ratified by ETSI (EN 302307) in March 2005. The standard is based on, and improves upon DVB-S and the electronic news-gathering (or Digital Satellite News Gathering) system, used by mobile units for sending sounds and images from remote locations world-wide back to their home television stations.
DVB-S2 is envisaged for broadcast services including standard and HDTV, interactive services including Internet access, and (professional) data content distribution. The development of DVB-S2 coincided with the introduction of HDTV and H.264 (MPEG-4 AVC) video codecs.
Four modulation modes are used QPSK(4PSK), 8PSK, 16APSK and 32APSK.
-QPSK and 8PSK are proposed for broadcast applications, and can be used in non-linear transponders driven near to saturation.
-16APSK and 32APSK are used mainly for professional, semi-linear applications, but can also be used for broadcasting though they require a higher level of available C/N and an adoption of advanced pre-distortion methods in the uplink station in order to minimize the effect of transponder linearity.
Two new key features that were added compared to the DVB-S standard are:
-A powerful coding scheme based on a modern LDPC code.
-VCM (Variable Coding and Modulation) and ACM (Adaptive Coding and Modulation) modes, which allow optimizing bandwidth utilization by dynamically changing transmission parameters.
Other features include enhanced modulation schemes up to 32APSK, additional code rates, and the introduction of a generic transport mechanism for IP packet data including MPEG-4 audio–video streams, while supporting backward compatibility with existing MPEG-2 TS based transmission.
DVB-S2 achieves a significantly better performance than its predecessors – mainly allowing for an increase of available bitrate over the same satellite transponder bandwidth. The measured DVB-S2 performance gain over DVB-S is around 30% at the same satellite transponder bandwidth and emitted signal power. When the contribution of improvements in video compression is added, an (MPEG-4 AVC) HDTV service can now be delivered in the same bandwidth that supported an early DVB-S based MPEG-2 SDTV service only a decade before.
DVB-S2 is Backward compatible with DVB-S, However it doesn't benifit from 30% extra bandwidth when in DVB-S mode.
DVB-S2 signal can be transmitted via a satellite or bird in diffrent bands, KU band (pay TV and FTA), C band (pay TV and FTA) and Ka band (DirecTV)
Such tuners may be integrated in a satellite receiver or an add on as a second tuner, USB box/PC card for computers.
