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What Is an SDTV Tuner?

An SDTV tuner is a device that decodes standard definition television signals, allowing older TVs to receive and display digital broadcasts. It's essential for those who haven't upgraded to HDTV but wish to enjoy the clarity of digital channels. Wondering how this technology can enhance your viewing experience? Let's examine the benefits of integrating an SDTV tuner into your entertainment setup.
Bobby R. Goldsmith
Bobby R. Goldsmith

An SDTV tuner is a digital tuner, included with a television or with a set-top box for a cable or satellite television service, that accesses channels in standard definition. Standard definition is digital signal broadcast for televisions that have no enhancements to the visual presentation such as high definition television (HDTV). An SDTV tuner receives a picture, in 480i resolution, while an HDTV tuner receives a picture in 1,080p resolution. A slightly enhanced definition resolution is also offered, EDTV, providing between 680p and 720p.

Every television produced since 1997 has an SDTV tuner, even HD and ED televisions. The tuner is the most basic model of television tuner on the market, and it is compatible with higher resolutions in that an SDTV tuner can view an HDTV signal. The HDTV signal, however, will appear choppy, blurred, and poor. SDTV provides the equivalent picture quality of an analog television with the absence of white noise and static due to signal interference being the only notable improvement.

An SDTV turner can view a HD signal, but the HDTV signal will appear in poor quality.
An SDTV turner can view a HD signal, but the HDTV signal will appear in poor quality.

More TVs are appearing in the marketplace that do not have integrated tuners. To save space, several makes and models of flat-panel televisions do not include a built-in tuner. In order to watch live television broadcasts on such a TV, the user must purchase and install a set-top peripheral tuner. Most peripheral tuners feature both SD and HD capability. Some SDTV tuners, however, require either an antenna or cable or satellite service.

The standard in North America for an SDTV tuner is a resolution of 480i. This means that a television renders a picture composed of 480 interlaced lines within a vertical frame. Depending upon the aspect ratio, an SDTV tuner presents a picture that is between 704 and 720 pixels in width. The European standard for SDTV features a resolution of 525 interlaced lines, with only 480 of those lines used to present signal information.

An SDTV tuner typically presents an image with a 4:3 display aspect ratio. This means that the width of the picture relayed is slightly larger than the height of the picture. Some such tuners, along with all HDTV tuners, present an image that features a 16:9 display aspect ratio. Some television models, along with several set-top boxes, allow a user to stretch an SD signal received in the 4:3 ratio to cover the 16:9 aspect ratio of full screen HDTV. This stretching process degrades the quality of the resolution and is not a substitute for an HDTV tuner.

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Discussion Comments


@miriam98 - Yes, I agree. You should definitely consider all the equipment you need before you make a purchase. Depending on your situation, you don’t necessarily need the satellite or cable box. It depends on what kind of transmission you’re receiving and what kind of television you have.

If you’re just getting regular TV stations over the air using the traditional “rabbit ears” and you still have an analog TV, then all you need is a digital TV converter. This converter will sit on top of your television and then convert the digital over the air signals to analog so that you can view them on your analog set.

I realize that most people have digital televisions nowadays, but some people still have analog sets. In this case the converter box and the SDTV tuner would be all that they need.


While most flat panel televisions on the market today are High Definition, it is still possible to get a flat panel with Standard Definition. In that case, an SDTV tuner would still be acceptable and not cause distortion of the picture.

I have a high definition flat panel TV and a HDTV digital TV tuner however, and it works fine, except I don’t have an HD satellite receiver as of yet. So I wind up with a problem of blurry pictures as a result of the conflict in resolution.

I was told that I needed both the HDTV tuner plus the HD satellite (or cable box) set, to get the best possible picture. So my word of advice to everyone is to look into all the equipment you’ll need before making a purchase. If you don’t plan on getting the HD cable box, then just buy a Standard Definition flat panel and an SDTV tuner and you should be fine.

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    • An SDTV turner can view a HD signal, but the HDTV signal will appear in poor quality.
      By: Ricardo Rohland
      An SDTV turner can view a HD signal, but the HDTV signal will appear in poor quality.