Difference Between QAM and ATSC (With Table)

Qam and ATSC are nothing but two digital standards that plays an important role in receiving and then decoding the digital signals that are sent by Television stations and the cable companies. QAM stands for Quadrature Amplitude Modulation that is one of the modulation methods mostly used by the telecommunication sections to decode messages or information.

ATSC, on the other hand, stands for Advanced Television System Committee. The ATSC is also a standard that is used in the United States. The purpose of ATSC is to provide HDTV picture quality. The audio provided by the ATSC signal is quite good.


The difference between Qam and ATSC is that Qam is primarily used to receive channel signals without any cable box while ATSC, on the other hand, is signals received through the air. ATSC signals are also digital channels.

Comparison Table Between QAM and ATSC

Parameters of ComparisonQAMATSC
Mostly UsedNorth AmericaNorth America
Standard forDigital standard for cableDigital standard for OTA
RequirementsIt needs much cleaner signal mediumThis too needs clean signal medium but can be much less when compared to QAM
DecodingQAM decodes fewer TV sets when compared with ATSCATSC can decode many more TV sets than QAM.

What is QAM?

QAM (Quadrature Amplitude Modulation) is a modulation that is used in the modern telecommunications sectors in order to transmit information. QAM is one of the standards that is responsible for receiving and then decoding the received signals that are sent by the Television stations and the cable companies.

The QAM signals are used primarily for decoding the signals received from a particular cable line. The QAM standard functions are quite different than ATSC and you can make out several differences between these two standards.

QAM maintenance is quite high because you will have to keep it clean as it is designed mainly for cables only. The cleanliness is because QAM standards does not have error correction capabilities which are very significant.

The bandwidth used in QAM standards is 6MHz and the signals received do not have much noise as compared to ATSC signals. QAM’s most advantageous feature is that it has the ability to squeeze many channels in the bandwidth without any kind of hindrance in the signal.

QAM is being used in most TV sets. So, we can say that this technology is available in all the latest TV sets. Older TV sets use a set-top box in the package which will help to decode the QAM signals. However, more and more people are shifting to latest the TV sets and soon QAM will be in all HDTV TV sets.

What is ATSC?

ATSC, on the other hand, stands for Advanced Television System Committee is another type of digital standard that has the capability to receive and decode the signals sent by the TV stations and the cable companies.

ATSC’s one standout feature that makes the standard different from others is that ATSC receives over the air (OTA) signals. Therefore the operations and implications are different when ATSC is compared with QAM.

QAM and ATSC might be different but surprisingly QAM is based on ATSC. The format that was established by ATSC is still used by QAM. Well, ATSC does not need cleaner cables for receiving and decoding signals which makes it an advantageous point.

TV sets having a connection to the antenna are the best example of ATSC signals. Most people still have this kind of connection at their house where we can see that the antenna is set in the open terrace and the TV set is connected to it.

ATSC digital signal was discovered way before QAM and ATSC also were installed in all TV sets that were meant to receive signals digitally. ATSC signals create some kind of noise which is a disadvantageous feature to point out.

ATSC have the ability to decode more TV sets compared to QAM and this is one of the biggest advantages. However, both QAM and ATSC have something in common and that is both of them carry IPTV streams.

Main Differences Between QAM and ATSC

  1. Both are digital standards for receiving and decoding digital signals.
  2. QAM, is a digital standard for cables whereas, on the other hand, ATSC is a digital signal for OTA (over the air)
  3. The ATSC digital signal does not need a much cleaner medium as compared to QAM’s digital signal.
  4. QAM’s bandwidth is almost double to that of an ATSC digital signals and this makes the difference between the two.
  5. QAM lacks when decoding several TV sets whereas, ATSC can have the capability to decode as much as TV sets as possible.


Both these digital standards are quite important while using a TV set and both perform a similar function but have a different operating system. ATSC was introduced way before QAM and ATSC can be seen in most old television sets.

However, the QAM digital standard is taking over nowadays and you will see that the latest television sets will compulsorily have this system in the system. If you are receiving signals through a set top box then it means that you are using an older TV set and it lacks the ability to tune but with the help of a set top box tuning becomes possible.

If you are using an old television set then you can check the specifications to see whether the television can handle QAM. If your TV can handle QAM then you can shift your system to QAM. However, most of the RF systems you cannot mix ATSC and QAM.


  1. https://ieeexplore.ieee.org/abstract/document/7937997/
  2. https://ieeexplore.ieee.org/abstract/document/7383281/
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