What does QAM mean in UNCLASSIFIED

What Is Quadrature Amplitude Modulation (QAM)?

In telecommunications networks, quadrature amplitude modulation (QAM) is a method for encoding digital information onto an analog signal by combining two amplitude-modulated signals with different phases. In essence, it creates a single signal composed of two separate amplitude-modulated carriers — one in-phase and one quadrature phase — that are transmitted simultaneously to increase the efficiency of data transmission over a given frequency range. Compared to traditional AM modulators, which use only one carrier phase, QAM offers an improved signal-to-noise ratio (SNR) and enables more bits per second (bps) to be encoded into the transmission medium.

How Does Quadrature Amplitude Modulation (QAM) Work?

At its most basic level, quadrature amplitude modulation combines two separate carrier waves — one in-phase and one quadrature — into a single signal that can be sent over the same frequency range as would normally be required for AM modulators. The two carrier signals are combined using vector addition or multiplication; they are either added or multiplied together depending on the desired output from the modulation process. When these two signals are combined correctly, they form complex waveforms which carry additional information regarding their phase differences relative to each other. This allows for more bits per second to be encoded onto the analog signal when compared to traditional AM modulators.

Advantages Of Quadrature Amplitude Modulation (QAM)

The primary advantage of using QAM over traditional methods such as FM or AM is its improved SNR; because both carrier frequencies are used simultaneously instead of just one, this allows for greater bit density per hertz on any given frequency range while still maintaining acceptable levels of accuracy and reliability in the received message. Additionally, varying levels of efficiency can be achieved depending on how many carrier frequencies are used; generally speaking, 8 or 16 carriers will yield better results than 4 or 2 carriers respectively due to their increased redundancy and ability to conjugate multiple data streams at once without significant interference or error rates occurring during transmission. Finally, since fewer components are required for this type of modulation technique than others like FM or PM (which require multiple stages), systems designed around QAM have lower costs associated with them as well as less maintenance effort required from operators over time; these factors make it attractive for applications like cellular communication networks where cost effectiveness is vital for success.