Pulssietäisyyskoodauksen

Pulssietäisyyskoodaus, often abbreviated as PAM, is a method used in telecommunications and digital signal processing to represent digital data as a series of pulses. Instead of simply turning a signal on or off (as in binary pulse-amplitude modulation), PAM uses discrete levels of amplitude to encode information. A common form is Pulse Amplitude Modulation (PAM-4), which utilizes four distinct amplitude levels. Each level can represent two bits of data, allowing for twice the data rate compared to a simple binary system with the same symbol rate.

The process involves modulating the amplitude of a carrier signal according to the digital data to be transmitted. At the receiving end, a decision circuit or a decoder samples the amplitude of the incoming pulses and maps them back to their corresponding digital values. The distinct amplitude levels are chosen such that they are sufficiently separated to minimize the risk of misinterpretation due to noise or signal distortion during transmission. This separation is crucial for maintaining signal integrity and achieving reliable data recovery.

PAM techniques are widely employed in various applications, including Ethernet standards, high-speed serial data links, and optical communication systems. By increasing the number of bits encoded per symbol, PAM allows for higher data transmission speeds over existing infrastructure, making it an efficient method for bandwidth enhancement. However, increasing the number of amplitude levels can also lead to increased susceptibility to noise and inter-symbol interference, requiring careful system design and equalization techniques.