Section II. PRINCIPLES OF PULSE-CODE MODULATION

TM 11-5895-458-14

Figure 2-2. Simplified 12-channel tdm system.

Section II. PRINCIPLES OF PULSE-CODE MODULATION

In the pcm process, standard amplitude levels are

2-3. General

assigned and are represented by digital codes. The

Pulse-code modulation is a communication technique in

incoming voice waveform is sampled at a high rate, and

which voice, data, or facsimile signals are converted into

each sample is converted to a pulse at the closest

a series of digital pulse codes. Each pulse code

standard amplitude, producing a pulse-amplitude-

represents signal amplitude at a particular instant and a

modulated (pam) waveform. The standard amplitude

series of pulse codes represents a complete waveform.

pulses developed are then measured and converted to a

Since the transmitted signal is in digital form, it is less

binary pulse code for transmission. The pulse codes are

susceptible to noise and distortion buildup over long

decoded at the receiving station and reconverted to a

distance lines, and may be regenerated at repeaters

pam waveform, which is then demodulated to produce

along the route without introducing additional distortion.

approximately the original waveform. As the sampling

frequency is increased, the waveform generated at the

2-4. Voice Transmission by Pulse Code

receiver more accurately resembles the original

Modulation

waveform.

(Fig FO-1.)

2-2