Terrestrial Microwave

Waves Hitting Satellite Dish

Microwaves do not follow the curvature of the earth and therefore require line-of-sight transmission and reception equipment. The distance coverable by a line-of-sight signal depends to a large extent on the height of the antenna the taller the antennas, the longer the sight distance. Height allows the signal to travel farther without being stopped by the curvature of the planet and raises the signal above many surface obstacles, such as low hills and tall buildings that would otherwise block...

Pulse Amplitude Modulation PAM

Modulateur Pam

The first step in analog-to-digital encoding is called pulse amplitude modulation PAM . This technique takes analog information, samples it, and generates a series of pulses based on the results of the sampling. The term sampling means measuring the amplitude of the signal at equal intervals. The method of sampling used in PAM is more useful to other areas of engineering than it is to data communication. However, PAM is the foundation of an important analog-to-digital encoding method called...

Phase Division Multiplexing

Time Domain Plot Phase 270 Degree

The term phase describes the position of the waveform relative to time zero. If we think of the wave as something that can be shifted backward or forward along the time axis, phase describes the amount of that shift. It indicates the status of the first cycle. Phase is measured in degrees or radians 360 degrees is 2n radians . A phase shift of 360 degrees corresponds to a shift of a complete period a phase shift of 180 degrees corresponds to a shift of half a period and a phase shift of 90...