In BPSK the two vectors, the signal set can be illustrated as two 180 opposing vector which is called as antipodal signal sets.

In general FSK the signal change from one frequency to another will be abrupt but in continuous FSK the signal change from one frequency to another will be gentle and gradual.

Some of the examples of coherent modulation techniques are phase shift keying, amplitude shift keying, frequency shift keying and continuous phase modulation.

The transmission of Em field in space is done with the help of antennas. Antenna size depends of the wavelength. The length of the antenna is equal to λ/4.

The first step of the detection process is to reduce waveform into a single or group of random variable. This first step in the transformation of waveform into a point in signal space. This point is called as predetection point.

The combination of ASK and PSK is called as APK. In APK each vector is separated by 45.

When the receiver uses carrier’s phase as major factor for detection then it is called as coherent detection and when carrier is not given importance it is called as non coherent detection.

In ASK modulation scheme the signal attains either maximum amplitude or zero point. Thus it is also called as on-off keying.

The term heterodyning means frequency conversion and frequency mixing that yields a spectral shift in the signal.

The two main parts of sinusoid carrier wave – real part is called as inphase and the imaginary part is called as quadrature.