The pseudo-noise (or pseudo random) sequence is a noise like high frequency signal. This signal is binary in nature. Thus it looks like pulses. The sequence is not completely random but it is generated by a well defined logic...
Archive - December 2021
Necessity of Secure Communication There are some applications where it is necessary for the system to resist external interference and to make it difficult for unauthorized receivers to receive the message being transmitted. This...
A convolutional coding is done by combining the fixed number of input bits. The input bits are stored in the fixed length shift register and they are combined with the help of mod-2 adders. This operation is equivalent to binary...
The analog waveforms are converted to digital signals by PCM, DM, ADM, DPCM etc. techniques. This digital data can be represented by different formats or waveforms. These waveforms are commonly known as digital data formats or...
To overcome the quantization errors due to slope overload and granular noise, the step size (δ) is made adaptive to variations in the input signal x(t). Particularly in the steep segment of the signal x(t), the step size is...
The first operation in digital communications is the sampling. Almost all the natural signals exist in analog form. For example, voice, any moving scene, environmental data etc. exist in analog or continuous form. Such...
The automatic frequency correction (AFC) is incorporated in FM transmitter to keep carrier frequency stable. The discriminator reacts only to small changes in the carrier frequency but not to the frequency deviations in the...
All the diodes exhibit small junction capacitance in the reverse biased condition. The varactor diodes are specially designed to optimize this characteristic. The junction capacitance of the varactor diode changes as the reverse...
Angle modulation has following advantages over amplitude modulation (AM): The amplitude of FM is constant. It is independent of depth of modulation. Hence transmitter power remains constant in FM whereas in FM it varies in...
The performance of a radio receiver is measured on the basis of its selectivity, sensitivity, fidelity and image frequency rejection. Selectivity The selectivity is the ability of the receiver to select a signal of a...