Basics of CDMA

In Code Division Multiple Access (CDMA) systems the narrowband message signals are multiplied by spreading signals. All users in CDMA uses same carrier frequency and can transmit simultaneously. The spreading signals are pseudo random code. The features of CDMA are as follows:

Basics of TDMA

Time Division Multiple Access (TDMA) systems divide the radio spectrum into time slots, and in each time slots only one user is allowed to either transmit or receive. Each user occupies a cyclically repeating time slot. Features of TDMA are as follows:

Basics of FDMA

Frequency Division Multiple Access (FDMA) assigns individual channels to individual users. The users is allocated a unique frequency band or channel. During the period of the call no other users can share the same channel. In Frequency Division Duplexing (FDD) systems the users are assigned a channel as a pair of frequencies; one frequency is used for forward channel, while other is used for reverse channel. The features of FDMA are as follows:

How To Avoid Race Around Condition in JK Flip Flop

  Race around condition is the most important condition in Digital electronics. In J-K Flip flop, when J=K=1 the output changes its state. When a clock pulse width tp is applied the output will change from 1 to 0 after a time interval of Δt, where Δt is the propagation delay through two NAND Gates in series. Now after Δt we have J=K=1, Q=0, After another interval of Δt, output Q will become 1. Hence the output will oscillates back and forth between 0 and 1 in the duration tp of the clock pulse width.

Basic Theorems in Digital Electronics

Digital Electronics is a core and important subject of Electronics and Communication Engineering. Its simple and easy to understand. The theorems used in Digital electronics minimizes the switching function of digital circuits.

The main theorem is "De-Morgan's Theorem"

Voltage-Current (V-I) Characteristics

Voltage and Current (V-I)characteristics of many devices are useful to know the nature of the device. Here are some V-I characteristics

Switches in Electronics

This time we shall be dealing with the practical application of the basic transistors; be it BJT or MOSFET each of these act as a switch in vivid applications. By the not just a switch!! These are high performance switches which work at very high switching speeds...may be in fraction of secs or milli secs!

Now, What do you understand by the term Switch??

Definition:  A switch is a device for making and breaking the connection in an electric circuit.