by Dinesh Thakur

The DSSS (Direct Sequence Spread Spectrum) is a technique spread spectrum, but unlike the FHSS, no frequency hopping is place: DSSS causes very rapid state transitions (chipping) which tend to spread the spectrum of the signal: in fact, we have seen that with the modulations FSK, PSK and QAM width of the spectrum was twice the rate of the source. Causing "artificially" very high throughput, spectrum is spread.

 
by Dinesh Thakur

A digital logic circuit that can store a single BIT of information, and is therefore used as the basis for the construction of MEMORY chips, LATCHES and the REGISTERS within processors. A flip-flop can exist in two states, with either a high or low voltage at its output, and flips from one state to the other at each pulse of a CLOCK SIGNAL. Two different implementations of flip-flop are commonly used, called the D flip flop and the j-K flip flop.



 
by Dinesh Thakur

The FHSS (Frequency Hopping Spread Spectrum) was invented and patented in 1942 by the actress Hedy Lamarr and pianist George Antheil, which were quite versatile! The principle of FHSS is quite simple: a wide frequency band is divided into multiple channels and communications are jumping (hopping) sequentially from one channel to another in a sequence and a rate agreed to advance between the transmitter and the receiver.

 
by Dinesh Thakur

DIP switches are those nasty, tiny plastic toggle switches that come mounted together in a row on a little box-like part attached to your computer's motherboard or on some of your add-in boards. Each individual switch in a DIP switch unit can be set either on or off, allowing you to control some aspect of your computer's function. For example, on the older IBM pcs and compatibles, you had to set the DIP switches to match the amount of memory installed in your computer, to tell it what kind of monitor you had, and so on. On the add-in modem board I just installed, I had to flip some of the DIP switches so the computer would know where to find the board electronically.



 
by Dinesh Thakur

The basic modulations

No modulation

Take the example of an opera broadcast on a radio station: how music, that is to say, an audio signal, it may be channeled through wave electromagnetic? Audible sound waves have frequencies between 20 Hz to 20 kHz for bass and treble. It would be tempting to simply convert the sound wave in radio waves of the same frequency. Unfortunately, there would be several problems: first, the low radio frequencies also are very difficult to produce and capture; then two simultaneous radios would overlap since they would be issued on the same frequency band (20 Hz to 20 kHz) and would cacophony.

 
by Dinesh Thakur

DIP is an acronym that stands for dual inline package and refers to the physical layout of most computer chips. The standard chip looks like a bug, or a little rectangular box with legs. Those two rows of metal legs are the "pins" that connect the chip to the computer's circuits. The whole chip is referred to as a "package," and it's a dual inline package because the pins are lined up in two rows. 



 
by Dinesh Thakur

This was first created by an English mathematician named George Boole in 1847 and yet, in one of the strange quirks of the computer industry, is now used in everything from circuit design to searching the Internet. In essence Boole developed a system for reducing complex questions into simple yes or no answers by using what are known as truth tables, sometimes called gates.



 
by Dinesh Thakur

A chip is that truly amazing and remarkably tiny piece of silicon that has an entire integrated electronic circuit embedded within it. Chips are what make the computer. Chips are the computer. A tiny chip is one of the biggest pieces of human-made magic on earth. There are different kinds of chips, the most common being the microprocessors which run the whole computer, and memory chips, in which the computer holds and works with your information until you send it to a disk.



 
by Dinesh Thakur

(Metal Oxide Semiconductor Field- Effect Transistor) The fundamental building block of modern VLSI chips such as microprocessors and memory chips. A microscopically small FIELD-EFFECT TRANSISTOR formed on the surface of a prepared silicon wafer by exposing it to a succession of chemical treatments through a sequence of masks.



 
by Dinesh Thakur

A breadboard is a thin board, sometimes fiberglass and sometimes plastic, with lots of little holes arranged in a grid. Electronics engineers use breadboards to create prototypes of circuit boards by wiring chips, resistors, and other electronic parts onto the board by hand, with the connecting wires running underneath. The term sometimes refers to the finished prototype itself, but more often it's applied to the hole-filled board to which the electronic components are attached.

 

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