Douglas Adams

We are stuck with technology when what we really want is just stuff that works.

Albert Einstein

It has become appallingly obvious that our technology has exceeded our humanity.

Jose Manuel Rodriguez Delgado

Can you avoid knowledge? You cannot! Can you avoid technology? You cannot! Things are going to go ahead in spite of ethics, in spite of your personal beliefs, in spite of everything

Sergey Brin

Technology is an inherent democratizer. Because of the evolution of hardware and software, you’re able to scale up almost anything. It means that in our lifetime everyone may have tools of equal power.

Douglas Adams

Most of the time spent wrestling with technologies that don't quite work yet is just not worth it for end users, however much fun it is for nerds.

Saturday, August 16, 2014

Characteristics of a Sine Wave

Electrical sin wave form graph is a showing the variation of voltage or current. The horizontal axis shows the passing of time, progressing from left to right. The vertical axis shows the quantity measured ( voltage, ampere or Power ). There are six must important characteristics of sine wave.

RMS value 
Root mean squared ( RMS ) value is the value of the equivalent direct voltage ( DC ) which would provide the same energy to a circuit as the sine wave measured. That is, if an AC sine wave has a RMS value of 230 volts, it will provide the same energy to a circuit as a DC supply of 230 volts.

RMS value Equation 

RMS = Peek X 0.707

Peek value or Max value = 326 V

RMS = Peek X 0.707

 RMS = 326 X 0.707

RMS = 230.48 V

Average Value or mean value 
This is normally taken to mean the average value of only half a cycle of the sine wave.

Mean value Equation 

mean = V Peek  X 0.637

Peek value or Max value = 326 V

mean = V Peek  X 0.637
mean =  326 X 0.637
mean = 207.66 v

Peak to Peak value
Peak to peak (pk-pk) is the difference between the maximum positive and the maximum negative amplitudes of a waveform. 

Peek to Peek value  

VPP = Peek + Peek 

Peek value or Max value = 326 V

VPP = Peek + Peek 

VPP = 326+ 326

VPP = 652 v

Instantaneous Value 
Instantaneous value of an alternating voltage is the value of voltage at one particular instant time. The value may be zero if the particular instant is the time in the cycle at which the polarity of the voltage is changing. It may also be the same as the peak value, if the selected instant is the time in the cycle at which the voltage stops increasing and starts decreasing. There are actually an infinite number of instantaneous values between zero and the peak value.

Instantaneous value Equation

v (t) = VMax sin (w t )

w = 2 x p  x f  or  w = 2 x p / T

v (t) = VMax sin (2*p*f *)

Amplitude is the difference between the maximum positive and the X axis of a waveform. It is equal to peek value.

Periodic Time
periodic time is that amount of time that elapses from the start of a occurrences until the commencement of the next identical happening.

T = 1/f 

T = Periodic time
f  = Frequency 

Frequency is the number of occurrences of a repeating event per unit time.

F =1/T

f  = Frequency
T = Periodic time

Friday, August 15, 2014

Introduction of Global system for Mobile communications ( GSM ) Lesson 1

GSM is a Digital wireless Mobile telephony system that is widely used in the world. GSM use a combination of both the FDMA ( frequency division multiple access ) and TDMA (  Time division multiple access ). using this both combination can be transmit more channel of same time.