Saturday, August 20, 2016

Content Management System

Content Management System 

Content Management System
Content Management System

Wednesday, August 17, 2016

Applications of Microwave Engineering

Applications of Microwave Engineering


The majority of today’s applications of RF and microwave technology are to wireless networking and communications systems, wireless security systems, radar systems, environmental remote sensing, and medical systems.

STAR DELTA connection Diagram and Working principle

STAR DELTA connection Diagram and Working principle

Descriptions: A Dual starter connects the motor terminals directly to the power supply. Hence, the motor is subjected to the full voltage of the power supply. Consequently, high starting current flows through the motor. This type of starting is suitable for small motors below 5 hp (3.75 kW).
Reduced-voltage starters are employed with motors above 5 hp. Although Dual motor starters are available for motors less than 150kW on 400 V and for motors less than 1 MW on 6.6 kV.
Supply reliability and reserve power generation dictates the use of reduced voltage or not to reduce the starting current of an induction motor the voltage across the motor need to be reduced. This can be done by 1. Autotransformer starter, 2. Star-delta starter or 3. Resistor starter. Now-a-days VVVF drive used extensively for speed control serves this purpose also.

Difference Between Transmission line and Waveguide

Comparison Between Transmission line and Wave guide :




Transmission line
Wave guide
Small cross-section transmission lines (like coaxial cables) can only transmit low power levels due to the relatively high fields concentrated at specific locations within the device
Metal waveguides can transmit high power levels. The fields of the propagating wave are spread more uniformly over a larger cross-sectional area than the small cross-section transmission line.
Large cross-section transmission lines can transmit high power levels.
Large cross-section (low frequency) waveguides are impractical due to large size and high cost.




Difference Between Transmission line and Waveguide

Sunday, August 14, 2016

Design and Implement of QPSK Modem Based on FPGA

 Design and Implement of QPSK Modem Based on FPGA.



Abstract :

This paper presents a method to designs QPSK modulator and demodulator of a spread spectrum system which use field programmable device. The method uses the tool of Quartus of American Altera Co. The whole system is divided into several small models based on top-down design method, and using VHDL hardware description language to design each model. 

Saturday, March 12, 2016

Comparison of wireless Access Technologies (WCDMA, HSPA, HSPA+, LTE)

WCDMA, HSPA, HSPA+, LTE



         "An information system formed by HAP (High Altitude Platform) will be a new generation-system for the wireless communications and HAPS (HAP Station) communication system combines the advantages of both terrestrial and satellite communication systems and avoids, to different extents, their disadvantages. Third generation (3G) mobile technology which is specified by the third generation partnership project (3 GPP) is definitely one of the candidates. With the success of wireless network, the IEEE 802.16 standard, with its wireless metropolitan area network (MAN) air interface appears to be a strong competitor. We provide initial practical comparison of these two technologies for HAPS Communication".



WCDMA
HSPA
HSPA+
LTE
Maximum Uplink Speed
128 Kbps
5.7 Kbps
11 Mbps
50 Mbps
Maximum Downlink Speed
14 Mbps
11 Mbps
28 Mbps
100 Mbps
Spectrum FDD
5 MHz
5 MHz
5 MHz
10 MHz
Latency Round trip
150 ms
100 ms
50 ms
10 ms
Access Method
CDMA
CDMA
CDMA
CDMA/SC FDMA











Table:  Comparison of wireless Access Technologies




Comparison of wireless Access Technologies (WCDMA, HSPA, HSPA+, LTE)
Comparison of wireless Access Technologies (WCDMA, HSPA, HSPA+, LTE)

Wednesday, December 9, 2015

Testability VLSI: Boundary scan

Testability VLSI: Boundry scan

  • Boundary scan is a test technique using scan methodology, involving digital services, digital devices, designed with shift registers (scan flip flops) placed between each devicepin and the internal logic.

  •   These shift registers can control and observe signal values present at each input and output pin and are connected together in serial fashion to form a data register chain, called boundary scan shift register with shift and update stages.

Sunday, December 6, 2015

JTAG Testability: JTAG Test Access Port Controller

JTAG Test Access Port


JTAG Testability: JTAG Test Access Port Controller
JTAG Testability: JTAG Test Access Port Controller
                                                           The TAP is a general-purpose port that can provide access to many test support functions built into a component, including the test logic defined by this standard. It is composed as a minimum of the three input connections and one output connection required by the test logic defined by this standard. An optional fourth input connection provides for asynchronous initialization of the test logic defined by this standard.

·                                                              The JTAG Test Access Port consists of four pins that drive the circuit blocks. The four pins, 'FMS, TCK, TDI and TDO.

o          TCK (Test Clock Input) : This pin sequences the TAP controller of the JTAG
registers.

o          TMS (Test Mode Select Input) : This pin is the mode input signal that provides
the control logic for JTAG.

o          TIM (Test Data Input) : This pin is the serial data input to all JTAG instruction
and data registers.

o          TDO (Test Data Output) : This pin is the serial data output for all JTAG
instruction and data registers.

comparison of nmos and pmos operation modes

Comparison of nmos and pmos operation modes:

For many years, NMOS circuits were much faster than comparable PMOS and CMOS circuits, which had to use much slower p-channel transistors.

comparison of nmos and pmos operation modes
comparison of nmos and pmos operation modes


comparison of nmos and pmos operation modes video:






Tuesday, December 1, 2015

Difference between Travelling wave tube and klystron

Difference between Travelling wave tube and klystron:

Difference between Travelling wave tube and klystron
Difference between Travelling wave tube and klystron


Travelling wave tube and klystron Video:


Monday, November 16, 2015

What is IPv4 ADDRESSES with example ?

IPv4 address Analysis:


An IPv4 address is a 32-bit address that uniquely and universally defines the connection of a device (for example, a computer or a router) to the Internet.

The IPv4 addresses are unique 


and universal.

 Dotted-decimal notation and binary notation for an IPv4 address

Dotted-decimal notation and binary notation for an IPv4 address


Ex.Change the following IPv4 addresses from binary notation to dotted-decimal notation.

IPv4 address
Solution
We replace each group of 8 bits with its equivalent decimal number (see Appendix B) and add dots for separation.

IPv4 address


IPv4 ADDRESSES with example Video:




Monday, November 2, 2015

Multiplexing and demultiplexing: Definition

Definition & Basics :


 "Multiplexing is the procedure in which numerous Data Streams, originating from diverse Sources, are joined and Transmitted over a Single Data Channel or Data Stream."

Multiplexing and demultiplexing: Definition


     In Electronic Communications, the two fundamental types of Multiplexing are Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM).

Tuesday, October 27, 2015

Multiplexing and Multiple Access

Multiplexing And Multiple Access :

Digital Communications

Difference between Multiplexing and Multiple Access:





Sr.No.



Multiplexing




Multiple Access




1

“In telecommunications and 
computer networks, multiplexing
is a process where
multiple analog
 message signals or digital data 
streams are combined into one 
 signal over a shared medium.”

“In telecommunications and
computer networks, a channel
access method or multiple access
 method allows several terminals
connected to the
same multipoint
physical medium to transmit
over it and to share its capacity.”



2

The multiplexed signal is transmitted
 over a communication channel,
 which may be a physical transmission medium.


A channel-access scheme is
 based on a multiplex method 
that allows several data streams 
or signals to share the 
same communication channel or
 physical media.





3

A device that performs the 
multiplexing is called a 
multiplexer (MUX), 
and a device that performs 
the reverse process is called
a demultiplexer (DEMUX).

A channel-access scheme 
is also based on a Multiple access 
protocol and control mechanism, 
also known as media access 
control (MAC). This protocol 
deals with issues such as addressing, 
assigning multiplex channels to 
different users, 
 and avoiding collisions.


4

It works on the physical layer 
(L1) of OSI model.

It works on the Data Link layer
 (L2) of OSI model.








5

Classification of multiplexing:
(w.r.t. channelization methods)

a.Time-division 
multiplexing (TDM)


b.Frequency-division
 multiplexing(FDM)

I.WDM
II.OFDM
III.SC-FDM







c.Code-division multiplexing
 (CDM):
I.DSSS
II.FHSS
III.OFHM
IV.MC-CDM

Classification of Multiple Access:
(w.r.t. channelization methods)

a.TDMA
MF-  TDMA


b.FDMA


I.Wavelength division 
multiple access (WDMA)
II.Orthogonal frequency
 division multiple access
 (OFDMA)
III.Single-carrier
 FDMA (SC-FDMA)



    c.Code division multiple access (CDMA):
I.Direct-sequence CDMA 
(DS-CDMA), based on 
 Direct-sequence spread 
spectrum (DSSS)
II.Frequency-hopping CDMA 
(FH-CDMA), based on 
 Frequency-hopping spread 
spectrum (FHSS)
III.Orthogonal 
frequency-hopping
 multiple access (OFHMA)
IV.Multi-carrier code 
division multiple 
access (MC-CDMA)












6

Classification of multiplexing:
(w.r.t. Applications)

a.Telephony:
I.Fiber in the loop (FITL)
II.FDM in DSL









b.Video processing
I.TDM


c.Digital broadcasting
I.statistical multiplexing                  



Classification of Multiple Access:
(w.r.t. Packet mode methods)

       a.Contention based random multiple access methods:
I.Aloha
II.Slotted Aloha
III.(MACA)
IV.(MACAW)
V.(CSMA)
VI.(CSMA/CD)
VII.(CSMA/CA)
VIII.(DCF)
IX.(PCF)

b.Token passing
    I.Token ring
II.Token bus

 c.Polling

      
d.Resource reservation 
(scheduled) packet-mode
 protocols
I.(Dynamic TDMA)
II.(PRMA)
III.(R-ALOHA)



7

Example:
Cisco Frame Relay and X.25 
systems are also categorized 
as Statistical TDMs.


Example:
Service providers can deploy 
Cisco-CDMA data services 
to track ongoing performance 
of their network end to end.


Difference in between Time division multiplexing (TDM) and Frequency division multiplexing (FDM)

Difference in between TDM and FDM:


This page on FDM versus TDM describes difference between FDM and TDM multiplexing. FDM is the short form of frequency division multiplexing and TDM is the short form of time division multiplexing.
In FDM each signal is modulated onto different unique RF carrier frequency and all carrier frequencies are separated significantly so that bandwidth of the signals do not overlap in frequency domain.
Difference in between TDM and FDM
Figure: Difference in between TDM and FDM