Google Amazing Tricks

Latest Google FUNS::
In Google : Search “let it snow” Or Just Visit HERE 
you will receive a wintery visual treat which adds snow fall and a “foggy glass” effect to the results page. After a few moments pass, you can then wipe away the fog away with your mouse cursor.

Some Other Google Easter Eggs:
Gravity: Type Google Gravity  and click “I’m feeling lucky” to observe Google collapse before your very eyes.
Askew: Type in tilt or askew  and Google will slant your search results in an interesting way.
ASCII: Type in ascii art  and Google will change its look to match your search criteria.
Alternative languages: Google doesn’t discriminate. They kindly provide search services in such important languages at Klingon, Pirate and more.
Anagram: Searching for anagram  causes Google to suggest “nag a ram”
Recursion: Searching for recursion  causes Google to suggest “recursion” once again, for good measure
The Loneliest number: It’s 1, of course
The answer to the universe: Most geeks know the answer to this one already.

New Google FUN::
In Google Search, Type: “do a barrel roll” and enter – you’ll be amazed!

Also Try searching for “tilt” and “askew” as well.

Lean n Get Amazed!

1.Go to www.google.com

2.Type “Google sphere”(without quotes) and press I’m feeling Lucky button.

or visit http://mrdoob.com/projects/chromeexperiments/google_sphere/ 
This is what you see

Want more?
Try type Google Gravity on search bar and click I’m Feeling Lucky button and see what will you find out after that.
or visit this page directly to see http://mrdoob.com/projects/chromeexperiments/google_gravity/ 

Want play pacman on google?
Try type Google Pacman on search bar and click I’m Feeling Lucky button and enjoy the game!

Try on other trick below as well and you can find its not only just a button there.

Type : Epic Box
Type : Sexy Snape
Type : Google Magic
Type : Google Loco
Type : ewmew fudd
Type : lol limewire
Type : Google Easter Eggs
Type : Who’s the cutest & Press pai button on right bottom screen *Warning! If you are under 18, please don’t click that button*
Type : googlegooglegooglegoogle (google 4 times)
Type : Google chuck norris
Type : Epic Google
Type : Rainbow Google
Type : elgoog
Type : annoying google
Type : Google Linux

Eigenfaces based Face Recognition

Eigenfaces based Face Recognition: So after more than a month, this is an implementation of Eigenfaces based face Recognition in Matlab. And the delay was mainly because of t...

Semi Conductor Devices Interview Questions

1) Why thyristor is also called bilicor-controlled rectifier (SCR)?
2) How many layers and junctions are there in a basic thyristors?
3) How many terminals are there and what are they?
4) How the thyristor is turned on?
5) How the turnoff is achieved?
6) Basically how many classifications of thyristors are there and what are they?
7) What is converter-grade thyristor?
8)What is inverter grade thyristor?
9) Where does Inverter-grade thyristor used?
10) What is forward voltage drop in thyristor?
11) What is a triac?
12) What is GTO?
13) Why there is no need for external commutation circuit to turn it off?
14) What is reverse-conducting thyristor (RCT)?
15) What is asymmetrical silicon controlled rectifier (ASCR)?
16) How is power transistor turned ON or OFF?
17) What is Darlington configuration?
18) Define RBSOA and FBSOA?
19) What are the voltage-driver devices?
20) What are the current-driver devices?
21) What is power MOSFET?
22) What is insulated-gate bipolar transistor (IGBT)?
23) How IGBT is different from MOSFET?
24) How is IGBT turned ON and OFF?
25) In general how IGBT’s are classified?
26) Why PT (punch through) IGBT’s cannot be used as easily paralleled as MOSFET?
27) Why NPT (non punch through) IGBT’s can be paralleled?
28) What is MOS-controlled thyristor (MCT)?
29) What is the advantage of MCT over IGBT?
30) What is a diode?
31) Define peak inverse voltage of a diode?
32) What is maximum surge current?
33) How a power diode is tested?
34) What are the elements against which power diodes must be protected?
35) Why a RC series circuit is connected across the diode?
36) What is schottky diode?
37) What are the advantages of schottky diode over a normal diode?
38) How schottky diodes are tested?
39) What is a DIAC?
40) What is silicon controlled switch?
41) Why silicon controlled switch has two gates?
42) What are the power Bi-polar junction transistors?
43) How many layers are there in a transistor and what are they?
44) What are the types of transistors?
45) How BJT is tested?
46) What is break down voltage in MOSFET?
47) What is dynamic avalanche in GTO?
48) What are choppers?
49) What are the functions of switch mode power supplies (SMPS)?
50) What is one -quadrant choppers?
51) What is two -quadrant choppers?
52) What is four -quadrant choppers?
53) What are buck converters?
54) What are boost converters?
55) What is co-converter?
56) What are the important diode current characteristics in single phase half wave rectifier?
57) What are the important diode voltage characteristics in single phase half wave rectifier?
58) What are the differences between controlled and un-controlled rectifiers?
59) Why diode rectifiers generate harmonics?
60) What are the harmonic mitigating techniques?
61) Why SCR’s are connected in series and parallel combinations?
62) What are the two major problems during series connection of the devices?
63) What are the primary methods in common use of triggering series connected SCR’s?
64) What is string efficiency of SCR’s connected in series / parallel?
65) What is Derating of SCR’s?
66) Explain principle of chopper operation?
67) What are the two types of control strategies for operating the switches are employed in DC   choppers?
68) What are step-up choppers?
69) What are step-down choppers?
70) Explain the various chopper configurations?
71) What are the different types of commutations techniques n chopper?
72) Explain AC Regulator?
73) What are the types of single phase regulators?
74) What are the six different methods of commutation by which thyristors may be turned off?
75) What is holding current and latching current?
76) What is meant by di/dt rating of thyristor?
77) What is the use of pulse transformer in triggering circuits?
78) What is pedestal and ramp triggering?
79) What is the difference between mid-point converters and bridge converters?
80) What is the use of free wheeling diode?

C interview questions

1. What does static variable mean?
Ans: Static variables are the variables which retain their values between the function calls. They are initialized only once their scope is within the function in which they are defined.

2. What is a pointer?
Ans: Pointers are variables which stores the address of another variable. That variable may be a scalar (including another pointer), or an aggregate (array or structure). The pointed-to object may be part of a larger object, such as a field of a structure or an element in an array.
3. What are the uses of a pointer?
Ans: Pointer is used in the following cases
i) It is used to access array elements
ii) It is used for dynamic memory allocation.
iii) It is used in Call by reference
iv) It is used in data structures like trees, graph, linked list etc.
4. What is a structure?
Ans: Structure constitutes a super data type which represents several different data types in a single unit. A structure can be initialized if it is static or global.
5. What is a union?
Ans: Union is a collection of heterogeneous data type but it uses efficient memory utilization technique by allocating enough memory to hold the largest member. Here a single area of memory contains values of different types at different time. A union can never be initialized.
6. What are the differences between structures and union?
Ans: A structure variable contains each of the named members, and its size is large enough to hold all the members. Structure elements are of same size.
A union contains one of the named members at a given time and is large enough to hold the largest member. Union element can be of different sizes.
7. What are the differences between structures and arrays?
Ans: Structure is a collection of heterogeneous data type but array is a collection of homogeneous data types.
Array
1-It is a collection of data items of same data type.
2-It has declaration only
3-.There is no keyword.
4- array name represent the address of the starting element.
Structure
1-It is a collection of data items of different data type.
2- It has declaration and definition
3- keyword struct is used
4-Structure name is known as tag it is the short hand notation of the declaration.
8. In header files whether functions are declared or defined?
Ans: Functions are declared within header file. That is function prototypes exist in a header file,not function bodies. They are defined in library (lib).
9. What are the differences between malloc () and calloc ()?
Ans: Malloc Calloc 1-Malloc takes one argument Malloc(a);where a number of bytes 2-memory allocated contains garbage values
1-Calloc takes two arguments Calloc(b,c) where b no of object and c size of object
2-It initializes the contains of block of memory to zerosMalloc takes one argument, memory allocated contains garbage values.
It allocates contiguous memory locations. Calloc takes two arguments, memory allocated contains all zeros, and the memory allocated is not contiguous.
10. What are macros? What are its advantages and disadvantages?
Ans: Macros are abbreviations for lengthy and frequently used statements. When a macro is called the entire code is substituted by a single line though the macro definition is of several lines.
The advantage of macro is that it reduces the time taken for control transfer as in case of
function.
The disadvantage of it is here the entire code is substituted so the program becomes
lengthy if a macro is called several times.
Related Fresher Interview Questions
11. Difference between pass by reference and pass by value?
Ans: Pass by reference passes a pointer to the value. This allows the callee to modify the variable directly.Pass by value gives a copy of the value to the callee. This allows the callee to modify the value without modifying the variable. (In other words, the callee simply cannot modify the variable, since it lacks a reference to it.)

12. What is static identifier?
Ans: A file-scope variable that is declared static is visible only to functions within that file. A
function-scope or block-scope variable that is declared as static is visible only within that scope. Furthermore, static variables only have a single instance. In the case of function- or block-scope variables, this means that the variable is not “automatic” and thus retains its value across function invocations.
13. Where is the auto variables stored?
Ans: Auto variables can be stored anywhere, so long as recursion works. Practically, they’re stored on
the stack. It is not necessary that always a stack exist. You could theoretically allocate function invocation records from the heap.
14. Where does global, static, and local, register variables, free memory and C Program instructions get stored?
Ans: Global: Wherever the linker puts them. Typically the “BSS segment” on many platforms.
Static: Again, wherever the linker puts them. Often, they’re intermixed with the globals. The only difference between globals and statics is whether the linker will resolve the symbols across compilation units.Local: Typically on the stack, unless the variablegets register allocated and never spills.Register: Nowadays, these are equivalent to “Local” variables. They live on the stack unless they get register-allocated.
15. Difference between arrays and linked list?
Ans: An array is a repeated pattern of variables in contiguous storage. A linked list is a set of
structures scattered through memory, held together by pointers in each element that point to the next element. With an array, we can (on most architectures) move from one element to the next by adding a fixed constant to the integer value of the pointer. With a linked list, there is a “next” pointer in each structure which says what element comes next.
16. What are enumerations?
Ans: They are a list of named integer-valued constants. Example:enum color { black , orange=4,
yellow, green, blue, violet };This declaration defines the symbols “black”, “orange”, “yellow”, etc. to have the values “1,” “4,” “5,” … etc. The difference between an enumeration and a macro is that the enum actually declares a type, and therefore can be type checked.
17. Describe about storage allocation and scope of global, extern, static, local and register variables?
Ans:
Globals have application-scope. They’re available in any compilation unit that includes an
appropriate declaration (usually brought from a header file). They’re stored wherever the linker puts them, usually a place called the “BSS segment.”
Extern? This is essentially “global.”
Static: Stored the same place as globals, typically, but only available to the compilation unit that contains them. If they are block-scope global, only available within that block and its subblocks.
Local: Stored on the stack, typically. Only available in that block and its subblocks.
(Although pointers to locals can be passed to functions invoked from within a scope where that local is valid.)
Register: See tirade above on “local” vs. “register.” The only difference is that
the C compiler will not let you take the address of something you’ve declared as “register.”
18. What are register variables? What are the advantages of using registervariables?
Ans: If a variable is declared with a register storage class,it is known as registervariable.The
register variable is stored in the cpu register instead of main memory.Frequently usedvariables
are declared as register variable as it’s access time is faster.
19. What is the use of typedef?
Ans: The typedef help in easier modification when the programs are ported to another machine.
A descriptive new name given to the existing data type may be easier to understand the code.
20. Can we specify variable field width in a scanf() format string? If possible how?
Ans: All field widths are variable with scanf(). You can specify a maximum field width for a given
field by placing an integer value between the ‘%’ and the field type specifier. (e.g. %64s). Such a specifier will still accept a narrower field width.
The one exception is %#c (where # is an integer). This reads EXACTLY # characters, and it is the
only way to specify a fixed field width with scanf().
21. Out of fgets() and gets() which function is safe to use and why?
Ans: fgets() is safer than gets(), because we can specify a maximum input length. Neither one is completely safe, because the compiler can’t prove that programmer won’t overflow the buffer he pass to fgets ().

22. Difference between strdup and strcpy?
Ans: Both copy a string. strcpy wants a buffer to copy into. strdup allocates a buffer using malloc().
Unlike strcpy(), strdup() is not specified by ANSI .
23. What is recursion?
Ans: A recursion function is one which calls itself either directly or indirectly it must halt at a definite point to avoid infinite recursion.
24. Differentiate between for loop and a while loop? What are it uses?
Ans: For executing a set of statements fixed number of times we use for loop while when the number of
iterations to be performed is not known in advance we use while loop.
25. What is storage class? What are the different storage classes in C?
Ans: Storage class is an attribute that changes the behavior of a variable. It controls the lifetime, scope and linkage. The storage classes in c are auto, register, and extern, static, typedef.
26. What the advantages of using Unions?
Ans: When the C compiler is allocating memory for unions it will always reserve enough room for the
largest member.
27. What is the difference between Strings and Arrays?
Ans: String is a sequence of characters ending with NULL .it can be treated as a one dimensional array
of characters terminated by a NULL character.
28. What is a far pointer? Where we use it?
Ans: In large data model (compact, large, huge) the address B0008000 is acceptable because in these
model all pointers to data are 32bits long. If we use small data model(tiny, small, medium) the above address won’t work since in these model each pointer is 16bits long. If we are working in a small data model and want to access the address B0008000 then we use far pointer. Far pointer is always treated as a 32bit pointer and contains a segment address and offset address both of 16bits each. Thus the address is represented using segment : offset format B000h:8000h. For any
given memory address there are many possible far address segment : offset pair. The segment register contains the address where the segment begins and offset registercontains the offset of data/code from where segment begins.
29. What is a huge pointer?
Ans: Huge pointer is 32bit long containing segment address and offset address. Huge pointers are
normalized pointers so for any given memory address there is only one possible huge address segment: offset pair. Huge pointer arithmetic is doe with calls to special subroutines so its arithmetic slower than any other pointers.
30. What is a normalized pointer, how do we normalize a pointer?
Ans: It is a 32bit pointer, which has as much of its value in the segment register as possible. Since
a segment can start every 16bytes so the offset will have a value from 0 to F. for normalization convert the address into 20bit address then use the 16bit for segment address and 4bit for the offset address. Given a pointer 500D: 9407,we convert it to a 20bitabsolute address 549D7,Which then normalized to 549D:0007.
31. What is near pointer?
Ans: A near pointer is 16 bits long. It uses the current content of the CS (code segment) register (if
the pointer is pointing to code) or current contents of DS (data segment) register (if the pointer is pointing to data) for the segment part, the offset part is stored in a 16 bit near pointer. Using near pointer limits the data/code to 64kb segment.

32. In C, why is the void pointer useful? When would you use it?
Ans: The void pointer is useful because it is a generic pointer that any pointer can be cast into and
back again without loss of information.
33. What is a NULL Pointer? Whether it is same as an uninitialized pointer?
Ans: Null pointer is a pointer which points to nothing but uninitialized pointer may point to anywhere.
34. Are pointers integer?
Ans: No, pointers are not integers. A pointer is an address. It is a positive number.
35. What does the error ‘Null Pointer Assignment’ means and what causes this error?
Ans: As null pointer points to nothing so accessing a uninitialized pointer or invalid location may cause an error.
36. What is generic pointer in C?
Ans: In C void* acts as a generic pointer. When other pointer types are assigned to generic pointer,
conversions are applied automatically (implicit conversion).
37. Are the expressions arr and &arr same for an array of integers?
Ans: Yes for array of integers they are same.
38. IMP>How pointer variables are initialized?
Ans: Pointer variables are initialized by one of the following ways.
I. Static memory allocation
II. Dynamic memory allocation
39. What is static memory allocation?
Ans: Compiler allocates memory space for a declared variable. By using the address of operator, the
reserved address is obtained and this address is assigned to a pointer variable. This way of assigning pointer value to a pointer variable at compilation time is known as static memory allocation.
40. What is dynamic memory allocation?
Ans: A dynamic memory allocation uses functions such as malloc() or calloc() to get memory dynamically. If these functions are used to get memory dynamically and the values returned by these function are assigned to pointer variables, such a way of allocating memory at run time is known as dynamic memory allocation.
41. What is the purpose of realloc?
Ans: It increases or decreases the size of dynamically allocated array. The function realloc (ptr,n) uses two arguments. The first argument ptr is a pointer to a block of memory for which the size is to be altered. The second argument specifies the new size. The size may be increased or decreased. If sufficient space is not available to the old region the function may create a new region.

42. What is pointer to a pointer?
Ans: If a pointer variable points another pointer value. Such a situation is known as a pointer to a pointer.
Example:
int *p1,**p2,v=10;
P1=&v; p2=&p1;
Here p2 is a pointer to a pointer.
43. What is an array of pointers?
Ans: if the elements of an array are addresses, such an array is called an array of pointers.
44. Difference between linker and linkage?
Ans: Linker converts an object code into an executable code by linking together the necessary built in
functions. The form and place of declaration where the variable is declared in a program determine the linkage of variable.
45. Is it possible to have negative index in an array?
Ans: Yes it is possible to index with negative value provided there are data stored in this location. Even if it is illegal to refer to the elements that are out of array bounds, the compiler will not produce error because C has no check on the bounds of an array.
46. Why is it necessary to give the size of an array in an array declaration?
Ans: When an array is declared, the compiler allocates a base address and reserves enough space in
memory for all the elements of the array. The size is required to allocate the required space and hence size must be mentioned.
47. What modular programming?
Ans: If a program is large, it is subdivided into a number of smaller programs that are called modules or subprograms. If a complex problem is solved using more modules, this approach is known as modular programming.
48. What is a function?
Ans: A large program is subdivided into a number of smaller programs or subprograms. Each subprogram
specifies one or more actions to be performed for the larger program. Such sub programs are called functions.
49. What is an argument?
Ans: An argument is an entity used to pass data from the calling to a called function.
50. What are built in functions?
Ans: The functions that are predefined and supplied along with the compiler are known as built-in functions. They are also known as library functions.
51. Difference between formal argument and actual argument?
Ans: Formal arguments are the arguments available in the function definition. They are preceded by
their own data type. Actual arguments are available in the function call. These arguments are given
as constants or variables or expressions to pass the values to the function.

52. Is it possible to have more than one main() function in a C program ?
Ans: The function main() can appear only once. The program execution starts from main.
53. What is the difference between an enumeration and a set of pre-processor # defines?
Ans: There is hardly any difference between the two, except that #defines has a global effect (throughout the file) whereas an enumeration can have an effect local to the block if desired. Some advantages of enumeration are that the numeric values are automatically assigned whereas in #define we have to explicitly define them. A disadvantage is that we have no control over the size of enumeration variables.
54. How are Structure passing and returning implemented by the complier?
Ans: When structures are passed as argument to functions, the entire structure is typically pushed on
the stack. To avoid this overhead many programmer often prefer to pass pointers to structure instead of actual structures. Structures are often returned from functions in a location pointed to by an extra, compiler-supported ‘hidden’ argument to the function.
55. IMP>what is the similarity between a Structure, Union and enumeration?
Ans: All of them let the programmer to define new data type.
56. Can a Structure contain a Pointer to itself?
Ans: Yes such structures are called self-referential structures.
57. How can we read/write Structures from/to data files?
Ans: To write out a structure we can use fwrite() as Fwrite( &e, sizeof(e),1,fp);Where e is a structure
variable. A corresponding fread() invocation can read the structure back from file. calling fwrite() it writes out sizeof(e) bytes from the address &e. Data files written as memory images with fwrite(),however ,will not be portable, particularly if they contain floating point fields or Pointers. This is because memory layout of structures is machine and compiler
dependent. Therefore, structures written as memory images cannot necessarily be read back by programs running on other machine, and this is the important concern if the data files you’re writing will ever be interchanged between machines.
58. Write a program which employs Recursion?
Ans: int fact(int n) { return n > 1 ? n * fact(n – 1) : 1; }
59.Write a program which uses Command Line Arguments?
Ans:
#include
void main(int argc,char *argv[])
{
int i;
clrscr();
for(i=0;i
printf(“\n%d”,argv[i]);
}
60. Difference between array and pointer?
Ans:
Array
1- Array allocates space automatically
2- It cannot be resized
3- It cannot be reassigned
4- sizeof (arrayname) gives the number of bytes occupied by the array.
Pointer
1-Explicitly assigned to point to an allocated space.
2-It can be sized using realloc()
3-pointer can be reassigned.
4-sizeof (p) returns the number of bytes used to store the pointer variable p.
61. What do the ‘c’ and ‘v’ in argc and argv stand for?
Ans: The c in argc(argument count) stands for the number of command line argument the program is
invoked with and v in argv(argument vector) is a pointer to an array of character string that contain the arguments.

62. IMP>what are C tokens?
Ans: There are six classes of tokens: identifier, keywords, constants, string literals, operators and other separators.
63. What are C identifiers?
Ans: These are names given to various programming element such as variables, function, arrays.It is a combination of letter, digit and underscore.It should begin with letter. Backspace is not allowed.
64. Difference between syntax vs logical error?
Ans:
Syntax Error
1-These involves validation of syntax of language.
2-compiler prints diagnostic message.
Logical Error
1-logical error are caused by an incorrect algorithm or by a statement mistyped in such a way
that it doesn’t violet syntax of language.
2-difficult to find.
65. What is preincrement and post increment?
Ans: ++n (pre increment) increments n before its value is used in an assignmentoperation or any
expression containing it. n++ (post increment) does increment after the value of n is used.
66. Write a program to interchange 2 variables without using the third one.
Ans:
a ^= b; ie a=a^b
b ^= a; ie b=b^a;
a ^= b ie a=a^b;
here the numbers are converted into binary and then xor operation is performed.
You know, you’re just asking “have you seen this overly clever trick that’s not worth applying on
modern architectures and only really applies to integer variables?”
67. What is the maximum combined length of command line arguments including the space between adjacent arguments?
Ans: It depends on the operating system.
68. What are bit fields? What is the use of bit fields in a Structure declaration?
Ans: A bit field is a set of adjacent bits within a single implementation based storage unit that we
will call a “word”.
The syntax of field definition and access is based on structure.
Struct {
unsigned int k :1;
unsigned int l :1;
unsigned int m :1;
}flags;
the number following the colon represents the field width in bits.Flag is a variable that contains three bit fields.
69. What is a preprocessor, what are the advantages of preprocessor?
Ans: A preprocessor processes the source code program before it passes through the compiler.
1- a preprocessor involves the readability of program
2- It facilitates easier modification
3- It helps in writing portable programs
4- It enables easier debugging
5- It enables testing a part of program
6- It helps in developing generalized program
71. What are the two forms of #include directive?
Ans:
1.#include”filename”
2.#include
the first form is used to search the directory that contains the source file.If the search fails in the home directory it searches the implementation defined locations.In thesecond form ,the preprocessor searches the file only in the implementation defined locations.

72. How would you use the functions randomize() and random()?
Ans:
Randomize() initiates random number generation with a random value.
Random() generates random number between 0 and n-1;
73. What do the functions atoi(), itoa() and gcvt() do?
Ans:
atoi() is a macro that converts integer to character.
itoa() It converts an integer to string
gcvt() It converts a floating point number to string
74. How would you use the functions fseek(), freed(), fwrite() and ftell()?
Ans:
fseek(f,1,i) Move the pointer for file f a distance 1 byte from location i.
fread(s,i1,i2,f) Enter i2 dataitems,each of size i1 bytes,from file f to string s.
fwrite(s,i1,i2,f) send i2 data items,each of size i1 bytes from string s to file f.
ftell(f) Return the current pointer position within file f.
The data type returned for functions fread,fseek and fwrite is int and ftell is long int.
75. What is the difference between the functions memmove() and memcpy()?
Ans: The arguments of memmove() can overlap in memory. The arguments of memcpy() cannot.
76. What is a file?
Ans: A file is a region of storage in hard disks or in auxiliary storage devices.It contains bytes of
information .It is not a data type.
77. IMP>what are the types of file?
Ans: Files are of two types
1-high level files (stream oriented files) :These files are accessed using library functions
2-low level files(system oriented files) :These files are accessed using system calls
78. IMP>what is a stream?
Ans: A stream is a source of data or destination of data that may be associated with a disk or other
I/O device. The source stream provides data to a program and it is known as input stream. The destination stream eceives the output from the program and is known as output stream.
79. What is meant by file opening?
Ans: The action of connecting a program to a file is called opening of a file. This requires creating
an I/O stream before reading or writing the data.
80. What is FILE?
Ans: FILE is a predefined data type. It is defined in stdio.h file.
81. What is a file pointer?
Ans: The pointer to a FILE data type is called as a stream pointer or a file pointer. A file pointer points to the block of information of the stream that had just been opened.

82. How is fopen()used ?
Ans: The function fopen() returns a file pointer. Hence a file pointer is declared and it is assigned
as
FILE *fp;
fp= fopen(filename,mode);
filename is a string representing the name of the file and the mode represents:
“r” for read operation
“w” for write operation
“a” for append operation
“r+”,”w+”,”a+” for update operation
83How is a file closed ?
Ans: A file is closed using fclose() function
Eg. fclose(fp);
Where fp is a file pointer.
84. What is a random access file?
Ans:
A file can be accessed at random using fseek() function
fseek(fp,position,origin);
fp file pointer
position number of bytes offset from origin
origin 0,1 or 2 denote the beginning ,current position or end of file respectively.
85. What is the purpose of ftell ?
Ans: The function ftell() is used to get the current file represented by the file pointer.
ftell(fp);
returns a long integer value representing the current file position of the file pointed by the
file pointer fp.If an error occurs ,-1 is returned.
86. What is the purpose of rewind() ?
Ans: The function rewind is used to bring the file pointer to the beginning of the file.
Rewind(fp);
Where fp is a file pointer.Also we can get the same effect by
feek(fp,0,0);
87. Difference between a array name and a pointer variable?
Ans: A pointer variable is a variable where as an array name is a fixed address and is not a
variable. A
pointer variable must be initialized but an array name cannot be initialized. An array name being a constant value , ++ and — operators cannot be applied to it.
88. Represent a two-dimensional array using pointer?
Ans:
Address of a[I][j] Value of a[I][j]
&a[I][j]
or
a[I] + j
or
*(a+I) + j
*&a[I][j] or a[I][j]
or
*(a[I] + j )
or
*( * ( a+I) +j )
89. Difference between an array of pointers and a pointer to an array?
Ans:
Array of pointers
1- Declaration is: data_type *array_name[size];
2-Size represents the row size.
3- The space for columns may be dynamically
Pointers to an array
1-Declaration is data_type ( *array_name)[size];
2-Size represents the column size.
90. Can we use any name in place of argv and argc as command line arguments ?
Ans: yes we can use any user defined name in place of argc and argv;
91. What are the pointer declarations used in C?
Ans:
1- Array of pointers, e.g , int *a[10]; Array of pointers to integer
2-Pointers to an array,e.g , int (*a)[10]; Pointer to an array of into
3-Function returning a pointer,e.g, float *f( ) ; Function returning a pointer to float
4-Pointer to a pointer ,e.g, int **x; Pointer to apointer to int
5-pointer to a data type ,e.g, char *p; pointer to char

92. Differentiate between a constant pointer and pointer to a constant?
Ans:
const char *p; //pointer to a const character.
char const *p; //pointer to a const character.
char * const p; //const pointer to a char variable.
const char * const p; // const pointer to a const character.
93. Is the allocated space within a function automatically deallocated when the function returns?
Ans: No pointer is different from what it points to .Local variables including local pointers
variables in a function are deallocated automatically when function returns.,But in case of a
local pointer variable ,deallocation means that the pointer is deallocated and not the block of
memory allocated to it. Memory dynamically allocated always persists until the allocation is freed
or the program terminates.
94. Discuss on pointer arithmetic?
Ans:
1- Assignment of pointers to the same type of pointers.
2- Adding or subtracting a pointer and an integer.
3-subtracting or comparing two pointer.
4-incrementing or decrementing the pointers pointing to the elements of an array. When a pointer
to an integer is incremented by one , the address is incremented by two. It is done automatically
by the compiler.
5-Assigning the value 0 to the pointer variable and comparing 0 with the pointer. The pointer
having address 0 points to nowhere at all.
95. What is the invalid pointer arithmetic?
Ans:
i) adding ,multiplying and dividing two pointers.
ii) Shifting or masking pointer.
iii) Addition of float or double to pointer.
iv) Assignment of a pointer of one type to a pointer of another type ?
96. What are the advantages of using array of pointers to string instead of an array of strings?
Ans:
i) Efficient use of memory.
ii) Easier to exchange the strings by moving their pointers while sorting.
97. Are the expressions *ptr ++ and ++ *ptr same?
Ans: No,*ptr ++ increments pointer and not the value pointed by it. Whereas ++ *ptr
increments the value being pointed to by ptr.
98. What would be the equivalent pointer expression foe referring the same element as
a[p][q][r][s] ?
Ans : *( * ( * ( * (a+p) + q ) + r ) + s)
99. Are the variables argc and argv are always local to main?
Ans: Yes they are local to main.
100. Can main () be called recursively?
Ans: Yes any function including main () can be called recursively.
91. What are the pointer declarations used in C?
Ans:
1- Array of pointers, e.g , int *a[10]; Array of pointers to integer
2-Pointers to an array,e.g , int (*a)[10]; Pointer to an array of into
3-Function returning a pointer,e.g, float *f( ) ; Function returning a pointer to float
4-Pointer to a pointer ,e.g, int **x; Pointer to apointer to int
5-pointer to a data type ,e.g, char *p; pointer to char

92. Differentiate between a constant pointer and pointer to a constant?
Ans:
const char *p; //pointer to a const character.
char const *p; //pointer to a const character.
char * const p; //const pointer to a char variable.
const char * const p; // const pointer to a const character.
93. Is the allocated space within a function automatically deallocated when the function returns?
Ans: No pointer is different from what it points to .Local variables including local pointers
variables in a function are deallocated automatically when function returns.,But in case of a
local pointer variable ,deallocation means that the pointer is deallocated and not the block of
memory allocated to it. Memory dynamically allocated always persists until the allocation is freed
or the program terminates.
94. Discuss on pointer arithmetic?
Ans:
1- Assignment of pointers to the same type of pointers.
2- Adding or subtracting a pointer and an integer.
3-subtracting or comparing two pointer.
4-incrementing or decrementing the pointers pointing to the elements of an array. When a pointer
to an integer is incremented by one , the address is incremented by two. It is done automatically
by the compiler.
5-Assigning the value 0 to the pointer variable and comparing 0 with the pointer. The pointer
having address 0 points to nowhere at all.
95. What is the invalid pointer arithmetic?
Ans:
i) adding ,multiplying and dividing two pointers.
ii) Shifting or masking pointer.
iii) Addition of float or double to pointer.
iv) Assignment of a pointer of one type to a pointer of another type ?
96. What are the advantages of using array of pointers to string instead of an array of strings?
Ans:
i) Efficient use of memory.
ii) Easier to exchange the strings by moving their pointers while sorting.
97. Are the expressions *ptr ++ and ++ *ptr same?
Ans: No,*ptr ++ increments pointer and not the value pointed by it. Whereas ++ *ptr
increments the value being pointed to by ptr.
98. What would be the equivalent pointer expression foe referring the same element as
a[p][q][r][s] ?
Ans : *( * ( * ( * (a+p) + q ) + r ) + s)
99. Are the variables argc and argv are always local to main?
Ans: Yes they are local to main.
100. Can main () be called recursively?
Ans: Yes any function including main () can be called recursively.

101. IMP>Can we initialize unions?
Ans: ANSI Standard C allows an initializer for the first member of a union. There is no standard way
of initializing any other member (nor, under a pre-ANSI compiler, is there generally any way of
initializing a union at all).

102. What’s the difference between these two declarations?
Ans: struct x1 { … };
typedef struct { … } x2;
The first form declares a structure tag; the second declares a typedef. The main difference is that the second declaration is of a slightly more abstract type.its users don’t necessarily know that it is a structure, and the keyword struct is not used when declaring instances of it.
103. Why doesn’t this code: a[i] = i++; work?
Ans: The subexpression i++ causes a side effect.it modifies i’s value.which leads to undefined
behavior since i is also referenced elsewhere in the same expression.
104.WHy doesn’t struct x { … };
x thestruct;
work?
Ans:
C is not C++. Typedef names are not automatically generated for structure tags.
105. Why can’t we compare structures?
Ans:
There is no single, good way for a compiler to implement structure comparison which is consistent with C’s low-level flavor. A simple byte-by-byte comparison could founder on random bits present in unused “holes” in the structure (such padding is used to keep the alignment of later fields correct). A field-by-field comparison might require unacceptable amounts of repetitive code for large structures.
106. How are structure passing and returning implemented?
Ans: When structures are passed as arguments to functions, the entire structure is typically pushed on
the stack, using as many words as are required. Some compilers merely pass a pointer to the structure, though they may have to make a local copy to preserve pass-by-value semantics.
Structures are often returned from functions in a location pointed to by an extra,compiler-supplied “hidden” argument to the function. Some older compilers used a special,static location for structure returns, although this made structure-valued functions non-reentrant, which ANSI C disallows.

General questions

1: What is difference between Microprocessor and Microcontroller ?

2: Why is Zener Diode always used in Reverse Bias condition ?

3: Difference between FM and AM, which is preferred & its advantages.

4: Questions on different coding techniques ?

5: Questions on signal processing techniques ?

6: What is RS in RS-232 ?

7: What is Lenz law ?

8: What is Transmission Frequency of Bluetooth, Wi-Fi and Wi-MAX ?

9: What is difference between Piconet and Scatternet ?

10: What is Moore's Law ?

11: How many satellites comprise the GPS and expand it ?

12: What is ZigBee and its specifications ?

13: What is FPGA ?

14: What is MIMO ?

15: What is VOIP ?

16: On what principle do Transformers work ?

17: What is EDFA ?

18: What are different types of antennas ?

19: What is Yagi-Uda antenna ?

20: What is latest satellite from ISOR ?

Q why the input resistance of an op-amp is high whereas it's output resistance is low?
A.Loading at the input point and to pass the maximum output to the load is the requirement of Op-Amp which is a current exchange device from input side to output side.

Q.what do you understand by microwaves? why these are called micro
A.micro waves are those waves whose wavelength is less than a foot(30 cms) or freq ranging from 1 GHz to 1000 GHz.Because of there tinyness these are called micro.

Q. how do microwave oven works??
A. Heart of microwave oven is magnatron which generates frequency of appox. 2.4 GHz.explain working of magnatron.

Q.What is CMRR? Explain briefly.
A. CMRR stands for common mode rejection ratio. It is a measure of the ability of a test instrument to reject
interference that is common to both of its measurement input terminals. It is expressed in decibels and it is the ratio of the actual or common signal level appearing on the
two input terminals together to the measured level.

1. What is meant by D-FF? D Flip Flop (or did you mean to ask its working?)
2. What is the basic difference between Latches and Flip flops? (Latches do not store information, here, a bit)
3. What is a multiplexer?
4. How can you convert an SR Flip-flop to a JK Flip-flop?
5. How can you convert an JK Flip-flop to a D Flip-flop?
6. What is Race-around problem? How can you rectify it?
7. Which semiconductor device is used as a voltage regulator and why? (zener diode in reverse bias, why because it allows for a large variation in current for a negligible variation in voltage)
8. What do you mean by an ideal voltage source? (Sources infinite current to any load without any change in o/p voltage)
9. What do you mean by zener breakdown and avalanche breakdown?
10. What are the different types of filters? (low pass, high pass, band pass, band stop, resonant)
11. What is the need of filtering ideal response of filters and actual response of filters?
12. What is sampling theorem? (minium 2 samples per time period? not too sure of this)
13. What is impulse response?
14. Explain the advantages and disadvantages of FIR filters compared to IIR counterparts.
15. What is CMRR? Explain briefly. (explained by someone a few posts above)
16. What do you mean by half-duplex and full-duplex communication? Explain briefly. (half duplex - both sender & receiver can communicate with each other, but not simultaneously...full duplex - same but simultaneous communication possible)
17. Which range of signals are used for terrestrial transmission?
18. What is the need for modulation? (transmitting over a distance, encryption?)
19. Which type of modulation is used in TV transmission?
20. Why we use vestigial side band (VSB-C3F) transmission for picture?
21. When transmitting digital signals is it necessary to transmit some harmonics in addition to fundamental frequency?
22. For asynchronous transmission, is it necessary to supply some synchronizing pulses additionally or to supply or to supply start and stop bit?
23. BPFSK is more efficient than BFSK in presence of noise. Why?
24. What is meant by pre-emphasis and de-emphasis?
25. What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB? (3dB is the half power value)
26. What do you mean by ASCII, EBCDIC?

·  What is meant by D-FF?(D-flip flop stands for Delay flip-flop, it delays input by one clock pulse)

·  What is the basic difference between Latches and Flip flops?(Latches are monostable and flip-flops are bistable)

·  What is a multiplexer?(It is used to multiplex data from different sources normally used in TDM)

·  How can you convert an SR Flip-flop to a JK Flip-flop?

·  How can you convert an JK Flip-flop to a D Flip-flop?( Connect J to D and K to not(D))

·  What is Race-around problem? How can you rectify it?( Race around condition occurs in a JK flip-flop when both the inputs are set to '1', it can be rectified using edge-triggered flip-flop or using master-slave flip-flops)

·  Which semiconductor device is used as a voltage regulator and why?

·  What do you mean by an ideal voltage source?

·  What do you mean by zener breakdown and avalanche breakdown?( zener breakdown takes place when very high voltage is applied to the diode this results in very high reverse current, as voltage is further increased minority carriers gain further momentum and strike atoms releases more carriers, which results in further increase in temp. It becomes vicious cycle and leads to avalanche breakdown or on other words "thermal runaway".

·  What are the different types of filters?( analog filters n digital filters not sure wht u meant)

·  What is the need of filtering ideal response of filters and actual response of filters?

·  What is sampling theorem?( sampling frequency should be atleast twice the maximum freq present in the signal)

·  What is impulse response?( response given by a digital system when impulse signal is applied to it. Used to find out stability of system)

·  Explain the advantages and disadvantages of FIR filters compared to IIR counterparts.

·  What is CMRR? Explain briefly.( Common mode rejection ratio)

·  What do you mean by half-duplex and full-duplex communication? Explain briefly.( half-duplex: either sender or receiver can use the channel at one time eg walky-talky and full-duplex: sender or receiver or both can use the channel at one time eg telephone)

·  Which range of signals are used for terrestrial transmission?

·  What is the need for modulation?

·  Which type of modulation is used in TV transmission?( video signal: vestigial side band modulation and audio signal: FM)

·  Why we use vestigial side band (VSB-C3F) transmission for picture?( why not DSBSC: large bandwidth req.why not SSBSC: To over come distortion by filters used at receivers thus demodulation becomes complex hence costly)

·  When transmitting digital signals is it necessary to transmit some harmonics in addition to fundamental frequency?( yup but not sure why)

·  For asynchronous transmission, is it necessary to supply some synchronizing pulses additionally or to supply or to supply start and stop bit?( for asyn tx it is necessary to use start and stop bits as no common clock is there)

·  BPFSK is more efficient than BFSK in presence of noise. Why?

·  What is meant by pre-emphasis and de-emphasis?( used in TV Tx for voice signal not sure why)

·  What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?

Resistance, inductance(dc short, ac open), capacitance (ac short , dc open)

Diodes:
types& definitions: p-n, zener(zener breakdown, voltage regulator),tunnel (tunneling effect),varactor,
Impatt,Trapatt, gunn, pin;

Transistors:
two types 1. Based on minority carrier(BJT:npn,pnp) 2. based on FET principle(IGFET,JFET,MOSFET,MESFET);

Amplifiers:
types:LNA,Power amp,feedback,balanced,distributed amp

Active state (for CE conf):Base if FB and collector is RB:
Saturation:Both bas and collector are FB
Cut-off:Both bas and collector are RB

Untuned Amp:Class A,B,AB,C

Oscillator:total phase shift at input is 0 or multiples of 2pi.


MPMC:

MP are memoryless.General purpose processors
MC have inbuilt memory and IO ports
to interface MP with ports 825 is used

MP types: 8085 (8-data, 16 address);8086(16data,16 address); 80186(16 data, 20 adddress); 80286(16 data, 24 address);80386(16 data, 32 address);80486 (32 data, 32 address); pentium (64 data, 32 address,Pipelining,More segmentations&memory banks);Pentium Pro(64 data,36 address)

MC: 4K rom, 128 bytes ram,2 timers,4 io ports,1 serial port, 8 bit cpu, 16 address lines, 40 pins


Control systems:

Definitions:
System:A no of elements are connected in a sequence to perform a specific function is called a system.

Control system: system in which o/p is controlled by i/p.
Open loop system(o/p does not change automatically)& closed loop system (output changes automatically)

Stability:BIBO condition :i/p=0 then o/p tends to 0.

Limtedly stable,absolutely stable and conditionally stable:

Three ways to check stability: Routh-herwitz criteria, nyquist criteria, root locus method

.what is the differnce between SCR and diode rectifier?
ans: diode is a 2 terminal device, in scr gate controls the rectifing.SCR is used in High frequency applications but diode is low freuency devices, SCR can be in high temparatures but not diode.

2.whatis intersymbol interference
ans:In telecommunication, intersymbol interference (ISI) means a form of distortion of a signal that causes the previously transmitted symbols to have an effect on the currently received symbol. This is usually an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable. ISI is usually caused by echoes or non-linear frequency response of the channel. Ways to fight against intersymbol interference include adaptive equalization or error correcting codes (especially soft-decoding with Viterbi algorithm).

3.Distinguish between Angle modulation and Amplitude modulation.
ans: In amplitude Modulation as the amplitude of given signal varies, the amplitude of carrier signal also varies in the same way.
In angle modulation, the frequency or phase may vary according to the amplitude of given signal

4.What is Biasing?
ans: biasing is a process of connecting dc voltage to a device by which we can select the operating point of the device. by biasing actually we select the operating point of the device.

5.What do you mean by ASCII, EBCDIC?
ans:ASCII (American Standard Code for Information Interchange), is a character encoding based on the English alphabet.

EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding used on IBM mainframe operating systems

6.What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?
ans:3db implies 70%(o.7o7) of the power,i'e we r interested to consider the bandwidth range from peak to 70% b'coz uptp 70% its reliable.hence 3db is called as half power freq. 3db value is the mean square value which is 70% of the maximum value.

7.What is meant by pre-emphasis and de-emphasis?
ans:Pre-emphasis
" Improving the signal to noise ratio by increasing the magnitude of higher frequency signals with respect to lower frequency signals"

De-emphasis
" Improving the signal to noise ratio by decreasing the magnitude of higher frequency signals with respect to lower frequency signals"

8.What is sampling theorem?
ans:It is defined as the sampling frequency should be greater than or equal to twice the sampling frequency then we can generate the original signal if the condition does not satisfy we get the signal in the distorted mannerit is given as ( fs >/ 2 fs)

9.What is Race-around problem? How can you rectify it?
ans: A condition in logic network in which the difference in propagation times through two or more signal paths in the network can produce an erroneous output.in jk flip flop race around problem will occur when both the inputs are high. it can be prevented by using master slave jk flip flop

10.What is the basic difference between Latches and Flip flops?
ans:latch works without clock signal,but works with a control signal and it is level triggered device.whereas flip flop is a 1 bit storage element and works with a clock signal.its a edge triggered device. normally latches are avoided and flip flops are preferred.

11. what is Barkhausen Criterion?
ans:
1./AB/=1,i.e. the magnitude of loop gain must be unity
2.the total prase shift around the closed loop is zero or 360 degrees.

12.what are active and Passive Components?
ans:ACTIVE COMPONENTS The components which produce the energy in the form of current or voltage are called as active components.Example:transistors etc,.

PASSIVE COMPONENTS
The components which stores the energy in the form of current or voltage are called as passive components.example:inductors,resistors,capacitors etc

1. What is a flip-flop?
   2.What is a register?
   3.Difference between GSM and CDMA technology?
   4.What is the difference between 8085 and 8086 microprocessor?:grab:

1. What is hole theory?
   2. What is avalanche effect?
   3. Difference between CDMA and GSM?
   4. What is GPRS? How does it work?
   5. Have you heard of 4th generation mobile techlogy?
   6. What is S/N ratio?
   7. What is transponder?
   8. What are the types of soldering?

Q-What are the disadvantage of FM ?(short coverage due to Line of sight comm.

whats the diff between GSM and CDMA?

GSM and CDMA represent different ways of sharing the spectrum.
CDMA uses same frequency for a number of signals. This is possible because of Analog to digital conversion and then encoded with a random signal. Then decoded at the receiving end using decoding algorithem. Hence lot of ppl can talk wiht out interference...

WHere as GSM, the no. of ppl who can share a particular freq is limited. Specturm is divided in frequency and then time slots are allotted....for callers... :

Due to spectrum constraints, CDMA which needs less spectrum for the same number of calls, has advantage over GSM. And it's less costly to set up as well.

How many states does signal has ?
there are 3 states in a signal: on state, off state, tri state

2.which software is used to design a software IC using VHDL
altera

3.How many type of resistances are there in a diode
Two, one when forward biased have zero resistance and the other when reverse biased has infinite resistance

4. What type of architecture is used in 8085 microprocessor?
Von-Neumann architecture

5.What are semiconductor devices
A semiconductor device is a device which has a pn junction in it.Ex. Diode, transistor.
Basically they are different in conduction property. these materials are not conductors by default they become conductors in some cicumstances like, increase in temperature or difference in the charge density, etc.
Germanium and silicon are the best examples of semiconductors...

Ideal voltage source is a circuit element where the voltage across it is independent of the current through it. It only exists in mathematical models of circuits. If the voltage across an ideal voltage source can be specified independently of any other variable in a circuit, it is called an independent voltage source.

Impulse response of a system is its output when presented with a very brief input signal, an impulse. A system in the class known as LTI systems (linear, time-invariant systems) is completely characterized by its impulse response. The Laplace transform of the impulse response function is known as the transfer function. It is usually easier to analyze systems using transfer functions as opposed to impulse response functions. The Laplace transform of a system's output may be determined by the multiplication of the transfer function with the input function in the complex plane, also known as the frequency domain. An inverse Laplace transform of this result will yield the output function in the time domain. To determine an output function directly in the time domain requires the convolution of the input function with the impulse response function.

Finite impulse response (FIR) filter is a type of a digital filter. The impulse response, the filter's response to a Kronecker delta input, is 'finite' because it settles to zero in a finite number of sample intervals. This is in contrast to infinite impulse response filters which have internal feedback and may continue to respond indefinitely.
A FIR filter has a number of useful properties which sometimes make it preferable to an infinite impulse response filter. FIR filters:
* Are inherently stable. This is due to the fact that all the poles are located at the origin and thus are located within the unit circle.
* Require no feedback. This means that any rounding errors are not compounded by summed iterations. The same relative error occurs in each calculation.
* They can be designed to be linear phase, which means the phase change is proportional to the frequency.

Infinite impulse response (IIR) is a property of signal processing systems. They have an impulse response function which is non-zero over an infinite length of time. The simplest analog IIR filter is an RC filter made up of a single resistor (R) feeding into a node shared with a single capacitor (C). This filter has an exponential impulse response characterized by an RC time constant.

Common-mode rejection ratio (CMRR) of a differential amplifier (or other device) measures the tendency of the device to reject input signals common to both input leads. A high CMRR is important in applications where the signal of interest is represented by a small voltage fluctuation superimposed on a (possibly large) voltage offset, or when relevant information is contained in the voltage difference between two signals.

Signal-to-noise ratio (often abbreviated SNR or S/N) defined as the ratio of a signal power to the noise power corrupting the signal. In less technical terms, signal-to-noise ratio compares the level of a desired signal (such as music) to the level of background noise. The higher the ratio, the less obtrusive the background noise is.

Asynchronous transmission uses start and stop bits to signify the beginning bit ASCII character would actually be transmitted using 10 bits e.g.: A "0100 0001" would become "1 0100 0001 0". The extra one (or zero depending on parity bit) at the start and end of the transmission tells the receiver first that a character is coming and secondly that the character has ended. This method of transmission is used when data is sent intermittently as opposed to in a solid stream. In the previous example the start and stop bits are in bold. The start and stop bits must be of opposite polarity. This allows the receiver to recognize when the second packet of information is being sent.

Synchronous transmission uses no start and stop bits but instead synchronizes transmission speeds at both the receiving and sending end of the transmission using clock signals built into each component. A continual stream of data is then sent between the two nodes. Due to there being no start and stop bits the data transfer rate is quicker although more errors will occur, as the clocks will eventually get out of sync, and the receiving device would have the wrong time that had been agreed in protocol (computing) for sending/receiving data, so some bytes could become corrupted (by losing bits). Ways to get around this problem include re-synchronization of the clocks and use of check digits to ensure the byte is correctly interpreted and received.

what is Moore's Law?
Explain Superhyterodyne reciever.
Diff between CDMA and TDMA...

What is 2G?
What is 3G?
what is 4G?
Why are video signals amplitude modulated and sound signal frequency modulated in composite video signal.?
Give Grassman's Equation.
Give IF frequencies for picture and sound..
Design a 101 sequence detector using Mealy/Moore and what is the difference between Melay and Moore
What is DTMF
what are Thevenin and Norton's theorems, Maximum power transfer theorem
what is 555 and why is it named so
Give Shannon's source coding and channel coding theorem
what is Hoffman coding
Design AND/OR/NOT using transistors..
What is Grey coding, XS-3 coding, K-Map
Why are nand gates and NOR gates called Universal gates.....
Make an and gate using NAND, NOR
What is the Nyquist Sampling theorem
What is Convolution theorem
What are FIR and IIR filters
What are the variopus windowing techniques used in FIR and what are their advantages/disadvantages
What is a Smith Chart
Give Keplers' law for Planetary motion.
Why is a common collector called an emitter follower..?

1)What is 2G?
2G is short for second generation wireless telephone technology.It is actually an upgradation of 1G which was analog in nature..but 2G is digital in nature..moreover its penetration in mobile networks is much higher.
Further there are 2 main standards where 2G is used - GSM(TDMA based) and CDMA.
2)What is 3G?
3G is short for 3rd generation wireless telephone technology.It is a further upgradation of 2G..its data rates are higher and it is supposed to be ranged upto 14 mbps. NTT Docomo of Japan used it first. (After this u may expect questions from Docomo,so i u r aware use this statement)
Many new applications like Mobile TV,Internet Browsing,Video Conf,Tele-Medicine can be used.
3)what is 4G?
4th Generation technology...very high data rates upto 100Mbps...can be used for Online Gaming, HDTV viewing,etc..

4)Why are video signals amplitude modulated and sound signal frequency modulated in composite video signal.?
both picture and sound signals from different stations are concentrated within the same range of frequencies. Therefore, radiation from different stations would be hopelessly and inextricably mixed up and it would be impossible to separate one from the other at the receiving end. Thus
in order to be able to separate the intelligence from different stations, it is necessary to translate them all to different portions of the electromagnetic spectrum depending on the carrier frequency assigned to each station. Also the sound signal is frequency modulated because of its inherent merits of interference-free reception.

5)Give Grassman's Equation.
Havnt heard of this..anyone please answer

6)Give IF frequencies for picture and sound..
Cudnt get the exact values Gulati kitaab dekh lena

7)Design a 101 sequence detector using Mealy/Moore
Chapter 7 Notes
Better to say cant recollect

8) what is the difference between Mealy and Moore
In Mealy machines the o/p is a function of the current state and the inputs whereas In Moore machines the o/p a function of current state only

9)What is DTMF
Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center.

10)what are Thevenin and Norton's theorems, Maximum power transfer theorem?
Sometimes we need to calculate current or voltage in a particular branch of a circuit.In that case we needn't calculate for all branches..so techniques like Thevenin and Norton are used.
In both theorems we replace the 2-terminal linear device which may contain voltage source,current source both independent and dependent with the following orientation:
If they are replaced with a resistor in series with a Voltage source then its Thevenin and if it is replaced with a resistor in parallel with a Current source then its Norton.
Maximum Power transfer theorem is basically a linear device when connected to its Thevenin equivalent it receives Maximum power .

1)what is 555 and why is it named so
555 Timer is used to produce accurate and stable time delays ranging from microseconds to hours.
inside the 555 timer, there are 3 resistors used in series
all the 3 resistors used are same and are 5k ohm resistors..
so its called 555 timer..

2)Give Shannon's source coding and channel coding theorem
Source coding theorem is stated as follows:
"Given a discrete memoryless source of entropy H(p), the average code-word length L for any source encoding is bounded as L >= H(p)"
This is basically used for Data Compression using different codes but following this rule.
Channel coding theorem says "Let a discrete memoryless scource with an alphabet p have entropy H(p) and produce symbols once every Ts seconds. "Let a memoryless channel have capacity C and be used once every Tc seconds. Then if
H(p)/Ts <= C/Tc there exists a coding scheme for which the source output can be transmitted over the channel and reconstructed with very small error."
This is basically used for Error Detection.

3)what is Hoffman coding
Hoffman code is a source code whose average word length approaches the fundamental limit set by the entropy of a discrete memoryless source.It is optimum in the sense that it follows Source coding very closely

4)Design AND/OR/NOT using transistors..
Refer books

5)What is Grey coding, XS-3 coding, K-Map?

6)Why are nand gates and NOR gates called Universal gates.....
Becoz using these 2 gates any other type of gates can be made

7)What is the Sampling theorem?
A continous time signal may be completely represented in its samples and recovered back if sampling frequency is greater than equal to twice the maximum frequency present in the signal
Fs >= 2Fm

8)What is Convolution theorem
Time convolution theorem
Convolution in time domain = Multiplicaiton in Frequency domain
x1(t) * x2(t) <---> X1(w) x X2(w) --

Frequency Convolution theorem
Convolution in freuqncy domain = 2pi x Multiplication in time domain
X1(w) * X2(w) <---> 2pi x x1(t) x x2(t)

9)What are FIR and IIR filters
Finite impulse response and infinite impulse response filters
finite impulse response settles to zero in a finite number of sample intervals. This is in contrast to infinite impulse response (IIR) filters, which have internal feedback and may continue to respond indefinitely
FIR filters are always stable but IIR may or may not be stable

10)Why is a common collector called an emitter follower..?
In this configuration the voltage gain is equal to unity and hence a change in base voltage appeears as an equal change across the load at the emitter.Thus the emitter follows the input signal. The most common use of this circuit is to use as a buffer stage which functions as resistance transformation from high to low resistance.

Q1)Why a MOSFET is preferred over a transistor?
A)A MOSFET is very small in size as compared to a transistor and its biasing is easier as compared to latter.

Q2)Please tell me why biasing is required in a transistor?
A)Biasing is required to get the loadline and the operating point of a transistor.Moreover different regions are achieved through different biasing types.

Q3)How different regions are got and what are those regions?Explain taking a Common Base connection.
A)Well the transistor can be biased in 3 different types to get three different regions-Active region,Saturation Region,Cut-off Region
Active Region-:Emitter is forward biased and collector is reverse biased
Cut-off Region-:Both emitter and collector are reverse biased
Saturation region:Both emitter and collector are forward biased

Q4)What is a tunnel diode ?
A)Tunnel diode was invented by Esaki and its different from the normal diode in terms of the doping concentration as in 1part of doping is present in 10^3 atoms whereas in normal diode it is 1 part in 10^8 atoms. It is basically used for very fast switching response.