Encoder

An encoder is a device used to change a signal (such as a bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another. This is usually done by means of a programmed algorithm, especially if any part is digital, while most analog encoding is done with analog circuitry.

Contents 1 Single bit 4 to 2 Encoder 2 Priority encoder 3 Connecting Priority Encoders 4 Examples 5 See also 6 External links

Single bit 4 to 2 Encoder

An encoder has 2ⁿ input lines and n output lines.The output lines generate a binary code corresponding to the input value. For example a single bit 4 to 2 encoder takes in 4 bits and outputs 2 bits. It is assumed that there are only 4 types of input signals these are : 0001, 0010, 0100, 1000.

Gate level circuit diagram of a single bit 4-to-2 line encoder

I3	I2	I1	I0	O1	O0
0	0	0	1	0	0
0	0	1	0	0	1
0	1	0	0	1	0
1	0	0	0	1	1

The encoder has the limitation that only one input can be active at any given time. If two inputs are simultaneously active, the output produces an undefined combination. To prevent this we make use of the priority encoder.

Priority encoder

A priority encoder is such that if two or more inputs is given at the same time, the input having the highest priority will take precedence. An example of a single bit 4 to 2 encoder is shown.

I3	I2	I1	I0	O1	O0
0	0	0	d	0	0
0	0	1	d	0	1
0	1	d	d	1	0
1	d	d	d	1	1

Connecting Priority Encoders

Priority encoders can be easily connected in arrays to make larger encoders, such as a 16 to 4 encoder made from six 4 to 2 priority encoders (four encoders having the signal source connected to their inputs, and two encoders that take the output of the first four as input).

Examples

• A compressor encodes data (e.g., audio/video/images) into a smaller form.
• A multiplexer combines multiple inputs into one output.
• A rotary encoder converts rotary position to an analog (e.g., analog quadrature) or digital (e.g., digital quadrature, 32-bit parallel, or USB) electronic signal.
• A linear encoder similarly converts linear position to an electronic signal.

See also

• Codec
• Endec
• Line code
• Modulation
• Redundancy in databases
• decoder

External links

• Encoding data to an ID Card: Using a Magnetic Stripe Encoder
• Absolute Encoder Using Gray Code - Absolute encoding for rotating shaft, with a comprehensive discussion of gray code.
• asic-world's Digital Combinational Logic (part III) - an overview of encoders in circuitry.

---

No comments have been added.

Your name:
City:
Country:	USA UK India Pakistan UAE Saudi Arabia Germany Afghanistan Albania Algeria Andorra Angola Antigua Barbuda Argentina Armenia Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bhutan Bolivia Bosnia Herzegovina Botswana Brazil Brunei Bulgaria Burkina Faso Burma Burund Cambodia Cameroon Canada Central African Rep Chad Chile China Columbia Comoros Congo Costa Rica Croatia Cuba Cyprus Czech Republic DR Congo Denmark Djiboutil Dominica Dominican Rep Ecuador Egypt El Salvador Eq Guinea Eritrea Estonia Ethiopia Fiji Finland France Gabon Gambia Georgia Germany Ghana Greece Grenada Grenadines Guatemala Guinea Bissau Guinea Guyana Haiti Honduras Hong Kong Hungary Iceland India Indonesia Iran Iraq Ireland Israel Italy Ivory Coast Jamaica Japan Jordan Kazakhstan Kenya Kiribati Kuwait Kyrgyzstan Laos Latvia Lebanon Liberia Libya Liechtenstein Lithuania Luxembourg Macedonia Macau Madagascar Malawi Malaysia Maldives Mali Malta Mauritania Mauritius Mexico Micronesia Moldova Monaco Mongolia Morocco Mozambique Namibia Nauru Nepal Neth Antilles Netherlands New Zealand Nicaragua Niger Nigeria North Korea Norway Oman Pakistan Panama Papua New Guinea Paraguay Peru Philippines Poland Portugal Puerto Rico Qatar Rawanda Romania Russia Sao Tome Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Slovakia Slovenia Solomon Islands Somalia South Korea South Africa Spain Sri Lanka St Kitts_Nevis St Lucia Sudan Suriname Sweden Switzerland Syria Taiwan Tajikistan Tanzania Thailand Togo Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Tuvala UAE Uganda Ukraine Uruguay Uzbekistan Vanuatu Venezuela Vietnam Western Samoa Yemen Yugoslavia Zaire Zambia Zimbabwe
Your comments:
Security check * (Please enter the number into adjoining box)