Encoder

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An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format, or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.

Contents 1 Examples 1.1 Media 1.2 Job positions 1.3 Security 1.4 Medical encoding software 1.5 Transducers 2 Encoder circuit 3 Single bit 4 to 2 encoder 4 Priority encoder 5 Connecting priority encoders 6 See also 7 External links

[edit] Examples

[edit] Media

Software for encoding audio, video, text into standardized formats:

• A compressor encodes data (e.g., audio/video/images) into a smaller form (See codec.)
• Windows Media Encoder captures, compresses, converts and can protect audio/video
• Riva FLV encoder converts AVI, DV, MPEG, MOV and WMV files to flash video files (*.FLV)
• An email encoder secures online email addresses from email harvesters
• A PHTML encoder preserves script code logic in a secure format that is transparent to visitors on a web site
• A multiplexer combines multiple inputs into one output.

[edit] Job positions

• A Data Entry Encoder may enter data from phone surveys in a coded format into a database.
• A Data Entry Encoder may enter payment amounts from legal tender documents from financial institutions into a database.
• A Manual Encoder may manually scan code tags on baggage that were missed by an automated system.

[edit] Security

• A device or person that encodes or encrypts military messages, such as the ADFGVX Cipher in WWI or the Enigma device in WWII.
• A Microchip hopping encoder integrated circuit for non-fixed-code secured entry.

[edit] Medical encoding software

• EncoderPro searches ICD-9-CM, CPT and HCPCS Level II medical codes, to increase accuracy and allow ease of auditing for compliance.

[edit] Transducers

Transducers for encoding position or orientation:

• 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.

Encoder circuits are described below:

[edit] Encoder circuit

An encoder can be a device used to change a signal (such as a bitstream) or data into a code. The code serves 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.

[edit] 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.

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.

[edit] Priority encoder

A priority encoder is such that if two or more inputs are 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	1	0	0
0	0	1	d	0	1
0	1	d	d	1	0
1	d	d	d	1	1

[edit] 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).

[edit] See also

• Decoder
• Codec
• Endec
• Line code
• Modulation
• Redundancy in databases
• Television encoding: NTSC, PAL and SECAM

[edit] External links

Look up encoder in Wiktionary, the free dictionary.

• 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.