Delay encoding

Delay encoding

In telecommunications, delay encoding is the encoding of binary data to form a two-level signal such that (a) a "0" causes no change of signal level unless it is followed by another "0" in which case a transition to the other level takes place at the end of the first bit period; and (b) a "1" causes a transition from one level to the other in the middle of the bit period.

Delay encoding is used primarily for encoding radio signals because the frequency spectrum of the encoded signal contains less low-frequency energy than a conventional non-return-to-zero (NRZ) signal and less high-frequency energy than a biphase signal.

Delay encoding is an encoding using only half the bandwidth as biphase encoding but has all the advantages of biphase encoding: To be rewritten: It is guaranteed to have transitions every other bit, meaning that decoding systems can adjust their clock/DC threshold continuously. One drawback is human readability (e.g. on an oscilloscope).

Delay encoding is also known as Miller encoding (apparently named after John Milton Miller).

Some RFID cards, in particular EPC UHF Gen 2 RF cards, use a variant called "Miller sub-carrier coding".[1] Such cards include the CharlieCard. In this system, 2, 4 or 8 cycles of a subcarrier square wave are transmitted for each bit time. The Miller encoding transitions are indicated by 180° phase shifts in the subcarrier, i.e. the subcarrier pauses for 1/2 of a cycle at each transition. (The resultant binary subcarrier is itself either ASK or PSK modulated on another carrier.)

References

  1. ^ UHF Gen 2 System Overview, p. 19. (March, 2005)

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C".


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Delay — Contents 1 Generally 2 Law 3 Telecommunications and broadcasting …   Wikipedia

  • Delay Insensitive Minterm Synthesis — Invented by David E. Muller, the DIMS (Delay Insensitive Minterm Synthesis) system[1] is an asynchronous design methodology making the least possible timing assumptions. Assuming only the Quasi Delay Insensitive delay model the generated designs… …   Wikipedia

  • Bipolar encoding — An example of bipolar encoding, or AMI (Alternate mark inversion). In telecommunication, bipolar encoding is a type of line code (a method of encoding digital information to make it resistant to certain forms of signal loss during transmission).… …   Wikipedia

  • Differential Manchester encoding — Differential Manchester encoding, also called biphase mark code (BMC) or FM1, is a line code in which data and clock signals are combined to form a single 2 level self synchronizing data stream. It is a differential encoding, using the presence… …   Wikipedia

  • Line code — An example of coding a binary signal using rectangular pulse amplitude modulation with polar non return to zero code …   Wikipedia

  • Miller (disambiguation) — Contents 1 Places 2 Biology 3 People 4 Fictional characters …   Wikipedia

  • Advanced Audio Coding — AAC redirects here. For other uses, see AAC (disambiguation). Advanced Audio Codings iTunes standard AAC file icon Filename extension .m4a, .m4b, .m4p, .m4v, .m4r, .3gp, .mp4, .aac Internet media type audio/aac, audio/aacp, au …   Wikipedia

  • MPEG-1 — Moving Picture Experts Group Phase 1 (MPEG 1) Filename extension .mpg, .mpeg, .mp1, .mp2, .mp3, .m1v, .m1a, .m2a, .mpa, .mpv Internet media type audio/mpeg, video/mpeg Developed by ISO, IEC Type of format audio, vid …   Wikipedia

  • MPEG-2 — Not to be confused with MPEG 1 Audio Layer II (MP2). MPEG 2 is used in Digital Video Broadcast and Digital Versatile Discs. The MPEG transport stream, TS, and MPEG program stream, PS, are container formats. MPEG 2 is a standard for the generic… …   Wikipedia

  • information theory — the mathematical theory concerned with the content, transmission, storage, and retrieval of information, usually in the form of messages or data, and esp. by means of computers. [1945 50] * * * ▪ mathematics Introduction       a mathematical… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”