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Topic: Isochronous

	Isochronous - Wikipedia, the free encyclopedia
		Isochronous means having an equal time difference or occurring simultaneously.
		For example, a pendulum's oscilliation is isochronous, regardless of amplitude.
		Of a periodic signal, pertaining to transmission in which the time interval separating any two corresponding transitions is equal to the unit interval or to a multiple of the unit interval.
	en.wikipedia.org /wiki/Isochronous (175 words)

	[No title] (Site not responding. Last check: 2007-10-08)
		Isochronous devices require the transfer of up to a specified maximum amount of data X, via one or more transactions, during each period in a series of time periods of fixed duration T. This requirement (henceforth referred to as the isochronous X-T contract) may be
		Isochronous signal source 270 may generate X isochronous transactions every time period T. Asynchronous signal source 205 may generate asynchronous transactions during the same time periods as isochronous signal source 270 produces isochronous transactions.
		Device 290 may correlate isochronous request transactions with isochronous return transactions and measure that each return transaction is delivered at exactly L time periods T after the corresponding request transaction was produced.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/27776.010419&ELEMENT_SET=DECL (5628 words)

	[No title] (Site not responding. Last check: 2007-10-08)
		The isochronous transport clock is derived from the 1394 cycle timer clock.
		The receivers' isochronous clock is synchronized with sender's isochronous clock (that is, on the same bus with the same cycle master).The per isochronous cycle bit rate of the isochronous packet transport is generally not constant.
		Isochronous arbitration is initiated upon the cycle count incrementing in the cycle master's cycle count.
	www.faqs.org /ftp/pub/internet-drafts/draft-fairman-rtp-61883-00.txt (3073 words)

	What is isochronous? - A Word Definition From the Webopedia Computer Dictionary (Site not responding. Last check: 2007-10-08)
		For example, multimedia streams require an isochronous transport mechanism to ensure that data is delivered as fast as it is displayed and to ensure that the audio is synchronized with the video.
		Isochronous can be contrasted with asynchronous, which refers to processes in which data streams can be broken by random intervals, and synchronous processes, in which data streams can be delivered only at specific intervals.
		Isochronous service is not as rigid as synchronous service, but not as lenient as asynchronous service.
	www.webopedia.com /TERM/I/isochronous.html (152 words)

	Definition: isochronous burst transmission (Site not responding. Last check: 2007-10-08)
		isochronous burst transmission: In a data network where the information-bearer channel rate is higher than the input data signaling rate, transmission performed by interrupting, at controlled intervals, the data stream being transmitted.
		Note 1: Isochronous burst transmission enables communication between data terminal equipment (DTE) and data networks that operate at dissimilar data signaling rates, such as when the information-bearer channel rate is higher than the DTE output data signaling rate.
		Note 4: Isochronous burst transmission has particular application where envelopes are being transferred between data circuit-terminating equipment (DCE) and only the bytes contained within the envelopes are being transferred between the DCE and the DTE.
	www.its.bldrdoc.gov /projects/devglossary/_isochronous_burst_transmission.html (163 words)

	1394 Isochronous Transfers
		Isochronous transfers are useful for situations that require a constant data rate but not necessarily data integrity.
		Depending on the topology of the bus and what other isochronous devices are present, the maximum number of bytes per frame requested may well exceed the available bandwidth capabilities of the bus at the point when the request is made.
		If the isochronous packet is smaller than the driver's buffer, then the contents of the remaining space at the end of the driver's buffer is undefined.
	www.wd-3.com /archive/1394IsochronousTransfersPart1.htm (4690 words)

	isochronous - a Whatis.com definition (Site not responding. Last check: 2007-10-08)
		In information technology, isochronous (from the Greek "equal" and "time"; pronounced "eye-SAH-krun-us") pertains to processes that require timing coordination to be successful, such as voice and digital video transmission.
		In feeding digital image data from a peripheral device (such as a video camera) to a display mechanism within a computer, isochronous data transfer ensures that data flows continously and at a steady rate in close timing with the ability of the display mechanism to receive and display the image data.
		Isochronous can be distinguished from asynchronous, which pertains to processes that proceed independently of each other until a dependent process has to "interrupt" the other process, and synchronous, which pertains to processes in which one process has to wait on the completion of an event in another process before continuing.
	searchnetworking.techtarget.com /sDefinition/0,,sid7_gci212403,00.html (248 words)

	MediaMatrix - Support - Networking for Audio Part 3 1 pg 3 (Site not responding. Last check: 2007-10-08)
		Muliple channels of isochronous data each with their own attributes (bit resolution, sample rate, etc.) may be carried in a single frame.
		The isochronous cycle on CobraNet is of fixed duration and encapsulates multiple transmissions of standard Ethernet frames from multiple DTEs.
		The isochronous cycle is initiated by the transmission of the beat frame generated by a single DTE designated as the "Conductor." Think of the conductor as you would a condutor of an orchestra.
	mediamatrix.peavey.com /support/networking_pt3c.cfm (506 words)

	Isochronous Ethernet
		Isochronous Ethernet glues together channels that handle isochronous and packet data separately and transports the two data types over existing Ethernet 10Base-T LANs that use Category 3 UTP (unshielded twisted pair) or higher.
		Isochronous Ethernet is closely related to ISDN in that they use multichannel protocols and are based on TDM (time division multip lexing), a technique for multiplexing multiple channels over a single physical medium.
		Isochronous Ethernet allows you to split the C channel into as many as 96 ISDN B narrowband channels (of 64 Kbps each) as desired, or it can combine the channels to add 64-Kbps bandwidth or make a single 6.144-Mbps wideband channel.
	www.atksi.com /prod_IE.htm (2178 words)

	RFC 1257 (rfc1257) - Isochronous applications do not require jitter-contro
		One of the properties of isochronous applications like voice and video data streams is that their users may be sensitive to the variation in interarrival times between data delivered to the final output device.
		Now consider a situation in which the sender of the isochronous data timestamps each piece of data when it is generated, using a universal time source, and then sends the data to the receiver.
		I argue that the receiver is processing data isochronously and thus we have shown that a network need not be isochronous to support isochronous applications.
	www.faqs.org /rfcs/rfc1257.html (1471 words)

	Isochronous Services (Linktionary term) (Site not responding. Last check: 2007-10-08)
		Isochronous (iso = same, chronous = time) network technologies are designed to deliver real-time voice and video over data networks.
		Isochronous is the opposite of asynchronous, in which data transmissions are broken up and not sent in a constant stream.
		Isochronous is similar to synchronous, but does not have the perfectly timed stream of bits or bytes that a synchronous stream adheres to.
	www.linktionary.com /i/isochronous.html (162 words)

	Quatech \| Isochronous Serial Commmunication Overview
		Isochronous clocking information is derived from or included in the data stream, and the delay factor is dependent on a channel's characteristics and can be logically determined.
		Isochronous communication is best suited for applications where a steady data stream is more important than accuracy.
		To ensure that isochronous transfers are not bogged down by other devices, the USB specification sets aside bandwidth for them.
	www.quatech.com /support/comm-over-isochserial.php (206 words)

	[No title]
		Isochronous speed governing is a method of controlling speed in which the steady state speed is independent of load or fuel control position.
		Isochronous load sharing is the ability of two or more governed systems loaded in parallel to share the load proportionally while operating isochronously.
		Isochronous load sharing is a system which monitors the power output of a given engine generator and modulates the fuel to the engine so as to produce equal or proportionate load sharing with respect to one or more other generator sets connected to the same electrical power bus.
	www.egsa.org /standards/_docs/final/std100e.doc (3388 words)

	EVGA \| Community
		Isochronous data transfer services provide a contract, established during application startup, that indicates precisely when data transfers may be requested and sets bounds on when the corresponding data transfers will occur.
		To simplify synchronization with the processor, isochronous write transactions are guaranteed to become visible to the rest of the system without the need for an explicit “flush” operation.
		What Intel Says: Since isochronous and asynchronous transactions may be concurrently processed on the AGP8X interface, it is necessary to ensure that a throttled (stalled) asynchronous transaction does not cause the isochronous latency specification to be violated.
	www.evga.com /articles/30.asp (1400 words)

	A Study of Isochronous Channel Reuse in DQDB Metropolitan Area Networks (Site not responding. Last check: 2007-10-08)
		Given a set of established isochronous connections and a set of isochronous connections requests, using a minimal number of isochronous bandwidth to service all of the connections is attempted.
		On the other hand, given a limited isochronous bandwidth, establishing a maximal number of isochronous connections is of primary concern.
		Simulation results indicate that for a limited isochronous bandwidth, the number of isochronous connections successfully established by the ICSA is significantly more than that of the isochronous channels allocation scheme in the DQDB standard.
	www.comsoc.org /net/private/1998/aug/475_06net04-huang.html (458 words)

	Fundamentals of Firewire (Site not responding. Last check: 2007-10-08)
		The maximum amount of bandwidth an isochronous device can obtain is only limited by the number of other isochronous devices that have already obtained bandwidth from the isochronous resource manager.
		Because there are no more isochronous devices left waiting to transmit, the idle time extends longer than the isochronous gap until it reaches the duration defined as the subaction (or asynchronous) gap.
		Isochronous channel allocation is performed by a node that wishes to transmit isochronous packets.
	www.embedded.com /1999/9906/9906feat2.htm (5030 words)

	Wireless Net DesignLine \| IEEE Works to Adapt Ethernet for Home A/V Designs (Site not responding. Last check: 2007-10-08)
		If both devices are isochronous capable they will start to exchange clock synchronization information, with the device "more distant" from the network timing master becoming a the link timing slave and adjusting its clock to match that of the device "closer" to the network timing master.
		Note that the isochronous data that is queued during cycle 0 is not transmitted until cycle 1, and isochronous data that is queued during cycle 1 is not transmitted until cycle 2, and so on.
		In this case, the isochronous data for one of the streams is delayed into cycle 4 — and this is the reason that there are three levels of scheduled priorities: delayed isochronous data, isochronous data queued for the current cycle, and then best effort traffic.
	www.wirelessnetdesignline.com /howto/showArticle.jhtml?articleId=59302147&pgno=2 (1471 words)

	[No title]
		Observe that if two users are conferring with each other from their Partridge [Page 1] RFC 1257 Isochronous and Jitter September 1991 workstations, then beyond sensitivity to interarrival times, the users will also be sensitive to end-to-end delay.
		I argue that the receiver is processing data isochronously and thus we have shown that a network need not be isochronous to support Partridge [Page 2] RFC 1257 Isochronous and Jitter September 1991 isochronous applications.
		Some Implications The most important observation that can be made is that jitter Partridge [Page 3] RFC 1257 Isochronous and Jitter September 1991 control is not required for networks to be able to support isochronous applications.
	www.ietf.org /rfc/rfc1257.txt (1486 words)

	Oak Ridge Isochronous Cyclotron (Site not responding. Last check: 2007-10-08)
		The Oak Ridge Isochronous Cyclotron (ORIC) is a variable energy, multiparticle accelerator which was completed in 1962.
		The isochronous, or azimuthally varying field (AVF), cyclotron concept was first proposed in 1938 by L.H. Thomas.
		Isochronism refers to the constant orbit frequency of circulating ions obtained by radially increasing the magnetic field to compensate for relativistic increases in ion mass.
	www.phy.ornl.gov /hribf/accelerator/oricweb (175 words)

	Isochronous signal - Wikipedia, the free encyclopedia
		In telecommunication, an isochronous signal is a signal in which the time interval separating any two significant instants is equal to the unit interval or a multiple of the unit interval.
		Note 1: Variations in the time intervals are constrained within specified limits.
		Note 2: "Isochronous" is a characteristic, while "synchronous" indicates a relationship.
	en.wikipedia.org /wiki/Isochronous_signal (121 words)

	IEEE 1394 - A Standard for a High-Performance Serial Bus
		In addition, 1394's support for isochronous transactions is ideal for the connection of devices that send a fixed amount of data in each transaction, where the transactions are equally spaced apart.
		There are a number of layers in the 1394 protocol model, and although, as data communications engineers, we are primarily concerned with the physical layers, it is useful to have some knowledge of the other layers, because they interact heavily with the physical layer.
		Since isochronous transactions are of fixed duration in time, this permits different packet sizes depending on the bus speed.
	www.aquezada.com /staff/julian/school/ieee1394 (2656 words)

	BYTE.com
		In March, the IEEE was scheduled to vote on specification 802.9a, which outlines the technical underpinnings of isochronous Ethernet, a technology that for a small but determined group of companies is currently the best hope for easily sending digital video and audio across a LAN.
		Supporters say isochronous Ethernet is a viable technology in itself, or it can economical ly serve video applications while the market sorts out standardization issues for more expensive technologies, such as ATM.
		Isochronous Ethernet can provide a transition as long as ATM is restricted to being the WAN connection to the isochronous Ethernet hub and not a link from the hub to desktops.
	www.byte.com /art/9505/sec10/art6.htm (2305 words)

	DVD Talk Forum - what does this mean (isochronous bandwidth)
		Also Windows, in conjunction with other hardware in your system, may be consuming all the isochronous bandwidth of the USB bus.
		USB frame rates that are out of specification - isochronous data transfer (required for audio) is not possible via USB with a frame rate that is too fast or too slow.
		Controllers don't enumerate devices correctly - some controllers don't send USB resets at the appropriate times or may enumerate one part of a composite device.
	www.dvdtalk.com /forum/printthread.php?t=257092 (383 words)

	Transmission of high rate isochronous data in MPEG-2 data streams (US5598415)
		A scheme is provided for communicating high rate isochronous data in an MPEG-2 type transport stream in a robust manner.
		The time resolution for presenting isochronous data presentation units at the decoder is increased by providing a presentation time stamp (PTS) extension to supplement a standard MPEG-2 PTS.
		packaging said PES into a plurality of isochronous data transport packets such that a first payload byte of each transport packet is the first byte of an isochronous data presentation unit and a last payload byte of each of said packets is the last byte of an isochronous data presentation unit.
	www.delphion.com /details?pn10=US05598415 (460 words)

	CSD January 2001 Standards & Protocols: IEEE 1394: Firing Up for Multimedia (Site not responding. Last check: 2007-10-08)
		All isochronous resources that occurred during the 1000-ms delay that had been allocated before the reset are to be reallocated.
		The isochronous data transfer of the 1394 bus provides the guaranteed bandwidth and latency required for high-speed transfer over multiple channels.
		The isochronous resource manager assigns a channel number (0 to 63) to nodes that request isochronous bandwidth based on values in the manager's Channel_Available register.
	www.commsdesign.com /main/2001/01/0101stand.htm (1659 words)

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