Word Clock - Revision history

Brad Johnson at 00:46, 5 December 2018

2018-12-05T00:46:54Z

Brad Johnson at 00:44, 5 December 2018

2018-12-05T00:44:09Z

Brad Johnson at 19:30, 12 April 2018

2018-04-12T19:30:49Z

Admin: /* Overview */

2015-01-15T21:16:31Z

Overview

Brad Johnson at 19:06, 14 January 2015

2015-01-14T19:06:18Z

Brad Johnson at 19:05, 14 January 2015

2015-01-14T19:05:34Z

Brad Johnson at 18:21, 23 July 2012

2012-07-23T18:21:39Z

Brad Johnson at 18:18, 23 July 2012

2012-07-23T18:18:54Z

Brad Johnson at 18:16, 23 July 2012

2012-07-23T18:16:40Z

Brad Johnson at 18:15, 23 July 2012

2012-07-23T18:15:57Z

@@ Line 25: / Line 25: @@
 There are three basic approaches to using Word Clock in systems larger than two devices:
-a.) Use a Word Clock source with multiple outputs. The Word Clock source must have as many outputs as there are "slave" devices with Word Clock inputs.
+a.) Use a Word Clock source with multiple outputs. The Word Clock source must have as many outputs as there are "slave" devices with Word Clock inputs. The Lavry [[Synchrony-16]] is an example of this type of source.
 b.) Use one Word Clock source and "chain" the same signal using [[BNC "T"]] connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the ''last'' slave device in the chain. The last device can either have fixed internal termination or a BNC "T" connector on its input with a [[BNC terminator]] on the "T" opposite in the incoming Word Clock cable.

@@ Line 32: / Line 32: @@
 ==Lavry Products==
 *[http://www.lavryengineering.com/products/pro-audio/ad122-96-mkiii.html LavryGold AD122-96 MkIII]- BNC Word Clock input and output + XLR AES Sync input; BNC input is not internally terminated
 *[http://www.lavryengineering.com/products/pro-audio/4496-12.html LavryBlue 4496] with MSYNC- BNC Word Clock output, BNC Sync input accepts Word Clock and AES3 Sync; not internally terminated

@@ Line 1: / Line 1: @@
 ==Overview==
-The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of [[digital audio]] equipment. The signal is typically [[TTL level]] 5 volt p-p and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
+The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of [[digital audio]] equipment. The signal is typically “TTL level” which is nominally 5 volt [[p-p]] and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
 ==History==

@@ Line 1: / Line 1: @@
 ==Overview==
-The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of [[digital audio]] equipment. The signal is typically "TTL level" 5 volt p-p and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
+The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of [[digital audio]] equipment. The signal is typically [[TTL level]] 5 volt p-p and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
 ==History==
 Earlier digital audio systems employed a number of formats of interconnection, many of which were proprietary. Some were [[parallel]]; in which case each [[bit]] was carried on a separate conductor and a Word Clock signal was used to synchronize the timing of the transmission of each complete [[word]] of 16 bits, once per [[sample]] period.

@@ Line 28: / Line 28: @@
 b.) Use one Word Clock source and "chain" the same signal using [[BNC "T"]] connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the ''last'' slave device in the chain. The last device can either have fixed internal termination or a BNC "T" connector on its input with a [[BNC terminator]] on the "T" opposite in the incoming Word Clock cable.
-c.) A "mixed" approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external [[AD converters]] and AES synchronization of the "master" AD converter to the digital audio interface.
+c.) A "mixed" approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external [[AD converter]]s and AES synchronization of the "master" AD converter to the digital audio interface.
 ==Lavry Products==

@@ Line 1: / Line 1: @@
 ==Overview==
-The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of digital audio equipment. The signal is typically "TTL level" 5 volt p-p and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
+The term "<nowiki>Word Clock</nowiki>" is used to describe a one cycle per [[sample period]] "square wave" signal used for synchronization of [[digital audio]] equipment. The signal is typically "TTL level" 5 volt p-p and is carried on 75 Ohm [[coaxial]] cable with [[BNC]] connectors.
 ==History==
-Earlier digital audio systems employed a number of formats of interconnection, many of which were proprietary. Some were [[parallel]]; in which case each "bit" was carried on a separate conductor and a Word Clock signal was used to synchronize the timing of the transmission of each complete "word" of 16 bits, once per sample period.
+Earlier digital audio systems employed a number of formats of interconnection, many of which were proprietary. Some were [[parallel]]; in which case each [[bit]] was carried on a separate conductor and a Word Clock signal was used to synchronize the timing of the transmission of each complete [[word]] of 16 bits, once per [[sample]] period.
-In other systems; the left and right channel's digital audio data was transmitted in a [[serial]] manner, in parallel with a Word Clock signal which was used to synchronize the receiver with the beginning of the transmission of each serial "word."
+In other systems; the left and right channel's digital audio data was transmitted in a [[serial]] manner, in parallel with a Word Clock signal which was used to synchronize the receiver with the beginning of the transmission of each [[serial]] [[word]].
-As digital audio systems grew in complexity and the need for synchronization with video equipment arose, Word Clock was used as the system "clock" even though newer formats, such as the AES3 digital audio format were "self-clocking."
+As digital audio systems grew in complexity and the need for synchronization with video equipment arose, Word Clock was used as the system "clock" even though newer formats, such as the [[AES3]] digital audio format were "self-clocking."
-Due to the fact that the Word Clock format is a relatively "low frequency" signal compared to the serial formats with an embedded "[[bit clock]]," with two transitions per sample period as versus hundreds of transitions per sample period; the Word Clock signal did offer advantages in terms of [[jitter]] issues. With reasonable care to use of the proper cable and [[termination]]; cable reflections (one of the main sources of jitter) have the time to decay before the next transition occurs; which is not the case with serial formats.
+Due to the fact that the Word Clock format is a relatively low frequency signal compared to the serial formats with an embedded [[bit clock]], with two transitions per [[sample]] period as versus hundreds of transitions per sample period; the Word Clock signal did offer advantages in terms of [[jitter]] issues. With reasonable care to use of the proper cable and [[termination]]; cable reflections (one of the main sources of jitter) have the time to decay before the next transition occurs; which is not the case with serial formats.
-Technology advanced; and as the speed of circuitry increased it became commonplace for digital systems to use high-speed serial transmission with the obvious advantage of fewer conductors needed to move the data from device to device. As wordlength increased from 16, to 32, to 64 bits; the advantages of serial transmission became even greater. Contemporary digital audio equipment commonly uses serial data transmission internally as well as externally; and this makes it necessary to have an internal bit clock which is in the range of 64 to 128 times the sample frequency.
+Technology advanced; and as the speed of circuitry increased it became commonplace for digital systems to use high-speed serial transmission with the obvious advantage of fewer conductors needed to move the data from device to device. As [[Wordlength]] increased from 16, to 32, to 64 [[bit]]s; the advantages of serial transmission became even greater. Contemporary digital audio equipment commonly uses serial data transmission internally as well as externally; and this makes it necessary to have an internal bit clock which is in the range of 64 to 128 times the [[sample frequency]].
-Due to advances in serial transmission technology and the fact that contemporary digital audio systems operate with a much higher frequency bit clock, the internal clock frequency is significantly higher than the one cycle per sample Word Clock frequency and better methods are available to deal with issues related to very high frequency transmission. The result is that many contemporary digital audio devices do at least as good a job, if not a better, sync’ing to an AES digital audio input than to a lower frequency Word Clock signal that requires generation of a synchronized much higher frequency bit clock. For these reasons, Lavry DA converters all “lock” to the incoming digital audio and use sophisticated methods of effectively “de-coupling” the internal clock used for conversion from the jitter in the incoming digital audio signal. Lavry AD converters also offer the option of synchronizing to AES sync, in addition to Word Clock.
+Due to advances in serial transmission technology and the fact that contemporary digital audio systems operate with a much higher frequency [[bit clock]], the internal clock frequency is significantly higher than the one cycle per sample Word Clock frequency and better methods are available to deal with issues related to very high frequency transmission. The result is that many contemporary digital audio devices do at least as good a job, if not a better, sync’ing to an [[AES]] digital audio input than to a lower frequency Word Clock signal that requires generation of a synchronized much higher frequency bit clock. For these reasons, Lavry DA converters all “lock” to the incoming digital audio and use sophisticated methods of effectively “de-coupling” the internal clock used for conversion from the jitter in the incoming digital audio signal. Lavry AD converters also offer the option of synchronizing to AES sync, in addition to Word Clock.
 ==Basics==
@@ Line 18: / Line 18: @@
 “Proper” termination requires two things:
 #Both the sending end and the receiving end must have termination at exactly one place.
-#The termination must be the correct value; which is the same as the characteristic impedance of the cable.
+#The termination must be the correct value; which is the same as the characteristic [[impedance]] of the cable.
 In (1) the sending end is generally a "given" as all Word Clock outputs have fixed internal termination by design. The important issue is termination of the receiving device(s).
@@ Line 28: / Line 28: @@
 b.) Use one Word Clock source and "chain" the same signal using [[BNC "T"]] connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the ''last'' slave device in the chain. The last device can either have fixed internal termination or a BNC "T" connector on its input with a [[BNC terminator]] on the "T" opposite in the incoming Word Clock cable.
-c.) A "mixed approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external AD converters and AES synchronization of the "master" AD converter to the digital audio interface.
+c.) A "mixed" approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external [[AD converters]] and AES synchronization of the "master" AD converter to the digital audio interface.
 ==Lavry Products==

@@ Line 32: / Line 32: @@
 ==Lavry Products==
 *[http://www.lavryengineering.com/products/pro-audio/ad122-96-mkiii.html LavryGold AD122-96 MkIII]- BNC Word Clock input and output + XLR AES Sync input; BNC input is not internally terminated
-*LavryBlue 4496 with MSYNC- BNC Word Clock output, BNC Sync input accepts Word Clock and AES3 Sync; not internally terminated
+*[http://www.lavryengineering.com/products/pro-audio/4496-12.html LavryBlue 4496] with MSYNC- BNC Word Clock output, BNC Sync input accepts Word Clock and AES3 Sync; not internally terminated
-*LavryBlack AD10- BNC Sync In accepts Word Clock and AES3 Sync; fixed internal termination selectable between 75 and 110 Ohms
+*[http://www.lavryengineering.com/products/pro-audio/ad10.html LavryBlack AD10]- BNC Sync In accepts Word Clock and AES3 Sync; fixed internal termination selectable between 75 and 110 Ohms
-*LavryBlack AD11- BNC Word Clock output, BNC Clock input accepts Word Clock, AES3, and S-PDIF sync; fixed 75 Ohm internal termination.
+*[http://www.lavryengineering.com/products/pro-audio/ad11.html LavryBlack AD11]- BNC Word Clock output, BNC Clock input accepts Word Clock, AES3, and S-PDIF sync; fixed 75 Ohm internal termination.
 [[Category:Terminology]]
 [[Category:Digital interconnects]]

@@ Line 26: / Line 26: @@
 a.) Use a Word Clock source with multiple outputs. The Word Clock source must have as many outputs as there are "slave" devices with Word Clock inputs.
-b.) Use one Word Clock source and "chain" the same signal using BNC "T" connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the ''last'' slave device in the chain. The last device can either have fixed internal termination or a BNC "T" connector on its input with a BNC terminator on the "T" opposite in the incoming Word Clock cable.
+b.) Use one Word Clock source and "chain" the same signal using [[BNC "T"]] connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the ''last'' slave device in the chain. The last device can either have fixed internal termination or a BNC "T" connector on its input with a BNC terminator on the "T" opposite in the incoming Word Clock cable.
 c.) A "mixed approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external AD converters and AES synchronization of the "master" AD converter to the digital audio interface.