Hi Lynne,

The most accurate answer is probably "neither."

A square wave, in the context of electrical signals, is a voltage that alternates periodically between a higher voltage level and a lower voltage level, spending an equal amount of time in each of the two states. An ideal square wave has infinitely fast transitions between the two states, and each voltage level is perfectly precise and constant, i.e., no noise (random fluctuation of the voltage levels) is present. Neither of those conditions is possible in the real world, so what are referred to as "square waves" are approximations of ideal square waves.

A square wave cannot normally be used to convey information, because its pattern of alternating between the two voltage states remains the same all the time. It can be used in many applications as a "clock signal," however, which controls the timing of whatever operations are performed by the circuit that is involved. Square waves can also be useful as test signals, to evaluate circuit or component performance.

1's and 0's are just numbers. The decimal (base 10) numbering system that humans like to use utilizes numbers whose individual digits can range from 0 to 9. The 1's and 0's you refer to are based on the binary (base 2) numbering system, where the only allowable digits are 1 and 0. Either system can represent all possible numbers; it just takes more digits to do it in the binary system. Computers and other digital devices are designed based on the binary number system because their practical implementation is facilitated by the fact that only two states have to be distinguished from each other.

A series of 1's and 0's can be used to convey information. An example of "information" is the amplitude (volume) of a music signal at a given instant of time. Since those 1's and 0's are numbers, though, they in turn have to be represented by something else, such as a voltage level, before they can be sent or communicated or processed by a physical circuit. In some applications, a 1 may be represented by a higher voltage, and a 0 by a lower voltage, or vice versa.

In the two cases you mentioned, though, those approaches aren't used, in part because clock and data are combined into a single signal, in such a manner that the receiving circuit can separate the two. S/PDIF encodes the 1 and 0 data, together with the clock and additional necessary information as described in the writeup, into something called Biphase Mark or Differential Manchester Code. Ethernet, since it is a networking standard that is designed to provide communications between multiple devices at arbitrary and intermittent times, and in its modern forms at very high speeds, is complex and is described further in this Wikipedia writeup and at the links it provides. Different codings, all of them combining clock, data, and other necessary information, are used for each of the commonly used link speeds (10, 100, or 1000 mbps).

Hope that clarifies more than it confuses :-)

Best regards,

-- Al

The most accurate answer is probably "neither."

A square wave, in the context of electrical signals, is a voltage that alternates periodically between a higher voltage level and a lower voltage level, spending an equal amount of time in each of the two states. An ideal square wave has infinitely fast transitions between the two states, and each voltage level is perfectly precise and constant, i.e., no noise (random fluctuation of the voltage levels) is present. Neither of those conditions is possible in the real world, so what are referred to as "square waves" are approximations of ideal square waves.

A square wave cannot normally be used to convey information, because its pattern of alternating between the two voltage states remains the same all the time. It can be used in many applications as a "clock signal," however, which controls the timing of whatever operations are performed by the circuit that is involved. Square waves can also be useful as test signals, to evaluate circuit or component performance.

1's and 0's are just numbers. The decimal (base 10) numbering system that humans like to use utilizes numbers whose individual digits can range from 0 to 9. The 1's and 0's you refer to are based on the binary (base 2) numbering system, where the only allowable digits are 1 and 0. Either system can represent all possible numbers; it just takes more digits to do it in the binary system. Computers and other digital devices are designed based on the binary number system because their practical implementation is facilitated by the fact that only two states have to be distinguished from each other.

A series of 1's and 0's can be used to convey information. An example of "information" is the amplitude (volume) of a music signal at a given instant of time. Since those 1's and 0's are numbers, though, they in turn have to be represented by something else, such as a voltage level, before they can be sent or communicated or processed by a physical circuit. In some applications, a 1 may be represented by a higher voltage, and a 0 by a lower voltage, or vice versa.

In the two cases you mentioned, though, those approaches aren't used, in part because clock and data are combined into a single signal, in such a manner that the receiving circuit can separate the two. S/PDIF encodes the 1 and 0 data, together with the clock and additional necessary information as described in the writeup, into something called Biphase Mark or Differential Manchester Code. Ethernet, since it is a networking standard that is designed to provide communications between multiple devices at arbitrary and intermittent times, and in its modern forms at very high speeds, is complex and is described further in this Wikipedia writeup and at the links it provides. Different codings, all of them combining clock, data, and other necessary information, are used for each of the commonly used link speeds (10, 100, or 1000 mbps).

Hope that clarifies more than it confuses :-)

Best regards,

-- Al