Dan Lavry
Member of the Trade: Lavry Engineering
- Joined
- Dec 30, 2008
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Quote:
Hi Benjamin,
Time domain and frequency domain are not two different things. They are a different way of looking at the same thing. You do not get to choose one over the other.
Jitter is usually viewed form a time stand point, but one can view it from a frequency stand point. A sine wave tone is usually often "viewed" by its frequency and amplitude (like an FFT plot), but one can look at it as a time domain signal (like as a scope).
Take some wave, say a 1KHz square wave, it can be looked at as a sum of harmonics. There is a 3Khz, 5Khz, 7KHz... If you change the amplitude or phase of ANY of the harmonics (frequencies domain alteration), when you look at the time domain (scope picture) the waveform is no longer the original square wave.
Now take say a sine wave (a scope picture). A single sine wave looks like a single tone in frequency domain (say FFT plot). Say you clip the top of it, or do anything to change its shape on the scope. When you look at the frequency domain, you will have more then one tone, the frequency picture changed.
You can not do one without the other. You do not get to choose one or the other.
Jitter decreases accuracy. It decreases the accuracy of the wave shape in the time domain, and it alters the frequency picture as well, such as smear, or adding side bands...
To have time domain transparency, you need low jitter. To have frequency domain transparency you need low jitter.
Once you have good time domain reproduction it is good at any domain. If a DAC is "bad with frequency response", it is also "bad with time response".
Altered frequency response means altered time domain wave shape. Cause and effect should be kept apart. Jitter is a cause for altering both time and frequency. Time and frequency are not separate entities. They are different points of view of the same thing.
Regards
Dan Lavry
Lavry Engineering
| Originally Posted by thisbenjamin /img/forum/go_quote.gif I would agree that "The technology doesn't exist to do both well, so you have to choose which you would prefer to have". makes sense to a point, in that many off the shelf dacs are either good with jitter , bad with frequency response, or the other way around - not both. In many of the higher end dacs - or the dacs like Lavry or PacificMicrosonics/Berkley, etc based on professional gear, you don't have to choose one of the other - the entire process is accurate, no sacrifices must be made. |
Hi Benjamin,
Time domain and frequency domain are not two different things. They are a different way of looking at the same thing. You do not get to choose one over the other.
Jitter is usually viewed form a time stand point, but one can view it from a frequency stand point. A sine wave tone is usually often "viewed" by its frequency and amplitude (like an FFT plot), but one can look at it as a time domain signal (like as a scope).
Take some wave, say a 1KHz square wave, it can be looked at as a sum of harmonics. There is a 3Khz, 5Khz, 7KHz... If you change the amplitude or phase of ANY of the harmonics (frequencies domain alteration), when you look at the time domain (scope picture) the waveform is no longer the original square wave.
Now take say a sine wave (a scope picture). A single sine wave looks like a single tone in frequency domain (say FFT plot). Say you clip the top of it, or do anything to change its shape on the scope. When you look at the frequency domain, you will have more then one tone, the frequency picture changed.
You can not do one without the other. You do not get to choose one or the other.
Jitter decreases accuracy. It decreases the accuracy of the wave shape in the time domain, and it alters the frequency picture as well, such as smear, or adding side bands...
To have time domain transparency, you need low jitter. To have frequency domain transparency you need low jitter.
Once you have good time domain reproduction it is good at any domain. If a DAC is "bad with frequency response", it is also "bad with time response".
Altered frequency response means altered time domain wave shape. Cause and effect should be kept apart. Jitter is a cause for altering both time and frequency. Time and frequency are not separate entities. They are different points of view of the same thing.
Regards
Dan Lavry
Lavry Engineering
