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In Reply to: RE: Sound Quality Changes caused by Sata cables. posted by Ugly on July 07, 2014 at 20:36:56
"The goal is to spread out the energy of energetic peaks to a wider band which will allow the manufacturers to utilize a loophole in the test method to attain compliance."
The test method was not a "loophole". It was good engineering to address a specific technical problem that was a result of interference actually observed. My knowledge is based on conversations with engineers for a large computer company where I worked that were specifically concerned with achieving conformance and which, of necessity, had a thorough understanding of the issues involved. The requirements were designed to protect the interest of competing radio services that used narrow band modulation. The advantage of spreading the interference over a wide band of frequencies is that it minimizes the probability of interference in any actual situation, where there are a small number of frequency bands that are active and most others are inactive. However, the active frequencies are specific to the particular installation, e.g. the local TV channels and the ones the neighbor actually wants to watch at the time the offending computer is powered up. Spreading the bandwidth of noise is not likely to affect systems such as pacemakers which are not narrow band radio receivers.
I've seen interference between computerized avionics where the noise from the computer killed certain of the VHF comm channels. The fix was to change the software to move the noise to different channels that were unlikely to be used. (This was done by the manufacturer of the offending avionics who happened to be a personal friend and I have personally experience the "before" and "after" effect on my radio reception.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Follow Ups:
I guess we'll have to disagree about the semantics about whether it is a loophole that a single frequency clocks larger energy content at a specific frequency per time is some how better than the same amount of energy spread over a wider band by utilizing spread spectrum techniques and allowing so called "quasi peak" measurements of this energy to now fall under legal limits in cases near the line.
"Spreading the bandwidth of noise is not likely to affect systems such as pacemakers which are not narrow band radio receivers."
perhaps not but as I was saying the limits were definitely conceived to help ensure proper operation of a wide variety of electronics within reasonable ambient environments. Not just radios.
Semantics is the guy's strong point and this is why I do not debate with him.Anyway, I thought I would post a picture of a small no of instruments I have to make measurements.
This includes:
1uV 1Hz-1MHz AC Volmeter
8 digit volt-ohm meter
HP digital scope 150 MHz with FFT function.I also use others such as -110dB thd+n meter, 64 bit pro FFT program etc.
If I am younger and more keen on measurements as I was then, I would buy an AP2 or better a Rhode and Schwarz
Edits: 07/07/14
I was getting dizzy...
A 150 Mhz scope is not going to be useful for examining signal quality of interconnects such as USB 2.0 and SATA. Look at the recommended test equipment in the link below. Big bucks are involved in test equipment, probably more than most audiophiles have in their entire system.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
to say or assume that I use a 150MHz scope with FFT to measure usb eye patterns.
It is actually far more useful in looking at the harmonics of XOs, with printout capability.
In other words, you admit the obvious. You don't have the tools necessary to measure signal integrity on high speed cables such as SATA and USB 2.0.
Have you found a connection between harmonics of XO's and sound quality?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
inappropriate comment that makes others wonder what you are up to. I never said |I have or did it.
''In other words, you admit the obvious. You don't have the tools necessary to measure signal integrity on high speed cables such as SATA and USB 2.0.''
And if it is obvious, why ask? Do you just want to read your own words as Ted posted earlier.
I posted because of comments inmates made regarding your equipment photo. It might have not been obvious to some that your tools were inadequate for the purpose of tweaking SATA and USB 2.0 systems.
I do not go into modifying computer hardware because I know what tools are necessary having worked with a hardware lab containing hundreds of thousands of dollars of test equipment. There are people here with adequate tools, but most (if not all) sport the (M) moniker. Because of the small size of the high-end audio marketplace, even manufacturers have difficulty affording the necessary tools. One advantage of IIS and SPDIF are the lower data rates, enabling less than a $20,000 scope to show eye patterns.
You did not answer my question about harmonics of XO's.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
you frequently put inappropriate interpretations on my answers to you, I decided a long while ago not to answer your questions and that has been made obvious to you. I note that you have also misinterpreted what was said by others about the picture of some instruments that I posted.
It is your privilege to ask and my privilege not to respond.
If you don't like having your posts misinterpreted then I suggest you take more care in writing them. You might also consider that your inability and/or unwillingness to answer simple questions might not put you in a good light.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
that you need to learn to read properly. Noone else misinterprets my posts like you have bee doing.
I reckon that it is deliberate.
Deliberately reading improperly. An interesting concept, almost an oxymoron.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Nice stuff. I wish my own lab were so nicely equipped.
and who have the expertise will buy instruments. I know a guy who sells toys and is a nuclear physicist who bought a wavecrest to check jitter.
So many amateurs who don't declare their methods of assessment are quite knowledgeable. It's a case of web citizens accepting at face value what is posted.
Why, because they don't want to spend time arguing with some so and sos who think they know better. I am one of them. I spend my time improving my systems instead.
how ridiculous posters can get, stating that my 150 MHz scope cannot be used for usb eye patterns.
Edits: 07/09/14
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