Hi Marce,
Sure thing. There is a test point labeled "RF" in most CD players, and if there isn't, seasoned technicians go looking for this test point. This is where you would be looking at the "eye pattern", which is a qualitative indicator of how many errors you will be facing in this CD / CD player combination. It may well be upsetting to you to know that the "digital data" off the CD begins life as transitions between two levels, land and pit. The reflected laser beam is detected by diodes, four in the Philips swing arm, and six in conventional machines. The pit edge transitions are converted into an analogue signal in the RF frequency range where they are converted into an EFM signal by the RF amplifier section or RF amplifier IC (older CD Players). The EFM signal is at the same frequencies as the RF signal and create their own pattern if viewed on an oscilloscope in the same manner that the RF eye pattern is observed. This is still an analogue signal, but with sharp transitions between high and low levels.
I'm sorry to report, but your CD player, hard drives and everything else all comes back to an analogue waveform. Sorry.
-Chris
Bit of a misnomer really, I would associate RF with signals that are going to be transmitted, so we are talking about the high frequency analogue signals... And usually when mentioned is a reference to radiated emissions, the range of RF frequencies is quite broad, from a few kHz to hundreds od GHz. These signals are digitised soon after reading to provide a data stream, a nice digi9tal wave form then to worry about with nice squareish edges. So I thought you were referring to airborne noise I didn't realise that the high frequency analogue signal was referred to as the RF signal...
Why are you sorry to report CD players etc. all come back as a analogue wave form and what do you mean by everything, storage media I would presume....
Again I don't know why you are sorry its not that its new info....
Again why would I find it upsetting to find the digital data begins as two transitions....
Gosh and eye diagrams, I wondered what they were, doing DDR layout and simulations I never seen them and on my work placement from collage at NCL in 1983 playing with floppy drives and setting the heads using an offset screw watching those pretty patterns on a scope, I always wondered what they were...
Next you'll be telling me digital waves are really analogue and made up of numerous harmonics of sine waves, the spectral content being defined by the rise time, and the range that has to be catered for can be quickly determined by finding the knee frequency from the rise or fall times, though I believe there are more precise method but for what I do the knee frequency gives me a good enough guide.
All this misunderstanding over the misuse of the term RF....
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This is incredible! The guy just can't think straight - his logic falls apart even before he finishes the fist few paras! But, hey, it's on the 'net so it must be true. What a sad affair.
Jan
Hey, you should see my ignore list!
But I think I discovered a corollary to some other law, can't remember which: the more morons you put on your ignore list, the more new ones will appear.
Jan
the more morons you put on your ignore list, the more new ones will appear.
Yes, the mother of stupidity is always pregnant.
The capital letters are grand, one can immediately vision the gent behind his keyboard, screaming and foam in the corners of his mouth.
The use of 'accept' instead of assume and 'fact' were somewhat dissapointing, a bit like telling the butler did it halfway down the flic.
(instead of hitting the ignore list, you could try expressing to them how much they excite you. By PM, if the first attempt turns out unsuccesful)
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Well good morning se ! It's a wondeful day here in beautiful, sunny downtown Cool, CA. How are you? Fine, I hope.
To answer your question..... not in my life-time.
Have a nice day.
THx-RNMarsh
Steve, calling Audio a "supermarket consumer audio magazine" is either very ignorant or disingenuous. Ignoring the proud and important history of that magazine is utterly disrespectful. It did unfortunately get run into the ground by the commercial interest that eventually took it over, but the history and importance of the magazine in communicating information about audio in the engineering world cannot be overstated.
for those unfamiliar with the past of that magazine, which actually was involved in the start of the AES here in the US, it can be found on line, scanned in to the modern age.
Alan Garren
for those unfamiliar with the past of that magazine, which actually was involved in the start of the AES here in the US, it can be found on line, scanned in to the modern age.
Alan Garren
I'm well aware of Audio's history.
That doesn't change the fact that at the time the Picking Capacitors article was published, Audio was just a supermarket consumer audio magazine, and was a far far cry from an "AES paper."
Here, I bookmarked this some time back.
How The AES Began
se
When I saw that I was reminded of the bass boost I'd incorporate into desktop powered speakers. Of course there was adjustment for the particular ported speakers, and usually the amount of boost was an active function of level.
Odd to see it undefeatable here!
Well good morning se ! It's a wondeful day here in beautiful, sunny downtown Cool, CA. How are you? Fine, I hope.
To answer your question..... not in my life-time.
Have a nice day.
Talk about "zero Cred."
se
Hi marce,
No problems then. I usually get that kind of question from folks who don't understand how the technology works just before they launch into a "how it sounds is all that matters" type of comment. Not having observed your posts before now, there was no background to place your comments into context. Now I know you have a similar practical background where observing signals is concerned.
Normally any comment that equates a digital signal to analogue waveforms provokes another outburst from some folks out there. That is why being sorry about undermining an entire belief system comes from.
I normally would call anything AM band or up as RF, yet I also firmly believe that you need to pay attention to at least 1 MHz for audio work. Most components we use will happily misbehave up there and beyond
-Chris
No problems then. I usually get that kind of question from folks who don't understand how the technology works just before they launch into a "how it sounds is all that matters" type of comment. Not having observed your posts before now, there was no background to place your comments into context. Now I know you have a similar practical background where observing signals is concerned.
Normally any comment that equates a digital signal to analogue waveforms provokes another outburst from some folks out there. That is why being sorry about undermining an entire belief system comes from.
Yup!
I normally would call anything AM band or up as RF, yet I also firmly believe that you need to pay attention to at least 1 MHz for audio work. Most components we use will happily misbehave up there and beyond
We are probably close in age ... please allow me to apologize for misreading your question. The timing and content were mistaken for something else.
-Chris
So to further satisfy my curiousity, I ran the simulation "experiment" in the other direction, and made a second stage out of ideal transconductances, but used it with the actual input stage. The distortion went down to very low levels: for the 20kHz 1V peak input signal the output distortion (out to 5th) is predicted as 270ppb for the low Z divider, 549ppb for the high Z divider.
So there is a tiny effect from the input stage loading compared to the real second stage distortion. With a real second stage it should be negligible.
My new AMD and many intels only work off of a 100-133mhz mainboard
clock . Memory uses rising/falling edge as multiplier and CPU uses a
internal 20-40X clock multiplier.
Ghz is only seen in the CPU silicon.
Edit - I fix so many 2K-2007 PC's (<133mhz) ....some newer ones have 200mhz+ clocks.
OS
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I always thought one of the greatest aspects of audio was the fact that it provided a chance for just about any approach to anything. The market would decide if it was right or wrong. Not some sef-appointed hanging judge a la Roy Bean who dishes out justice while forthing at the mouth and possiby elsewhere.
Not agreeing is not the same as slamming down on anyone who thinks differently, no matter what's the issue. By comparison, in his day people said nothing as simple as an 8 transistor amp could play the big sound game, yet Jean Hiraga's little amp proved very clearly all those naysayers to be as wrong as can be. People are making them to this day, and still it sounds better than most of the fare on the market. True, you do not have megawatts to play with, it needs relatively efficient loudspeakers, but then so do most tube amps as well and they are still being made and going strong.
Plain, elementary manners have been lost here in search for ever lesser distortion figures and whose is bigger. I believe those who shout the loudest are covering up for their lack of actual hardware, those who have it don't need to advertise.
Not agreeing is not the same as slamming down on anyone who thinks differently, no matter what's the issue. By comparison, in his day people said nothing as simple as an 8 transistor amp could play the big sound game, yet Jean Hiraga's little amp proved very clearly all those naysayers to be as wrong as can be. People are making them to this day, and still it sounds better than most of the fare on the market. True, you do not have megawatts to play with, it needs relatively efficient loudspeakers, but then so do most tube amps as well and they are still being made and going strong.
Plain, elementary manners have been lost here in search for ever lesser distortion figures and whose is bigger. I believe those who shout the loudest are covering up for their lack of actual hardware, those who have it don't need to advertise.
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