The I2S is what Steve from Empirical highly recommends.
I believe until an audiophile wireless solution ever falls into place, this is the preferred connection.
You'd think with all the computer and digital technology someone would have the answer by now. |
So, why not go for I2S?
Chris |
Please report back your findings, Agear. |
Eric, you soooo right. We are all sick of this crap. I have been researching and researching and waiting for "that" product to appear but to no avail. One of the sonic themes that comes out in reading reviews pretaining to digital audio is a certain thinness of sound...ultra detailed yes, but lacking warmth, bloom, bass weight, etc. That is what I crave. You mentioned the Memory Player, and while it sounds promising, who is 10K+ lying around? Anyway, I am planning to a little blinded, A+B testing of digital front ends in the not too near future, and I would like to involve non-audiophiles with good ears and music backgrounds (my wife for example) to keep things real. The potential contenders at this point are:
1. Granite Audio 657 (my CDP)
2. Bolder modded SB3 (Ultimate mod)
3. Modded Sonos + Pacecar + DAC (Empirical Audio)
4. Sonos (w/ ? USB mod or converter) + Exemplar USB DAC
Should be interesting..... |
Thanks Ehider for spending the time/energy with these topics. |
Agear, IMHO you are absolutely correct that USB intefaces are not created equal. (If it was only that simple!). I think we will see just a select few USB based digital standouts in the next year or so. Most likely, many of their competitors will be "scratching their heads" to why they cannot achieve the same sonic greatness when they try to implement a USB connection within their digital products. Steve Nugent is absolutely spot on with his assessments regarding USB variability. Only a very talented digital design staff (that understand digital like Steve Nugent) will be able to implement USB connectivity and actually achieve true sonic greatness due to the myriads of technical issues that Steve pointed out. As you surmised, the most important thing I've learned with this is that the SPDIF connection itself has always "sucked the life" out of what digital was capable of giving us. Of course, the Esoteric $15K Rubiduim clock probably helps fix some of this. ;-)
Bosrt; The wonderful pre-production USB DAC I heard was actually by accident. If their production USB DAC sounds as good as the beta unit I heard I think I will be "beating the drums" very loudly about it. I am so VERY TIRED of seeing the multitudes of huge dollar digital offerings that are being talked up in the rags and on the audio forums that don't actually meet the expectations? (Can we say "almost everything"). I think many audiophiles are getting burned out with digital as they spend STUPID money yet still end up flipping their digital front ends year over year. When are we going to see the super digital "revolutionary" product actually going to meet the hype about it?
BTW: Your "Alien Invasion" statement really cracked me up! |
Perhaps a naive question from someone technically challenged, but will any of this have an impact on, or improve upon, the performance of pc-based music delivered not by USB but wirelessly, as with a Sonos or Squeezebox? (Oh please, oh please, tell me it will!!!)
I think THIS is the real future of music delivery, whereby you DON'T have to plug a pc into your system via USB or anything else. Whereby you can sit anywhere in your house and pull up music and play it, via your laptop or your sonos, squeezebox, etc. This is truly the future. Hardwiring is NOT the answer in my book. Convenience equal with reference quality playback is the answer. I wish more effort was being put into this aspect of delivery. |
Ehider, "I am thinking I may start a specific thread with the USB DAC's name and some other details when the company gives me the "green light" to talk about them in detail"
Do you have a formal or informal relationship with this un-named company?
Can't wait for your thread on the specific DAC you are mentioning. I have a Pro Mac waiting for a higher purpose now, just in case.
Reading the comments from the reviewers regarding the Memory Player, it seems like this a new paradigm, a new cult, or an alien invasion starting. |
Triode, I have the G0s working with the P0s VUK and DCS Elgar plus. Have you heard the Rubidium clock in action with the Esoteric , DCS, or EMM separates? Have you done A/B comparison?
Some fools buy "crazy" things, but the others speak about things they don't know. WHy don't you tell us about your experience with the Rubidium Clock and explain your statement?
Kyomi Audio |
Eric, I agree in essence with what you are saying. S/PDIF is inherently flawed. USB has advantages in terms of the ease of reclocking, etc. However, not all USB interfaces are created equal. Steven Nugent himself told me that there is a fair amount of variability in the quality of USB reclocking chips, which is where the $ is. That being said, I wonder if the sonic attributes of this WDP (nice Dgarretson....) are simply a byproduct of the USB interface or is it something more? I think you are operating under certain assumptions about the purported sonic attributes of USB data architecture. There are USB products out there which, while very good, are not a quantum leap beyond current offerings.
I will leave you with a quote from the Benchmark gang taken from a Stereophile thread:
We did measure the audio performance (Freq response, THD, IMD, etc) of the USB input, and it was completely similar to the all other digital inputs of the DAC1 up to 96/24. We also did listening tests. I am continuously conducting this test (as we speak ), as are several others here at Benchmark. Testing with a CD transport feeding the Coax input, and the computer feeding the USB with the same music, no one has been able to differentiate the two inputs.
--------------------
Elias Gwinn
Engineer
Benchmark Media Systems, Inc
www.BenchmarkMedia.com |
Enjoyed reading this thread, but until a stable, audibly proven, simple and affordable solution is in place with say, flash drive PC transmission (via which cable) to my Dac, my CEC transport might go to Joseph Chow for some power supply reworking around the clock, he's good at addressing low-level signals. |
So let's try to make this less confused *. Here are some of my points:
- This Esoteric clock and other's like it are not the wave of the future IMHO. They are more 'band-aids" trying to correct issues of our past way of doing digital transports and DACS with that horrible SPDIF connection!
- The future of "amazing sounding digital" (read; As good as analog, if possible) will be coming from manufacturers NOT using SPDIF connections, or Esoteric re-clockers, but from OTHER forms of connectivity, such as USB.
- The "non-technical" reason that helps an audiophile "wrap their head" around the reason a USB connection can have the ability to sound much better is do with the fact that it doesn't interleave* clock signals on top of music data like the SPDIF format does.
*Please note; the above statement is a VERY SIMPLIFIED way of explaining this point. Not all of us went to engineering school! I will attempt to explain the technical detail in my direct response to Agear below;
Warning, the rest of this posting is VERY LONG.....
Yes Agear, your statements are absolutely true "in form". There is quite a bit of engineering "tech speak" that I didn't explain to Audiogon readers (such as yourself) who actually understand the detailed technical side of digital interface methodologies and their inherent topological underpinnings.
Such as;
-The clock signal itself on a USB is much different than that of a clock on a SPDIF. So much so in fact, that many engineers don't even think of it or label it as a clock anymore as compared to "the clock" within a SPDIF connection methodology. Here are some reasons why they think this way. The timing is sent on the USB sort of like a "when to start" signal. Sort of a "Hey USB! You are going to get a stream of digital data in the form of bits, now GO!" This is not the same as a clock being put on top of a continuous data stream like in the SPDIF. That is where the HUGE difference is that supports the "interleaving" statement. It also explains why you aren't having the major sync ssues associated with SDIF. In the end though we are talking about the actual interface between the transport and the DAC's input receiver and the inherent connectivity downfalls associated of the actual "clocking" data itself, how it is configured, how it is married to the data stream and how that clock information is different "in form" as opposed to a SPDIF and it's real ugly sonic mess comparably.
Both USB and I2S connectivity are a superior way of connecting digital transports and DACS than SPDIF comparably. The conversion to I2S can actually happen in a properly designed USB Dac too. This conversion to I2S would happen later time in the digital chain itself. With this in mind, I do think we need to think of a properly designed USB DAC as having I2S (it just starts with USB cable before I2S). What does this all mean to the comparison of USB versus I2S connections if we convert earlier in the chain as opposed to using a simple computer USB connection? Well, that is where the sound quality itself will show the merits of both of these connectivity methodologies. Here are my thoughts ; since a computer has a built in USB connection, it makes it much more straight forward to connect the computer via USB to the DAC (Can we say "elegant"?). It also makes it easier for the audiophile to hook up (Can we say "simple"?) There is less cost associated with the USB connectivity (Can we say "We like to save money"?). Lastly and most importantly; the most impressive DAC I've ever heard up to this point was a USB Dac. That is where the "proof is in the pudding" for myself. Whatever format gives us the best sound and is actually closest to analog is where are measuring stick should be. All of these technical "explanations" and "tearing down" the engineering side of digital is interesting but the end sonic result is what really counts IMHO (not necessarily the technical methodology).
Since Agear pointed to Steve Nugent, I'll let some of Steve's statements outline what I've been trying to convey also (this information is from Steve Nugent himself):
"In an outboard USB converter, the data is received from the sending computer and precise timing information is added. The jitter from the computer clock can be effectively eliminated. The interface is then translated into an interface that a DAC can understand, such as S/PDIF, AES/EBU or I2S (the native DAC chip interface). The clock that generates the timing can be very precise and does not depend on data rate coming from a rotating optical disk, like a CD player, or the rate at which a hard disk is read. It does however depend on uninterrupted data flow from the computer." |
There is some confusion in the above thread about USB (at least as we know it....) Here is what Steve Nugent has to say about this subject:
USB indeed does transfer a clock, similar to the way that S/PDIF has an embedded clock. The primary difference between the two is that the chips available for clock recovery for USB are actually better at jitter rejection than the receiver chips for S/PDIF clock recovery. That is the primary advantage of USB, as well as an apparent lower sensitivity over long USB cables compared to long S/PDIF cables.
And the Synchronization comment is false. These interfaces all use forms of Phase-locked-loops or delay-locked-loops. The rubidium clock or a Superclock are just providing a low-jitter clock for the PLL. Nothing to do with "synchronization". Both USB and S/PDIF have embedded clocks.
An I2S interface actually has separated clocks, so this is a big advantage and results in even lower jitter than USB or S/PDIF.
Steve N. |
Drubin, I just finished Robert Harley's complete review in AS and I was wrong!. Both 6 moons and AS have similar comments with use of G-0Rb clock. As 6moon best describes as "Zandenification" of sound. Not a bad thing! |
Thanks, I will check that out. |
Drubin, You should review the G-0R's review at 6moons also where they review Esoteric P03/D03(?) combo and its effect when used. I thought 6 moons review quite different than Robert Harley's impressions. |
Hi Chris, The prototype USB DAC that surprised my ears is not related with the Burwen Bobcat/Daniel (note, a few audiophiles with ears I trust say that the Burwen is very special indeed). The USB DAC I heard was a pre-production unit from a company most of us don't hear much about. I am thinking I may start a specific thread with the USB DAC's name and some other details when the company gives me the "green light" to talk about them in detail. |
Dazz it looks like the Daniel Hertz USB DAC is PC only with the Burwen Bobcat DSP a plug in for Windows media so I doubt this is the "WDP"...waiting for a response from Ehider though. |
Ehider, are you talking about the Daniel Hertz USB DAC with the proprietary Burwen Bobcat DSP?
Chris |
Dgarretson; Ha! You really cracked me up with that 'WDP' moniker! I am not sure what I am allowed to say about the prototype USB DAC that I heard - The digital front end consisted of an Apple computer (that had the CD's transferred to it's internal hard drive via error correction) and it is connected to the DAC via a USB cable. The true proprietary information is not in my hands. It would be up to the designers to reveal once they launch this DAC sometime this year. |
Ehider, I agree that too few direct comparisons are made between RBCD and the benchmark of great vinyl when judging the performance of a CDP. However, I make this comparison every day, and have come to the conclusion that it is indeed possible for a traditionally architected CDP to equal or surpass an excellent vinyl front end. Moreover, as the CDP's analog section is critical, I would like to know more about the analog section of your USB WDP(Wet Dream Player). |
Chris, your question about repairing source material jitter involves a bit more complexity than what the Esoteric Rubidium is actually accomplishing. A good way to think of exotic reclocking devices (such as the Esoteric) is they are repairing the myriads of synchronization issues associated with the abysmal SPDIF connection. With a SPDIF's flawed approach, the clocking information is interleaved with the music data. The Esoteric Rubidium's incredible improvements seem to prove how poor the idea of interleaving clock information along with the music data has been all along! Of course, we can do this much more elegantly if we don't even try to interleave the clocking data on top of music in the first place. Can we say "USB" ;-)
Lapaix; Linn seems to be on the right track in choosing a high bandwidth connection. The ability for a DAC to be able to talk "back and forth" to the computer hard drive (while the music is playing!) assures a much better opportunity to achieve a perfect data tranafer to the DAC. It also is apparent that a standard USB connection easily exceeds the bandwidth requirements for the DAC to talk back and forth to the computer. Is Linn's higher bandwidth approach even better? I think the jury is still out here. I do know that the USB DAC I heard sonically eclipses Linn's best offerings by MORE than just a hair. Perhaps Linn should take a second look at the other parts within their music servers? If they can develop similar advancements elsewhere, the stratospheric pricing of Linn's music servers could be more easily justified IMHO. |
The very expensive Linn music servers use an ethernet connection to an NAS drive (as I understand it; i.e., quite imperfectly). Is this intrinsically superior to a USB connection, or is the interface irrelevant? |
All of this sounds promising and something to look forward to. I'm wondering about any improvement here that can possibly address the limitations of red book brick wall filtering at the high freq. level , or will that still be the final impassable frontier to analog comparisons. |
Why is it not possible to repair a jitterized recording? Jitter is the minute variations in the time intervals between the bits, so if you remaster the recording using some form of reclocking device, you can get rid of these minute variations. How would a jitterized recording sound if it was remastered using the atomic clock in the reclocking circuit?
Chris |
Rgt; I seriously applaud the Nova player designers. They are solving issues that most other digital solutions fail to address. I have no doubt that the Nova is very close to the "top of the heap" digital offerings at this point in time. Much closer to analog, absolutely. Close your eyes and absolutely match analog though, just a smidgent short (but the Nova is very special sonically IMHO). From a technical analysis, the USB solution (that sonically amazed me) avoids interleaving the clock data with the streaming digital information (as compared to the Nova and others). I should note that there are many similarities here with both the Nova and USB solutions. They both address the read error issues which I suspect are part of the sonic 'breakthrough" toward analog. I still hold the direct comparison to analog as my final "tool", i.e. the digital solution that comes closest to sounding like a great analog rig or a master tape deserves the "top of the heap" moniker.
Askat; I think you are correct to assume we need to watch out for EMI/RF issues in the computer. I myself was wary of sonic gremlins associated with a computer's hard drive as the digital transport. Thankfully, the potential problematic gremlins seemed to be entirely absent when I heard the computer to USB DAC solution. (The computer was a current generation Apple computer with the CDs transferred to the computer's hard drive via Apple's internal error correction enabled). Are Apple computers inherently low EMI/RF designs? I have no idea. I do know that the particular Apple to USB DAC was the best digital solution that I've ever heard in terms of managing to sonically emulate a great analog front end. |
Ehider,
Sounds like you are talking about a music server which utilizes USB because you mentioned streaming? If not, what about the playback software and EMI/RF issues with PC playback. These have a huge impact on sound. Will there be a special PC with this new USB wonder device? I thought music servers utilizing network protocols may have been the future?
I can't wait to replace my transport/dac with an HD based system. Seems like not much can beat the Meitner/Esoteric stuff yet, but it certainly seems close. Do you have experience with these transports and would you say this new device bests them? I hope so. |
This might answer all your questions.
http://www.audioasylum.com/forums/critics/messages/25316.html
I believe that the reactions of all the reviewers that first heard the Memory Player were NOT all hype. For Harry Pearson to say "He was in AWE" is huge. If his statement was hype, well he must be a "silent" investor in Nova Physics Group.
To be able to explain the shortcomings of the CD playback system and the approach they took to mitigate it is simply not a band aid approach, in my opinion. |
Sean; the USB DAC that I have been citing does NOT connect to a CD transport, It connects directly to a computer i.e. my posts statements regarding the "hard drive" . With this methodology, the computer does not have a SPDIF (traditional) connection whatsoever. It streams pure data directly from the hard drive, WITHOUT the subsequent clock data. It is much different with this methodology. (It is also much more elegant). This is the ONLY way the sonic improvements that I am discussing can have any meaning. If there was a "traditional" CD transport involved, the USB carrying the data wouldn't yield any sonic improvements whatsoever (BTW: this is where your assumptions would be absolutely spot on). So, the complete elimination of having to carry clocking information from the CD transport to the DAC is where the huge jump factor relies (remember, the music data is now on a hard drive). With this in mind, any simplification of transferring the music data from point A to point B really does yield sonic wonders.
Drubin; Yes i have heard the Nova Physics player. I think it is an admirable attempt at solving many of CD issues. Like other offerings though, it is still a band-aid approach that doesn't simplify the transfer of music data as well as the USB approach . Again, the proof is in the pudding though. And this player doesn't actually stand at a complete different level above other UBER priced digital products. It is really good, yes. Revolutionary, well if so, then it should absolutely crush any other digital offering IMHO (which it doesn't achieve).
BTW: Even though my posts have been heavy handed technological discussions, I will always favor the digital product that sonically comes closest to a top level analog rig. IMHO way too many technological assumptions, WITHOUT direct comparison to a source of great music perfection (in my case, a great analog rig) are one of the reasons we are now accepting the crazy expensive digital mess and these inherent "band-aids".
Even if the best sounding digital front end turns out to be a Donkey spinning a CD, using a fifty cent flashlight, connected to an electronic slide rule, amplifying via a megaphone. If this "front end" truly sounds closer to a great analog rig, I'm buying it! ....and alot of Donkey food ;-) |
Chris, I can't imagine how you could remove jitter from an existing digital recording as there's no inherent information that would allow you to determine the jitter in order to subtract it.
I think a bad digital recording is destined to remain a bad digital recording. However I hope to be proven wrong, because a lot of good music is otherwise beyond salvation. |
Ehider ... USB DACs are RAM buffered because USB does not stream the data at the bit rate required by the DAC.
Since it's possible to buffer for USB then it's possible to do the exact same for SPDIF.
A more likely explanation is that the USB DAC you heard happened to be a better designed DAC (or more to your taste) than any other SPDIF DAC you'd previously heard. |
Ehider, I'm reluctant to open this can of worms, but have you heard the Nova Physics Memory Player? If so, how does it compare to the USB DAC you heard? |
Perhaps a re-iteration of my explanation is in order. All SPDIF digital connections (read "traditional") cannot sonically compete with a properly designed USB Dac (being driven by a hardrive). Even if the traditional digital connection is being "buffered" or "re-clocking" the data, etc. The traditional digital connection scheme was seriously flawed from the get-go. UBER designed "re-clockers" or "buffering" schemes are only band-aids. They work to a point, but still don't quite give us the true analog purity we were all hoping to achieve. Closer yes. Perfection, not by a country mile! Too many of these "band-aids" are damn expensive at that. Of course the proof is in the pudding. The recent USB Dac I heard comes so close to sounding like analog that I was shocked that ANY digital could sound this good. No other digital scheme I've heard comes nearly as close (and I've heard way too many to count). |
Sean, is it possible once jitter is introduced into a specific recording to remaster this recording in such a way that the jitter could be eliminated? If this is not possible, why not? Are those early digital recordings sounding bad because of the high jitter content? There are also oldskool digital recordings (from 1980/1981/1982) that sound great, how could you explain that? Pure luck?
Chris |
Ehider ... you don't need USB, you just need a buffering and reclocking DAC, like the Lavry 924. A relatively small RAM buffer will allow for any drift between the transport clock and the DAC master clock.
Of course, the more stable the DAC master clock the better. This may be where a rubidium type clock is useful .... I don't know.
I'm not sure where current technology is with respect to the relative influence of clock imperfections versus DAC non-linearity (both are probably an order of magnitude better than current speaker technology).
One last thought ... it's true that ADC clocks are equally important, and therefore a better ADC clock will lead to a better remaster. However, the implication is that all early digital recordings (ADAT) are forever unrecoverably distorted by the relatively poor clocks used at the time. |
Kamil is correct about the need of some sort of "clock" . The point I've been making with my posts is that the synchronization of TWO clocking signals, between a "traditional" type of transport and a DAC, is completely eliminated with USB connectivity (provided it is designed correctly). With USB, we are down to just ONE clock at the DAC. With a hardrive having the ability to stream perfect music data and NOT having to carry an overlying clocking signal on the USB cable, the improvement is substantial. The sonic benefits are HUGE. Most importantly, the need for a "bank account breaking" UBER clock like the Esoteric is eliminated altogether. The sonic potential of the USB approach is way cheaper (no need for an UBER clock) and yields a superior sonic result to boot. This is the future of the best digital sound. |
AFAIK any digital signal that requires conversion to analog (which is the format of the sound that we hear) requires a clock. So even USB based DACs will require a clock for the data (asynchronous or otherwise) to be converted to analog. Though not exactly the same, it's like tuning into your FM radio station.. If you're not tuned into the right frequency, you won't get the full sound. If your recording runs at 44.1khz, you need a clock that runs at 44.1khz.. Can't get away from that clock.
Bottom line: bits can be bits until the point where it's converted to analog, at which point you would need the most accurately constant (i.e. lowest jitter) clock possible to ensure the sound's integrity with the lowest jitter. One solution?...the atomic clock. |
So, now we are finally approaching the pure "bits-are-bits" theory with the USB based digital music reproduction (as was intended from the beginning) and we're leaving the vagueness of the bits-are-bits + something magical concept. This could be a manifesto. To all audiophiles worldwide: Get rid of those mediocre CD transports!
Chris |
I wish I could talk more about what I recently heard (I've been sworn to secrecy). As to my earlier posts, I was not talking about a USB DAC that is currently available to the audiophile public at this very moment. Based on my discussion with the designers, it should be released within the next six months or so. In terms of the question regarding Gordan Rankin's product, this may be part of the "new wave" of revolutionary USB connected products that sonically prevail over typical transports/DACs. Unfortunately, I have yet to hear Gordan's product myself to determine if it also reaches above the levels which we are accustomed from typical "statement" digital offerings. As far as the "Beta" pre-production USB DAC that I heard though (from a company other than Gordan Rankin's) it was a serious jaw dropping experience! |
Most of this conversation is over my head, but Ehider are you talking about the Asynchronous Mode USB Audio in Gordon Rankin's new DAC's? |
C'mon Ehider, tell us who is doing it right today. Whose gear did you hear that convinced you of this rosy future? |
The big breakthrough in upcoming Dacs has much more to it than just if they are USB connected. It's more to how the data is streamed from a hard drive to the USB dac. There are HUGE sonic gains to this methodology ONLY if it is properly executed. At this moment, there are only a few select digital designers that even know how to do this correctly. Most that have a USB connection are not taking advantage of the elegance of streaming the data via a USB to avoid the jitter and many other problematic issues that are inherent in our current way of digital playback. Once we get a digital couple of companies that surface into the mainstream (that actually know how to do this correctly via USB), I think many audiophiles will be STUNNED to hear the analog fluidity that cannot be achieved with any other form of connectivity. Other digital companies will have to notice of this leapfrog improvement in sonics. Subsequently, they will (most likely) just follow suit and copy, i.e someone else does it right first, then the "other" digital companies will copy the "correct" way to do it. I figure we are looking at sometime later this year for the first breakthrough USB dacs to surface. I know, I know... we've all heard these sort of "statements" many times before. This time though, I think we will finally have digital offerings that can actually have most (if not all) of the inherent musicality that was only inherent via an analog front end. It's about time! |
Since there are already plenty of USB DACs out there, what is the big breakthrough that is coming? |
This type of product is already obsolete and I am sure that many audiophiles aren't even aware of it. We are on the verge of a imminent change to USB driven computer front ends that will sonically outclass the traditional CD transport and D/A converters here. Even the cost no-object "Uber" technology products. Here is a short understanding to why: once a CD is properly converted to a computer hard drive (with a true lossless format) there just isn't a need for something like the Esoteric "Superclock". With the hard drive containing the music data in a much purer form, it can then be sent to a USB D/A converter, via a USB cable, without the overlying clocking issues that creates such a headache sonically, i.e. a much purer methodology. In this new methodology, only one decent clock (read not overtly expensive) will be needed inside the D/A converter itself (instead of one at the tranport then another "Uberclock" at the other end attempting to "fix" and "massage" very ugly timing issues). Therefore, in an excellent designed USB D/A converter being driven from a hardrive without the ugly timing issues. We will be able to say "Goodbye!" to typical transmitted jitter problems. Say "Goodbye!" to transport differences! Say "Goodbye!" to CD treatments! And finally, say "Goodbye!" to high dollar "band-aids", uh..errr..."Superclocks" - (such as this Esoteric). We are on the precipice of a very exciting breakthrough with some new upcoming USB dacs that will sound much more analog than most of us have ever imagined. Sorry Esoteric, I'd really like to give you credit for this "breakthrough", but in my opinion, the true sonic breakthrough in digital will be in USB connected products that don't even need a clock such as this. |
The new dCS Scarlatti sepearte clock generator has got an option where you can put an antenna on the roof and syncronize the clock with the international world clock by sattelite. |
I thought we were talking about the international atomic clock which keeps the official time. That is not a rubidium oscillator but a caesium oscillator. There is now however a new invention unveiled a couple of days ago which breaks new ground.
http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2008/02/14/sciclock114.xml |
The main implication is that some fools will pay $15K for a clock. |
I believe this is defined more by the time-base("atomic accuracy" as determined by atoms within an element shifting between discrete states of energy) than it is by the element per se. Clocks with atomic accuracy can utilize Rubidium, as stated by European Space Agency in its description of the Galileo satellite:
"The Galileo satellites will carry two types of clocks: rubidium atomic frequency standards and passive hydrogen masers. The stability of the rubidium clock is so good that it would lose only three seconds in one million years, while the passive hydrogen maser is even more stable and it would lose only one second in three million years. However this kind of stability is really needed, since an error of only a few nanoseconds (billionths of a second) on the Galileo measurements would produce a positioning error of metres which would not be acceptable.
An atomic clock works like a conventional clock but the time-base of the clock, instead of being an oscillating mass as in a pendulum clock, is based on the properties of atoms when transitioning between different energy states.
An atom, when excited by an external energy source, goes to a higher energy state. Then, from this state, it goes to a lower energy state. In this transition, the atom releases energy at a very precise frequency which is characteristic of the type of atom. This is like a signature for the type of material used. All that is needed for making a good clock is a way of detecting this frequency and using it as an input to a counter. This is the principle behind an atomic clock.
The transitions between energy states can take place by releasing or absorbing energy at optical or microwave frequencies. An atomic second corresponds to 9 192 631 700 counts of the frequency of the energy detected in the transition of the Cesium 133 isotope when exposed to suitable excitation." |
Rhagen, WRONG! NASA uses both Rubidium and Caesium atomic clocks. As a matter of fact most of the recent space probes and satellites use the Rubidium Atomic clock that I use in my system, it is built by EG&G. |
The G-0Rb uses a Rubidium clock. That is not an atomic clock. An atmoic clock is a Caesium clock! |
