# Aristo RC "faster" than DCC? What is this about?



## Greg Elmassian (Jan 3, 2008)

Well, lownote asked a question on another thread, and it's a completely different subject. He said that Lewis is talking about their system being faster than DCC.

(Again, why the **** this is a confrontation between him and DCC, you figure out the motive, I guess the product cannot stand on it's merits alone. If Lewis thinks he can obsolete DCC with his system, then the problem is more serious than just Kool Aid!).

Here's the quote from the Aristo forum:

"The prime reason was that DCC's signal is slower than we felt was effective and we did not want to slow down the delivery of information to our receivers. Wifi and wireless have taken over the world for remote delivery of signals and we wanted to join that style of response. The engineers that delivered DCC were schooled a generation ago and did not learn RF engineering." 



I think Lewis has some fundamental misunderstandings. 


1. The DCC protocol was intended to be transmitted as part of track power only. It's true that AirWire basically sends the raw DCC command sequence over the air, and does it very successfully. 


2. What Lewis fails to comprehend, even though he says that DCC engineers did not understand RF engineering, THEY DID NOT NEED TO, SINCE DCC IS NOT AN RF PROTOCOL.

3. The raw data rate for DCC is about 10KHz, 10,000 times a second you get a one or a zero. Since this is a protocol destined for a wired connection, there is no additional error correction or encapsulation of data packets. You do not have to worry about interference, since the signal stays on your rails.

4. In wireless communication, you typically have to use TWICE as much data because of error correction and id's to make your signal different from all the other stuff out there. So the frequency of your transmitter has basically NOTHING to do with the actual data rate. The more complex the protocol, the more bits are transmitted that are NOT your commands to your train.

5. For example, in 802.11 (your wireless laptop at 2.4 GHz) roughly 50% of the data transmitted is error correction. Also, since it is on a "Channel", you cannot transmit and receive at the same time, one transmits, and the other listens, then they trade, this is called half duplex. So your 54 megabit connection is cut in half twice. The true data rate of 802.11G is about 13 megabits throughput. 

Therefore, just because Aristo uses 2.4 GHz as a frequency, it does not mean it's true data rate is faster than another. You have to look at the actual data throughput. Since the Aristo system uses Zigbee, a standard that is best for networks, it has greater overhead, and less throughput than you would think.

Do you need speed of commands faster than 1,000 times a second? Well DCC has worked on large club layouts for years, so obviously, DCC protocol is fast enough.

Lewis is confusing the operating frequency of the radio with the actual rate of commands. It just shows a lack of understanding of the way RF works. I'm sure that the engineers that worked on DCC years ago know more than he will ever know about RF.

Finally, the Zigbee protocol, is not well suited for the Aristo application, and it's becoming unpopular in the industry:

*http://blogger.xs4all.nl/ivonoorh/articles/13939.aspx* 


Research it for yourself.

Regards, Greg

p.s. note the part where it mentions that 900 MHz has less interference than 2.4, something I have been telling people over and over who are saying that 2.4 GHz just by being a higher frequency, is better.


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## John Allman (Jan 2, 2008)

Research it for yourself. 

No need. You can execute this Jihad on your own.


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## altterrain (Jan 2, 2008)

Posted By John Allman on 18 Oct 2009 08:13 PM 
Research it for yourself. 

No need. You can execute this Jihad on your own. 

Good one!









-Brian


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## Greg Elmassian (Jan 3, 2008)

So if this was some manufacturer it would be ok? Like I could say that my car is better than yours because it revs higher? 

or my house is better than yours because I use 220v? 

Misinformation is good? 

It's not ok to respond to claims on products not founded in fact? 


OK... 

Greg


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## altterrain (Jan 2, 2008)

Greg, 

Sit back, have a nice cold glass of Kool-Aid and enjoy playing with your toy trains! 

-Brian


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## Dave H (Jan 5, 2008)

Did you post your information on the Aristo site? 

Does Lewis KNOW he is wrong? 

What has Lewis said about this, ACCURATE information? 

Did you make it clear to Lewis & Aristo? 
(He & the Aristo Staff, should be made to understand this, so NOT to give false infromation & claims to anyone.)


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## aceinspp (Jan 2, 2008)

He sure does not need to drink the cool aid as the other folks are, we need someone with some sense. Later RJD


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## lownote (Jan 3, 2008)

Greg is banned from the Aristo forum. Aristo doens't allow too much negative posting about their products.

I can understand why--it's their business, and it's their forum. They are under no obligation. But Lewis posts stuff like this about speed that just doesn't seem to make any sense. I understand about hype and I expect manufacturers to do some hyping, but if I'm investing a lot of dough in some gear I kind of want to know some facts.


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## jmill24 (Jan 11, 2008)

So, which is faster and why does DCC not need error correction?.................Coolaide drinker


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## Scottychaos (Jan 2, 2008)

I was banned from the Aristo forum a few years ago.. 
for pointing out that Aristo's "real name" policy was pointless.. 

I was simply saying (calmly, politely, and logically) that anyone can make a fake name that *sounds* real! 
you cant use "traindude67" as a user name..but you can use "Joe Smith" even if your real name is "Scot Lawrence".. 
and no one would ever know or care that "Joe Smith" isnt your real name.. 
it only has to _sound_ real..there is no way they can enforce _actual_ real names! 
"Joe Smith" ends up being just as fake as "traindude67"..probably half of their "real names" arent real..
so why even have the "real names" policy in the first place?? its pointless.. 

So I signed up with the _obviously_ fake name "Apu Nahasapeemapetilon"..just to make the point,
in what I thought was a humorous manner..and I was banned for that! 
(personally, I consider it no big loss..) 

They have to blindly follow his directives..even when he doesnt know what he is talking about.. 
He simply doesnt understand the technology, and makes meaningless directives based on his lack of understanding..but you cant tell him that.. 
and the mods have to enforce his ignorance.. 
You arent allowed to point out that "the Emperor has no clothes" ..even when its true! 


this was 3 or 4 years ago..it sounds like nothing has changed on the Aristo forum..
IMO, its a battle that cant be won (over there)..so we have to spread the word in other forums..which is what Greg is doing here..
IMO, this is a good thing, and it should be discussed..

Scot


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## Torby (Jan 2, 2008)

Greg... Give it a break.


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## Pete Thornton (Jan 2, 2008)

So, which is faster and why does DCC not need error correction 

I think you need to go back and read Greg's post... 

You are confusing the _*message*_ with the *messenger*. A DCC command can be delivered by any mechanism - though it was originally intended for delivery via track power, there's no reason (in the definition) why you couldn't use WiFi, infrared or a cell phone for that matter. The receiver expects to get a command (a sequence of characters). 

The problem with sending things is that the medium can corrupt them. Just as a letter that gets wet may become unreadable, a DCC command sequence sent over the air can get garbled by other stuff going on. So you use 'error correction' around the message to help the receiver understand it. The error correction consists of things like: "I sent 56 characters - did you get them all" and "if you add up all the characters, the sum is 1324 - do you agree?" to which the transmission electronics (*not* the DCC chip,) sends back the appropriate answer. 

[ As an aside, I was quite surprised that Airwire didn't separate the DCC functions from the RF system, so you could use anyone's DCC chip. They are disctinctly different functions. ] 

"Faster" is a function of the communications mechanism - Airwire is probably faster than Aristo's, but both are slower than track power transmission?


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## lownote (Jan 3, 2008)

Posted By jmill24 on 19 Oct 2009 06:46 AM 
So, which is faster and why does DCC not need error correction?.................Coolaide drinker
I don't know about error correction in DCC, but I still can't figure out what Lewis means by speed. Check me if I'm wrong, but I believe a 27 mhz signal, a 900 mhz signal, and a 2.4 gigahertz signal all move at the speed of light. When he says "faster" he must be referring to the frequency, not the speed

As I understand it--and I'm far from an expert--2.4 ghz is better than 900mhz because it's a higher frquency, which means you can transmit more information in the same time. I supose it's like a truck compared to a car--they both travel at 60 mph, but one contans more cargo than the other.


Greg's argument is that a lot of that information is error correction--as if the truck had t be partialy filled with GPS gear and some kind of autosteering and speed control apparatus, so there is in effect less room in the truck than the size would seem to indicate


Anyway, is that what Lewis meant by speed? I'm persuauded by the RC radio guys that 2.4 is better, but I have yet to exerience a range problem wih the 900 mhz thrttle in the NCE radio system


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## Greg Elmassian (Jan 3, 2008)

There were some good questions and some comments that I would expect from people that apparently do not care. 

Jmill24: Jim Miller of the Aristo forum: The amount of error correction is driven by the interface, and as I did point out, over the air is MUCH more error prone than over wires, and there is also the fact that there can be interference over the air you do not get on a constrained set of wires. I did state this. It's true. Ask an RF or basically any communications engineer. In Ethernet, the extra overhead to go wireless is about double. So you need to transmit twice the number of "raw" bits to get the same data through wirelessly than as wired. 

Mike: the waves all move at the speed of light, so from that point of view, neither is faster. But the "raw bit rate", i.e. how fast you theoretically can send 1's and 0's is higher with higher frequencies. 

What you need to consider is actual data throughput, how fast does your error-free data get from your throttle to the loco. 

This concerns the protocol used to send the data, and believe me Zigbee is not "low overhead".... it has networking infomation that creates more overhead than needed in a non-networked situation. 

The bottom line is people are being told that the Revo sends commands "faster", and implies faster response. 

Unfortunately, since it is not an integrated system, but just a number of pairs of throttles and locos, things like ALL STOP is not a single, universal command like DCC, but a sequence of FIFTY stop commands, to each possible loco. Obviously the ALL STOP takes some time to execute, and does not work immediately on all locos. 

So, in the "speed" department, it's not the frequency band used, but the true operational speed of the commands in the system. 

People are being misled. It's blatant untruths that are irresponsible. Any RF engineer knows this stuff. Why are all the errors in information consistently for Aristo and against DCC? 

This is wrong, it's untrue, it's misleading, and I won't stop reporting this kind of information until it stops. 

It's bad for the hobby, and it is unnecessary. 

Regards, Greg


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## Cougar Rock Rail (Jan 2, 2008)

OMG this is hilarious! Lewis must lay awake at night trying to figure out which descriptive terms he can try to apply: "Slimmer, smoother, smaller, bigger, faster, newer..." 
I think what we need is a test-off at the OK Corral. 

Keith


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## jmill24 (Jan 11, 2008)

My cover is blown............Jim Miller of the Aristo Forum, A.K.A. Kool aid Drinker

By the way, I think that DCC is a great system. I also think the REVO is good also.
I personally think marketing is weak on the DCC, it apears to be a black box to us novices.
I also own a MTH DCS system, it works great if the track is clean, I love it.


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## lownote (Jan 3, 2008)

I agree with this--that the REVO is a good system and also that DCC suffers from bad PR, or bad marketing. I had zero experience with DCC, and was scared of it for the longest time, and I found the manuals and descriptions really puzzling and hard to understand. But it's actually quite easy--there's nothing to it at the basic end, and it has more and more complexity if you want it. It's fun and reliable.


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## Greg Elmassian (Jan 3, 2008)

Jim if you are asking questions and really want honest information, I'm afraid we cannot classify you in the Kool Aid squad!!! Sorry !!! ;-) 

I played a lot with the Revo yesterday, my evaluation period is up and I'm returning it to the company who loaned it to me. It's got some nice points, and after you go through the drill a bit, and figure out what the buttons do (too many with unlabeled arrows!!) it's relatively simple. 

I found out a few more things in my more extensive testing, some pro's some con's. I was surprised at the motor control, it's the first time I got down into tuning the step size, starting voltage, etc. Aristo needs BEMF is all I can say. 

But there's many people who I would (and have) recommended the system to, and I think it has a "niche" between small layouts and large ones (meaning number of locos and/or operators). 

Regards, Greg


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## parkdesigner (Jan 5, 2008)

Lewis must lay awake at night trying to figure out which descriptive terms he can try to apply: "Slimmer, smoother, smaller, bigger, faster, newer..."

I just want to know when the Revo will start shipping with a customized belt holster made of *Fine Corinthian leather*!?!










Seriously Greg, I love watching you debunk the lies, line by line, like the good methodical researcher that you are... the problem is zealots and snake-oil salesmen don't care about right and wrong... science, math, _data_... oh no - those have no place in this argument... 


"The leader is good, the Leader is great..."


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## Greg Elmassian (Jan 3, 2008)

I'm not trying to dissuade anyone who has made their decision. My motivation is mostly aimed at newcomers trying to make a decision, and that they get a "fair shake"... 

If the head of a company was saying: "Track power only, batteries never work" I would be debunking the same way. If someone said "DCC only, that the TE does not work" I would also be out there protesting. 

It's a case of a company taking a position that is based on untruths. It is not necessary. It is not good for the hobby, and there are MANY other ways to market your product, concentrating on it's strengths. 

EVERY post made by a certain individual on his site takes a pot shot (and untruthful one) at DCC. EVERY ONE. It's even on the Revo TE box. It's in the instruction sheet. This is the Jihad. I did not start it. I warned them when I left the forum. 

By the way, you are right Josh, they need a nice holster... I need one for my NCE too, it's even bigger. 

Hope to see you at the Halloween train show... 

Greg


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## Curmudgeon (Jan 11, 2008)

Geez. 

I WARNED you the responses would start once they had printed directions of what to say. 
You didn't believe me, Greg-o. 
BTDT. 
Truth NEVER wins out initially against misrepresentation. 
Eventually it will, but when those who misrepresent (and it is immaterial who) had a brigade behind them to "support" their misrepresentations, it isn't worth fighting. 
However: 
To push this hard MUST mean something else is going on. 

Remember the Super Socket? 
Ever hear of the BS on the early Shay trucks? 

"Oh, there is nothing wrong with the Shay, it is ONE COMPANY inventing problems....." 

Initially, the BS won out. 
Long term, everybody knows. 
And, we know who the shills were, too. 

Why not a holster? 
He copies so much, and since we've had TX holsters available off and on for 15 years (still have some), why not copy that, too? 


Interesting commentary from the peanut gallery, however. 

Good thing you can't edit comments after a certain time frame. 
Means, later on, the comments are going to make them look awfully silly. 
And they can't change them.


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## TonyWalsham (Jan 2, 2008)

Posted By lownote on 19 Oct 2009 07:51 AM 
SNIP 
Anyway, is that what Lewis meant by speed? I'm persuauded by the RC radio guys that 2.4 is better, but I have yet to exerience a range problem wih the 900 mhz thrttle in the NCE radio system 



Hi Mike.

I cannot say for sure that 2.4 GHz does gives better range than 900 MHz. I am not able to test it as 900 Mhz is illegal to use in Australia. 
The selection of 2.4 GHz by AC probably has more to do with that frequency being legal Worldwide than it having (claimed) superior range to 900 MHz. 900 MHz is not legal Worldwide.


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## George Schreyer (Jan 16, 2009)

Just some comments from a communications engineer.... me. 

a higher carrier frequency allows more data to be sent based on percentage bandwidth. However, there are other things that have much more significant impact like frequency allocations. In various bands, the amount of information bandwidth is regulated. It just so happens that the 2.4 GHz band has some pretty good allocations for bandwidth. That is one reason that WiFi is there. 

However, the Revo doesn't take advantage of the available bandwidth. Aristo picked a comm protocol, called Zigbee, that is designed for LOW BANDWIDTH. This is primarily because the low bandwidth also allows low transmitter power and therefore lower DC power consumption and longer battery life. Zigbee limits the available information bandwidth much more than allocations. 

The data rate for DCC is also low, within the Zigbee capability. Since I don't know what data rate that the Revo uses, I can only guess that the data throughput is roughly similar, hence the whole argument is bogus. Even at the low data rates that DCC uses, it handles large numbers of parallel users on large layouts. It is good enough. This implies that Zigbee is good enough for the intended use. 

DCC does not use error correction. There is a checksum byte at the end of each packet. If the checksum fails, the decoder tosses the packet. DCC systems repeat each packet sent to make sure that they all eventually get through. More important and newer commands are resent sooner and more often. Less important and aging commands are sent less often. Within the bandwidth constraints of resending packets, there is no real penalty in doing this on track power. Radio throttles (AirWire and such) should also do some resending but this eats into the battery some so that they have to be careful. The original 27 and 75 MHz TEs did not resend commands at all, a major weakness in that system. 

Zigbee is a two way protocol, the RX has potential of error checking packets as they arrive and acknowledging the receipt of good packets. The TX could then tell if it's message got through and not need to resend. I don't think that the Revo actually does this though. 

All this stuff happens so fast that the user doesn't even recognize the delay even though the actual data rates are pretty low. Electronics are much faster than we are. 

The range capability of any given system will depend on primarily two factors, TX power and RX sensitivity. Of these, RX sensitivity is the biggest factor. The RX antenna efficiency is usually the biggest part of the RX sensitivity. It is easier to make efficient antennas as the frequency goes up, at 2.4 GHz a quarter wave is only about 1" so it is easy to make a good antenna. 900 MHz is not hard, 27 MHz is a problem. Going higher than 2.4 GHz won't help any as the antennas are already short enough to package inside even HO locos. 

TX power is usually regulated, the rules for some bands allow more than others but it doesn't vary a lot for unregulated consumer equipment. The TX antenna also has issues but a 900 MHz, the antenna is shorter than the handheld so that it is easy to fit inside. 

Most cell phones operate in the 850 to 2.1 GHz range (in several bands) All except the phones that use the lowest frequencies have completely internal antennas. Some phones that use the lower bands have a pull out antenna that can help in weak signal conditions. We have reached the frequencies that allow efficient handheld antennas.


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## Dr Rivet (Jan 5, 2008)

GS 

Thank you, thank you, thank you!!! THE SYSTEM is much faster than the human in control!!!! People get confused about the command response with DCC when their train doess not "STOP INSTANTLY". Duh!! Look at the CVs set for the DCC receiver, it is probably programmed to do a resonably smooth stop. But New folks often never had a "momentum throttle" on their train set, and OFF means OFF [STOP]. So they equate throttle response with communications speed. MORE EDUCATION. [Mostly for LP [MR. MS in Marketing]]. 

In almost 40 years in the ADP, oops, "computing infrastucture" world, I have seen Marketing win out 100 to 1 over Engineering and design excellence. NOTHING new here. 

Regards


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## aceinspp (Jan 2, 2008)

Wow it does not get any better than this. All this good free info. Later RJD


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