deadrail is DCC with no power (thus no DCC) through the rail… not just battery power.
Link to deadrail society, started in 2010:
https://www.deadrailsociety.com/
Steve, usually R/C is a wireless control system used originally in model planes, boats, cars, and originally worked with servos… later expanded to run ESCs (electronic speed controls)
originally worked on frequencies like 27MHz, and on “channels”, i.e. only one person could use a channel at a time.
DCC is a protocol using a modulated square wave for data and power, and strictly defined is on powered rails. There are systems (like deadrail and Airwire) that take pretty much the unmodified signal and transmit it wirelessly, and then turn it back into “track power DCC” to run decoders
HTH
Greg
From their website, the headline.
The Deadrail Society
No track power, no problem
Battery power and radio control:
The future of model railroading!
So, I ask again, is there a difference? Some seem to say that deadrail is the latest mojo to come down the pike.
Gregg, I have a fair idea what dcc is. I use it when I run H0, but thanks for 'explaining it. (https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)
Greg Elmassian said:
Steve, usually R/C is a wireless control system used originally in model planes, boats, cars, and originally worked with servos… later expanded to run ESCs (electronic speed controls)
originally worked on frequencies like 27MHz, and on “channels”, i.e. only one person could use a channel at a time.HTH
Greg
Hi Greg.
Please allow me to clarify the use of the word Channel.
R/C system separation has always been by frequency. Yes, once upon a time there were a (very) limited number of available frequencies on say 27 Mhz. Users had to have flags issued by meet organisers so that no two operators were trying to use one frequency.
Nowadays on 2.4 Ghz there are many more discrete frequencies available and no two TX’s are the same.
The word Channel actually describes the individual servo/ESC functions available on each R/C Rx. That can vary from 3 channels right up to 12 channels and more, depending on physical requirements and cost etc.
The 2.4 Ghz radios self seek available frequencies all the time.
It is now legal to have all sorts of models on the one 2.4 Ghz frequency band.
Hi Steve.
It just so happens that the use of the term “Dead Rail” seems to have been coined by specialist makers/suppliers of battery powered DCC systems. Primarily designed indoors use.
More commonly, battery R/C users in smaller scales use BPRC. Battery Powered Radio Control. The term is gaining more acceptance for battery R/C in Large Scale as well.
That nomenclature isn’t consistent. “Channel” is used to designate frequency in some systems in the same way that it’s used for TV channels - to spare the end user the need to remember actual frequencies. AirWire, for example, has 17 channels available for use, which correspond to various center frequencies within the 900 mHz ISM band.
Hello Eric.
I can assure you the nomenclature is consistent where it matters to mainstream R/C users. EG Cars, boats and planes.
Yep, for r/c users that’s what channel means… to the rest of the world, and RF engineers, who are driven by the rules/laws by entities like the FCC here in the us, channel implies a frequency range.
So, for my explanation to Steve, where I was comparing different wireless technologies, I use the engineering definition. This is like “switch”.
Also, I believe that my statement as made is still accurate. Let’s not get into what frequency for what radio, the example was that R/C systems were using the entire “channel”, it was not shared, like Wi-Fi, newer cordless phones, Bluetooth, etc. The point was the inability to share the “frequency space” with another user (channel)
Greg
Steve, what “deadrail” offers is a modicum of standardization… where if you are transmitting “raw” DCC protocol, you can buy any decoder you want and any “command station” (as per NMRA definition). “Mix and match”
In this case, most systems are designed as one throttle to one loco, i.e. the throttle has the “DCC command station” smarts inside.
Greg
Greg Elmassian said:
Steve, what “deadrail” offers is a modicum of standardization… where if you are transmitting “raw” DCC protocol, you can buy any decoder you want and any “command station” (as per NMRA definition). “Mix and match”
Greg
OK, that makes sense.
In a track powered DCC setup, is there a “command station,” for each locomotive? Probably not.
Are the electronics for a multipurpose “command station”(CS), such that one multipurpose CS cannot be installed in a Tx? I’m learning here, be gentle. (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)
So in the definition of DCC, there is a throttle/cab… and several can connect (wired or wireless) to the Command Station.
So, what goes between the throttles and the command station is not usually DCC, but a set of commands to tell the command station what to do. This allows commands like “go to setup menu”, etc.
Then in the Command Station, the “requests” from throttles are translated into DCC commands and output as usually a low level (volts and amps) DCC signal.
Then this output is sent to a “booster” which raises the voltage and amps as desired.
This is a system, and there are a lot of advantages to this architecture. Not all throttles have to be the same. You don’t need a computer program running in the throttle to “make DCC”.
You can have a system where you use different boosters to fit with your scale (different scales use different voltages) and number of locos (different amps).
Also since everything goes “through” the Command Station, it knows about consists, so you can use the same consist from any throttle, and it can store information that is common (so you don’t have to do dumb stuff like copy throttles from one to another)
Also, since it “knows” what loco is being controlled by who, you can do sophisticated stuff like not allow certain people to “take over” a certain loco, or allow one person the rights to take over any loco, and on and on. Having a system allows many features like “all stop” to work better.
Now the DCC standard allows you to put several “blocks” into the same box… so many DCC systems put the booster and command station in the same box.
And you can combine the throttle and command station in one box too, like AirWire. It’s designed to be modular, both in architecture and command structure.
HTH
Greg
In addition to what Greg explained, I’ll add a couple of things. DCC has to provide both power and data to the locomotives through the same connection (track pickups). It does this by creating a voltage that is constantly switching polarity (AC, but square). The rate at which it switches is determined by the 1s and 0s of the DCC data packets. A 1 is represented by 50 us at one polarity and then 50 us at the other. A zero is 100 and 100.
The command station cues up commands from various throttles attached to the system and spews them out continuously. If you have 3 engines on the track, it will rotate through the last speed/direction packet it received from the corresponding throttle over an over again until an updated packet is available. Other packets (functions/CV changes/accessory control) are interjected as they become available, but it’s always transmitting in order to maintain the alternating voltage on the track.
If no packets are available (e.g. when you first fire up the system), it will send an idle packet over and over, which is ignored by decoders, but maintains the required polarity switching.
Here’s a DCC stream. You can see the same packet repeated twice. The short bursts are 1s (including the preamble, which is a string of 22 1s at the start of each packet) and the longer bursts are 0s.
Steve Featherkile said:
Greg Elmassian said:
Steve, what “deadrail” offers is a modicum of standardization… where if you are transmitting “raw” DCC protocol, you can buy any decoder you want and any “command station” (as per NMRA definition). “Mix and match”
Greg
OK, that makes sense.
In a track powered DCC setup, is there a “command station,” for each locomotive? Probably not.
Are the electronics for a multipurpose “command station”(CS), such that one multipurpose CS cannot be installed in a Tx? I’m learning here, be gentle. (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)
Steve they answered you question, but I will answer it in simple terms. No, one command station can control several locomotives.
As for what can be in a transmitter, I guess that would depend on the architecture of the system.
There’s no reason that a single unit that had the throttle and command station could not transmit to multiple locos, and at the same time using deadrail techniques.
Greg
I actually tried this yesterday using JMRI to multiplex packets for two locomotives over AirWire (something its throttles don’t do), and it worked fine. With the Wi-Fi throttle app, you can actually have two or more throttles up on the screen at once.
2 or more? I have found at the shows that I can run 2 trains at a time, but not 3. Well, I can run 3 for short spells, but eventually one train gets too close to another, and my brain looses track of what throttle is what train and…
What I meant was that the AirWire receivers are able to parse a DCC stream with packets for multiple locomotives interleaved. There was no reason to expect that they wouldn’t, but they don’t normally encounter this. On the T5000 throttle, when you switch locomotives, it only sends packets to the one that is currently selected, and the others just freewheel until they see data again.
Using my JMRI interface, you could theoretically have 10 locomotives on a single AirWire channel, each controlled by a separate WiFi throttle. The command station (Arduino) would aggregate the throttle data and generate a DCC stream that includes a rotation of packets for all the locomotives. In fact, with an iPad running WiThrottle, you can control 4 locomotives on the same screen (screenshot attached). I haven’t tried this out yet. Here’s a screenshot:
That’s great research Eric, so people could get an inexpensive laptop, run JMRI, run EngineDriver (which was updated just the other day) on their cell phones, and control multiple AirWire locos.
I’ve just bought a small wireless router, about the size of a tangerine, so the wifi side with the laptop, JMRI and access point are covered.
Greg
Ok, my question above was poorly worded. I know that a track power dcc command station will handle multiple locos, turnouts, etc ad nauseam. Greg made the statement that in derail, most systems are designed to be one throttle, one loco. To me, that seems wasteful, as most folks only use one loco (or consist) at a time. Indeed, most folks have trouble keeping 2 consists separated on a roundy-round.
Are the deadrail Tx designed for only one loco, or is that just laziness on the part of well heeled operators?
This is only page 2. How did a discussion of REVO II get hijacked to deadrail dcc? Gregg will be very put out.