In the April 2006 edition of Australian Model Railway Magazine a corresspondent, after mentioning DCC as having a “legacy of old technology in using the rails to transmit electrical power”, questioned why we don’t use wireless, or perhaps more correctly, “trackless” loco control. He ended his letter with – “is this a realistic future to look forward to?”

Well I can assure this reader that his crystal ball is spot on. Wireless technology exists, is being used all around you and is now as cost effective as was the developments in microcontrollers that drove the initial DCC development 15 years ago. But before I elaborate let’s look at the relevant NMRA standards…

The DCC Standards adopted by the NMRA consist of two parts, the first part S-9.1 stipulates how power and data are sent to a loco decoder via the track, the second part S-9.2 specifies the data protocol of the control “packets” that are sent to the loco. These standards were the first written by the NMRA using an international (ISO) model and this has been the major reason for the success and durability of the standards.

To adopt direct wireless control we write an additional standard to complement S-9.1. The control data can (and should) still use S-9.2. All radio control systems these days use some form of data packet simply because it works well. Using S-9.2 we also maintain backward compatibility. The new Standard S-9x will define a new form of wireless “connection” to the loco…

The authors Fairymead Mill 4WDM Loco with UHF Receiver, decoder, and sound module sandwiched between roof and ceiling

DWiDCC in operation

It’s Thursday evening and Ron is expecting some friends for an operating session.
His hand throttle beeps and the screen the display reads:

New loco detected: AD6035 BobG AMRM Allow Connection?

Ron presses the “yes” button on his way to the door. He lets Bob in and while they shake hands Bob’s loco, still in its (cardboard) box, is also shaking hands – with Ron’s LMRN (Local Model Rail Network). Bob is completely unaware that his loco has a 20 digit loco address much like the Ethernet Mac address of his home computer. It was assigned by the manufacturer and is unique in the world. All Bob did when he bought the loco was place it on a 12Volt powered piece of track near a convenient PC (at the shop or home), ran some supplied software, entered his name, railway and confirmed AD6035 as the loco number. This same information was supplied by the loco when interrogated by Ron’s handset as Bob came within range and knocked on the door.

Back on the layout the new DWiDCC (Direct Wireless DCC) controlled loco was put through its paces. Its top speed was spot on as the decoder had read the track voltage as 13.5Volts and realigned the manufacturers speed table to cope with the over voltage. Of course if Bob wanted to he could play with the CV values in the speed table but why should he when he can reprogram the loco at anytime by placing it near a computer and downloading some nutters “new and improved version” off the internet. With DCC now being supplied with a loco you don’t need to play with CVs, in the future you shouldn’t need to know they exist. After all do you know what frequencies your phone sends when you press button 3?

Ron’s LMRN has all the features of a modern wireless network. All devices (locos, throttles, accessories and coffee machines) are automatically connected and have bidirectional communication – the NMRA Working Group had been struggling with loco feedback over the track for years!

His handset is a generic pocket PC with free DCC software. One of his mates uses his mobile phone; another built his own for under $50. The only devices on his layout made by a DCC vendor (Northlenztrax) are the decoders. The track is powered by a standard 12 Volt DC 5 Amp power supply; luckily he hadn’t thrown it out. He could if he wished use his old DCC system to power the track and controlling “old” DCC fitted locos simultaneously.

Sound data is no longer contained in the loco. The handset matches the loco ID with its sound library and sends MP3 quality sound direct to the loco. Of course the sound is still tailored to the speed and load information returned by the loco but is not limited by the decoder technology. A separate receiver, amp and large speaker under the layout reproduces the lower frequencies of all transmitted sounds far better than the on board speaker; adding depth to the layout.

Video (relax Bob) is possible and while in train movies haven’t been shown yet in the commissioner’s car Ron is building, colour video is able to be returned over the network from a pinhole camera mounted at the front of the loco. Combined with a PC this allows Microdaft Train Simulator software to run a camera equipped train on Worry Creek.

What is required from DWiDCC?

1. Reliable communication over the distances found in layout rooms or backyards.
2. Cheap components, including the use of existing consumer products such as pocket PCs & mobile phones. Multiple purpose components reduce cost.
3. Bidirectional communication at full data rates (unlike present DCC systems which have much slower return data rates)
4. User oblivious automatic connection and network setup
5. Every feature found in an existing DCC system with backward compatibility.
6. Several choices of track power such as 12V DC, AC, existing track controlled DCC system, batteries or battery/track/super capacitor hybrids.

I’m not dreaming, even though I’m writing this on April 1. All the above is possible using today’s technology. We just need a manufacturer to bite the bullet. But which technology should we use?

433MHz UHF is currently the easiest and cheapest to implement and it appears CVP products have used similar technology in their AirWire system for garden railways. They use 900MHz modules which are available in Australia. I have implemented a similar system on my garden railway using 433MHz data modules available from Jaycar & Altronics in Australia. The prototype unit was built on a HO loco chassis (it was cold outside at the time!) Modified Digitrax & Lenz decoders are used.

UHF Transmitter	UHF Receiver

While UHF wireless data modules have given me a cheap DCC system for my garden railway (DIY transmitting throttle ~$40, decoder at $xx +$10 receiver per loco). But if we are going to lobby manufacturers we may as well ask for “one with the lot”.

Bluetooth is similar to a wireless LAN but is tailored for portable personal equipment. It meets all the requirements listed above. Many mobile phones and most pocket PCs have Bluetooth and can be used as hand throttles. With this technology now very cheap it appears to be the way to go. Next time you’re in a computer shop ask to see a “Bluetooth-USB dongle”. At around $20 it’s about the size of a decoder and uses similar components to a decoder.

DWiDCC Hardware

DWiDCC has less hardware than conventional DCC. The command station is now redundant and is replaced by the networking software contained in the handheld throttles microcontroller. The booster is no longer required and can be replaced with any DC power supply capable of supplying enough current for the layout. Having pure constant DC on the track makes powering of accessories easier. Alternatively NiMH batteries or super capacitors can run the loco with track power only used to top up the battery. This is what Lenz does already with their Power 1 module. I will be using this technique on the logging branch of my garden railway using prototypical wooden track. Another alternative that maintains backward compatibility uses an existing DCC system running concurrently on the same track. It can supply power to the wireless decoders at the same time as supplying power and control signals to conventional decoders. A wireless receiver connected to the input of a booster could also place the DCC signal from the Bluetooth hand throttle on to the track to control a conventional DCC loco.

A basic DWiDCC decoder is not much different from a conventional decoder. It has a power supply, microcontroller as well as motor, function, and sound controllers. Where they differ is how the DCC data signal is obtained and supplied to the microcontroller.

In conventional DCC the control data signal is picked off one of the wires to the rail, before the decoder power supply, conditioned to remove noise and adjusted to the correct voltage level before being supplied to the microcontroller.
With DWiDCC the data signal is received via a small antenna and fed to a radio receiver, network module and then to the microcontroller. The microcontroller will eventually handle the networking as well.

Hang on a minute! Did I say antenna, we don’t want those ugly things sticking out of our locos do we! Well it just happens that antenna technology has progressed alongside wireless technology. Most Bluetooth devices have their antenna as a copper track on their printed circuit board – inside the case and unseen. A loco manufacturer could mask and spray a metalised paint antenna on the roof of the loco between the undercoat and top coat. You wouldn’t see it. A cheaper alternate would be a 10 thou sheet that sticks under the cab roof or anywhere it can fit inside a plastic loco. Another is to use a handrail.

When?
This is the million dollar question. While you can experiment today with the simplest forms of DWiDCC what are the manufacturers doing?

I bet they are working on some form of direct wireless but, except for CVP, they are not talking about it. If you get an opportunity ask them. At the same time tell them you’re not buying until a non proprietary NMRA standard is established that uses an existing communications protocol such as Bluetooth.

* DWiDCC – Direct Wireless DCC (pron. DeWhy DCC) is a direct non wired connection between throttle(s) and loco(s) as distinct from wireless throttles which communicate with a command station that sends a signal to loco(s) over the rail track.