RANT: DCC Decoders

If you've precious little space then you're probably better off removing the socket (it takes up space) and wiring the decoder in direct. The Zimo MX620 will do 0.8A continuous as oppposed to the Gold mini's 0.5A. Latest versions support railcomm.

MBQ

Why do you need RailCOM??? What are you expecting to do with it??

BVM

Program software to use it. It's taking time, but RailCom is getting into more decoders (Hornby, Bachmann now as well as Lenz and others). Just need a computer interface that can read it (Lenz have 'said' that at some point they will provide support on there LI-USB, but I'll believe it when I see it).

Ian .

With respect that did not answer the question - what would your software do and how?

I think RAILCOM is a solution looking for a problem!

BVM

Ask Digitrax users what they use transponding for. It has it's uses but Lenz seem to have done a poor job with only a standalone reader available and no means of getting the information back into the command station or computer.

MBQ

Live feedback from a running train on its speed, location, state of lights, and I'm sure there are various other things. Most of these are possible with a combination of other (both DC and DCC) solutions, but RailCom puts them all into one system for DCC. Ultimately (in theory) it could be used for communication from one vehicle to another, allowing for some kind of electronic signal to indicate how far a loco is away from say a carriage or wagon that it is going to connect to. If this becomes feasible, then a fully automated model railway (with the flexibility to deal with unforeseen circumstances) becomes that much closer.

Ian J.

How is a DCC control system going to report location?

I don't know the details yet, but I'm fairly sure it can be done. I'm not an electronics or DCC expert, so I'd have to defer to other people for the nitty gritty (probably a MERG member could answer the question?).

Ian J.

I'm fairly sure it's an impossibility! It could be done on a block by block basis - the "advantage of DCC apparently is that it has only one block, so any given loco could only report that it was on the layout!

- it could be done by resistance (perhaps) which might tell you how far it was from a single feed point.

- it could be done by GPS - to the nearest metre on a single level layout.

- it could operate a whistle or bell on the loco - sort of backwards position reporting. What have I overlooked???

Regards, Greg.P.

How about Time Domain Reflectometry? Sound decoders already use a DSP chip ;-)

Seriously, a loco could calculate it's position from a known point by dead reckoning, just so long as the wheels never slip. Bit of a pain programming the decoder for the particular combination of motor, gearing and wheelsize, though.

MBQ

Something to do with the Tardis?

Locomotives slip! Modern Diesels are built with slip limiting radar etc to keep individual axle slip within certain bounds - which axle are you going to go by? Steam locos often slipped - not to mention unbraked trains pushing the braked loco.

From a given point, the decoder would need a map of the layout and knowledge of turnout positions from the moment of passing the marker point to the instant of reporting. My track diagrams are generally a layout alteration behind, so I can't imagine I'd ever have decoder layout maps up to date.

Regards, Greg.P.

OK how about a device connected one side to main track so communicates with controller. Passes power and comms to an isolated section. Device detects loco on isolated section, sends request for id, loco responds. Device forwards info to main controller.

Cheers, Simon

That would work;

- rather like a bar code reader and bar codes underneath rolling stock ... or

- an ID chip as applied to pets. It still only IDs at a specific point, rather like a signalman noting loco numbers as trains pass, or a model railway operator recognising his train as he drives it out of the station.

The difference between that which you first suggested/implied is locating specific locos on a layout and recognising a loco passing a specific point on a layout.

Hi Simon,

I'm not trying to knock and hopefully I'm not coming across that way! My layout consists of station/mainlines/staging yard (branch etc) The hidden staging yard has 5 queuing tracks and the mainline has several holding sections. Recognition of trains/locos would be very useful, as at present ID is based on computer input/memory/movement recognition. It works, but there's always the possibility of error, which can compound. I need recognition! Applying DCC decoders to every loco just for recognition would be a major expence. Problem 2 with DCC is sound - how do I get the sound to turn off automatically in tunnels and staging yard? Can I fit a reed switch in the speaker line and switch with lineside magnets? No-one seems able to answer that question.

Regards, Greg.P.

You could use RFID tags as used by shops - but you have to have a reader at each point of interest (and nobble it so it could only "see" the immediate area) - probably not cheap! Nore affordable might be a cheap camera system. A 5in screen and 4 camera's can be had quite cheaply these days and run off 12V.

Richard

That's why I've rejected RFID - my layout is multi-level. I suppose I could make the top level baseboard of plate-steel or lead or something but weight might become significant.

If you have connections in the fbi then you might be able to get some object recognition software. A webcam would be cheap but it is partly manual. Anyone tried getting photo into OCR system to read the loco number ? Nice university project perhaps.

As for the sound deaden, now thats more pure electronics - totally out of my knowledge. However have you considered sound proofing the tunnels ?

Cheers, Simon

If you are track circuiting, for signalling etc, then you will have blocks which with a system like this the train would report its number and the signalling would route the train appropriately. DCC does not necessarily mean you have less power feed wiring just that you do not need banks of switches to isolate trains.

Chris

I don't have banks of switches!

- Peco turnouts kill the non-selected route.

- computer turns off non-required tracks.