RSC Class 91 DSD

[749006]

I might have to try this mod as the DVD is one of the reasons I don't use this loco.

Anyhow nice of DTG to listen to it's customers and provide an on/off switch - NOT!

Peter

[davep]

Gave it a run on Newcastle-Edinburgh today - works a treat, so thanks again to all involved.

[Springer6]

I had been concerned that this mod may affect AI traffic , in that you would be able to hear the external DSD and AWS alarms when a Class 91 AI train passes your driven train. This may not have been a great problem at normal passing speeds, but could have been more serious if, in a scenario your driven loco was passing an AI 225 very slowly or was stopped alongside one that had it's DSD alarm sounding.

Therefore, I set up an experiment by creating a Free Roam scenario on a cloned Testrak, where a 225 was set up to run to a fixed point by giving it a destination about a mile from the scenario start point i.e. making it act like an AI train . I then started the scenario. The AI 225 set started to run and just as it did so you clearly heard the AWS "ping" once as if the reverser had moved to forward and the AWS test had sounded but had been immediately cancelled.

I followed the 225 set closely with the zoom control on the keyboard (well within 500 metres). The AI train passed over several AWS permanent magnets that I had placed in it's path, without emitting any AWS sound. The train also ran for well over 1 minute and did not emit any DSD warning sound. The only sounds it made after the initial brief "ping" were the normal running sounds for an AI 225 set.

To further check this I placed another Class 91 alongside the path of the AI train. On the start of the scenario I clicked on this loco which became a "driven" train in which I selected outside view.

As the AI train passed the driven train, it passed over a deliberately placed AWS magnet, but it did not emit any audible warning sound.

This "test" may be flawed (please point this out if it is), but if it is not flawed, I can only conclude that an AI train modded to give external AWS and DSD warnings does not seem to emit those audible warnings after the initial "ping". Which, if true, is very good news

I repeated these tests several times and at no time did I hear any warnings from the AI train other than that initial "ping". It may be that the sound heard by others from AI trains was the initial "ping" ?

Also I confirmed that when driven from the Flat cab (as well as from the DVT), the 225 outside audible alarms behave just as they do when driven from the front Class 91 cab.

[gptech]

I've spent a while playing about with different values in the 2 edited files tonight, if anybody would like to/feels brave enough to see if they get the same or similar results....

First thing, Activation Distance:
Basically how far away from the sound source you can be to still hear it. Using the extremely scientific method of helicopter view 2 (rear of the train) and flying out as far as I could I found that the AWS and DSD were inaudible when set to 300, but OK when at 350... so it's somewhere between those 2 distances. Being scientific again I decided 350 was as good as it gets.

Attenuation values:
Attenuation is the loss of quality/quantity/strength of a signal over a given parameter---time, distance for example.
I asked my partner about this; she's an astrophysicist by training, taught as a physics teacher for 20+ years and you could say she 'knows her stuff'--30 seconds into the explanation I realised I need a new woman in my life..........

Going back to my definition of scientific I played about with numbers....

I found that setting the Attenuation Start value of AWS Clear, AWS Caution Start, AWS Caution Loop and DSD to 50 (how far away from the source the sound starts to degrade) and the No Further Attenuation to 100 (how far away from source it stops degrading and holds that particular strength value) gave a nice compromise between being able to hear the sounds externally and them being overpowering. This has reduced the reverb effect from bridges when driving externally considerably, not eliminated it but it's much less. Still had the odd occasion where through an accident of timing/location a passing 91's AWS sounds were audible, but this was lessened too.

If anybody would care to make those edits too, it'd be interesting to see/read whether it's getting that wee bit closer to being 'JustRight' (gotta praise him a bit, haven't you?) Alternatively, if anybody wants to try these new (very, very much experimental) values and isn't sure how to edit the files I'll happily pass them on to you; just drop me a pm.

(Jeeeeeez...the things some folk will do just to get messages so they can pretend they have friends...)

EDIT:

Missed springer's post there, all in all it's that proverbial cat's whisker away from being perfect,

It may be that the sound heard by others from AI trains was the initial "ping" ?

I'll happily go along with that, any extraneous sounds I've heard haven't been confusing or 'dangerous' and haven't detracted in any way from the driving experience.