How does a QSI decoder calculate scale speed? I have a couple of QSI equipped diesels and can get a verbal speed announcement by pressing F10. The readouts are pretty accurate as measured with a stop-watch over a measured distance and the speed-step/ scale speed seems to vary according to the number of cars the engines are pulling. Any insights?
John in Carolina
I believe they use BEMF from the decoder. As long as the decoder is being used on one of the loco's it's made for the speed would be accurate. IF you used it on a different type of loco it may not be because of wheel size and gear ratio differences.
Springfield PA
Thank you for your reply. That answers my question.
John,
I tend to find that the verbal sMPH from decoder is difficult to hear over the ambient locomotive sounds - even though it does lower the sound. For me, I have a 3' portion of track and a table to calculate sMPH.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Tom,
I also measure smph this way but as my layout is small (8' x 6' x 8', "U" shaped, point-to-point), I use a 6" measure, with yellow dots on the side of the rail or use a 40' car as a measure, calculating the time it takes to pass a specific point. Since the majority of my decoders are LokSound and do not have the QSI feature, I have to use this method as well. Of course, after some time, you get to know the speed per each engine based on the number of speed steps showing along with your sense of how fast the train is moving visibly. Since the maximum permitted speed on my switching layout is 10 mph, a 6" measue is reasonably accurate. Thanks for the comment.
John