How to measure signal strength on a MTH DCS based layout without using an MTH engine to perform this function?

You could probably measure the signal from a TIU running on aux power and track power turned off with an oscilloscope. I'm not sure what it would tell you since MTH doesn't publish any specs on the signal. What MTH does for signal strength is simply count packets sent and compare that to acknowledgements received.

@turkey_hollow_rr posted:

You could probably measure the signal from a TIU running on aux power and track power turned off with an oscilloscope.

With track power off, the DCS signal is not present.

We had a long discussion about this topic in this thread: Design of a $10-20 DCS-TIU Port Tester Tool?

The upshot of it all was I laid out this board for a DCS signal tester.  It's designed to use for testing the TIU output signal strength, testing the signal on the tracks encompasses so many variables that it's pretty hard to do useful tests.

Note that for all these tests using a 'scope, you need to be supplying the TIU with a pure sine wave, the filter won't properly screen out any chopped waveform on the voltage.

If you want to test the signal directly with a 'scope, you'll need a filter, this is part of the board above.

Here's one that I made for portable measurements.

Thanks John. I forgot that track power triggers DCS watchdogs, etc.

Is this available to purchase somewhere?

I believe @rtr12 was doing kits, and maybe some assembled versions.  I did the original board, but I don't have any of the parts in stock anymore.

Yes, he still has a few kits left!   I think there are maybe 9 or 10 left, will have to check.  After that I guess will depend on part availability, I have not checked on that since about this time last year, before the chip shortages got going.

I am interested.  However, electronic analysis is not my cup of tea,, so would need a finished "tool" and some instructions.   What kind of price are we talking about?? Should I talk with him directly or how should I proceed?

Thank you rtr12 and Gun Runner John for the info.  

Ron

Send me an email, it's in my profile.

To be clear the device is best suited to test the output of the TIU.  My experience even with a small test track and lighted lock on is the device no longer provides a good output.  Frankly a good engine is the best method.  Your actually seeing the two way communication.  The device only test output strength of the TIU, not how the receiver is working.  That can effect signal strength just as much as the transmitter.   The device is best to isolate a bad transmit signal at the output of the TIU only.  G

Correct George, that's all the TIU tester was ever intended to be, a TIU DCS output signal tester!  Given the propensity of the Rev. L to eat it's output DCS drivers, it's a useful tool to have.

This is more complex than I want to deal with.   I am going to do what my friend Bill suggests, find an MTH engine with PS 2 or 3 that is damaged physically and use its functioning Signal Strength detection capability to do the work.   Hopefully this will work.

Thank you all for the thoughtful analysis and ideas.  Ron

You mention getting a damaged MTH DCS engine to use for TIU signal strength testing. Are you just attempting to check the signal strength of various TIU's and their 4 outputs to then purchase one of them? You can't rely on the engine as a true testor, some engines see the signal clearly and respond to commands perfectly, others don't see it so well and their response to (or lack of) a command is terrible.