@gunrunnerjohn posted:The "signal strength" measurement is really a misnomer. What is actually being checked is sending packets to the locomotive from the TIU and then counting the returned responses. If you are reading 10's, that means all packets are being responded to and received by the TIU back from the locomotive. However, that doesn't actually measure the signal strength on the track, it is really just checking if there's enough signal for packets to go back and forth.
@rplst8 posted:
Actually, the track is NOT an antenna in the world of TMCC. The "antenna" inside the TMCC locomotive is picking up the radiated signal from the earth ground (3rd prong of house wiring), the track side of the signal is connected through the wheels to the electronics directly. In this regard, the RF propagation model is kind of upside down, but the effect is still the same.
Dale Manquen wrote a significant piece on TMCC Signal Basics, and he clearly explained it much better than I will. Sadly, his website is no longer up, but I captured that topic here.
Dale's TMCC Signal Basics.pdf
Dale's description is spot on.
@rplst8 posted:
I believe when Barry was around he stated that exact same thing. I know both the Rev. L and PS/3 chipsets got a much more powerful DSP signal processor for better performance.
John, Thank you for taking the time to explain what exactly the DCS "signal strength" means.
On behalf of all of us newer forum members, an even bigger thank you for saving and re-posting Dale Manquen's TMCC Signal Basics article.
I highly recommend that anyone with a TMCC/Legacy system read it. For the first time, I think I now understand the two different parts of the Legacy 455kHz transmitting antenna:
1st - Connected to the Legacy base's U post is the Outer track rail. This serves as the antenna base (but as you point out, also a direct conductor to the Loco)
2nd - the "earth ground" connected from the TMCC/Legacy base back through its wall wart to the House wiring, is essentially the "whip".
From the receiving Loco's perspective, these two electrically opposite Antenna "Poles" (sort-of) both need to be somewhat balanced. When the signal strength of one Pole overwhelms the other, poor reception by the Loco results.
Sorry for the TMCC tangent here, but this is really good information, and I'm a bit excited to finally understand it, I think.
Now back to DCS...
