The WiFi monitor is available starting with CTC-App version 4.15. It displays the received signal strength of a locomotive's WiFi as a graph over time.
You can open the WiFi monitor via the "WiFi Monitor" button in the locomotive configuration of the respective locomotive.
The example shows the WLAN signal progression during a lap on our garden railway test layout (see article Automation in the Garden :
The vertical scale shows the signal strength in dB, the horizontal scale the time. The time axis label is the time in tenths of a second (x 0.1 s), followed by the last passed beacon. In the example, the locomotive's received signal strength was -79 dB after 23.0 seconds (and after beacon TS5) . Between 44.8 seconds and 55.3 seconds between beacons TS1 and ST3, there were two brief dropouts (-100 dB) .
From CTC-App 4.38, the red line shows the "Signal min. dB" value of the locomotive, i.e., the point at which the locomotive actively starts searching for a better WiFi connection.
The following image shows the layout where the measurements were taken:
- In the foreground, the outdoor access point (TP-Link AC1200) to which the locomotive was always connected
- At the back, marked with "A", the two spots where the WiFi briefly drops out: a slight dip and bushes of currants in front of it
- The arrow marked with "T" points to a roughly 2 m long tunnel, which obviously does not pose a problem. However, it is only covered with concrete slabs (no soil above) and is open towards the access point
- The two unmarked horizontal arrows mark the track layout. The route circles the apple tree, then runs along the concrete wall to the end of the garden about 15 meters from the access point, and finally returns through the tunnel.
- The test run was carried out with the red BR 251 locomotive visible in the center left of the image.
After three laps, the graph looks like this. The three repetitions are also clearly visible graphically:
Notes:
- For detailed analysis, the data transmitted during the measurement can be found as "Wifi-XXX.csv" in the CTC-App's data folder (XXX is the locomotive's name). This can be opened, for example, with LibreOffice Calc (Excel may work but is not guaranteed) and evaluated in detail.
Mesh Operation
In mesh operation (multiple access points with the same SSID), a separate line is displayed for each access point (here green and blue), making it easy to see when the locomotive switched access points. The legend shows the MAC addresses of the access points.
Our garden railway test layout has since been expanded, and the access point marked in the photo has been moved four meters to the left to the other support of the terrace roof. This results in larger areas of the layout that are no longer covered by this single access point. The second access point is located at the back corner of the house near the two spots marked with "A" in the photo.
The red line now shows the minDb value of the BR251 locomotive also used here. Again, three laps were driven on the same route as in the previous example:
The dropouts behind the berry bushes found in the first example are now optimally covered by the blue access point. However, there is now a critical point between the raspberries (center of the image at the concrete wall, hidden by the apple tree). There, the signal of the blue access point is shielded by the pear tree (in the image behind the lamp) and that of the green by the apple tree.
Note:
- For mesh operation, the locomotive should have at least firmware 20250627 (CTC-App 4.40). In earlier versions, mesh operation was partially available but not yet convincing.