DCC occupancy detections false positives

I just installed DCC block occupancy detectors and am getting false
positives only when the layout is in an operating session with lots of
people and trains. When I'm by myself there are no false indications.
I'm at a loss what to do, or how to test if the changes have been
effective.

I'm using a variant on the VT-5 inductive (transformer-type) occupancy
detector (see http://home.cogeco.ca/~rpaisley4/DccBODvt5.html).
Specifically, the variant by Richard Napper is described on page 18 in
http://www.mcor-nmra.org/Publications/Kibitzer/Volume56-2.pdf .

During the operating session I saw the occupancy indication change
from unoccupied to occupied and then back to unoccupied in about 30
seconds. Most of the time it showed occupied when there was nothing
on the track. Now that I'm by myself, it is steadily showing
unoccupied.

I had a thought that there might be stray fields. I was going to try
using aluminum foil to shield the detector, but then I got to
wondering if that would be effective if the fields were magnetic.

Suggestions would be very much appreciated.

I also posed this request to mrrelectronics@xxxxxxxxxxxxxxxx
.

Relevant Pages

  • Re: DCC occupancy detections false positives
    ... I'm using a variant on the VT-5 inductive occupancy ... During the operating session I saw the occupancy indication change ... There isn't any 'magnetic field' to shield. ... can be loaded (some current drawn) by either capacitance or resistance. ...
    (rec.models.railroad)
  • Re: DCC occupancy detections false positives
    ... When I'm by myself there are no false indications. ... detector. ... During the operating session I saw the occupancy indication change ... I.E. a DRY finger across the rails shouldn't trip things, ...
    (rec.models.railroad)