My son called me yesterday evening with the interesting problem described
below.. I haven't been able to get to the location yet to try any kind of
experiment or survey. I have no portable EMI test equipment other than an
HF (Yacht Boy 400PE) and VHF receivers (mobile and HT).
The car is a 2017 Toyota 4Runner. Remote start and door unlock from the key
fob works reliably at distances of up to about 50 feet in all directions
under normal circumstances. This includes from windows in hotel rooms and
at home to the car parked outside.
At his workplace, the fob will not activate either function until he is a
few feet from the car. This is true in the open ground level parking lot
with no obstructions.
Yesterday evening at work he noticed that the fob started operating
normally at about 6:30pm local time. Earlier at 6pm it had not. The fob
never works in the morning when he arrives at work. He has not tried it on
Sundays.
I suspect enough EMI is present to put the legit signal under the minimum
working SNR. I think the transmitting side in the fob itself being affected
is less likely. The office is in a mildly industrial suburban area. The
closest other businesses are two auto body shops and an auto service
center. There is some construction going on not far away.
I have asked my son to stand just outside the fringe of where the fob works
and do a "body DF" scan, holding the fob near his chest and try facing
different directions around the axis of his body. Perhaps he can crudely ID
the direction of the source that way (his body blocking it).
Is there anything you know or can think of that might be the source? My
plan is to use my receivers first and then try to borrow a portable
analyzer or SDR dongle-laptop setup. Other ideas?
The area is Stevensville, Maryl;and (Kent Island).
73, Dan
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