Help with interference affecting my keyless entry FOB

jpapos · Oct 18, 2018

Hi Everyone

I have a very weird issue. I have a 2018 Subaru Outback with a FOB. For the past week or so when I park my car in the back of my house the fob does not work. Tonight I decided to see what is up and if I drive the car to the front of my house it works fine as soon as I drive to the back it no longer works.

I looked it up and the frequency in use is 315. I have tried un-pluugging all electronics in my home and it does not seem to be coming from my home. Does anyone know how I can find what is causing this issue? Really hoping someone can guide me to a person, company or government department that can help me?

Thanks T

mmckenna · Oct 18, 2018

Any strong RF source nearby can overload the receiver in the vehicle, doesn't need to be on the same frequency. Could be a neighbor, cell site, cable TV leakage, etc.

Since it's an issue in the back of your home but not the front, it's probably in that direction. Cable TV lines back there? Cellular site nearby?

Finding the source would take some work if it's not obvious. Do you have a scanner or something else you can test with? Even if it doesn't cover 315MHz, you can try down the bottom end of the VHF spectrum, that may be where the cable TV signal is leaking.

jpapos · Oct 18, 2018

There really is nothing back there as the cable is at the front and connected on the side of my house. I have a uv-5R Baofeng would that work?

mmckenna · Oct 18, 2018

jpapos said:
There really is nothing back there as the cable is at the front and connected on the side of my house. I have a uv-5R Baofeng would that work?

Might work. Tune up something around the 140MHz range and see if you hear some noise. See if that noise is stronger in the back of the house. If it is, take the antenna off and start sniffing around. That might help narrow down the source.

Short of that a spectrum analyzer and a directional antenna would be my choice, but that's high end stuff.

jpapos · Oct 18, 2018

If I buy something like this would that work? I will try what you said and see what happens.

https://www.amazon.ca/RF-Explorer-H...ocphy=9061009&hvtargid=pla-493632351756&psc=1

mmckenna · Oct 19, 2018

jpapos said:
If I buy something like this would that work? I will try what you said and see what happens.

https://www.amazon.ca/RF-Explorer-H...ocphy=9061009&hvtargid=pla-493632351756&psc=1

I wouldn't buy anything. Try your existing radio and see what you find.

Also,
Any metal siding, structures, sheds, chain link fence, anything that could be reflecting RF?

slicerwizard · Oct 19, 2018

A $25 rtl dongle and a laptop/netbook would get the job done.

derevs · Oct 19, 2018

Here's a trick I learned many years ago from Rogers.
Tune your scanner to 121.500 and open the squelch if necessary.
With the antenna removed walk around and by turning down the volume slowly you can usually locate an open cable or other source.

RFI-EMI-GUY · Oct 19, 2018

Any outside lighting like LED lamps? Those can interfere with garage door openers so interfering with Key Fob is likely .

jpapos · Oct 19, 2018

Thanks guys,

Sorry new to this. I am unable to go below 140 on the uv-5r is their a trick? When I choose 140 and press monitor I just get static.

I ordered this RTL will be here tomorrow what app should i use and any tips?
https://www.amazon.ca/Nooelec-NESDR-SMArt-Bundle-R820T2-Based/dp/B01GDN1T4S

Thanks T

jpapos · Oct 19, 2018

Is there a better RTL Dongle? What software will help me track the interference down?

Thanks T

slicerwizard · Oct 20, 2018

SDR# or FMP are all you'd need. Just tune around and look for very strong signals or a high noise floor.

jpapos · Oct 21, 2018

Help Tracking Down Singal affectint my Car!

Hey Everyone,

About a week ago my Subaru Forester FOB stop working and I could not get into my car or start it while parked at the back of my house. If I am parked at the front or anywhere else but while parked at the back I cannot do anything.

It comes and goes throughout the day but I would say 80% of the day I cannot use the FOB to get into my car. I today received my RTL device (Nooelec NESDR) and installed SDR#. I can see stuff on SDR but that is where I am stuck!

Can someone please help me with how I would go about the below

1) What do I need to do in SDR# to find the signal
2) What do I need to do to locate the signal?

Thanks T

KevinC · Oct 21, 2018

All of your threads concerning this have been consolidated into this one for better continuity.

jpapos · Oct 21, 2018

Sorry I was hoping to use one new thread as the other one was localized at finding help. In either case I found the signal from the FOB and what I think to be the issue.

Here are my questions.
1) Is the signal I have the arrow pointing to the one causing my issue?
2) How do I go about finding this signal?
3) The signal next to the one with the arrow is the FOB unlock press.

mciupa · Oct 21, 2018

First thing I would have done is get out the voltmeter and check battery strength.

jpapos · Oct 21, 2018

It is strong, replaced it on the FOB and it is happening on both FOB's.

slicerwizard · Oct 21, 2018

jpapos said:
Sorry I was hoping to use one new thread as the other one was localized at finding help. In either case I found the signal from the FOB and what I think to be the issue.

Here are my questions.
1) Is the signal I have the arrow pointing to the one causing my issue?

Highly likely, although I would look further afield - at least 10 MHz on either side of the fob's carrier frequency.

2) How do I go about finding this signal?

Wander around and see where the signal is strongest.

3) The signal next to the one with the arrow is the FOB unlock press.

Is that a question?

RFI-EMI-GUY · Oct 21, 2018

I think that could be the culprit. You are going to either have to walk around and find it or turn off stuff. The frequency band is ISM and so it is likely some low powered device stuck on, like a remote thermometer from a home weather station, or a super regenerative receiver for some other remote control device in the area. Perhaps a garage door opener etc.,

You gotta do some leg work at this point. I assume when you go to the side of the house where your remote FOB works, this signal is gone or weaker?

jpapos said:
Sorry I was hoping to use one new thread as the other one was localized at finding help. In either case I found the signal from the FOB and what I think to be the issue.

Here are my questions.
1) Is the signal I have the arrow pointing to the one causing my issue?
2) How do I go about finding this signal?
3) The signal next to the one with the arrow is the FOB unlock press.

Sent from my SM-T350 using Tapatalk

majoco · Oct 22, 2018

It may have nothing to do with it, but I found with my earlier model Outback that the remote door lock is much more sensitive to the "Unlock" command, say 10yards away, than it is to the "Lock" command, which only seems to have a range of a couple of yards. Also I have to be on the drivers door side (RIGHT hand side!) for it to work best.

Help with interference affecting my keyless entry FOB

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