Interference from other vehicles

[hanlonmi06]

I'm curious, with all the new technology that vehicles seem to now have associated with them for "sensing" the world around them, is there RF interference to be expected from them? I have a lot of VHF frequencies still loaded in a couple of mobile radios and I feel like there is an ever increasing number of times where a radio will open the squelch on some frequency where it just sounds like noise and when traffic moves, shifts, light turns green, what have you, suddenly the detected signal is gone and the radio resumes scanning.

I've noticed it enough time now here it seems like some sort of RF is being emitted and detected from a very close by vehicle that I got to wondering if the there aren't signal present of some sort from some system within the vehicle. I know to expect the typical hash and trash of RF in a city, but this pattern seems different. and only within the last few years. Or is it more and more LO broad banded noise from all the dozens of computers cars now seem to have?

 

[tvengr]

It is probably due to a proliferation of LED headlights in the newer vehicles. The LED lights can radiate noise over a wide range of frequencies.

 

[K5MPH]

Scanner radios dont have the greatest of filtering along with weak front end you are going to receive some interference at times and could be a number of thing.........

 

[trentbob]

If you are having this issue with Vhf high frequencies I would think you would be able to solve the problem by making sure you have the proper CTCSS set. Without a PL tone Vhf High frequencies are very noisy with all kinds of things these days.

 

[mmckenna]

I frequently run up and down a major interstate.
I have a number of frequencies in my radio that are either 2 meter simplex or public safety interop channels that do not have PL tones on them by design.

Very often I'll have the squelch break when passing large semi's. It appears to be cheap LED lights, but I suspect there are other sources since the type of interferences isn't always the same, and sometimes it'll be worse near the engine/cab area.

 

[hanlonmi06]

Just to clarify, I'm not experiencing problems per-say that need resolutions. I've had mobile radios for the better part of 25 years now, so I know what to expect, but thank you for the input on wide front ends and using PL tones. The pattern I've noticed recently is that there is definitely something up with newer vehicles. I'll go with LED technology to an extent, I hadn't thought of that. A lot of my driving is day time and less likely that its headlights exclusively though I'm curious if I can correlate that. I know diesels throw an awful lot of garbage out...its just a curiosity. I wondered if anyone in the automotive arena would chime in if lane departure or other object/vehicle detection systems were playing a part in raising out overall noise floor...

 

[IdleMonitor]

I've seen this happen before. I used to work traffic control for a construction company. Every single time that I had a Lincoln Navigator type of SUV pull up to be the first vehicle at me, there was always interference coming through on my radio. The interference quickly left as soon as the vehicle continued on. Took me a bit to figure that out but when ya start noticing interference coming through all the time when certain vehicles are in your presence it wasn't too hard to figure out. Our radios that we used were simple CP200s on a VHF frequency. Our frequency did not use a PL Tone at all. I don't believe however that even if we did have that, that it would've helped.

The problem too was when I got this interference it made it very hard to hear the other person I was talking too on the other end. It was like the frequency sound was being suppressed. Like when 2 FM Broadcast stations are competing with each other on a frequency when those conditions are really good.

 

[hanlonmi06]

Exactly that.

Though, I'm not experiencing "problems" but its definitely certain vehicles.

 

[RFI-EMI-GUY]

There was a patent to detect and catalog vehicles by their EM emissions. It was from a simper era where the alternator noise and the drive belt pulley size was a significant element along with spark plugs, number of cylinders and axle drive ratio. I would expect it is a lot more complex now, yet rich with discernible information.

 

[mmckenna]

I would expect it is a lot more complex now, yet rich with discernible information.

Easier to just track the bluetooth systems now. When the vehicle/occupants are beaconing out a unique ID, and all you have to do is set up a receiver along side the road, it's much easier.

I'm wondering if some of the semi-truck noise I hear is from trailer anti-lock brake systems.
And then there's Dodge with their notorious RFI issues.

 

[tweiss3]

I'm curious, with all the new technology that vehicles seem to now have associated with them for "sensing" the world around them, is there RF interference to be expected from them? I have a lot of VHF frequencies still loaded in a couple of mobile radios and I feel like there is an ever increasing number of times where a radio will open the squelch on some frequency where it just sounds like noise and when traffic moves, shifts, light turns green, what have you, suddenly the detected signal is gone and the radio resumes scanning.

I've noticed it enough time now here it seems like some sort of RF is being emitted and detected from a very close by vehicle that I got to wondering if the there aren't signal present of some sort from some system within the vehicle. I know to expect the typical hash and trash of RF in a city, but this pattern seems different. and only within the last few years. Or is it more and more LO broad banded noise from all the dozens of computers cars now seem to have?

Yes, Dodge/Jeep are horrendous. Its bad enough that every time I have to see how close that Dodge or Jeep was that it broke squelch. It's happened as far away as 2 lanes over, but it also can happen passing the opposite direction at a net 100mph (50 each direction).

Easier to just track the bluetooth systems now. When the vehicle/occupants are beaconing out a unique ID, and all you have to do is set up a receiver along side the road, it's much easier.

I'm wondering if some of the semi-truck noise I hear is from trailer anti-lock brake systems.
And then there's Dodge with their notorious RFI issues.

We (my field) does traffic modeling based on bluetooth MAC addresses. I saw some of the research, which was pretty cool. The can take this box, chain it to the median guardrail and even if your BT is not in discovery, it captures it passing. Put out a few hundered of these boxes across a state's interstate and highway system, you can get a pretty decent traffic pattern in just a few days.

 

[mmckenna]

Yes, Dodge/Jeep are horrendous.

The county radio shop here hates the Dodges. Way too many issues with them. Reading some of the posts on this website with the RFI issues, no way I'd buy one.

We (my field) does traffic modeling based on bluetooth MAC addresses. I saw some of the research, which was pretty cool. The can take this box, chain it to the median guardrail and even if your BT is not in discovery, it captures it passing. Put out a few hundered of these boxes across a state's interstate and highway system, you can get a pretty decent traffic pattern in just a few days.

I'm not paranoid about such things, but my work and personal trucks don't have any bluetooth in them, and since I rarely use it, I keep the function turned off on my phone. But I have heard that it's easy to track vehicles with this.

Back on topic.
Back in the heyday of CB radios, ignition noise was a thing. I remember being around older cars and the ignition noise being a problem. Modern cars tend to be quieter when it comes to that stuff, but all the other electronics raise the noise floor. Now add in composite body panels and there's less shielding.

USB chargers are an issue, also. Had the tire pressure monitoring system in my wife's old car throw an error light once. Realized it was the cheap USB charger my son had. Pulled it out and the error cleared. Since most people are not aware of this stuff, they'll run around with the USB chargers spewing noise.

 

[gary123]

I have actually had to research this very issue . The research was done using spectrum analyzers and then commercial radios programmed to the more common noise humps. I say humps as the noise is not a nice clean spike but a speed bump shaped wave pattern. Also the speed bump will often slowly travel up or down the spectrum area.

Sorry to be the bearer of bad news the results of the testing showed a lot of the interference is indeed from LED lighting systems and in car cigarette USB chargers But these are not the only sources. Some vehicles have noise coming out of the ECM and other electronics especially the in dash info screens as well as dash cams. Also to blame is fixed localized noise coming from traffic monitoring hardware, environment sensors ( heat sensors and visibility sensors) and a pile of assorted electronics including home computers and laptops.

Bottom line on all this is. The cheap 'Chinese' electronics are not shielded at all so all the complaining in the world is not going to fix or stop this. The same goes for in vehicle manufactured hardware. These devices have 'passed' FCC inspection or are exempt under part 95. Again they are not going to get fixed unless a pile of influential people in the community push very very hard to get some type of updated standards made and enforced.

As far as PL tones etc to get rid of the noise yes they will stop the squelch from opening on the random noise. You must remember if your where the noise is its like standing in line and closing your eyes you wont see the person in front of you but they are still there. You cant move forward (hear the desired signal) until they move out of the way.