Hummer H3 is a rolling EMI generator

I was approaching a stoplight the other day while listening to my car radio. I had a semi-distant AM station punched up.

As I approached the light, I slowly passed an H3 that was sitting in the other lane. From the back I could see that it had the rear DVD player in operation, and it probably had a lot of other electronics going at the same time (GPS, etc). As I passed the H3, I lost the AM station on the radio, which was replaced by an ever-increasing sound that was something like ...zzzzzzzZZZZZZZZZPLPPLPPLPPLPPLPPLPRATTATTATTATEEEEEEEEZZZZZZZZZZZZPLPPLPPLPPLPPUTPUTPUTPUT...
Yeah, it was coming from the Hummer.

So it occurred to me that whenever we need to deploy radio jamming in a tactical situation, we don't need to bring out a lot of sophisticated military electronics - just park an H3 in the general vicinity. That oughta do it.

I'm just amazed at how mucg RF crap was emanating from that thing.

Heh...

Isn't it illegal to contaminate the air with "harmful interference"? I know the FCC frowns upon it.

As far as your radio is concerned: ehhh "This unit complies with Part 15 of the FCC rules which states: a) This unit may not cause any harmful interference, and b) This unit must accept any and all inteference, including inteference which may cause undesired operation"

Something close like that...I'm close to memorizing it...

Yes, Icecube... harmful interference. I'm sure that vehicle doesn't even come close to complying with Part 15.

Of coruse it doesn't help when you're listening to a weaker station with the radio's RF AGC runnig close to wide open., but still, that was way more interference than I've ever experienced from any other vehicle, including busses (which are also loaded with electronics).

Not sure which vehicle emissions are worse, the EMI or the ego... :ironic:

Usually that's due to something like a loose ignition wire, or wires replaced with solid-core versions. Generates a surprising amount of broadband RFI.

Yep, the big question is whether this is a problem with all of the H3's, or if it's just a single H3 that's had some poor maintenance or modifications.

There is a set of EMC standards for automotive products: SAE J1113. Among these are a handful of emissions tests. The requirements for radiated emissions in the low frequencies where the AM radio stations exist are fairly tough. I'm an electrical engineer for an earthmoving equipment company, and some of our sensors use a small digital hall cell that fails the low frequency emissions test. Of course, these tests are just design guidelines, and not a true requirement. Still, we've checked to ensure that it doesn't interfere with AM radios in our equipment. Seems like the boys at Hummer would have done the same.

Steve K.

bfg9000 said:

Usually that's due to something like a loose ignition wire, or wires replaced with solid-core versions. Generates a surprising amount of broadband RFI.

Click to expand...

While normally yes, I'd bet that easn't the cause with the H3. Most of the new Gm's are using advanced ignitions that can't just be reaplaced with parts from Joe Bob's parts store. That H3 might even be coil on plug, I can't remember.

The Hummer was probably configured with a Remotely Detonated IED jammer. Those Hummer drivers like to be safe! Which war zone were you driving in?

I'm not fond of the Hummer myself, but I imagine it's an isolated case like everyone else is saying - probably a case of some maintenance that has to be performed.