17 May, 2023

The Recent Rise of Advocacy for a Vehicle AM Radio Regulation

I thought it was just "AM" talk radio hosts such as Clay & Buck trying to make their program sound more important...you know, entertainment and "content."  But during their very show recently, at least on WLVL, there was a sponsored political ad urging people to go to a URI and ultimately e-sign a pettition to demand action, presumably in the form of legislation or regulation, for vehicle manufacturers to include AM radios in their cars.  They even enlisted former US Vice President Mike Pence to help deliver the message.  To paraphrase, Mr. Pence talked about how AM stations are a part of your safety, as participants in the EAS. I think this is quite disingenuous, because that implies FM, or for that matter, any other broadcast station, such as TV, is not part of EAS, whereas by regulation each of them has to be.  I will grant them that MF propagation characteristics (AM broadcast band) are not going to be like VHF (FM broadcast band).  But that's partly why FM is typically allowed more power than AM, to cover more area.

Please give me a break.  Along the lines of terms like "Big Oil," "Big Pharma," etc., this isn't "Big Vehicle" conspiring to silence talk radio, which has its primary home on AM. Automotive electric motor controllers accomplish what they do by turning the current to the motor on and off very rapidly.  This is the very same effect you would have experienced with an AM receiver years ago with cheap incandescent light bulb dimmers (that is to say, cheap because they lack noise suppression circuitry).  It does the very same thing as the EV motor controller, it chops up the current so that the duty cycle is varied, thus ultimately controlling the temperature of the bulb's filament (or the motor's speed).  All those square waves produced are similar to the spark gap transmitters that were used it the very early days of radio, very wide band emissions.  Without specific noise suppression components in the dimmer, the power wiring acts as a transmitting antenna for this broadband noise.  Also keep in mind the scale; a lamp is going to be a few tens or hundreds of watts, whereas an EV motor is typically tens of kilowatts, an order of magnitude or more bigger.  Unless some fairly expensive components are added in the circuit for noise suppression, typically all you're going to hear on that AM radio is hash.  EV manufacturers do not want their customers complaining about how their radio doesn't work, all they hear is noise.

It's the same reason why many mobile SoCs (for phones/tablets) will have an FM radio but not AM; a computer is absolutely chock full of square wave signals, so FM is the only practical reception.

This is also not to mention, by implication, they're making it sound like it's going to be illegal or something to carry your own AM radio into your EV.  Yes, it's less convenient, but if you want to try it, there's really nothing holding you back from bringing your own receiver along for the ride.  You're likely going to be quite disappointed with the results, except maybe if you're within a couple of kilometers of a clear channel station.

I have confidence that the market will sort this out.  If people genuinely want their AM radio without having to carry a portable around with them, EV manufacturers will include an option.  It may be a few hundred dollars, considering the heavy duty chokes, capacitors, and shielding it will likely require, but if you want an AM radio badly enough, you can pay for it.


English is a difficult enough language to interpret correctly when its rules are followed, let alone when the speaker or writer chooses not to follow those rules.

"Jeopardy!" replies and randomcaps really suck!