General – Page 6 – Engineering Radio

AM radio in Electric Vehicles

I have been reading with interest the ongoing discussion about AM radios in Electric Vehicles. Rather than rehash the what, I thought it would be nice to dig into why it is happening.

My first thought is that many of the electronics use PDM or PWM to control various stages of charging, converting, or discharging the storage system. I quick review of a typical EV basic diagram shows that there are several systems involved

Searching through various chip makers’ data sheets on Li-ion battery chargers, DC voltage to voltage converters, regenerative braking systems, traction motor inverters, and so on shows that all of those systems use PWM. Some of those PWM frequencies are right in the AM band, while others are not. That explains why different manufacturers have different takes on AM radios in EVs.

All of those electrical components are controlled by an electronic system that handles battery charging,

This basic diagram shows several sections that rely on PWM to function. The traction inverter is very complicated, with sensors running to each motor and each wheel for traction control, etc.

I imagine the average EV driving down the road in a cloud of PWM-based electrical noise. Whether or not that creates interference with AM reception depends solely on the PWM frequency the chip manufacturer chooses. That is not all, even when sitting in the garage charging, the Li-ion battery chargers use PWM.

It seems a monumental task to attempt to mitigate the noise issue. The real question is; does the general public and more specifically, those who want to own an EV care about AM broadcasting?

There are many alternative entertainment options these days. I would say the average Tesla driver listens to iTunes.

It would be interesting to test MA-3 reception in a Tesla. That would be a real-world test to see how the HD Radio codec stands up to electrical noise. I would say the same about DRM, but you would need to find a receiver first.

One of the perks

Occasionally, I get to go for a nice walk in a snowstorm. No, I am not being sarcastic. It is the middle of March and winter has decided to make an appearance. One of the FM stations we take care of went off the air and the remote control was not able to get the transmitter to come back on, so a stroll through the woods was necessary. This station is located at Sam’s Point Preserve, in Craigsmore NY.

Self-supporting tower has ATT and a Low Power TV station

The site is owned by Vertical Bridge. There are a few tenants on the tower and fortunately, somebody left the gate open before it snowed. I was somewhat dreading trying to wrestle with it when I got to the site.

The problem itself seems to be due to a power hit; the main transmitter was off and the remote control, a wheezing Genter VRC-2000, was not able to control either the main or the backup. Those should be replaced at some point.

There are several other towers up here for various cell carriers, 911 dispatch, etc.

My SO decided to come along.

My phone said we walked 2.7 miles round trip, which sounds about right. The station is back on the air. When I can get up there with a vehicle in a few weeks, I will look into the remote control problem.

Continental 816R2 still chugging along

Had to do some work at a transmitter site today and had to put the backup transmitter on the air for a few minutes.

These were good units in their day and many continue on. This transmitter was new in 1986 and served as the main transmitter until 2015 or so. This unit still has the tube driver (4CX250B) which tended to use a set of tubes every year or so. The PA tube normally lasted 4 years or so.

I miss the analog meters sometimes. There is something satisfying watching all the meters come up together when the plate on button is pushed.

RIP Ray; you were a good guy

By now, most have heard of the passing of Ray Topp, publisher of Radio Guide magazine. I was shocked when I first learned about it in the middle of February. The family has decided to cease publishing the magazine, which is understandable, but also a loss for the industry. The goal of Radio Guide was to provide “real-world technical information.” When I wrote an article, I always thought about the various people I worked with over the years and what they were concerned with.

If you have not read the Radio World article: Ray Topp, Publisher of Radio Guide Dies

The last I heard from Ray was the third week in December. He said he had a bout of COVID and there were some complications. He said he was trying very hard to get the January/February 2023 issue done. I sent in my article in early January but never heard anything back, which is unusual. When the publishing date came and went, I thought that perhaps he was still recovering. Unfortunately, that was not so.

My final article for Radio Guide was to be titled: Learning with the Libra VNA

learning with a Libra VNA Download

Since it was never published, I figured perhaps some might find it useful.