Can AM reception in car radios be improved?

[Greg Strickland]

Thank you ajaynejr.

btw- yes, I think the rolled off treble you mentioned was mostly a result of narrow RF bandwidth used to improve selectivity and reduce interference from adjacent channel stations, and other strong stations on the AM band.

As a young teenager I made a radio that was just a tuned circuit with a wire on one end for an antenna, a diode and a capacitor, driving an audio amp. Bandwidth was huge, the audio had excellent high end. Predictably, I heard only the local stations at sound volume in proportion of each station's signal strength at my location.

A most interesting part of this was static from lightning strikes was heard as clicking pulse, not a crash with low end audio. This suggests subsequent bandwidth restriction in superheterodyne radio IF stages might have "smeared" the brief pulses into the booming crashes of thunderstorms when they were demodulated to audio. This in turn suggests RF noise blanking in analog early days was done at the initial RF stage, where static had a short rise time and minimum duration, and then the demodulator "integrates" it into something that might sound reasonable.

 

[vchimpanzee]

Continuouswave- thank you for contributing. "From what I have read" overall efficiency of the utility distribution system is about 95 percent, and less during time of heavy load. And the margin between long term average consumption and available production can be less that 5 percent. If this is correct, these are horrible metrics. Imagine if at 55 mph your car was at 95 percent of redline RPM.

So, in high demand power company voltage sags, as a result of their design choices. Thus, I endure a rolling blackouts and have to either buy a generator or pay to replace spoiled groceries. And they still send me an electric bill.

North Carolina had a problem similar to what happened in Texas last year at Christmas this year. A lot of people weren't happy. Of course, we've had cold weather like that before, and you'd think during a holiday there would be less demand but somehow Duke wasn't prepared. Duke is the power company for most of the state, and if you're a sports fan yes, the man who started the power company gave a huge donation to a certain university. Duke also took over most of what was CP&L, so except for the municipalities and rural cooperatives and a small area near Norfolk, they have a monopoly.

 

[vchimpanzee]

Utilites are not going to spend billions of dollars reducing interference caused by their power distribution system.

There was an old tower design being used. I was getting a lot of interference on America's Best Music where I could see those towers. Why they were still using something that old I had to wonder.

And yet the man I reported this to said listen to FM. Actually, the local FM station did sound pretty much like America's Best Music sounds now, but that wasn't what I wanted to listen to.

 

[CentralFL]

Are you sure that's not a rear window defroster built into the back glass?

Not 100% sure. But there are 2 separate patterns of wires in the back window. The parallel ones which are definitely the defroster and addition ones near the roof that don't follow the same parallel pattern. I think that is the antenna? There is no "shark fin" antenna on the car.

 

[Greg Strickland]

CentralFL- It is very easy for the defroster wires to also be used as an AM/FM antenna. Defroster is almost certainly DC powered from the car battery, and radio is a much higher AC frequency. A filter could enable shared use.

 

[CentralFL]

CentralFL- It is very easy for the defroster wires to also be used as an AM/FM antenna. Defroster is almost certainly DC powered from the car battery, and radio is a much higher AC frequency. A filter could enable shared use.

Thanks for the info. The antenna works great on both AM and FM so no complaints.