My radio market has a "bunch" of ZIP codes, ranging from Palm Springs to Thermal. In radio, we don't deal with "cities" but with Metro Survey Areas. And there are 7 AMs in the MSA.
With the noise in desert areas like Phoenix, Las Vegas, Hermosillo, and similar large metros being even higher than more temperate or rainier locations, it takes at least 10 mV/m to be listenable in most situations.
One observation: the language of Iran is Farsi, and sometimes acceptably called Persian but "Iranian" is not a language. And most of the ones listed as "Asian" (which is not a language) are in a single language, such as Vietnamese on 1480, while 1540 and 1190 are in Korean, 1430 is in Cantonese Chinese, and so on.
And this observation mirrors why the ITU has revised its "standard" in regards to the necessary signal strength of an AM station in order to be able to serve an area. I can remember when the ITU observed, back in the 70's, that 5 mV/m was needed in noisy urban areas. Then they said it was 10 mV/m and now it's 15 mV/m.
There is more background noise than before, I agree. I have to respectfully disagree with you about station facility deterioration, though. Copper in the ground will corrode over time. Many AM facilities are now upwards of 70-80 years old. If their ground systems haven't been refreshed, you have to wonder how effective is the copper still in the ground. Then there are copper thefts. For example, KDAZ in Albuquerque changed frequency, lowered power and went non-directional because of repeated problems with copper thefts. There are other instances. I've been made aware of one of the larger Kansas City broadcasters that has constant problems with theft due to its location in an isolated corner of Kansas City. So there are multiple factors involved: the noise is up and the quality of transmission is often down.
I don't think Family made much in the way of processing changes on KEAR-ex-KFRC. Family's engineering is usually pretty competent.
Would PG&E burying power lines to prevent fires affect groundwave propagation?
Mark, I promise you that whatever processing 610 is running now is nowhere near the loudness and clarity when it was KFRC (I said “RKO” earlier, but it applied to Bedford and Infinity as well).
I've never heard of such a thing, and I can tell you from my time at that company that it would not have been a consideration at all.
It could be a conscious choice, then. It wouldn't surprise me. The old KEAR(FM) had pretty conservative processing from what I recall.
From the Peninsula, 25-or-so miles due south of Aquatic Park: I just tuned in 610 KEAR using a 50 year old Sony tuner (into a Sony amp and H H Scott speakers), where the AM section has the old full-fidelity mask. It actually sounds pretty good (for a station I'd never intentionally tune in). If Family plugged in an aircheck of Dr. Don, I think it would sound quite acceptable. (BTW, no more than 6 feet from a wall of computing equipment.)
It would be hard for me to judge. My former residence was in Oakland; where I stay on visits is in Emeryville where I could probably get KEAR on an electric toothbrush.
I noted down "Asian" because I can't distinguish many of those languages from one another by ear, and didn't want to check dozens of sites. However, you got me on Farsi. I knew that and wrote down Iranian without thinking.
Since you mention that, what do plate boundaries do to groundwave? I recall hearing that the San Andreas fault attenuated AM groundwave propagation. Michael posted right after you, mentioning his history of hearing numerous San Francisco stations in Sacramento, but without knowing which side of the fault their sticks are on, that doesn't tell me a whole lot. (Also, I would assume that if it did have an attenuation effect, it wouldn't necessarily be so severe as to stop propagation to such a short distance away as Sacramento.)
740 always comes in down here like a semi-local, with only a soft layer of white noise in the reception. It's easily heard indoors. (I wonder if its CE is ever going to finish his transmitter tour video on Youtube. "Part 1" went up a few years ago, but nothing has come along since.)
That brought back a memory. When I did occasionally DX in the 90s, for some reason I was virtually always able to pull in little KCTC-AM 1320 down here in the San Gabriel valley, with surprising clarity (about 2/3 audio, 1/3 noise). And I do mean almost always, even though nothing else from Sacramento -- including big signals like KFBK -- seemed to ever be audible to me. I recall the station being 5,000 watts day/night back then, which made its regularity all the more unusual. So much so I nearly wrote them to request a QSL card. But it was just an Entercom-owned automated MOYL station and I figured nobody would be around to reply.
If this is a factor in reception, more important than the San Andreas would be the Hayward Fault, which runs under the Warren Freeway (Highway 13) and under the University of California football stadium. Mike would be on the other side of the Hayward Fault from those stations. I actually was, too, when I lived in Oakland because I was on the east side of 13. The Hayward Fault hasn’t had a major earthquake since 1868; experts have repeatedly said it’s overdue for one, and there are fairly frequent small quakes along it that tend to come at 3 or 4 o’clock in the morning.
This is a truly interesting subject, and has not been well-studied. Our points of reference are generally AM stations that have randomly moved to the "other side" of a major fault line, and there is usually no comparative operation to contrast data with.
It might reduce AC hash near the transmission lines. Not sure it would affect groundwave. Most power poles are grounded somewhere, making the earth connected in some way to the AC used by the powerlines.
