I agree with David, a very interesting topic. I'd add one other consideration: is a fault that's got a lot of pent-up unreleased force (i.e. a fault like the Hayward, where after ~150 years there's tons of pressure just begging to be released) different that a fault that's had a temblor event in recent years and released whatever forces had built up? Would one or the other inhibit signals more or less, or would that be a non-issue? I wonder if that's ever been studied, and if not, might the Hayward not be a great place to try observing pre- and post-quake changes? Maybe with stations like KNBR (super-strong low-band omni), KGO (mid-band, figure 8, moderately strong to the east in its side lobe) or KZDG (high-band, limited to the east)? All three of those have their transmitters and towers within a few miles of each other, between the San Mateo and Dumbarton bridges, so at least that aspect would be an apples-to-apples comparison.
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% Reduction - AM reception range - increased noise - 1920 to 2024
- Thread starter kfbkfb
- Start date
There are/were stations on The Island that put their best signal into Bermuda. (I'm thinking of the late WGLI 1290. You could be within viewing distance of their towers but not able to receive their night signal on your car radio, it was so narrow a pattern on L.I.)
I'm familiar with WGLI because I knew the Beck Ross Communications people who managed their stations in Michigan, and later bought them from Beck Ross. Also, my next door neighbor was the Accounting Manager for Metrocom, who owned WPAC AM/FM in Patchogue and WHRF AM/FM in Riverhead. She and their Engineer went to Long Island to do a Physical and Engineering Inventory when Metrocom sold the stations. WPAC-FM became WBLI after Beck Ross bought it. My neighbor always had interesting radio stories, as did their Engineer. After WADO 1280 downgraded WGLI 1290 to go 50000 watts Day, WGLI had a sad end.
There are definitely some interesting discontinuities in the LA basin that aren't reflected on the M3 maps.
I have long believed that KFWB suffers even more than the maps would suggest over in the mid-Wilshire area, for instance. There's something going on between their east LA site and downtown.
I have long believed that KFWB suffers even more than the maps would suggest over in the mid-Wilshire area, for instance. There's something going on between their east LA site and downtown.
Is there anyone here who has experimented with how far out you need to be from the shoreline of a Lake or Ocean before the electrical noise falls off to an acceptable or imperceptible level? I have gone out on a dock 100 feet or so and have noticed a good reduction. I am always afraid I'll slip and drop a good radio in the water though, so I haven't done much experimentation. And to the boaters here, what's your experience with how far out you have to be to have no perceptible electrical interference? Of course, the electronic devices, GPS, etc., on a decent boat would interfere. I'm thinking that if you had a short vertical antenna at the end of the dock, connected to transmission line, you could bring it on shore a ways to hook it up to a radio with an external antenna input or inductive coupling to the radio. That works best with a simple tuned preamp in my experience.
The 1920s and 1930s were relatively noise free because what was there to interfere? Lightning? Car ignitions? Incandescent light bulbs? There wasn't really very much besides heavy machinery to cause problems
I think when modern home appliances and TV came into widespread use, the RF noise skyrocketed. And the high power, computerized and LED everything we've had since the 1970s just dogpiled what was already a noticable problem even back then.
If you want a guesstimate, I'd say it's gone up to about 80% from what would be 5% in 1940.
But really, there's variables from place to place. And there are still a few radio dead zones where nothing transmits and nobody lives that you can DX pure magic from.
I think when modern home appliances and TV came into widespread use, the RF noise skyrocketed. And the high power, computerized and LED everything we've had since the 1970s just dogpiled what was already a noticable problem even back then.
If you want a guesstimate, I'd say it's gone up to about 80% from what would be 5% in 1940.
But really, there's variables from place to place. And there are still a few radio dead zones where nothing transmits and nobody lives that you can DX pure magic from.
Of course, that leads me into the area of scientific fantasy that fueled Gernsback's mind for decades: could a change in conductivity across a fault line, measured by strategically placed transmitters and receivers on each side, reveal changes that might indicate when a quake might occur?
I'd say that the first major deterioration in Medium Wave reception was caused by a widening adoption of fluorescent lights. We already knew that neon lights on business signs were a detriment to AM DX, but most of us did not live above stores or next door to such signs. Fluorescents slowly made their way into the home, but were hampered by the need for new fixtures, transformers and quirky bulbs.
TV set were the next phase in the increase of Medium Wave band increasing interference.
Excellent point. (I forgot about the neons and fluorescents)
It's been many years since I've heard the harmonics of the 15750 Hz synch oscillator on the AM BC Band, or the the 15750 Hz audio from the TV. Between hearing losses of high frequencies, designs to minimize the audio and RF harmonics, and total redesign of TV receivers, you just don't hear it anymore.
I could hear the harmonics on the AM radio from neighboring houses when there was no TV on in the house.
I could hear the harmonics on the AM radio from neighboring houses when there was no TV on in the house.
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Great thoughts from everyone on conductivity and fault zones. I wanted to add one further point of interest: not all faults are created equal. Many ordinary faults are just fractures where the earth is "settling" or "stretching its arms." But plate boundary faults, in particular, move past one another (e.g. San Andreas), or subduct (e.g. Indian continent), over enormous distances through eons. I once heard a seismologist say that if human civilization is still possible in the state of California one million years from now, the Los Angeles Dodgers and Oakland As will eventually play the fall classic together as a freeway series. On that note, the deep soil and rock layers on the west side of the San Andreas fault are from some ancient location quite different from what's beneath the topsoil on its east side. Sudden discontinuity in conductivity because of mineral composition changes was my primary thinking as far as there being any possibility of meaningful distortions in groundwave propagation, if anything could do that at all.
Have any of you ever seen this delightful AT&T archival video on wave behavior (standing waves, reflections, cancellation) upon enconutering discontinuities in physical and electrical mediums? It makes the mind consider potential effects beyond simple attenuation, like, theoretically, reflections and various degrees of cancellation in the event of multiple discontinuities "ping ponging" small amounts of RF energy around the basin of a valley, for instance. Could AM be subject to multipath effects in ground with crustal defects the way FM is in a city full of skyscrapers? Could this sort of behavior be behind the KFWB phenomenon @fybush mentioned?
Have any of you ever seen this delightful AT&T archival video on wave behavior (standing waves, reflections, cancellation) upon enconutering discontinuities in physical and electrical mediums? It makes the mind consider potential effects beyond simple attenuation, like, theoretically, reflections and various degrees of cancellation in the event of multiple discontinuities "ping ponging" small amounts of RF energy around the basin of a valley, for instance. Could AM be subject to multipath effects in ground with crustal defects the way FM is in a city full of skyscrapers? Could this sort of behavior be behind the KFWB phenomenon @fybush mentioned?
It would be fun, before AM completely dies, to take DC DXing gear into one of those colossal quiet zones and spend a week listening to skywave late at night, one last time. With my Qodosen DX-280 in southern California late last night, I heard all the usual locations (California itself, Arizona, Utah, New Mexico, and Texas), but was surprised to additionally snag KOKC 1520 Oklahoma City, KRKK 1360 Rock Springs Wyoming, and apparently, WPGP 1250 Pittsburgh, WHO 1040 Des Moines, and WIBA Madison. As sensitive and selective as this little tuner is (it hears 99% of the stations radio-locator.com says my zip code should in the daytime, even indoors with noise sources like desktop PCs right next to me), I bet that it would really shine in one of those "great RF outbacks."
AM in some form will likely outlive you, so there's still time to test.
Back in the late 1960's and early 1970's there was excellent reception on the New Orleans top 40's (WTIX and WNOE) if you were within a couple of miles of the Gulf as far as Pensacola. On a fishing boat (diesel) thirty or 40 miles out of Panama City you would get all kinds of AM stations during the day. IIRC when you tuned a from station to station, if there was an empty channel there was no static. Last time I drove over the I 10 bridge (1999) leaving New Orleans headed to Mobile WWL got louder on the East end of the bridge. If you get out an old pre Hurricane Camille map of Biloxi MS, you see where WLOX had their antenna at the end of a pier.
Next time I am at Saint George island, most likely 2026 (as long as nobody dies) for the rotating family Thanksgiving dinner, I will see how bad the junk RF signal is. It won't be scientific just a hybrid car radio.
BTW except for your car, it really "quiet" around Green Bank WV. That facility does interplanetary DXing. Also take a portable radio when you ride the Cass Tourist rail way all the way to the top. Limited 19th century equipment. Amazing daytime reception on both AM and FM.
Once I'm on my feet again (two more weeks!) one of the things I want to do, maybe next year, is to drive out to the eastern plains of Colorado and see what it's like there. I was in Burlington, Colorado near the Kansas border in 1982, where the major Denver AMs of the time - KLZ, KHOW, KOA - all had good coverage. I recorded them, too. A comparison with >40 years later would be instructive.
As it is, I'm on the very western edge of those plains. I sometimes joke that Kansas really begins at the intersection of Josephine-York and Colfax. It's surprising what I've been able to pull in, though some of it is at noise levels that no normal person would tolerate.
You might want to check out one of my former employers: KIUL Garden City KS. Back in the 1990's they would usually stop the scan as far east as Greensburg. At that time they converted more "populated" area than it's sister KWKR which was hampered by a power reduction due to be cross owned by the G. C. newspaper.
It was a Harris station which somehow was related to the Harris printing press people. I have never seen a station before where everything except the ITC card machines and the EBS box was all Harris.
It's going to be 2025 before I can do any extensive traveling in-state. Another challenge is dealing with a spouse who hates long-distance driving.
Looks like the electrical height of the KIUL antenna is 218° and it dates from late 1976. Even though it's on a graveyard channel (1240), those attributes should give it some heft compared to the typical class C station.
There's a feeble heterodyne on 1240 that's constant at my Denver location in the daytime, but I figure that's coming from a mix of Colorado Springs (KRDO) and Cheyenne, Wyoming (KFBC). I think KIUL is too far away to enter the picture. There may even be some interference from local KLDC's HD carriers centered on 1220.
In other words, Gates equipment, after Harris acquired Gates.
I think KHOW still gets in to Western Kansas, there have been a few callers to Tom Martino’s show from there. KOA probably does too, since I’ve gotten it fading in and out some nights here in Eastern Kansas.
When I was in Western North Dakota about 14 years ago, near Bismarck, I got KNX crystal clear during the daytime. There were some stations in from Regina, Saskatchewan too.
Around 30 years ago, whenever I was in Lawrence around sunset (probably buying CDs at Kief's), KOA came in quite well.
KNX is a regular in Denver once the sun goes down in Los Angeles. It's of moderate strength and there is some noise.
As has often been said hereabouts, noise is the real problem with AM radio.
Cool, did you ever go to Love Garden?
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