I wonder if I'm the only one here who is already kind-of used to this forum software, having already been active on other forums that have used it for at least a couple years or so now? I do agree there are some wrinkles that need to be ironed out. I definitely would like to change my display theme, but there's nothing else available that I can see, except mobile. (I prefer desktop mode, even on my Android phone.)
Speaking of "dreams" ... well idk if you'd call these "dreams", but there's a couple scenarios I've thought about, wondering what it'd be like if they actually happened.
Scenario 1 (multi-part)
You're a schoolteacher taking a couple dozen or so preteen-age kids on a cross-country field trip in a tour-type bus. (These kids are basically 5th to 8th graders, and a few of them are your own kids.) The trip can be for whatever reason, but you'll also include a little bit of science here and there.
You've already taught them some things about radio - for example lower frequencies get out farther on AM, higher power is also heard farther, better antennas are heard farther away as well. You haven't yet taught them about e-skip, tropo, etc, but have in passing mentioned the basics about AM nighttime skywave.
You start by leaving the school campus, located somewhere in NH or VT, around lunchtime. There's a Radio Disney outlet (or similar-format station that's popular with that age group) somewhere in the 600s or maybe low 700s that runs 50kW daytime non-directional into a half-wave antenna. Their tower is adjacent to the school, and you go right by the billboard that announces their frequency, call format, 50kW and 1/2-wave antenna, as you're pulling out of the parking lot.
By the time you're about a 60-mile radius from the transmitter, the station is pretty much completely lost in the noise - if you hear anything, it'd be the occasional cymbal crash every 45 seconds or so, or if the radio had that feature, a barely audible heterodyne from a BFO.
So you and the kids agree... ok, so it looks like a low-band 50kW station with a good antenna is gone by 60 miles.
A couple days later, you're in the midwest / great plains, where the ground conductivity is much better (but the kids haven't learned about that yet). You all have an early breakfast after checking out of the hotel, then get on the road.
As you're on your way to the interstate, you pass the transmitter of another Radio Disney outlet. This one's somewhere in the 1300s, 5 kW, and uses a tower JUUUST short enough to avoid needing paint and lights. You and the kids remember the other 50kW station in the 600s that barely made it to 60 miles, so you decide to see how far this one goes. The kids quickly get distracted, and forget about it, although you leave the radio on.
Maybe about 4.5 hours later, if not sooner...
"Hey teacher? Are we still listening to that same sta---" (she's interrupted by their TOH ID) "OHMYGOSH!! My GPS on my phone says we're 360 miles from their transmitter, and yet it's still a perfectly clear signal! Well ok there is some road noise that could be masking the radio's noise, but still!! How is that even possible!?!?"
Then you take the opportunity to explain ground conductivity.
At the end, you add something like "you think this is good? this is nothing compared to -- well I'll show you when we get to the west coast."
Then, on a deserted beach (or Gary Debock's cliffside FSL DU DXing venue off Highway 101) in Washington (or Oregon), you turn the engine off, and tune in a station in the 1600s, that's not on the 10kHz frequency plan. The signal is perfectly clear - so much so, in fact, that if you crank the volume up so the music is comparable to sitting next to the speaker at a Disney concert, then the unmodulated carrier would be so silent that the kids couldn't tell when you switched the radio off.
"Hey, this isn't a frequency divisible by 10 like USA stations are. Where is---" (then "__________, Melbourne!" identifies) "--WOW!!!"
You explain saltwater. "But even so, wouldn't they have to be using extremely high power to be getting this distance?"
"Not necessarily. Remember what I taught you about transmitter and antenna safety - how you don't climb tall towers without proper equipment, and you don't touch high powered transmitting antennas without shutting it off first? Check this out." You pull out your tablet and show them the live video feed - of preschool-age kids climbing the on-air(!) transmitting antenna, unsupervised, completely safe.
Yes, I know I'm dreaming.
Or, WOULD it be possible to have that big of a difference in ground conductivity? Where, for example,
50kW on 620 with a 1/2-wave antenna would, over poor ground, have a 0.1dB S/N ratio at 60 miles,
5kW on 1350 with a 198-foot antenna would, over good ground, have a ~40dB S/N ratio at 360 miles,
500 milliwatts on 1683 with a 5-foot antenna would, over saltwater, have a 120+dB S/N ratio at 7500 miles.
Scenario 2
This one involves a (fictitious) high-band AM station on a "clear channel" common with the 9kHz plan, maybe somewhere in the west central Great Plains. (I'm thinking 1530 kHz.) It'd be far enough from KFBK and WCKY that night operation would be possible as a Class B with a very directional antenna.
There's a very conservative community that combines retirees and their school-age grandchildren (and families, etc) that's some distance outside the COL on the other side of the towers. Due to the non-directional day pattern, though, it's a good clear signal at midday. It's far enough away so that around sunset/sunrise it'd be possible to hear the 10kHz heterodynes from adjacent channels, and residual spits from adjacent skywave stations now and then, and KFBK or WCKY might also be copyable by a DXer with good ears. I don't expect it'd have its own skywave/groundwave cancellation, though. I'm thinking the distance between conservative community and transmitter would be such that if there was an FM on there, an LPFM would be undetectable, and a Class C would be switching back and forth between stereo and mono on a PL-390 or XDR-F1HD.
BTW that community is conservative in the extreme - saying relatively tame words like d@rn in their hearing would be about like someone else saying f**k to their Baptist or Catholic grandmother!
and seeing a hint of cleavage revealed by a woman's shirt would to them be like full on hardcore you-know-what to a Catholic nun.
There's a program on that's VERY popular (counting that community alone, it'd get a 99+ share on a BAD(!) day) with those people. I'm not thinking a religious program, but at least as family friendly as anything imaginable. So they're listening to it around dinner time... then the host has to say goodbye right before a break in the program, due to a pattern change that will cause those listeners to lose the signal completely.
And boy will they lose that signal upon pattern change! The night pattern's null is so deep toward them - that a groundwave signal circling the planet all the way around the other way, assuming 0.1 mS/m conductivity (remember this is 1530 kHz), would be 100+dB STRONGER than the combined peak direct groundwave (assuming 5000 mS/m conductivity for purposes of calculation) and skywave from direct reception!
To make matters worse...
there's a station somewhere in or near south central Asia, that switches to ITS day pattern at the same time. This Asian station is a few hundred km away from its COL, and has to use extremely high power and a very directional array to be heard to the north - for example 40 Franklin antennas, each fed with its own 2 MW transmitter. Ground conductivity is so bad it'd make Long Island look like saltwater, and noise is so bad in that city that a 316mV/m signal wouldn't even produce a heterodyne or carrier on a SDR.
Naturally, having such a high powered focused signal would be aimed over the pole, and could be a huge signal in part of the US, including where this conservative community is. Of course I'm guessing I'm dreaming to think that the signal would be so strong as to be like
this video of my PL-606 overloading from KCBQ, with NO antenna hooked up to the receiving radio.
Not to mention the language in the heavy metal music (or whatever) they happen to be playing (in English, because NONE of their audience could tell the difference between that and Mandarin Chinese) would be so vile as to - remember how conservative I said the "local" community of retirees and their school-age grandchildren is? This would be the other way - for example it'd make the F-word seem like a very polite term you'd use at Sunday School!
Of course that's just a conjured up dream so I expect it'd never happen ... but I wonder what the reaction of the people in that community, and the FCC, would be if it did?
Scenario 3, speaking of poor ground conductivity...
Would I be dreaming, or is it possible there could be a city that combines a large area within the city limits with extremely poor ground conductivity, so that ....
you could have TWO co-channel 50kW omnidirectional stations below 1100 kHz, with their protected (100µV/m) groundwave contours entirely contained within the city limits, with half-wave antennas, and (also) like Class A, protecting each other so one's 5µV/m doesn't overlap the other's 100µV/m?
Or has the board software also affected my dreams?
