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Radio waves, satellites and stuff

RoseCat

RoseCat

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So this has been bugging me for a long time, and I know there are some brainiacs here who might be able to shed a light on this very important first world complaint. :rolleyes: I'll try to be as succinct as possible:

I have a 50 minute drive to work every day, morning and evening. During my commute I listen to an AM news radio station (weather, news, sports) that covers the New York metro area (I live an hour south of that metro area).

When I leave in the morning heading north (towards the radio station) the station starts off a little fuzzy, but "hearable", and within about a mile or less is crystal clear the entire way to work.

When I leave work in the evening the station is crystal clear, but there is an area - an EXACT area that I can almost time with a watch or plot on a map - about 18 miles north of home when the signal goes out. All of a sudden it's all garbled alien sounds and static. Some days it's really bad and lasts that way for the rest of the way home. Sometimes it comes back a bit to where I can kind of understand what they are saying. Sometimes there are two radio stations intermingling together (my station and another), and, most weirdly of all, sometimes that other station comes through almost crystal clear. Wanna know where that station is located? TORONTO, CANADA, about 500 miles north. (There was a period of time several/many ?? months ago when the NYC station stayed clear and pretty strong the entire commute home... :alien: )

So I'm left with these unanswerable, burning questions:

  1. Why is the station fine in the morning as I am starting off at the furthest point away from the station? Shouldn't it be super fuzzy/unintelligible until I hit that point 18-ish miles north?
  2. Why, when I turn my car off upon arriving at home, is the station garbled, but when I get back in my car in the morning it is almost perfectly clear? The car has been sitting in a parking lot, not moving.
  3. That same area that makes the radio station unclear is also an area that, if I'm talking on my iPhone (hands free over my car speakers, 'natch) the person who I'm talking to will suddenly not understand/hear what I'm saying (although I can hear them perfectly) and sometimes the call might drop out. But again, that usually only happens on my way home, not in the morning heading north.
I totally get that as you drive away from a station, reception can get fuzzy or it disappears altogether and you pick up another station the farther you drive, but these occurrences just aren't making any sense to me.

Explain, please and thank you. :mobibabe:
 
I've got only a passing acquaintance with radio, so this is all subject to correction by any of the many people who know more about it than I do.

Radio signals radiate in many directions, some parallel to the ground (more or less) and some into the sky. Those radiating into the sky can bounce off the ionosphere and be reflected back to earth -- that's known as "skip." The skip distance varies according to not only the power and frequency of the signal but also the atmospheric conditions, which can change day to day or even hour to hour.

Skip is likely the reason that you sometimes receive the station from Toronto.

There can also be a dead zone for a particular station -- an area of poor or no reception that falls in between the area covered by radio signals moving parallel to the ground and the area covered by skip.

In addition, although commercial radio licensing attempts to control interference between stations transmitting on the same (or nearly the same) frequency by controlling their physical location and transmitting power, there can still be areas where two such stations overlap (like the overlapping circles of a Venn diagram). So you might find that even though you are moving toward a station in NYC, you may also be coming into the range of another station located somewhere else (and this can also be affected by the skip).

I'm sure there's more, but I've already gone somewhat beyond what I actually know.:D
 
WOW. :notworthy: I knew you'd know something.

terse said:
Skip is likely the reason that you sometimes receive the station from Toronto.
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Cool! Thank you for clearing this bit up!

terse said:
There can also be a dead zone for a particular station -- an area of poor or no reception that falls in between the area covered by radio signals moving parallel to the ground and the area covered by skip.
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Yes, this makes sense and I figured it was something like this. But what is weird/sense-less to me is that this dead zone seems to only be on the side of the Turnpike heading North ---> South, as when I'm traveling to work in the morning, heading South ---> North it doesn't seem to happen. Can dead zones be actually that specific, like on one side of the turnpike vs the other?
 
terse said:
That doesn't seem likely, no. But it might have to do with the time of day (atmospheric conditions in the morning vs. evening) rather than which side of the turnpike you're on.
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I wondered about weather.... but it still seems weird because it's so consistent, i.e. particular side of the road, and weather seems like it would not be consistent/predictable. This bit may just remain a mystery forever.
 
RoseCat said:
I wondered about weather.... but it still seems weird because it's so consistent, i.e. particular side of the road, and weather seems like it would not be consistent/predictable. This bit may just remain a mystery forever.
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It's not your local weather that's having an effect; it's the ionosphere, which varies between day and night.

From https://electronics.howstuffworks.com/question1.htm

Certain radio stations, however, especially the short-wave and AM bands, can travel much farther. Short-wave can circle the globe, and AM stations transmit hundreds of miles at night. This extended transmission is possible is because of the ionosphere -- one of the layers of the atmosphere. It is called the ionosphere because when the sun's rays hit this layer, many of the atoms there lose electrons and turn into ions.

As it turns out, the ionosphere reflects certain frequencies of radio waves. So the waves bounce between the ground and the ionosphere and make their way around the planet. The composition of the ionosphere at night is different than during the day because of the presence or absence of the sun.
​
If I'm right (always questionable) and it is the ionosphere that's causing these effects, then if you happen to be driving home from work in the morning (after pulling an all-nighter, say), you should have the same reception at the same spots as you do when driving to work in the morning.

Things like mountains can also affect reception. we live in a little valley outside of Santa Cruz, and radio, TV, and cell phone reception are all poor until we get close to town. In our neighborhood, reception can vary from poor in one place to non-existent just around the corner.
 
terse said:
It's not your local weather that's having an effect; it's the ionosphere, which varies between day and night.

From https://electronics.howstuffworks.com/question1.htm

Certain radio stations, however, especially the short-wave and AM bands, can travel much farther. Short-wave can circle the globe, and AM stations transmit hundreds of miles at night. This extended transmission is possible is because of the ionosphere -- one of the layers of the atmosphere. It is called the ionosphere because when the sun's rays hit this layer, many of the atoms there lose electrons and turn into ions.

As it turns out, the ionosphere reflects certain frequencies of radio waves. So the waves bounce between the ground and the ionosphere and make their way around the planet. The composition of the ionosphere at night is different than during the day because of the presence or absence of the sun.
​
If I'm right (always questionable) and it is the ionosphere that's causing these effects, then if you happen to be driving home from work in the morning (after pulling an all-nighter, say), you should have the same reception at the same spots as you do when driving to work in the morning.

Things like mountains can also affect reception. we live in a little valley outside of Santa Cruz, and radio, TV, and cell phone reception are all poor until we get close to town. In our neighborhood, reception can vary from poor in one place to non-existent just around the corner.
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Wow!! Thanks Ted!!!! I bet it’s totally the ionosphere making this happen. AND, if I’m remembering correctly, I think it was summer when things were more normal, which makes sense because it was still light out when I was driving home.

YOU. ROCK.

:notworthy::notworthy::notworthy::notworthy::notworthy::notworthy:
 
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RoseCat said:
Good question... but since I only listen to 1010 WINS, err... o_O
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Aside from your excellent technical responses, perhaps a little experimentation is in order? Radio station location plays a part, I’m sure. Also, there’s the audio package and antenna for your car. Ionosphere may be the major factor, but they all contribute.
 
A lot of the reason why many stations switched to FM was less susceptibility to interference, and of course being able to transmit stereo. I fully expected AM stations to be phased out after a while. If you ever have a chance to look at the antennas close up you will see a lot of effort is put into shaping the strength of the signal heading in different directions. It isn't simply a spherical signal radiating equally from the antenna in all directions. There may be natural things between you and the antenna blocking of partly blocking the signal. Tall buildings can cause weak spots in the signal. They may be limiting the signal strength in particular directions to avoid interfering with other stations or other radio frequency devices. The signal may also be reflecting off things and arriving slightly out of phase which would cause partial cancellation of the signal.
In recent years there has been a lot of messing around with the atmosphere in the attempt to control weather and also to improve military radio signals by seeding the atmosphere with nano aluminum, which increases the range of radio signals somehow. I would imagine nano aluminum in the atmosphere would assist "skip" as well.
 
FundyBrian said:
In recent years there has been a lot of messing around with the atmosphere in the attempt to control weather and also to improve military radio signals by seeding the atmosphere with nano aluminum, which increases the range of radio signals somehow. I would imagine nano aluminum in the atmosphere would assist "skip" as well.
Click to expand...
UGH!!!! That sounds like something from a Sci-Fi movie. :mad: :barf:
 
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