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Old 12-08-2008, 10:03 AM
 
Location: Pittsburgh, PA
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I have a baby monitor i use at night for my dd. Why is it, in the winter time, I get radio stations or weird conversations interfering with my reception? It never happens in the summer time, only in colder weather. Why? Why only in the winter? What can I do to stop it? I am finding myself laying there at night listening to some kind of voices and it drives me batty! It is continuous and it does not stop as long as it is on. Any input??
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Old 12-08-2008, 10:16 AM
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Location: San Antonio
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Baby monitors use the same frequencies as older cordless phones. Maybe you have a neighbor who has a cordless phone that they only use in the winter?
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Old 12-08-2008, 10:01 PM
 
Location: Maryland not Murlin
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Bed springs (in a box spring mattress) and metal fillings in teeth have also been known to pick up a radio signal.
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Old 12-09-2008, 10:51 AM
 
Location: Beaverland, OR
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Sounds like your baby monitor uses frequencies near the HF radio band, whose behavior is strongly influenced by the condition of the ionosphere, a charged group of layers in the earth's atmosphere.

Certain levels of the ionosphere are denser (more heavily charged) in winter than in summer. This means they can reflect radio waves from far away locations. You may be hearing radio stations or two way transmissions from quite a distance when this happens.

Solution: get a baby monitor that uses a higher frequency band, either 900MHz or 2.4GHz. Make sure you don't have a cordless phone that operates at these frequencies, though, or you'll will get more interference. The frequency-hopping algorithms in most modern cordless phones will mitigate the interference risk, but it is still present to some extent.
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Old 12-10-2008, 12:27 AM
 
Location: Somewhere in northern Alabama
11,701 posts, read 26,972,989 times
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Quote:
Originally Posted by *Danielle* View Post
I have a baby monitor i use at night for my dd. Why is it, in the winter time, I get radio stations or weird conversations interfering with my reception? It never happens in the summer time, only in colder weather. Why? Why only in the winter? What can I do to stop it? I am finding myself laying there at night listening to some kind of voices and it drives me batty! It is continuous and it does not stop as long as it is on. Any input??
LOL! Makes you have second thoughts about those poor folks who hear voices, huh?

Propagation of radio waves and interference is a part of using the radio spectrum. I used to listen to Cousin Brucie in NYC on AM radio, even though I lived a long way away. Atmospheric effects always played a part.

Consider it an honor that you can listen in on shortwave and other conversations, but also consider a wired monitor for any serious listening to baby.
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Old 12-11-2008, 12:58 PM
 
Location: Hopewell New Jersey
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Or it could be aliens talking to each other as in the movie Signs. (Mel Gibson)
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Old 12-30-2008, 11:20 AM
 
Location: Victoria TX
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Distant radio signals on certain frequencies can follow a "skip" pattern during hours of darkness, but not in daylight, when the suns rays affect the ionosphere differently. The signal hits the ionosphere and bounces back to earth only when that part of the ionosphere is in dark, shielded by the earth from sunlight. There are many more hours of darkness in winter, then your house is susceptible to receiving these interfering signals. That's why you can get a constant spectrum of stations through the entire AM radio band when it is dark out, but not in the daytime. You are probably noting an increase in this interference that is related to darkness, rather than cold. This can happen even though it is daylight at your house, as long as there is a darkened ionosphere within a couple of hundred miles of you.
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Old 12-30-2008, 01:09 PM
 
Location: Texas
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Another thing is that the FCC mandates that daytime stations power town, presumably so weaker stations can operate. I get the feeling that this regulation is a little too sweeping.
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Old 12-30-2008, 05:17 PM
 
Location: Somewhere in northern Alabama
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Originally Posted by Brian.Pearson View Post
Another thing is that the FCC mandates that daytime stations power town, presumably so weaker stations can operate. I get the feeling that this regulation is a little too sweeping.
No, it actually makes a lot of sense. My father used to build and run radio stations. I remember many a trip around the countryside with him taking field strength meter readings for one station. That station had a directional array, meaning that the signal was allowed by the FCC to go farther in directions where it would not interfere with other stations. 50K watts during the daytime covers about the same area as 10K watts at night (with a whole lot of technical caveats and such).

Part of the problem is that skip is not consistent. A skip of 500 miles might happen easily one night, and the next night be a dud. The opening up of the FM band and different type of circuitry eliminated a lot of the problems for new stations, but the AM band sits where this will always be an issue. Radio wave propagation is a science in itself.
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Old 12-30-2008, 05:39 PM
 
Location: Texas
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Maybe someday they'll figure out how everybody can get the radio they want. I know some of it is on the Internet.

If I'm driving between Amarillo and Lubbock (about 125 miles apart) at night, I get hardly anything on my car radio.

But occasionally, I do hear a station in the Dallas/Ft Worth area (actually coming from Arlington) when conditions are just right.
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