A M Radio Static
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AM radio inherently is susceptible to interference. AM radio is "amplitude modulation" so anything that varies the STRENGTH of the incoming signal is heard as an audio signal. (eg: bad plug wire causing a tick-tick-tick sound).
FM is "frequency modulation" and is almost immune to outside interference. That's why it was embraced as the method of choice by most stations.
FM is "frequency modulation" and is almost immune to outside interference. That's why it was embraced as the method of choice by most stations.
AM (amplitude modulation) has the sound information transmitted through varying amplitude for a given frequency. Any nearby electronic emissions by appliances or electric discharge is transmitted through the air that over shadows any radio amplitude transmission. This is equivalent to having a conversation with someone and a nearby louder sound by a passing Harley or train horn drowns out your conversation. Those sounds have higher [louder] amplitudes than your conversation.
The world has grown since 1920, when AM was all they had, and you had light bulbs and if lucky a vacuum cleaner running on electricity, so the noise was not there when it got popular. It's still around because a licensed "clear channel" AM station has advantages with the ionosphere and can be heard coast-to-coast after dark (another advantage.)
You would have to shield all your appliances with (more) metal to block the electrical noise escaping. You could try an external AM antenna (wire loop) which you can rotate for the strongest signal, if your receiver supports it. Also most receivers have pretty cheezy AM pickup, as the manufacturer considers it vestigial.
http://en.wikipedia.org/wiki/Electromagnetic_interference
You would have to shield all your appliances with (more) metal to block the electrical noise escaping. You could try an external AM antenna (wire loop) which you can rotate for the strongest signal, if your receiver supports it. Also most receivers have pretty cheezy AM pickup, as the manufacturer considers it vestigial.
http://en.wikipedia.org/wiki/Electromagnetic_interference
Originally Posted By: Jerryb
This board has the most knowledgable people. Why is there so much A M radio static from microwave, lights, washer, wireless phones etc.?? What can I do about it? Keep your answers simple. Thanks
Depends on your radio, signal strength, orientation, quality of front-end. First, turn it in a complete circle while listening to your station. Does the noise level decrease at any point? Station signal strength improve? Second, lay it down and rotate. Does it help?
If there's not enough signal for the front end to lock on to (full quieting), all kinds of noise will be heard. If your radio has 'fine' tuning (1kHz steps), this may help to tune above or below the set freq.
Some stations will be stronger during the day, then fade at night due to FCC power rules. Others you'll only be able to receive at night. They'll fade as the Sun rises.
CCrane sells a quality AM radio (I own one) + AM antennas that may help.
This board has the most knowledgable people. Why is there so much A M radio static from microwave, lights, washer, wireless phones etc.?? What can I do about it? Keep your answers simple. Thanks
Depends on your radio, signal strength, orientation, quality of front-end. First, turn it in a complete circle while listening to your station. Does the noise level decrease at any point? Station signal strength improve? Second, lay it down and rotate. Does it help?
If there's not enough signal for the front end to lock on to (full quieting), all kinds of noise will be heard. If your radio has 'fine' tuning (1kHz steps), this may help to tune above or below the set freq.
Some stations will be stronger during the day, then fade at night due to FCC power rules. Others you'll only be able to receive at night. They'll fade as the Sun rises.
CCrane sells a quality AM radio (I own one) + AM antennas that may help.
Originally Posted By: Papa Bear
AM radio inherently is susceptible to interference. AM radio is "amplitude modulation" so anything that varies the STRENGTH of the incoming signal is heard as an audio signal. (eg: bad plug wire causing a tick-tick-tick sound).
FM is "frequency modulation" and is almost immune to outside interference. That's why it was embraced as the method of choice by most stations.
To simplify this a bit. Amplitude Modulation is like varying the "volume" of the signal. The problem with this approach is any noise is added to the signal and when received, the receiver has no way to distinguish between what was the original signal, and what is added noise, so the receiver simply plays it all back to you.
With FM, frequency modulation, even if the noise gets added to the signal, it matters less because the receiver is using the frequency of the signal, not the amplitude to extract the intelligence out of the signal. Think of FM as if someone varied their pitch from a low tone to a high tone. Pitch, or in this case frequency changes of the signal are not impacted by most electrical noise, so the receiver can more accurately reproduce the original broadcast in spite of the noise.
They both have their place in broadcasting as both have advantages and disadvantages.
You don't hear any FM stations over the air from the other side of the nation at night because they don't get the skip wave you can get with some AM stations at night. So with AM, you can get greater range, but at the cost of more potential noise.
I don't know if it's still used, but when I was in the Army, we still had radio teletypes using AM radios for the range.
AM radio inherently is susceptible to interference. AM radio is "amplitude modulation" so anything that varies the STRENGTH of the incoming signal is heard as an audio signal. (eg: bad plug wire causing a tick-tick-tick sound).
FM is "frequency modulation" and is almost immune to outside interference. That's why it was embraced as the method of choice by most stations.
To simplify this a bit. Amplitude Modulation is like varying the "volume" of the signal. The problem with this approach is any noise is added to the signal and when received, the receiver has no way to distinguish between what was the original signal, and what is added noise, so the receiver simply plays it all back to you.
With FM, frequency modulation, even if the noise gets added to the signal, it matters less because the receiver is using the frequency of the signal, not the amplitude to extract the intelligence out of the signal. Think of FM as if someone varied their pitch from a low tone to a high tone. Pitch, or in this case frequency changes of the signal are not impacted by most electrical noise, so the receiver can more accurately reproduce the original broadcast in spite of the noise.
They both have their place in broadcasting as both have advantages and disadvantages.
You don't hear any FM stations over the air from the other side of the nation at night because they don't get the skip wave you can get with some AM stations at night. So with AM, you can get greater range, but at the cost of more potential noise.
I don't know if it's still used, but when I was in the Army, we still had radio teletypes using AM radios for the range.
OP - is it a battery powered radio ? Try running it on battery power and see if helps with the static.
Most common sources of this static and noise are SMPS type power supplies which are now in every small-mid appliances around the house and motor brush static noise and relays clicking on and off.
SMPSs throw a lot of noise back on to the power lines. Essentially the wiring of the whole house becomes a huge antenna "broadcasting" all that noise. There is not much you can do if you live in a densely populated area. If you are a little isolated you could put surge suppressors on all appliances, that might help cut the hash that goes back into the power lines.
Most common sources of this static and noise are SMPS type power supplies which are now in every small-mid appliances around the house and motor brush static noise and relays clicking on and off.
SMPSs throw a lot of noise back on to the power lines. Essentially the wiring of the whole house becomes a huge antenna "broadcasting" all that noise. There is not much you can do if you live in a densely populated area. If you are a little isolated you could put surge suppressors on all appliances, that might help cut the hash that goes back into the power lines.
I assumed he was talking car radio.
unless he is hauling (and using) the microware, washer etc..in the car
Electromagnetic waves are generated by electrical arcs (sparks). Electromagnetic waves from sparks can be picked-up by AM radios as "interference". For example, lightning is basically a huge spark, and we've all heard the crash of lightning on an AM radio.
Another common source of electrical arcs is brush-type electric motors such as found in a vacuum cleaner. The whine heard on an AM radio is basically the electricity flow being interrupted by the brushes and commutator in the electric motor. The frequency of the whine = the number of interruptions per second.
Some solid state speed (power) controllers interrupt the flow of electricity by "chopping" the line voltage sine wave, they can be "noisy" too.
Wireless telephones use radio waves. I'm not 100% sure of this, but I believe that while wireless phones use higher frequencies, they may at times produce repetitive bursts of radio waves where the frequencies of the bursts fall into a region to cause interference. I have noticed occasionally hearing certain patterns of buzzing on computer sound systems that is attributed to cell phones "pinging" the cell tower.
When you think about all the radio signals zipping around (both intentional transmissions and unintentional interference, both man-made and natural)it's a wonder there isn't more "cross-talk" and that everything works as well as it does.
PS I'm a mechanical engineer, not electrical, but I have been hanging around with them for a few decades so some of it rubbed off.
Another common source of electrical arcs is brush-type electric motors such as found in a vacuum cleaner. The whine heard on an AM radio is basically the electricity flow being interrupted by the brushes and commutator in the electric motor. The frequency of the whine = the number of interruptions per second.
Some solid state speed (power) controllers interrupt the flow of electricity by "chopping" the line voltage sine wave, they can be "noisy" too.
Wireless telephones use radio waves. I'm not 100% sure of this, but I believe that while wireless phones use higher frequencies, they may at times produce repetitive bursts of radio waves where the frequencies of the bursts fall into a region to cause interference. I have noticed occasionally hearing certain patterns of buzzing on computer sound systems that is attributed to cell phones "pinging" the cell tower.
When you think about all the radio signals zipping around (both intentional transmissions and unintentional interference, both man-made and natural)it's a wonder there isn't more "cross-talk" and that everything works as well as it does.
PS I'm a mechanical engineer, not electrical, but I have been hanging around with them for a few decades so some of it rubbed off.
continuation...
Well, you could wrap your radio in metal foil. That would keep the interference out. (of course you wouldn't receive much...)
Seriously, try moving the radio, adding filters to electrical noise generators, there's not much you can do, it's just the nature of AM radio.
The birth of FM radio was a long and laborious process. AM radio was well entrenched and there were forces at play that stymied the development of FM radio. Here's a link to a Wikipedia page: Edwin Howard Armstrong
Sorry, I got going there, I find it an interesting subject.
Well, you could wrap your radio in metal foil. That would keep the interference out. (of course you wouldn't receive much...)
Seriously, try moving the radio, adding filters to electrical noise generators, there's not much you can do, it's just the nature of AM radio.
The birth of FM radio was a long and laborious process. AM radio was well entrenched and there were forces at play that stymied the development of FM radio. Here's a link to a Wikipedia page: Edwin Howard Armstrong
Sorry, I got going there, I find it an interesting subject.
Originally Posted By: youdontwannaknow
unless he is hauling (and using) the microware, washer etc..in the car
Well, my older cars get a lot more static on the AM band than my newer cars. I guess I was just wishing.
unless he is hauling (and using) the microware, washer etc..in the car
Well, my older cars get a lot more static on the AM band than my newer cars. I guess I was just wishing.
probably due to modern(digital) very high Q (narrow band) notch filters at 60hz and 3-4 multiples of 60hz, and sharp cut off low pass filters just before the noise spectrum. That would eliminate most of the noise.
The notch filters are so narrow that they dont really affect the information(audio).
The notch filters are so narrow that they dont really affect the information(audio).
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