| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
19 Apr 2007 08:16:45 AM |
| Object: |
A really simple question |
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
in means of static fields that affect AM, but doesnt FM.
Why an Amplitude is being affected by static fields, but frequency is
not?
Thank you all!
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| User: "Sam Wormley" |
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| Title: Re: A really simple question |
20 Apr 2007 12:41:26 AM |
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wrote:
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
in means of static fields that affect AM, but doesnt FM.
Why an Amplitude is being affected by static fields, but frequency is
not?
Thank you all!
Communication Channel Capacity
http://www.qsl.net/n9zia/capacity.html
Greater channel capacity ==> greater noise immunity
A Mathematical Theory of Communication by Claude E. Shannon
http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html
http://cm.bell-labs.com/cm/ms/what/shannonday/shannon1948.pdf
Claude E. Shannon
http://scienceworld.wolfram.com/biography/Shannon.html
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| User: "Sam Wormley" |
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| Title: Re: A really simple question |
19 Apr 2007 05:07:05 PM |
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wrote:
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
in means of static fields that affect AM, but doesnt FM.
Why an Amplitude is being affected by static fields, but frequency is
not?
Thank you all!
What is the effect of bandwidth? Commercial radio AM and FM bandwidths
are substantially different.
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| User: "H. Wabnig .... .-- .- -... -. .. --. @ .- --- -. DOT .- -" |
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| Title: Re: A really simple question |
19 Apr 2007 01:41:32 PM |
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On 19 Apr 2007 06:16:45 -0700, "saduikis.tomas@googlemail.com"
<saduikis.tomas@googlemail.com> wrote:
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
AM is not worse than FM, it depends.
If the signal is very weak, one will always be able to pick up
something from AM, while on FM there is only distorted noise
coming out of the receiver.
in means of static fields that affect AM, but doesnt FM.
Static creates noisy amplitude variations in the receiver.
Because the amplitude variations get filtered out on FM,
FM is better as long as signal reception is good.
Only on weak signals FM ain't not that good.
Why an Amplitude is being affected by static fields, but frequency is
not?
Because the noise adds to the signal on the receiver side,
while the frequency sent by the transmitter remains unaffected.
Thank you all!
You are welcome.
w.
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| User: "Igor" |
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| Title: Re: A really simple question |
19 Apr 2007 11:34:05 AM |
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On Apr 19, 9:16 am, "saduikis.to...@googlemail.com"
<saduikis.to...@googlemail.com> wrote:
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
in means of static fields that affect AM, but doesnt FM.
Why an Amplitude is being affected by static fields, but frequency is
not?
Thank you all!
The way I've always understood it, this has very little to do with the
type of actual modulation involved, but in the placement of the
frequencies. Apparently, there are just more things that can
interfere at the lower AM frequencies than at the higher FM ones. And
FM is not completely interference free, but very nearly so.
But I'm not completely sure what you mean by static fields interfering
with radio. You may be confusing that with the old term "statoc" used
to describe such interference. Most people now use the word "static",
so that may be the source of your confusion. In any case, it has
nothing to do with static fields.
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| User: "Greg Neill" |
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| Title: Re: A really simple question |
19 Apr 2007 12:05:34 PM |
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"Igor" <thoovler@excite.com> wrote in message
news:1177000445.604777.263520@y80g2000hsf.googlegroups.com...
On Apr 19, 9:16 am, "saduikis.to...@googlemail.com"
<saduikis.to...@googlemail.com> wrote:
Hi,
I have a really simple question that I can't answer by myself so I am
asking you, my friends.
Why Amplitude Modulation (AM) is worse than Frequency Modulation (FM)
in means of static fields that affect AM, but doesnt FM.
Why an Amplitude is being affected by static fields, but frequency is
not?
Thank you all!
The way I've always understood it, this has very little to do with the
type of actual modulation involved, but in the placement of the
frequencies. Apparently, there are just more things that can
interfere at the lower AM frequencies than at the higher FM ones. And
FM is not completely interference free, but very nearly so.
But I'm not completely sure what you mean by static fields interfering
with radio. You may be confusing that with the old term "statoc" used
to describe such interference. Most people now use the word "static",
so that may be the source of your confusion. In any case, it has
nothing to do with static fields.
I interpreted his use of 'static' in the sense of
interfering noise, rather than as 'without motion'.
It's a fairly common use of the word outside of
scientific writing.
Note that in broadcast television the FM sound and AM
video signals are at nearly the same frequencies, yet
the video signal suffers from interference far more
than the audio.
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