[K3PZN-List] AM and FM

Mon Feb 29 10:29:01 EST 2016

Kyle,

This might help you: https://www.youtube.com/watch?v=uZa6C0VY8p0

73,
Dave N3ZPC

On Mon, Feb 29, 2016 at 9:21 AM, Scott, KB3JQQ via K3PZN-List <
k3pzn-list at mailman.qth.net> wrote:

> The strength of the carrier is unchanged when you modulate am. Only
> sidebands are added. In fm, the carrier deviates from the center frequency.
>
> It's very common for people to believe the carrier changes when am is
> produced.
>
> - Weird words are due to my iPhone correcting me wrongly! -
>
> > On Feb 29, 2016, at 09:09, Kyle Thornton <kyle.3599 at outlook.com> wrote:
> >
> > Ok I think the way I see it is AM when you modulate the sine way so it
> goes up and down more as voice or data is added to the carrier. FM I
> believe is essentially just adding vertical lines to the sine was to
> represent voice or data.
> > Kyle
> > 73 de KC3FMP
> >
> >> On Feb 29, 2016, at 8:11 AM, Curt Milton via K3PZN-List <
> k3pzn-list at mailman.qth.net> wrote:
> >>
> >> Let me help just a little.  When we think of modulation there are two
> different domains to 'see it.'
> >>
> >> First, the time domain.  An unmodulated RF signal is a clean sine
> wave.  For AM the modulation is input to change the amplitude keeping the
> frequency the same.  You can imagine FM does the opposite -- changing the
> frequency around while leaving the amplitude constant.  By time domain, the
> X-axis is time.
> >>
> >> Second it looking at the same with the X-axis being frequency.  An
> unmodulated signal is just a vertical line.  When a audio signal at say 1
> kHz is input, two more lines form 1 kHz below and above the carrier.  FM
> looks a bit more complex, as it creates sets of lines.  The result of both
> is that the 'bandwidth' increases based upon the modulation.
> >>
> >> AM and FM are just two fundamental ways to modulate a signal.  SSB is
> just a special form of AM.
> >>
> >> Keep up your reading -- and of course discuss your questions - and you
> will figure it out well enough.
> >>
> >> 73 curt
> >>
> >>
> >>   On Sunday, February 28, 2016 10:16 PM, Kyle Thornton <
> kyle.3599 at outlook.com> wrote:
> >>
> >>
> >> Ok so your get the same carrier but double the side bands hence more
> noise.
> >> Kyle
> >> 73
> >> KC3FMP
> >>
> >>> On Feb 28, 2016, at 10:15 PM, Kyle Thornton <kyle.3599 at outlook.com>
> wrote:
> >>>
> >>> Ok so I think I got that basically when you modulate an AM signal your
> actually creating a duplicate of the carrier and side bands so essentially
> the whole signal and then when you transmit your power is being amplified
> due to the way the signal is being modulated? I'll have to read that
> section again but it was really confusing to me. FM I think I got down good.
> >>> Kyle
> >>> 73
> >>> KC3FMP
> >>>
> >>>> On Feb 28, 2016, at 10:11 PM, Scott, KB3JQQ via K3PZN-List <
> k3pzn-list at mailman.qth.net> wrote:
> >>>>
> >>>> AM is a mixing process. You add 50% audio to your carrier andget the
> unchanged carrier and 2 mirror image sidebands with25% of the modulation
> power. Average, you get 150% more powerthen unmodulated but 400% more in
> peak power. That's why a 100watt radio only has 25 watts of AM. When you
> add 50% more voltageto a fixed resistance (your antenna) you get 50% more
> current,so it squares at full modulation since power is voltage X current.
> >>>>
> >>>>    From: Kyle Thornton <kyle.3599 at outlook.com>
> >>>> To: k3pzn-list at mailman.qth.net
> >>>> Sent: Sunday, February 28, 2016 10:04 PM
> >>>> Subject: [K3PZN-List] AM and FM
> >>>>
> >>>> Hi all,
> >>>> I was reading though the general class license book and came across
> how AM and FM work. I haven't been on the radio lately cause of work but I
> can't quite grasp how AM is modulated. I think I have FM down as when you
> modulate the signal you're modulating the frequency so you get clearer
> sound but less range. This is probably something that was gone over in the
> tech book but I don't remember it.
> >>>> Kyle
> >>>> 73
> >>>> KC3FMP
> >>>> ______________________________________________________________
> >>>>
> >>>> 73 de K3PZN Westminster, MD
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> >>
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> >>
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