Thread: FM Radio Signals

Can someone please help, I live in a region that has marginal reception on FM for a particular radio station that I listen to, but with a dedicated aerial and a signal booster I have enjoyed good reception since 1990 but in 2004 the signal strength and therefore reception has been terrible, but only on fine clear days and nights ?, I asked the station technicians why and was told it was due to Sun Spot Activity, does this make sense

I asked the station technicians why and was told it was due to Sun Spot Activity, does this make sense

Possibly, over a short period of time.


Could be radar, that happened around my area a few years back. AWAK, I think.

Got frequencies?
The FCC or a related entity should have frequency allocation charts available for your area.

Well sunspots only impact signals that hit the ionosphere. In other words signals that are not direct line of sight. I suppose they could impact line of sight signals slightly, but I doubt to a large degree. The ionosphere can do all kinds of cool things to radio waves, normally it just bounces them back down at a right angle. The reason short wave radio works is because of the hop from land to ionosphere back to land, etc.

can't they penetrate the ionosphere or are the beams bend by the descending air pressure?

Originally Posted by Zwolver

can't they penetrate the ionosphere or are the beams bend by the descending air pressure?

Yes they can, and often will travel inside for hundreds or sometimes even thousands of miles. Just bouncing up and down. The frequency makes a difference. Higher frequencies just don't do it as well.

It's been a long time since I've been in that field.

So, how does an electromagnetic wave carry information anyways? Seeing as how we are on the topic.

i know the answer to that one

the normal "wave" of a frequency is what the radio tunes into a steady line. all the "distortion" on this frequency will provide the music/vocal.

so it's actually the extra vibrations on a wave that cause the tones.

Originally Posted by DaBOB

So, how does an electromagnetic wave carry information anyways? Seeing as how we are on the topic.

In this case FM (frequency modulation) consists in changing a carrier wave's frequency in order to represent different levels of timbre... this timbre changes are the information that a radio reciever demodulates and presents as a radio transmission (voice, music)

So if you are distorting the standard wave how does the receiver pick it up? Or is this why you often here the same station over multiple stations?

Originally Posted by DaBOB

So if you are distorting the standard wave how does the receiver pick it up? Or is this why you often here the same station over multiple stations?

Okay, in a nutshell, here it is, simply, in simple terms.

Modulating signal, say something like a voice, is "combined" with a carrier signal or local oscillator.

This creates sidebands (regardless of FM, AM, PM or any combo) at the sums and differences of the two original frequencies.

These sidebands "carry" the information, in this case, a voice.

The carrier itself contains no information, but is still usually transmitted along with the sidebands in order to drown out adjacent or interfering signals from nearby frequencies. If you didn't, you would hear the other stations between any pause in our voice signal.
You can asupress the carrier (SSSC or Single Sideband Suppressed Carrier). Giving you less transmitted bandwidth to deal with and more available power.

Many times sidebands are suppressed with the use of a bandpass filter. In SSB (Single Sideband) communications only one sideband or set of sidebands are transmitted. The upper and lower sidebands are identical, so the energy it takes to transmit both can be concentrated on one SB + the carrier. (Similar to SSSC in results).

However transmitted, and there are many variations, the sidebands, or envelope, carry the information (voice).

The receiver is tuned to a center frequency where the carrier is, or is supposed to be. The sidebands are picked up by the receiver on this frequency, demodulated, and then sent through various channels/filters/or processors in order for you to hear it clearly.

That's the basics, hope it helps.

Oops. A little redundant.

SSSC communications is a suppressed carrier AND a supressed sideband.

Let us be acurate.

I wouldn't call that simple terms but, YES it helps alot. Thank you and sorry if I sorta changed the topic here.

I am trying to keep up with you

Taken from Sun Spot web site

[The number of sunspots reaches a maximum about every 11 years, but successive maxima have spots with reversed magnetic polarity. Thus the whole cycle is 22 years long]

So we are bombarded with extra photons at the peak, and this will interfere with the FM signal? Have I got this right.

I seriously doubt your problem is a result of sun spot activity. But, then again, I'm not overly familiar with the phenomenon.

It is much more likely that something has changed on a local level.

Power reduction of the stations trasmitter.

Power increase of an adjacent station or a new station in the area around the same center frequency as the one you listen to.

A change in the geographical location of the trasmitting antenna.

Radar.

Etc. . .

If it were me, I'd call the station's engineer and ask him/her.

Caveatlector
I think you are correct and that it is a transmission problem, it would make a bit more sense if it had been Sun Flares,
I did ask the technician and he said Sun spot activity???