3 ms·

"Zero sunspots but working DX on FT8!" I don't get it. I thought sunspots killed radio communications?

dbcurtis 8y ago
More sunspots are associated with increased solar flux, which cause ionization in the upper atmosphere. HF (3-30MHz) communication is generally enhanced by increased ionization (to a coarse first-order approximation -- the nuances fill many books and are not entirely understood.) At other frequencies, sunspots may or may not be a good or bad thing, depending on your definition of "good" and "bad".
AWildC182 8y ago
Simple explanation, sunspots energize the atmosphere making it easier for lower frequency signals to bounce off the upper atmosphere back down to the ground allowing longer range because you're not horizon limited.
Vendan 8y ago
DX is a term for a long distance contact. Increased sunspot activity results in increasing ionosphere ionization, resulting in an increase in the refracting power of the ionosphere. Higher refracting power means radio waves can be bent more, resulting in longer distance communication (also, the ionosphere bends lower frequencies better, so you get an increase in the MUF, or Maximum Usable Frequency that will get bent back to the earth.)
exabrial 8y ago
Depends on the band and your application. So what the HAM radio operators are doing is bouncing signals off the ionosphere. With more sunspots active, the ionosphere is more electrically charged, making is easier to bounce signals off of. People have bounced signals off of the ion trails of meteorites, space shuttle reentry, and other absurd stuff :)
topspin 8y ago
> I thought sunspots killed radio communications? They can. Sunspots can also greatly enhance radio communications. Outside of amateur radio this effect is rarely appreciated; ordinary radio service users usually only become aware of sunspots when they interfere with communication. Amateurs, however, operate on many different frequencies, and they achieve communication under unusual, rapidly changing conditions. They often use solar activity to their advantage. The story mentions "10m DX." This is ham speak for the 10 meter or 30 megahertz band (the high end of the 3-30 MHz "high frequency" or HF band, which is extremely low frequency by today's standards) long range (DX; multiple "hop", frequently international) communication. Using traditional modes the 10 meter band is presently "closed" to long distance communication, meaning you get nothing but static when you listen and no one detects your transmissions. The lack of solar activity is the reason the band is closed. When solar activity is high (lots of sunspots) one can use a low cost transceiver, a small antenna and an easily obtained license and reach people thousands of miles away.

More sunspots are associated with increased solar flux, which cause ionization in the upper atmosphere. HF (3-30MHz) communication is generally enhanced by increased ionization (to a coarse first-order approximation -- the nuances fill many books and are not entirely understood.) At other frequencies, sunspots may or may not be a good or bad thing, depending on your definition of "good" and "bad".

AWildC182 8y ago

Simple explanation, sunspots energize the atmosphere making it easier for lower frequency signals to bounce off the upper atmosphere back down to the ground allowing longer range because you're not horizon limited.

Vendan 8y ago

DX is a term for a long distance contact. Increased sunspot activity results in increasing ionosphere ionization, resulting in an increase in the refracting power of the ionosphere. Higher refracting power means radio waves can be bent more, resulting in longer distance communication (also, the ionosphere bends lower frequencies better, so you get an increase in the MUF, or Maximum Usable Frequency that will get bent back to the earth.)

exabrial 8y ago

Depends on the band and your application. So what the HAM radio operators are doing is bouncing signals off the ionosphere. With more sunspots active, the ionosphere is more electrically charged, making is easier to bounce signals off of. People have bounced signals off of the ion trails of meteorites, space shuttle reentry, and other absurd stuff :)

topspin 8y ago

> I thought sunspots killed radio communications? They can. Sunspots can also greatly enhance radio communications. Outside of amateur radio this effect is rarely appreciated; ordinary radio service users usually only become aware of sunspots when they interfere with communication. Amateurs, however, operate on many different frequencies, and they achieve communication under unusual, rapidly changing conditions. They often use solar activity to their advantage. The story mentions "10m DX." This is ham speak for the 10 meter or 30 megahertz band (the high end of the 3-30 MHz "high frequency" or HF band, which is extremely low frequency by today's standards) long range (DX; multiple "hop", frequently international) communication. Using traditional modes the 10 meter band is presently "closed" to long distance communication, meaning you get nothing but static when you listen and no one detects your transmissions. The lack of solar activity is the reason the band is closed. When solar activity is high (lots of sunspots) one can use a low cost transceiver, a small antenna and an easily obtained license and reach people thousands of miles away.