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Why does my computer mointor interfere with 540?

W

wellander

Hi,
Why does my computer mointor interfere with 540? I can hear the interferance across my house.
It ia a Hp P1110.
It just interferes with 540.
I can not hear interference on other stations unless I put it (the radio) right next to it.
Any info will be good.
 
Computers generate square waves which radiate over a wide frequency spectrum - generally up to 300Mhz. The AM band is more prone to computer interference than say....the FM band. (Gee....just about everything interferes with AM ::)

The 540 signal is probably lower powered than your other local AMs therefore cop's more interference.

dxer2_2000
 
Bryan -- As DXer suggested, the monitor is definitely generating very small, low-powered radio signals of its own... radio signals just the same, even though they don't carry any interesting programming. ;) This is common to all computer monitors -- the interference doesn't indicate anything wrong with yours.

My own monitor seems to fiddle with AM signals every 90 kHz, all the way up the band (though the interference becomes progressively weaker as the frequency increases.) Even on 630, where we have a relatively strong local station (2000 watts from 20 miles away), a faint high-pitched hum can be heard behind the music.

I'm not *completely* certain about this, but I think it's caused by some aspect of the display itself, rather than other internal components "backstage" in the monitor. I'm guessing this because of a program I've seen on the Internet, which effectively converts your monitor into a low-powered AM transmitter! It accomplishes this by generating changes in your video display. The variations in the display "match" the mp3 you're playing at the time, causing modifications of the radio waves your monitor is already generating, such that they carry the music you're playing. (If you happen not to be familiar with radio terminology, the whole process of modifying a "carrier" wave, so that the modifications carry useful information and program material, is known as "modulation." :))
 
Hi,
Thank you both for answering my question.
The 540 that I listen to is over 100 miles away with I believe 25 kw (25,000 watts) XESURF.
 
I've always thought it to be the high voltages in CRT (tube) monitors, (something like 20-25KV) that messed with AM. My old monitor, before I got an LCD, would interfere with AM and FM (creating a false stereo on FM).
 
Try changing the refresh rate for the monitor (from within the software... Windows, Linux, etc.). You'll find that the pattern of blocked frequencies across the AM band will shift so that 540 might be uncovered. I can almost any channel on AM by switching the refresh rate between 70 Hz and 75 Hz.
 
I recently replaced my 17" CRT with a 20" LCD panel. There is far less interference, and that trick of changing the refresh between 60, 70, or 75Hz allows me to get any frequency.

100Hz... that must be a pretty sweet monitor! My old CRT could only do 85Hz.
 
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