Every single day when my wife and I commute to work we pass by this one very specific spot on the freeway passing by a couple of office complexes. At that point no matter what we're listening to on the radio, the station gets overridden by another signal for just a second or so. Its not really bothersome but I've wondered what could possible be able to override all stations like that?

Sounds like you are driving past a transmitter site.
If it is an AM transmitter you should see a large vertical tower or towers of some sort.
A FM station will have a single tower and not be as obvious.

There are several ways a very strong, off channel signal can overwhelm a radio receiver in the way you describe
The actual mechanism depends upon circumstance, the interferer modulation type and the receiver design

Same thing happened in the `60s while driving past this KMPC transmitter,

but lasted a few blocks. Everyone expected interference with all that hardware.

That looks just like the station Wolfman Jack broadcasted from.
Mark D.

A bit off topic. I was servicing a bank drive up audio system where the complaint was that a radio station could always be heard when the system was switched on. Turns out that a local FM station had their studios and transmitter on a building just across the street, and the signal was detected through the audio system with very good fidelity. I tried shielding, and bypass caps to no avail, and to this day I'll bet the station still comes in loud and clear at the drive up. Haven't been back in many years, and glad of it haha.
Kevin

50,000 watts? thats quite a bit of power isnt it? even for a radio station??

Absolutely not. The most powerful transmitters ever, in the late 20's and early 30's, were 500,000 watts and even more.

Think i am going to build one of those tomorrow. Should teach people in my area what good music is. 500,000 watts baby cakes
Stan Ski

Here's a link with a list of 'em, from 540 to 1580 Kc, throughout the U.S. and Canada;

http://www.northpine.com/broadcast/50kwam.html

Looks like my last reply got dropped. My problem in all likelihood...

I was just mentioning longwave transmitters in and near europe that can go as high as 2 or 3 megawatts. Here is a wiki about one of them:

http://en.wikipedia.org/wiki/Roumoules_ ... ransmitter

Tony

Clear Channel Radio Stations generally broadcast with 50,000 watts and under FCC regulations they must broadcast with a minimum of 10,000 watts just to retain their clear channel status.

Wikipedia lists over 75 clear channel stations in North America and Mexico alone.

Where is this exact location Seth? I'd like to duplicate the experiment.

The maximum power that is allowable in the USA is 50 Kilowatts for an AM station.

In 1934, as I recall, Crosley Radio Corporation got a license for a 500 KW station, and broadcats with it for several years, interfering with, and jamming AM stations all over the country. Even metal sheds "sang" the modulation from WLW. In 1938, they finally had to cease use of the 500KW transmitter. Its remains are still on display at the WLW transmitting site, north of Cincinnati. RCA had built the transmitter. It was serial No. 1 for that model. Tjhere never was a serial No.2!

Use a scanner to find the frequency ????

To the OP, it is probably a mix of strong paging system mounted on the top of one of the buildings, with your FM and whatever happens, your tuned station is blocked out.

You ... never know...

A couple yrs ago my (1985 era) garage door remotes would not seem to operate between 7-11pm for about a week.
(Normal range is a few hundred feet)
The manual button on the door wired into the opener worked fine.. but not the remote hand-held transmitter things.

Both doors with separate receivers were BOTH acting the same. Each receiver is set to different codes.
I also have 3 remotes and all 3 would not work.
Replaced all the 9v batteries... still no deal.

I got suspicious of some "blanket RF signal" blocking my signal.

Sure enough... when I placed my hand-held transmitters right smack-dab next to each of the receiver's antenna... the door would open.

I looked up info online and read that people in Denver had JUST had the same problem and all of them ran out to Radioshack for new batteries... only to find out that the Air-force out there, was testing on that frequency.

So I contacted the FCC by email to ask who owns the Garage-door frequencies... sure enough Uncle Sam.

I don't know of any large military operation near here except Ft. Hamilton I think ...in NY harbor.

And sure enough... a few days later... everything worked normal again.. and ever since.

On Burbank Blvd, right by Valley JC.... it would desense many a radio as you drove by.

If it's AM radio, you may be driving through the null of the station you're listening to, and another strong signal is audible while you're driving through it.

I know there was a certain intersection in my hometown where one of the AM stations I was listening to would literally disappear for a second while I was driving through it -- the station would fade out and all I would hear was static. Then, on the other side of the intersection, it would fade back in again.