Best "interference" story you've heard.

[LEH]

There have been a couple threads here on radio interference and I was wondering who has any good 'stories' about interference with radio signals.

I'll start with a 'war story' from when I was in the Air Force. In 1986 or so I attended a short school at Brooks AFB in San Antonio, TX. The base has no active flying, but there is (was when I was there anyway) a fairly large segment of the old flight line on the base.

My school was located in a building right next to the old ramp area. Several of the instructors had taken up flying RC model aircraft during the lunch break for the class. One of them told us they did this, but were having occasional problems with the planes just suddenly going out of control and crashing.

Well on first day, I went out and watched the instructors flying their RC planes around. I asked one of them if there was any particular location where they had the problem and he said yes and pointed to a nearby building. I hate loaded questions like that as I already knew where and what the problem was.

About a hundred or so yards further down from the ramp area where the instructors flew their planes was another building. Home to the base security police and with a small outside antenna adjacent to the building.

Now I have no idea how much power they were putting out on their simplex system, probably not more than 25 watts as the base is small. But enough to reek havoc on a model airplane receiver flying close to the antenna when the transmitter is keyed up. I know that with my old Regency 5500 and an external antenna on the car, I couldn't pick them up more than two miles away.

They moved their 'flight' operations a bit further down the ramp the other way and didn't fly toward the SP building anymore. No more unexplained crashes.

 

[KC0QNB]

Shame on me, but I have one, this one I caused, related to RC cars, the former neighbor kid had a cheap rc car, that ran on 27MHz, I don't remember the exact freq, I listened to the tones the transmitter, which tone did what, I have near perfect pitch so it was easy to emulate the tones just whistling on the right pitch (frequency). Ok I need to set this up a bit more, while I was listening I noticed when the car really took off (turbo) mode, I keyed up my cb and whistled that particular pitch, just as a trial, that car took off like a rocket (I new I could really mess with this car, and make it do what I wanted it to do) for a few seconds the kid was freaking, he had no control. I decided to be nice and be quiet for a few minutes and let him regain control, he brought the car back to him, picked it up and looked it all over, as if trying to see what was wrong, all was ok.
The next day he was at it again, fresh batteries, he was driving around having a ball, he pointed the car north on the street, moving pretty fast then I keyed up again, whistled a sweep scale covering the frequencies the the transmitter used, the car went into turbo mode turned a sharp right and bounced off the curb, and landed bottoms up on the lawn. I decided to let him alone before I trashed his car.

 

[mitaux8030]

Being both a pilot and airband listener, my receivers tend to spend a lot of time on the airbands. For whatever reason, I dialled up 121.5 MHz and heard a funny escalating tone. Hmm, didn't quite sound like an EPRIB going off, but maybe it was one with near-flat batteries?
Well, I made a quick call to our RCC (Rescue Co-ordination Centre) and asked them if they'd had any reports of an EPRIB in my area - they replied in the negative and asked me to give them a sample of the audio heard on 121.5 MHz. They thought that it wasn't an EPIRB but worthy of further investigation. Later, our ACMA (Australian Communications & Media Authority - the Government entity responsible for administering the RF spectrum here) contacted me and asked a few questions. They later found the source of the signal on 121.5 MHz... it was a TV set top box, a full suburban block away from me. I can just imagine the headlines "DVD player sparks major search & rescue operation"... sheesh.
Back in the early 1990s, I had a 9600bps dial-up modem that would radiate a strong spurious signal on our local ATC 'centre' frequency 123.8 MHz. I could hear that quite some distance from the house too.

 

[scrotumola]

There have been a couple threads here on radio interference and I was wondering who has any good 'stories' about interference with radio signals.

I'll start with a 'war story' from when I was in the Air Force. In 1986 or so I attended a short school at Brooks AFB in San Antonio, TX. The base has no active flying, but there is (was when I was there anyway) a fairly large segment of the old flight line on the base.

My school was located in a building right next to the old ramp area. Several of the instructors had taken up flying RC model aircraft during the lunch break for the class. One of them told us they did this, but were having occasional problems with the planes just suddenly going out of control and crashing.

Well on first day, I went out and watched the instructors flying their RC planes around. I asked one of them if there was any particular location where they had the problem and he said yes and pointed to a nearby building. I hate loaded questions like that as I already knew where and what the problem was.

About a hundred or so yards further down from the ramp area where the instructors flew their planes was another building. Home to the base security police and with a small outside antenna adjacent to the building.

Now I have no idea how much power they were putting out on their simplex system, probably not more than 25 watts as the base is small. But enough to reek havoc on a model airplane receiver flying close to the antenna when the transmitter is keyed up. I know that with my old Regency 5500 and an external antenna on the car, I couldn't pick them up more than two miles away.

They moved their 'flight' operations a bit further down the ramp the other way and didn't fly toward the SP building anymore. No more unexplained crashes.

The BRAC (Base Re Alignment Committee) brought an end to Brooks AFB about 10 years ago. As I kid, I flew gliders and other airborne RC toys on the flightline at Brooks. The real source of the RF was a huge antenna farm on the southwest corner of the base (think Mission Rd or S. Presa side of the complex.)
There was all sorts of RF activity on base that I wished I had photographed. The Gov't has since turned over Brooks to the city of San Antonio and is now known as Brooks City-Base. There are still very limited military ops and base housing on the facility, but nowhere near what it used to be. The northern flightline/tarmac is now a HUGE shopping center. Check googlemaps satellite for 3200 SE Military Dr, SATX
Some of the runway structures still exist.

Back to the topic, here is my RF interference solution to those pesky kids with booming stereos http://www.radioreference.com/forums/showthread.php?p=825928#post825928

 

[kb2vxa]

Once upon a time in the mid 1960s there was a WILD pirate broadcaster in my town operating on 1550KHz or so they thought. I couldn't hear it across town but found it had harmonics and spurs throughout the spectrum, one in the 10MHz band was audible and in the clear so that's where I listened to the nonsense. Somewhere in the middle of all this the two head cats set their sights on the brand new PA console in the HS principal's office thinking it would make a nice audio board and wouldn't you know it, they got caught red handed carrying it down the front steps. Well duh, the school has a back door to the parking lot and some punk must have a van but no, right out the front door into the waiting arms of the cops.

Now to the interference part, remember those harmonics and spurs? Well as luck had it they were all over the aero band too and 4 miles from the third busiest international airport in the country is not the place for entertaining pilots on the radio. Along comes my favorite uncle Fox Charlie Charlie with his trusty can of bug spray, those little cockroaches awaiting sentencing on grand theft charges had just a little more to think about.

I wish I still had the article I clipped from the regional newspaper to post as an image attachment, it was SO beautifully written using phrases borrowed from popular song lyrics like this... more or less.

Callin' out around the dial
Are you ready for a brand new beat?
Summer's here and the time is right
For dancing WILD in the street
They're dancing in Rahway
Down in Perth Amboy
Up in New York City
All we need is music, sweet music
There'll be music everywhere
There'll be swingin' and swayin' and records playing and
Dancing WILD in the street...