Oregon man's T-V signals for help

wavy ^

[Chemist_Geek]

These signals are not a simple CW anymore.

Yes, but... New EPIRB models, the ones for 406 MHz, are digital signals but the older 121.5/243 models are still out there and monitored.

there is no fine for malfunctioning equipment like this.

Yes there is, transmitting a distress signal without an actual emergency is a violation. It's likely that the first event will be forgiven - the guy didn't know his entertainment center was a distress beacon and he therefore lacked the intent to commit an offense.

[TheGeezer]

At some points on the cord you will find a standing wave ranging from 10 hertz all the way up to a gigahertz

The cord cannot generate such waves on its own, even if it is long enough to comprise multiple electrical subwavelengths of ELT RF frequencies. The set would have to be dumping that energy into the power cord, which would mean the decoupling of the AC power cord would not meet FCC standards for receiving equipment.

The bypass/choke decoupling system Samsung uses might be defective, or even may have accumulated random resonances that actually boosted coupling between the cord and unwanted RF. But what power level would be available for radiation into space? A few milliwatts (good grief, I hope not!)? With the radiator (power cord) laying on a floor, presumably, without benefit of a counterpoise of any sort, the SWR between the signal source and the antenna would be rather high. That would mean high ohmic losses, as RF current recirculated between generator and feedpoint repeatedly. Add to that radiation path losses, and very quickly beyond a few wavelengths form the antenna the signal will be unrecoverable by any but receivers with negative noise figures. Do ELT receivers a few hundred miles above earth enjoy even 0 noise figure front ends?

I'll stick to urban legend status for this story.

[RightWhale]

One of the helicopters at the pipeline construction camp was always doing that. The pilots had a lot of trouble flying that one smooth. The alarm would go off and rescue had to run out to the strip even though they knew the pilot would be standing there with a s-e grin and there would be a new pilot within days.

[Old Professer]

True story: About 9 months ago, my garage door started opening and closing on its own; I was puzzled and decided to check the time of finding it in one position or the other and realized that it always seemed to take place in the early morning hours.

One day, I was reading my paper with the door in the open position about 7:30A.M. and off it went, closed and stayed that way.

I test-operated it several times and it seemed to respond to the remote just fine. The next morning, it did it again.

I remembered that the house directly behind mine had recently been bought by a new family and the garage on it was in the back of the house like mine.

I trimmed 1/3 of the length off the antenna wire and reprogrammed my remotes; hasn't happened again, strange.

[blackdog]

And by the way, it's been my experience that pilots have no clue when they are doing a walk-around preflight. The best and longest preflights usually overlook the nose wheel pins missing, the tie down line still holding the tail, fuel caps left off, fuel sump drains that never closed after draining, pitot tube covers, attack angle covers(which by the way melt quite nicely), wasp nests in the cowling, mouse nests in the gear housing(a mouse nest in the gear housing will cause the metal to bend under hydraulic pressures when the gear is raised, then prevent it from falling when actuated. It's also what causes all those bolts to mysteriously shear), baggage doors left open, towbars left attatched to the nosewheel, and even GPU's left plugged into the aircraft as it's rolling from the ramp.

I wouldn't count on a pilot to spot much structural damage in a preflight. They are too preoccupied with inspecting the deflection distance present in the nose strut.

[NRA1995]

Beat me to the punch!

[Dominick]

transmitting a distress signal without an actual emergency is a violation.

FCC rules are clear. If this is a part 15 emaniation, even on those frequencies, there is no violation. This story still doesn't sound right, in FL, we get a CAP officer and a couple a pimply faced kids helping them. (I in no way deman the CAP, because they do great work.) No way could they be mistaken for Air Force.

Finding an old ELT beacon in a garage that went off is a regular occurance. I have to wonder how a TV could even send out a ELT CW signal like that. They sure don't threaten people with fines for having PELTS go off.

This still smacks of BS.

[blackdog]

I used to do a demonstration in our shielded room for visitors. We had a simulated glideslope signal set to a a Mark 12D receiver. We had it set to 1/8 watt signal strength which represented the signal strength about 20 miles out from a localizer. We would then turn on an elevator motor, which would completely make the glideslope disappear. We then ran the powercord CISPR antenae the length of the main until we hit the spot that showed the same frequency on the spectrum analyzer. We then used shielded mains and presto! The glideslope returned.

It was a demonstration to sell EMI design importance to product developers of all kinds of "Stuff".

I won't argue your engineering explanation of signal strength on this guys power cord radiation, nor the fact that it would need to be amplified by something to be problematic, but I wouldn't rule it out. I've seen something as simple as unequal ground distances or exceedingly long grounds cause some mighty strange stuff too. I've seen circuit boards so poorly designed by engineers with no consideration to EMI, that they actually mounted a DC to AC inverter(2000volts) to operate a fluorescent operators display right next to the microprocessor and can't figure out why they experienced memory crashes.

[ops33]

Emergency freqs are 121.5 and 243.0

[Vic3O3]

Anybody check Snopes on this one yet?

[TheGeezer]

I've seen something as simple as unequal ground distances or exceedingly long grounds cause some mighty strange stuff too.

Unequal grounds have made me question my sanity. Trying to figure out how two points at "ground" have different potentials referenced to some other common point have given me headaches, too. Loops can generate strange effects.

I've seen circuit boards so poorly designed by engineers with no consideration to EMI, that they actually mounted a DC to AC inverter(2000volts) to operate a fluorescent operators display right next to the microprocessor and can't figure out why they experienced memory crashes.

LOL! I once worked on a microprocessor-controlled fire alarm system for a municipality. The system ran off a 120 VDC battery stack simultaneously attached to a "floating" charger. The guy who was told to check electrolyte in the batteries simply dumped distilled water into the holes of the batteries one night, and electrolyte spilled onto the battery cases and down onto the grounded metal racks supporting the stack. When I arrived, the microprocessor was behaving very squirrelly, and I measured 4 volts DC or so between the system's chassis and earth. Who knows how current was dividing in that mess! Washing the battery cases solved the problem immediately.

[brianl703]

I wonder he's got cabble TV and he's using it with the incoming cable TV line plugged directly into it.

Sometimes a poorly designed TV set (or poorly-constructed TV cable with poorly-installed connectors) will radiate the incoming cable TV signals, which range in frequency from 50MHz on up to 550MHz, 750MHz, or even 860MHz for the newest systems.

This signals do encompass the range used for aviation. In fact, the FCC will fine the cable company if they leak too much signal.

[blackdog]

The worst offender I've ever seen was a guy down the street from us with a triac switching defective waterbed heater. As the zero cross would come as the temperature had met the demand, the neighborhood radio's, television sets, computer monitors would all start to fizzle and crackle. At the point it finally switched, POW! Everybody would get a whollop followed by calm for about a half hour until the heater would turn on again.

It took the assistance of the local utility company to find it. I hear hot-tub heaters(the cheap ones) can do the same thing.

Certain areas onboard navy ships can be a bit scary. When they are in dock and switch to shore power in the day, they'll run all kinds of crazy stuff plugged into anything. You grab tables and equipment and feel a hummmmmmm. Normal shipboard approved electrical gear is supposed to be less than .05ma earth leakage. There is not much commercial equipment that complies with less than .05ma leakage current. Also on a ship, you are supposed to have the hot and neutral providing protection. Commercial equipment is just the hot. Any device plugged into a hot/neutral reversed outlet on ship is an unpleasant experience because everything is stainless steel, welded to the deck(floor).

When the ship switches to shipboard power at night, they unplug all the nonsense. I alway's laughed as a civilian when boarding ships in port to do service work. The duty guy controlling entry to the ship has a .45 caliber gun at his side. Sans bullets or clip. Imagine not letting the military posess a loaded weapon? I sure hope times have changed.

[television is just wrong]

Thanks, I'll check it out.

[television is just wrong]

This is quite possible according to the technical specification used for digital video systems. The sample rate use when converting the video signal to a digital form is 13.5 Mhz. This being a Square wave form it is made up of a series of odd multiples of the primary frequency. The ninth multiple happens to fall at 121.5 MHz. 121.5 MHz happens to be the international distress frequency, reserved for emergency communications.

[television is just wrong]

This is quite possible according to the technical specification used for digital video systems. The sample rate use when converting the video signal to a digital form is 13.5 Mhz. This being a Square wave form it is made up of a series of odd multiples of the primary frequency. The ninth multiple happens to fall at 121.5 MHz. 121.5 MHz happens to be the international distress frequency, reserved for emergency communications.

[Petruchio]

A couple of weeks ago the Toshiba with built-in V-C-R, D-V-D and C-D player starting emitting the international distress signal.

I wonder if any Kerry/Edwards ads were being broadcast at the time . . .

[television is just wrong]

It's 121.5 MHz. This is a known problem with so called "CCIR 601" digital video signals.

Back when the standards were being set there was a need to pick a sample rate that would be a compromise between NTSC and PAL. Each has it's own sub carrier frequency, but there was a desirre for compatibility and interchange between the 525 line NTSC and 625 line PAL systems. As it works out 13.5 Mhz falls between the fouth multiple of the subcarrier frequencies of both system and is a multiple of a certain number of samples per horizontal line used by both systems. Unfortunatley the 9th harmonic or multiple of this is 121.5MHz

[television is just wrong]

Oh. I forgot ... CCIR is french for the "International Radio Consultive Committe" or "Consultive Committe for International Radio"

Yet another reason why Television is just wrong.