Dave's Keyless Remote

The Show
61

The optical receiver in TV for the remote may actually be blinded/overpowered by the signal coming from the remote. That is why bouncing it off a few walls actually causes it to work. Either the receiver is defective or the remote is transmitting too high of power. It may have something to do with the accuracy of the transmitter but it’s a tv remote, not a laser.

Example: Cisco makes an adapter that can be temporarily blinded(defect) by getting too strong of a signal from the telephone company. We fixed this problem by installing a DS3 attenuator(-5db?). Prior to installing the attenuator, the interface would work for a bit and then reset.

Want another example? Try putting to CB radios 10-15 feet apart or in different rooms of a house(so you can’t hear each other). Have one person talk, have the other listen. Typically you will hear distortion on the receiver because the signal is so strong it is over powering the receiver. Move them apart even farther and you can now hear what the other person is saying.

62

Another vote for the line of sight theory with a small caveat: Is it at all possible that Dave’s remote is an infrared system rather than radio? If it is radio, then it is safe to assume that the transmitter has an omni directional radiation pattern. On the other hand, an infrared system uses an light emitting diode source which is focused into a more or less tight beam. Some led sources have nasty “side lobes” which spring out off the axis of the main beam. Many ccd tv cameras and digital still cameras can directly image an infrared source so it’s fairly easy to figure out what’s going on using a camera as a detector.
In short:
Line of sight applies to infrared and radio.
Direction likely only applies to infrared.

63

I am a pure hobbyist (not even) in the physics of these sorts of things. I cannot say for sure what causes the keyless entry system to work better (though I sort of agree with Dave himself, that it may be coming out the eye sockets).

However, it was mentioned in the call about pointing the remote control at the back wall to make the TV respond better. This has some merit, though not for the reasons described. See, infrared remote controls do not shoot a straight point of IR light. They act just like a lightbulb, dispersing the light in all directions (allowable by the plastic hood). What in fact may be happening is that you are in fact lighting up the back wall (or your forehead), and the detector is receiving that.

You can see IR remote controls work by using most video cameras or webcams. The CCD’s that capture the light and turn it into electronic signals also capture infrared light. Take a video camera, and point your remote at the lens, You should see that it lights up significantly. You could also see as the signal can be used to light up other surfaces, exactly like a visible lightbulb.

My two cents,
poly-p man

64

I’ve read the posts so far, and that by Eric Jacobsen seems to me to be the most accurate. My PhD in physics is from Tom and Ray’s esteemed citadel of higher education; have worked as an electrical engineer most of my life since then, however. I’d like to see more experimental testing of the various theories. I really enjoy listening to Car Talk; glad to know about this discussion forum.

65

This is the right answer. I did an experiment. I moved away from my car, pointing the remote directly at it, until the remote no longer unlocked the car. I then pointed the remote at my chin. Success. I then kept the remote in the same orientation, but with my hand above my shoulder. Thus, I was “pointing” the remote up into empty space. The remote also worked this way. It is the orientation of the remote, not some bogus theory of dispersion, that affects the range.

Steve Glaser

66

The internal antenna is pointing in a sideways direction perpendicular to the length of the remote. Reason? They’re made in Japan. Japanese garage doors open sideways, not up and down.

67

The antenna inside the keyless remote may be omnidirectional but it works better in some directions than others. Pointing the remote at your chin is actually pointing the antenna at the car.

68

Click and Clack have asked for someone to shed some light on this “with authority.” Once I got done laughing at the IR (Infrared) forehead TV remote story I pulled myself off the floor just to get sent back down by the ‘chin as a disperser’ comment.

I’m sure its been said and said again. But where’s the authority? So I enforce comments posted before this by stating:

Keyless entry devices are as diverse as Honda Elements are ugly. Some use RF (Radio Frequency) energy; others use IR (Infrared) signals to tell the car what to do.

Like garage door openers once upon a time; when they were new they used high powered AM (Amplitude Modulated) signals to activate the “button push” causing the motor to run. The irony was that they only had 4 codes on the first release which meant you could open 25% of openers out there.

Signaling changed, criminals adapted, signaling changed again, criminals adapted, – AM, FM, PM, analog, digital, PSK, QPSK, gray code, binary, preambles, 10 digit codes, rolling codes, I could go on and on for years.

Point being this: If the remote in question uses someone’s “chin” as a disperser; what you are doing is radiating RF energy from a key fob and into your head or body. What is the body made of (mostly)? Salt Water. Salt water is a conductor and in a human’s case - a poor one but none the less the RF energy excites molecules in our own philosophy causing the car to see that key fob like its a file cabinet sized key fob.

Remember when RADAR guns were new to speed enforcement? There was a drastic increase in cancer among officers using the first generation K band RADAR guns? This was related to the fact that officers would store the unit under a thigh between cars or as they initiate the vehicle stop. Their bodies were being bombarded with RF. As if they strapped one of those ship to shore sweeping RADAR antennas to their belt buckle. Eventually they turned power levels down and created safety features that would inhibit the gun from radiating energy unless criteria had been met.

But! If the keyless entry of the Audi used IR (Infrared) energy then its a case of Line Of Sight. This means- just like your TV that you must have direct beam of signal to the antenna. Remember early Chrysler vehicles that had that little “dome” on the under side of the center mounted rear-view mirror? If you didn’t point your key at “the car” or more specifically “the dome” then you were wasting precious battery life of your key fob.

By that logic - pointing an IR transmitter to your head won’t increase range to the vehicle - unless as in Click’s example you have a mirror made of greasy forehead from a long day and the IR (just outside of the visual spectrum) bounces from your head like the image of whatever you are watching on TV. Am I looking at the TV or your head? haha.

The actual problem: range decreasing as time goes on from the Audi’s key fob.
2 diagnoses:
a) If the battery of the transmitter is over a year old; replace it. Lots of people let 3 years + go by drastically reducing the performance of the transmitter.
b) If the range always suffers “in the parking lot at work” or only “in the driveway” then you have localized interference. Don’t worry the FCC has you covered by placing that “this device must accept any interference regardless of performance, haha, thanks for the taxes sucker” disclaimer right on the back or internal cover of the device. In this case - simply accept the interference by standing closer - or … don’t park there.

Thank you for the opportunity to fire back on this issue. Thanks again for the laugh - the greasy head IR bounce, the RF entering the chin and firing out via the eye sockets.

So now I’m going to pour on the authority. Not because you care but because your question specifically addressed desire for ‘authority’ in an answer:
I’m a government radio specialist that programs / tunes / and troubleshoots radios in all flavors of municipal apparatus - from base station to handheld devices from garbage truck, to fire engine, to BAIT vehicle, to police cruiser, undercover car, to mobile command center.

I have Marine Corps RADAR experience, and an EE Degree. I’m a member of the IEEE as well as APCO Intl. Plus I do a mean impression of Sean Connery. If that doesn’t qualify then I surrender to “Dispersion Theory.”

Let me know if you want formulas to back this up. :slight_smile:

Scotty / AZ

69

I actually learned about this at the US Air Force Academy SERE school. We were learning about pilot’s emergency survival radios, and there are two points that apply here. First, is the ability of the human body to shape the radio transmissions, reflecting them off the body. The second is the “cone of silence” that extends from the top of an antenna; we were taught not to point the radio towards an aircraft; but to hold it in front of your body and point the antenna up, but away from the aircraft.

70

Scotty;

I am indeed interested in the math here.

Most range issues are battery related (okay,check)

Localized interference FCC Part 15 (Okay, check)

Salt water = conductor (okay, check)

Body mass = Signal reflector amplifier (Okay. No, wait, I still cannot get my head around this. I am unclear as to how the signal levels produced by the fob would not still be lesser then the original signal. Salt water or no, the absorbtion by the tissue mass should not allow the range increases suggested. How would the Salt Water produce such an effect? My tests indicate that the increased height alone gives the same results.)

Did you leave the line of sight issue out of the RF explaination as to disregard it or in omission?

I am intriqued to say the least.

71

Hey guys,

Love the show. And I agree, I have tried this recently and it WORKS. I drive a 2005 Ford Focus ZX5 and was having trouble with my keyfob not working until I got right up to the car. Tried the chin and works.

Rick

72

Ray said you were looking for opinions from persons who had “authority” and/or persons whose opinion was based on the fact that they had hung out a “shingle” -I have both. I have been a Mental Health Commissioner for nearly 17 years in a medium sized County in New York State. (That’s as close as you’re going to get to an identity) Although I am not sure at all that he has the credentials to be diagnosing things, it is my PROFESSIONAL OPINION that Tommy’s expressed diagnosis that Ray’s theory about the keyless entry transmittor working better when the signal is bounced off one or more walls is BO-O-O-O-O-O-Gus was right on target. You’d have to have a screw loose (that’s a professionmal term) to believe the number of times the signal bounces off walls matters one bit. My son Mark, who uses this technique over and over again, is proof that pointing the transmitter to your jaw from underneath and opening your mouth actually does significantly increase the distance from which the transmitter will work. We think it has something to do with a person’s biological energy field being tapped into as an enhancement to the strength/range of the transmitter. Ray’s theory is that of a quack, and I should know…

Best wishes,
Doctor A.

73

I made some discoveries through experiment.

  • The signal won’t go through metal.

  • On my car, the radio antenna receives the remote signal.

  • Raising the fob to your head level gets it above the fenders of other cars in the lot - and above your own car’s body if you are behind your car.

  • It often malfunctions if you try to use it while you are walking. Often it responds as though you had double-clicked the button (which does something else on my car).

74

Ray’s dispersion theory could possibly be the most wrong possible answer.

Imagine a laser. It basically is a linear ray. Lets say this ray has a range of 20 feet. You shoot it at your car 21 feet away: it doesn?t work. 20 feet: it does. Now, set up a mirror 20 feet away from your car, put your back to the door of the car and bounce the ray off the mirror and, even assuming the mirror is a perfect reflector, nothing bounces off the mirror, because the ray only goes 20 feet. The mirror would have to add energy to the beam in order to reflect. That?s why you have to plug amplifiers into the wall. Because they only amplify by adding energy and the wall socket provides the energy. Move the mirror to 10 feet and shoot the laser, the doors would open. Its 10 feet out and 10 feet back for a total of 20 feet. So, unless Ray plugs his head in, it can?t possibly increase the energy in the beam and so can?t possibly increase the distance.

Lets add dispersion into the mix; lets take that mirror and imagine it to have four convex facets, kind of like a 1/2 disco ball with the roundy side facing the car. Lets also imagine that the diameter of the faceted mirror is the same as the diameter of the laser beam, and that each facet is equal in surface area. We?ll move the laser in closer, about 8 feet away, which would give it about 12 feet of range off the original flat mirror, for a total of 20 feet. But when we shoot it at the faceted mirror, it divides the energy of the ray 4 ways, emitting four beams 3 feet in length.

When you assume the emission isn?t a ray, the same thing happens for all the radiation hitting the mirror. All energy leaving the emitting devise emanates linearly, as though it were an infinite number of infinitely minute rays. Reflection would still have no impact and dispersion would still make the problem worse at least in terms of energy.

In terms of aim, its hard to see how that can be the problem. If we assume that the ray isn?t a beam but, say a cone, moving closer would make the aim problem worse, since the cone is narrower closer to the emitting device. Moving farther away would reduce the need for accuracy and make the remote more likely to work. That?s not the case.

If it?s a beam, the only factor would be the accuracy of the shooter, since the beam is the same diameter up until it runs out of energy and ceases. One would expect the problem to get gradually worse as one moved away from the target, as it does with any sort of shooting. Also, some shooters would be more accurate than others. We’d have marksmen. The range problem with remotes doesn?t behave that way either. There seems to be a general area beyond which things get sketchy and then cease to work all together. It seems to behave more like an actual range problem, more like a limit to the distance the emission can travel.

Now add the study showing that some how the energy is greater bouncing off the head then other parts of the body, and we, not only have no need for Ray?s theory, but have a real problem explaining where the additional energy came from. Unless, of course, one plugs one?s head in, the explanation has to be the opposite of dispersion. The human head has to act as a reflective lens that concentrates the energy (the oposite of dispersion) and redirects it toward the car.

So it would seem that Ray did in fact give the most wrong possible answer. But remember, inverse genius is no less genius.

75

Exactly! The most powerful RF signal is in lobes perpendicular to the flat antenna, i.e., out the “top” and “bottom” of the remote fob. I’ll bet the fob was designed to be pressed while being held up 90 degrees to the car (you looking at the “top” where the buttons are), and not “aimed” at it like a TV IR remote. The engineers who designed this thing are probably laughing themselves silly reading all this crap about reflections off the backs of empty skulls and whatnot!