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Phantom Frequencies
by
Tom Heald

Exclusive Feature Article in Video Magazine, April 1994


 

For the first two months my new universal remote control worked flawlessly. Then, for no apparent reason, it simply stopped controlling my cable box but still worked fine with my TV and VCR. One afternoon I bought a couple of new batteries. Eureka, the remote worked -- for two hours.

Then the gremlins came. One fall evening, while entertaining friends, the cable box came on. We watched as it switched through several channels and then turned itself off. Nobody was near the remote control; nobody touched the box. What was going on? Did I have a ghost in my equipment?

I called my cable company, Falcon Cable TV in Gilroy, California, and spoke with Robert, a customer service representative. "It's those universal remotes," he said, "there always causing problems with our boxes. If you rent one of our remotes it'll work just fine."

Not quite satisfied with Robert's explanation, I called Universal Electronics, maker of my One For All remote. "Do you know what could be causing the problem?" I asked after described the symptoms. "I haven't heard of it," said Tammy, a customer service rep from Universal "but it could be the code for the cable box." She gave me detailed instructions for resetting the cable portion of the remote, and we tried reprogramming all the codes for the Scientific Atlanta cable box from Falcon. Nothing helped.

Neither company had any idea what was causing the problem, although each assured me it couldn't possibly be their units. Three cable boxes and two remotes later the problem still persisted. In a typical incident, the cable box, apparently unhappy with the movie we were watching, started jumping randomly from channel to channel; the remote control had no affect on it at all.

It can't be all three boxes, I mused. Something must be interfering with the remote's signal to the box. Or maybe it's the signal from the cable. Everything seemed to work fine during the day, but not in the morning or evening. What was different? Feeling a bit foolish I turned off all the lights. To my delight, the remote worked again. Turning the lights on one at a time narrowed the problem down to the new energy saving fluorescent lights we had installed several months back, in midsummer, when we weren't watching much TV.

Apparently, the new fluorescents produced a broader spectrum of light than the standard incandescent bulbs they replaced. They seemed to be producing an infrared signal that blinded our cable box and occasionally mimicked the remote control's signals.

Energy efficient fluorescent lights are manufactured by many companies. I contacted several of the leading manufacturers and all acknowledged the problem. Though it is widespread, fluorescent light interference with remotes is so intermittent and unpredictable that nobody I spoke with could indicate how many homes might be affected.

"Yes, we have had some complaints," Scott Mack, a spokesman for Philips Lighting told me. Don Lowry, Director of Engineering for Matsushita Electronics (parent of Panasonic, Quasar, Technics) also acknowledged that, "We have had some problems." However, Lowry added that Matsushita feels "we have the problem well in hand in our product line," and is working to help define standards for the industry.

Compared with the energy savings fluorescent lights can yield, remote control interference "is a minor inconvenience," Mack asserted. His best advice was to move the lamp to a different electrical circuit and make sure it was at least ten feet away from any equipment. When I pointed out the impracticality of his solution, he assured me the problem is being worked on, and Philips hoped to have a solution soon.

I followed Mack's advice, but the same failure occurred with the light moved to the far corner of the room, sixteen feet away. Using an extension cord to connect it to a separate circuit didn't help either. Next I tried a different type fluorescent tube that produced a more natural "daylight" color spectrum. It didn't make any difference. Both lights -- eight inch circular tubes -- caused the same failure.

Gremlin Hunting

To prove it was the fluorescent light being emitted and not electrical interference on the line, I placed the lamp in a large cardboard box in the middle of the room. Sure enough, with the lamp turned on inside a closed box everything worked fine. As soon as I opened the box, the problem returned. Undaunted, I tried one last test. Using a magnetically ballasted fluorescent lamp from my office, I tried the same test. It didn't fail at all. In fact, I could shine the light directly into the infrared receiver from a few inches away without any problems. Both fluorescent tubes caused problems in the electronically ballasted lamp, but not in the magnetically ballasted one. What was the difference? It had to be something in the way the electronically ballasted lamp worked.

Traditional fluorescent lights use a heavy magnetic ballast to limit the current flow of standard 60 cycle power through the tube. This is what produces that annoying flicker we sometimes notice from older fluorescent lights. Electronically ballasted lights, on the other hand, generate a 25 to 50 kilohertz signal and use it to power the tube. This also produces a flicker, but it is much too fast for our eyes to detect. It is this flicker that most experts believe is causing the problem. It doesn't bother us, but it annoys the heck out of our remotes.

"Most lights, incandescent and fluorescence, emit light in the infrared range -- that's not the problem," said Tarry Olson, manager of Electronic Lighting Systems - Applications at OSRAM Sylvania "The problem," he continued "is the frequency of the power that's applied to the light. When it's 60 cycles there's no problem; however, when it's 25 to 50 kilohertz there are problems." Simply put, the higher frequencies can blind an infrared receiver by producing a signal "tuned" to its frequency.

Florescent lights flicker at twice the frequency of the applied power, according to the Lighting Research Center at Rensselaer Polytechnic Institute in Troy NY. They flick once for each positive and each negative swing of the sign wave. So lights operating between 25 and 50 kilohertz produce a 50 to 100 kilohertz flicker, in the form of a switched infrared signal.

Remote controls also use switched infrared signals. Typically, they produce signals in the 50 to 100 kilohertz range to transmit binary information to infrared receiver on cable boxes, TV sets, VCRs and the like. Better infrared receivers use a sophisticated automatic gain control and clocking circuit to help isolate the remote signal from spurious infrared radiation.

Some infrared receivers not only look at the center frequency of the signal but also look at its pulse width and reject any shorter duration noise spikes. Newer units are better shielded, and they limit the view from the infrared receiver so it only sees light coming from a narrow cone in front of the equipment. It all helps, but it's not the total answer.

Fluorescent light manufacturers also have to clean up their act. Because most of the electronically ballasted lights generate a pulse instead of a nice clean sign wave, it produces harmonics that walk all over the frequencies used by remotes.

The electronic and lighting industries are working together to solve the problem by developing compatible standards for both infrared remote controls and electronically ballasted fluorescent lights. The standards, being developed by committees of the National Electrical Manufactures Association and the Electronics Industries Association will assign specific frequencies to each, and set limits on the total harmonic distortion produced. "But it's going to take time," Lowry told me. "It may be a year or so before the industry has the final answer."

More Light Less Heat

With all these gremlins on the loose, why should you even consider buying one of these energy-saving fluorescent lights? To save money, that's why. Because fluorescents produce more light and less heat they cost 60 to 75% less to operate than the equivalent incandescent bulb, and they last ten times longer. With prices dropping below $10, this can mean real savings.

A typical 100 watt incandescent bulb costs about 90 cents and lasts 750 hours, where a 22 watt compact fluorescent tube will last 10,000 hours while giving an equivalent amount of light. So if you can pick up a compact florescent for less then $12, the cost of thirteen replacement bulbs, you have already saved money. If you use a light an average of three hours a day, at a typical rate of 8.5 cents per kilowatt-hour you will save $7.26 per year on each light bulb replaced. At a New York City utility rate of 20 cents per kilowatt-hour, you'll save $17.08 At that rate each fluorescent light will save you $154 over its nine year life. I wish my stocks did as well.

Two Ways To Go

If you are considering buying an energy-saving fluorescent light, you have two types to choose from.

Electronically Ballast lights are light weight and instant starting. Unfortunately, most of them interfere with some, but not all infrared remote controls. With all the different infrared receiver chips being used by equipment manufactures and the dozens of lights operating at different frequencies there is no way for you to predict which combination will cause problems. So, before you plunk your money down, check the store's return policy. If they will take it back, you have nothing to lose and dollars to save on your electric bill.

Magnetically Ballast lights are bulkier and can weigh over ten ounces which may make a table lamp top heavy. A repackaged version of the same technology used for years, some flicker for a few moments when you turn them on while others tend to hum. In general, they won't interfere with your infrared remote and they save just as much on your electric bill.

 

Side Bar - How Does Your Remote Control Work?

The hundreds of different remote controls available today use a variety of techniques to communicate with TVs, VCRs, and a myriad of electronic devices. Though the codes used may vary, they all work pretty much the same way. Most remotes send out pulses of infrared light at a specific frequency, say 56 kilohertz. Each time you press a key, a group of coded pulses is generated.

In a typical code consisting of 24 bits of binary information. The first four bits determine which one of sixteen possible devices it's talking to. For example: 0 is for the TV, 1 is for VCR set one, 2 is for VCR set two, 3 for a laserdisk player, and so on. The next eight bits describe which key you've pressed, allowing for a total of 256 possible key codes. The last twelve bits are check bits, which are compared with the first twelve bits to detect any errors.

When the receiver detects the infrared signal, it's compared to a clock pulse operating at the same frequency. If the signal is up, a binary one is generated; otherwise, it's a zero.

 

Side Bar - Light Spectrum

Light Spectrum Visible light occupies a small portion of the electromagnetic spectrum with wave lengths from 400 (violet) to 700 (red) nanometers. Infrared remote controls operate at wave lengths around 1000 nanometers or one millionth of a meter.

Fluorescent lights produce colors at different intensities depending on the phosphor coating used inside the lamp. Different phosphors produce warmer or cooler colors depending on the mix. The light spectrum shown is for one of the more common "white" fluorescent lamp. Most if its energy produces visible light, with only a small amount wasted as heat (infrared) radiation.

An incandescent light, on the other hand, wastes about 90% of its energy as heat, which shows up as infrared radiation on the chart. It's easy to see why fluorescent lights use 75% less electricity than incandescent lights, most of their energy goes into visible light instead of heat.

It's not the amount of infrared radiation that cause problems with remote controls, it's the frequency of the power applied to the light. Electronically ballasted fluorescent lamps can blind a remote control by producing a signal "tuned" to the infrared receiver's frequency.

Electromagnatic Spectrum

 

Side Bar - Test Results

The degree of infrared interference with the equipment tested is shown in the last five columns of the table. The lights were tested in a typical living room situation, using a table lamp and chair positioned eleven feet in front of the equipment. The lamp was connected to a different electrical circuit than the one being used by the equipment and the remote controls were operated from the chair beside the lamp. This is a very limited test. Other combination of electronically ballast lamps and equipment are likely to produce different results.

If you decide to buy an electronically ballast lamp, look for one of the newer ones with a reduced THD (Total Harmonic Distortion); they should produce fewer phantom frequencies. My favorites are: The Lights of America 22 watt, which looks like the DS9 space station; and the GE 20 watt, which looks like something Scotty would use to "beam you up."

Equipment Tested

  • "One for All" model URC-2085 universal remote control from Universal Electronics Inc. There was no difference in performance between the this unit and the remote controls that came with the equipment tested.
  • Scientific Atlanta model 8500321 cable converter.
  • RCA model VR680HF VCR.
  • Technics model SA-R277 stereo receiver with a Technics model CL-PC10 CD player and a Technics model SR-TR155 double cassette deck.
  • Mitsubishi model CS-2655R TV. (TV1)
  • Toshiba model CE2058 TV. (TV2)
Lights Tested Watts:
Rating /
Replaces
Model
Number
Replacement
Tube
Cost Type C
A
B
L
E
V
C
R
S
T
E
R
E
O
T
V
1
T
V
2
Lights of America eight inch circular tube 30 / 115 C2030TP-L FCL30EX-L $14.99 EB S   I    
Panasonic Twin Light Capsule 27 / 100 EFD27LE Integrated $19.99 EB          
Lights of America eight inch circular tube. (Reduced THD) 22 / 100 2022TP FC8T9EX-L/RS $12.99 EB S        
GE Energy Choice 26 / 90 22857 Integrated $9.99 EB          
OSRAM DULUX EL 20 / 75 DULUX EL Integrated $16.99 EB   I      
GE Soft White (Reduced THD) 20 / 75 11302 Integrated $9.99 EB          
Philips Earth Light 18 / 75 SL*18 Integrated $16.99 EB   S I    
Panasonic Light Capsule 15 / 60 BFG15LE / A-C Integrated $14.99 MB          
Lights of America Lifelight U-tube 12 / 60 6000-1 FUL12T60W 9308 $9.99 MB          
FEIT Electronic U-tube 9 / 60 BPMLPL9 9W/2700K $12.99 MB          
Dana swing arm magnifier lamp with a circular tube. 22 / 75 370WHT FCL-22D $47.99 MB          

Legend:
  • All "Lights Tested" were screw-based fluorescent lights designed to replace standard incandescent bulbs, except for the Dana swing-arm magnifier lamp.
  • "Watts" shows the actual wattage ratting of the fluorescent tube and the manufacture's approximation of the incandescent bulb it replaces.
  • "Price" is the actual price paid at the Gilroy, Orchard Supply Hardware store.
  • EB = Electronically Ballast, MB = Magnetic Ballast.
  • S = Solid failure, I = Intermittent failures, and a blank indicates no failures.

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