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Discussion Starter #1
I searched all over this site and could not find a reference to my problem. Where I live my cell phone gets no signal. Whenever I leave home my cell captures a signal about the same location each day. What I've noticed is that if I have the radio on I hear, what I think, is the cell phone signal through the audio system. It sounds exactly the same every time, a beep, beep, followed with more beeps closer together. I'm sure that it's the cell phone because I once heard the same beeps on a radio at work when I turned on my cell. So-- if anyone can else has had this proplem I'd like to know. My intention is to mention it to Acura next time I take the MDX in for service.
 

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jst4fun said:
I searched all over this site and could not find a reference to my problem. Where I live my cell phone gets no signal. Whenever I leave home my cell captures a signal about the same location each day. What I've noticed is that if I have the radio on I hear, what I think, is the cell phone signal through the audio system. It sounds exactly the same every time, a beep, beep, followed with more beeps closer together. I'm sure that it's the cell phone because I once heard the same beeps on a radio at work when I turned on my cell. So-- if anyone can else has had this proplem I'd like to know. My intention is to mention it to Acura next time I take the MDX in for service.
What the _h_e_double hockey sticks kinda phone do you have?

Do you realize the effective radiated power of a cell phone is supposed to be like 1000 time less than even the lowest power FM station, to say nothing of an AM station???

Even if we are talking "intermediate frequency interference" (whereby the internal tuning circuits of your radio(S) are somehow amplifying or being interacted with the signal from YOUR cell phone) this would be something the FCC & FDA should be notified of!

I'm serious, if you can verify that this is happening I would a) notify the cell phone manufacturer b) contact a major university with an electrical engineering depart & med school c) call the FBI d) call 60 Minutes e) hire Erin Brockovich's law firm...
 

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Cellular Interference

Yes, I have this interference too. I'm on a VoiceStream service here in NY. But I had this beeping occur in my old Prelude which had a Pioneer sound system I installed back in 1999. So when this beeping occured in the MDX, I did what I did in the Prelude - I moved the phone away from the source.
 

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interference from Cell phone.

Yeah I have that problem when I put my Nokia phone under the tray under the CD changer radio console. I think it is kinda strange. ONE thing that I can think of is that ACURA did not SHIELD the Radio head unit. I betcha am right :2:
 

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The cell phone's radio shouldn't interfere with the car radio. Cell phones operate at 800 Mhz or 1900 Mhz at extremely low power (about 0.5W for a handheld). AM and FM radio operate at much lower frequencies and higher power levels so interfence is not a real possibility. I have never experienced this problem in our MDX nor in any other vehicle I've owned. Is this problem occuring when you switch the phone's power on while you are in the vehicle? Does it happen with any cell phone or just yours?
 

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My cellphone does that to all my car and my computer too! Same beep it doesn't matter if it the MDX or computer. I even made it as a "ringer" because it beeps ahead about a second before the phone rings or gets a message.
And it doesn't matter what brand of phone. My ericcson T68 used to do it. Now my Siemens S40 does it too!
 

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I noticed this problem as well. When someone is using the cell phone, more static can be heard from the the radio/CD. Shield may help. Perhaps a copper screen that's grounded and wrapped around the radio chasis (Making sure not to short anything).
 

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Definately an IF problem...

cardingtr said:
My cellphone does that to all my car and my computer too! Same beep it doesn't matter if it the MDX or computer. I even made it as a "ringer" because it beeps ahead about a second before the phone rings or gets a message.
And it doesn't matter what brand of phone. My ericcson T68 used to do it. Now my Siemens S40 does it too!
I think I know what is happening. There is a circuit in the phone that they are using to energize the ringer. That circuit is emitting RF that spills into the radio (probably its preamp circuitry...). I don't think this is much power, it really just an oddball interaction because the radio designers failed to shield their circuits from the EXACT SAME frequencies that the phone designers failed to shield in the ringer.

You can verify this by making a little cocoon of aluminum foil. Slip the phone in and voila you've got a Faraday cage to shield the RF emmision. If you don't have an external antenna pluged into the phone you will also shield anybody from contacting you...
 

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Discussion Starter #9
Thanks for Input

Man, I love this board. Thanks to all who responded. There is no doubt that the cell phone is causing the beeping. Tonight, I'm going to shield the cell and to a test (via renov8r's idea) and see what happens. My cell is a nokia 6100 and my service is Pac Bell. The beeping also happens with my wife's phone (same type and service). Also, I realize that an interference signal being generated in, say, a hospital coud be very serious. I'll keep you all posted.
 

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Re: Definately an IF problem...

renov8r said:


I think I know what is happening. There is a circuit in the phone that they are using to energize the ringer. That circuit is emitting RF that spills into the radio (probably its preamp circuitry...). I don't think this is much power, it really just an oddball interaction because the radio designers failed to shield their circuits from the EXACT SAME frequencies that the phone designers failed to shield in the ringer.

For anyone who has ever used a Nextel phone, they know that they cause unbelievable interference with ANY electronic device in close poximity (a couple of feet). The familiar phhht-phhht-phhht eminating from the radio, computer speaker, office phone, (anything with a speaker) every time in the seconds before a call comes in may seem like pre-cognition, but eventually becomes very distracting.

I believe that Nextel does use CDMA, just on an oddball frequency, so I am not sure why but they also will scramble the image on a CRT monitor (as if the monitor freq. doesn't match the card freq.) for the length of the call - makes you wonder what it is doing to your brain cells :(
 

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Re: Re: Definately an IF problem...

donsev said:



For anyone who has ever used a Nextel phone, they know that they cause unbelievable interference with ANY electronic device in close poximity (a couple of feet). The familiar phhht-phhht-phhht eminating from the radio, computer speaker, office phone, (anything with a speaker) every time in the seconds before a call comes in may seem like pre-cognition, but eventually becomes very distracting.

I believe that Nextel does use CDMA, just on an oddball frequency,
Donsev...your observations are EXACTLY what mine were. I no longer use Nextel, but the "phht phht phht" pre-ring, primarily on the AM band in my case, made for interesting conversation when someone else was in the car. "Hold on, I have to answer the phone". Ring! Ring! Passengers always wondered how I did that :)

I believe Nextel is using a hodgepodge of "leftover" frequencies rather than a contiguous block.

All that said, I don't have any issues w/the X and my current phone (tri-mode Verizon) either on AM or FM; it's mounted right next to the radio/nav stack w/a Panavise mount. :confused:
 

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Probably the oscillator...

All phones or electronic devices use some kind of oscillator (clock) that when activated will emit RF.
 

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My cell phone caused a "clicking" sound ...

... through the radio on our TL-S. I used to keep the cell phone in the little tray underneath the radio and it caused a "click-click" sound. I moved the cell phone to the small hole in the door handle and I've had no more problems.

I have had no trouble at all in the MDX.
 

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Here's the broad technical explanation.

Whether Code Division or Time Division Multiple Access (CDMA or TDMA), your transmissions are pulses imposed on the electromagnetic carrier. The better the circuitry that generates the pulses, the more sharp the pulses are. (In the sense of how rapidly they rise and fall.) They can never be perfect square waves.

The finite rise and fall introduce spurious frequencies. The sharper the rise and fall the more the energy in them is spread through a broad spectrum, effectively introducing no signal above perceptible noise anywhere in the spectrum. The more slowly the pulses rise and fall, the lower the frequencies and the greater the energy in these low frequencies.

Even though the digital transmission may be gigahertz, this "spreading" or "aliasing" can be in the megahertz, which your radio would respond to. The phenomenon is analogous to bass distortion in low quality stereo systems or low quality recordings. This principle also manifests itself in digital artifacts that appear digital satellite TV.

It is real. How much you perceive depends on the quality of the circuitry in your cell phone and the quality of your radio receiver. Sadly, this is more pronounced the better your radio and the worse your phone.
 

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spacedoc said:
Here's the broad technical explanation.

It is real. How much you perceive depends on the quality of the circuitry in your cell phone and the quality of your radio receiver. Sadly, this is more pronounced the better your radio and the worse your phone.
Selection of a better phone over a lesser quality radio is really a dilemma then.
Is there sufficient information to tell you which phone is better? Are not most phones evaluated on a minimum peformance level, and from that point the number of features determines the price?
Most quality after-market auto receivers have numerous specifications for noise, selectivity, sensitivity, spurious rejection, etc. So if you go that route, how much better does the phone have to be? Or will the radio always be that much better because there is no need to provide phones of such quality for just voice and messaging?
I woud think a phone that could surpass the quality of a highly rated reciever in your car would cost more money than most anyone would be willing to pay. However most of us are concerned with audio quality on other media like CDs, or DVDs, rather than the performance of the tuner, so you could have the best of both worlds within reason IMHO.
 

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This phenomenon demonstrates the significance of the battle raging between manufacturers of digital electronics and the Federal Communications Commission.

The level of spurious emissions (those outside of the spectral band authorized for a particular kind of device) is constrained. You'll find a sticker somewhere on almost every piece of electronics you own. (I'm sure there's one on your computer monitor.) The sticker states that tests have been done that prove the device meets whatever part of the FCC regs apply to it.

HOWEVER .... Part 15 of the FCC regs applies to unintentional spurious emissions. As my first post noted, every device generates frequencies outside of the intended band. As long as these spurious emissions are below a specified level FOR EACH DEVICE everything is supposed to be OK. THESE FCC REGS WERE WRITTEN IN THE 1930'S, WHEN EVERYTHING THAT EMITTED CORRUPTED LOTS OF SPECTRUM AND WHEN EVERYTHING THAT RECEIVED WAS NOT VERY SENSITIVE.

Now, "dirty" emitters are easily perceived by our more sensitive receivers. Devices that meet Part 15 standards can easily interfere with our sensitive electronics. There is also no reason for manufacturers to make their emitters "cleaner." They meet the regs, and it would cost more to clean things up. People hesitate to pay twice as much for a cell phone that doesn't do any more than a cheap one just to cut down on the pollution. (Same applies to automobiles, although we MDX owners did spend more for a much cleaner exhaust!) Folks don't realize that pollution doesn't end with air and water -- it includes the electromagnetic spectrum.

By the way, it doesn't matter much whether you're listening to the radio or playing a CD. It's the electronics inside that respond to the spurious emissions.

A final word. Hold your hats. There is a new generation of ultra-wideband devices with extensive, low level spurious emissions. A single device is only a problem at short range. But these wonderful contraptions include things like distance sensing radars on automobiles. When there are hundreds of thousands of them they add up, and the level of interference might be significant. For example, when everyone has a backup sensor on his car, the GPS in your MDX might not work!

I deal with these matters frequently, and your experiences prove that this is a problem.

-------------------------------------------

2002 Touring, Mesa Beige, Manik Side Steps, Rear Spoiler, Mud Flaps, front Air Deflector/Bug Guard, Sunroof Windscreen, Body Side Mouldings, etc.
 

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interference

I experienced similar click click noise last Sunday..
Nextel phone under passenger seat...nearby was an inverter, RF modulator.

I also have some lines running thru video screen in MDX..still trying to figure out a cause and solution.
 

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My TL made that "click click" sound

click click is the exact way I would describe the cell phone interfrence in our TL. Thankfully no problems in the MDX, but very annoying in the TL. I finally tracked down the source by one day noticing the sound near a tower. I could reproduce the clicks by driving by that tower with cell phone near the radio. Move the cell phone no click; don't drive by the tower no clicks.
 

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spacedoc--thanks for your expertise and input....VERY MUCH APPRECIATED. i first noticed this crackling, horribly loud and annoying noise when i had an '03 TL loaner. what kind of 3-month old car has radio problems ALREADY??!!!, i thought. then, just last week noticed it with my 7 day-old MDX....what the heck?!:confused: had a feeling that it has something to do with the cell phone, cuz annoying noise only happens when the phone is under the radio in that storage area. move phone to cupholder, no problem. i'm still wondering if there's anything Acura can do to rectify this problem, though. like does anyone know if they would be able to install a copper shield or something similar to block a cell phone's emissions?
 

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Re: Re: Re: Definately an IF problem...

TheWorm said:

...the "phht phht phht" pre-ring, primarily on the AM band in my case, made for interesting conversation when someone else was in the car. "Hold on, I have to answer the phone". Ring! Ring! Passengers always wondered how I did that :)
....

Worm, I also have fun mystifying passengers with my 'prescience'.
 
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