PPRuNe Forums - View Single Post - Any PROOF of Mobile Phone "interference"?
Old 22nd May 2006, 09:38
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ionagh
 
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As an RF and EMC engineer I can tell you that there is a definitive answer to the question:

Yes but.......

The interference depends on three critical factors, the RF power used, the frequency band used and the type of modulation. All these three vary in different countries.

Cellphones can be 450MHz, 800MHz, 900MHz, 1800MHz etc... Interference is VERY frequency selective and the airborne systems MAY only be susceptible to one of those bands.

Cellphones can also use different modulation, on-off pulse types like GSM, wideband like spreadspectrum or fixed carrier. Interference will be more noticeable from on-off pulsed types like GSM.

Given also that the RF power used is controlled by the system and can vary from almost nothing to 'beyond the certified limit' of the airborne systems you have a huge range of possible scenarios. Most people will quite rightly be able to say that 'their phone never caused a problem'.

I have instruments mis-read, computer systems crash, volatile memories scrambled, other radio receivers go 'deaf' etc....

Then add the 'invisible' effects. Such as the RF causes the computer system to crash but the computer uses as watchdog program that re-boots the system after any such crash. No visible sign of interference but the computer has effectively gone awol for a percentage of the time.

So to complete the answer:

Yes BUT only a small percentage will.
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