Repair guides for the MacBook Air, Apple's current line of consumer laptops.

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MacBook Air RF waves

I was wanting to know what radio frequency the wire going to my screen gives off. And another question is if the screen is turned all the way down, to black, is the computer still sending the video signal to a screen that is just dimmed all the way or is the signal cut off ?

Know they aren't typical questions and in one case might take someone who knows what they're doing with a spectrum analyzer, but thank you to anyone who might know the answers to these questions.

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Alan - What are you really looking for here? EMI emissions? WiFi and/or Bluetooth radio spectrum signals?


I have taken the airport/Bluetooth out. And so yes, would be curious if that is still giving off a signal somehow. But overall emissions, especially from the video signal to the screen is what I'm looking for. It is a MacBook Air only a few months old. Can't find anyone who has done those rf emission measurements. ...and thank you for the answer about screen dimming.


Great video! What beautiful EMF. ...don't think my airbook is tempest proof. Pretty sure it's not with screen up and running, but you mention covering the external ports. Is this an area of rf leakage? Thank you again


No, your system is TEMPEST rated with the mods. The older CRT systems just beamed signals all over the place. Basically you need a Faraday Cage to control emissions the unibody systems are as close to one as you can get.


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Maybe this visual will answer your question Visualization of EMI radiation on MBP Luke Sturgeon's work is quite beautiful. He has some stills on his Vimeo site as well. Note the emissions are very low grade (the detector was in direct contact with the MBP). All of Apples current systems will be very similar to this one. As they all use a common architecture it the LCD screen and it's signaling (as most other laptops for that matter).

Apples unibody models meet or exceed NSA TEMPEST Spec with very little modification (only the power adapter needs filtering and the external ports covered with shielding).

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Don't know the frequency - but screen brightness would be an adjustment separate from the data signal reaching the screen. Backlight intensity is usually controlled by varying a few volts DC, or generating a PWM signal, or adjusting a potentiometer or simply fixed. So the display data signal is always present.

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Alan will be eternally grateful.
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