Doesn't even try a crisp packet? Madness.
Testing Phone-Sized Faraday Bags
201–205 of 205 posts
Re: Testing Phone-Sized Faraday Bags
#202Earlier quoted context omitted.
As well: because of reed solomon a modern digital signal can be reconstructed from flickers and fragments of the radio waves
What does this mean? A fragment of a radio wave is still a radio wave and can carry information irrespective of whether reed solomon or other encoding is used, no?
Think of it like trying to receive morse code:
If the signal gets choppy and you miss some of it, how do you know what you missed?
`..--- -.... ----- -----` (2600) could come through as `..- -. —` (Uno). Uno is a valid word, so passes validation, but it’s the wrong message.
What Reed-Solomon allows us to do is pad the message with n% of error correcting ‘bits’. That way, if >100-n% of the message gets through, the whole message can be reconstructed from whatever bits that made it. And if not enough of the message made it, it immediately fails the validation check and so you know you must resend the message.
It’s so handy and so solid that it’s used almost everywhere. From optical discs to ECC ram to radio communications and a bunch more.
Re: Testing Phone-Sized Faraday Bags
#203Earlier quoted context omitted.
It’s all well and good until you get enough clout that a bad actor offers you a very large cheque to rig the game.
Is this a veiled accusation against CR? If so I’d appreciate some specifics. If not, I’ll just mention that AFAIK CR has always foregone all advertising, specifically to avoid such conflicts of interest.
Not directly, though I have some personal doubts that have zero basis in evidence.
It’s more a misplaced disappointment along the lines of “this is why we can’t have nice things” (because at a certain point money corrupts it). The number of times I’ve seen products and brands really have something special, and believe in them, and purchase and use the products, only to have them sacrifice integrity for money at some point is heartbreaking.
But that’s a me problem (and society’s problem), and not a Consumer Reports problem.
Re: Testing Phone-Sized Faraday Bags
#204Earlier quoted context omitted.
If you're interested in simple cages similar in effectiveness to the EDEC Window Pouch (they drop off above 3GHz)... try a Microwave Oven. They are highly available, reasonably convenient and well designed, with pretty good quality control. You can even still see your phone inside has zero bars. I do, however, recommend unplugging the microwave (or even cutting the power cord) as a fire would likely result from cooki…
The door seals in most microwave ovens consist of tuned slots (eg half-wave stubs) to prevent the RF escaping. These are ineffective at frequencies other than 2.4Ghz. The reason for the tuned slots is that it's basically impossible to make a conventional metal joint which will seal sufficiently well.
I encourage you to test a few. I found that the cheap ones blocked 2.45GHz ~60dB, but that they were still down 40dB at 600MHz... the real problems were at higher frequencies and 5GHz was only down ~20-30dB at the worst case polarization. I tried using RF absorbing tape, but while it's possible to improve another 10-20dB it's painful and not repeatable without testing, if you need to remove it.
I've also worked in RF Antenna test rooms with seals that are expensive, finicky, and easy to damage... they're also at least $10k and usually much much more. In a corporate environment that's not a problem, but for a home lab it's unrealistic.
If these bags were big enough to put a few phones and a small base antenna in they'd have other uses.
Re: Testing Phone-Sized Faraday Bags
#205I can see a 99 dollars Faraday Cloth in the future