[Replicant] électromagnetics fields

[Denis 'GNUtoo' Carikli]

On Sun, 25 Feb 2018 01:24:56 +0100
"Victor Dumoulin" <hb3 at gmx.fr> wrote:

>  
>  
> Good Morning,
>  
> The replicant website says that for the galaxy s2, the gps do not
> work. I guess because there is no driver. But does the gps still emit
> électromagnetics fields anyway ? Same question if i do not install
> the firmwares for wifi and bluetooth. If i put the phone in airplane
> mode there will be really no more electromagnetics fields ?
The GPS system works by having satellite tranmit some data, and the GPS
chip then decode that data and calculate the position. The GPS chip is
not supposed to transmit anything. That said, if the GPS chip firmware
is non-free, it may be able to transmit stuff, but it's not supposed to
do it. 

As for the GPS, Wifi and Bluetooth without a firmware, it should not be
able to tranmit anything. I would be extremly surprised if it did, but
we didn't check. Given that it's very unlikely I don't think it's worth
checking.

As for the airplane mode, when you put the modem in airplane mode,
old version of Replicant kindly asked the modem to put itself in
airplane mode, and we don't know what the modem really does....
Since proprietary software is running on it, it might could transmit
beacons for instance. The only way to prevenr the modem from
transmitting is not to load the firmware.
There was a plan not to load the modem firmware if the device was
booted in airplane mode, but I don't know if it made it in the last
replicant version or not. However this would not enforce airplane mode
if the device is already on.

> This is because i don't like too much the electromagnetics fields, i
> like to put it in airplane mode Thank for your answer.
All the common electronic devices that you use are emmiting
electromagnetic fields. Even with all the transmitters being off.
Hoever transmitters emmits way more electromagnetic fields.

It might be possible to use salamandra[1] to check if your device is
emmiting or not, but it probably requires a really good SDR to be able
to check frequencies like 2.4GHz. It might not give conclusive answer
either as a beacon might not be easy to find.

References:
-----------
[1]git://github.com/eldraco/salamandra.git

Denis.
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