other8026
The OP.
Request for Opinions on "Airplane mode is a Myth"
Good afternoon, didn't want to create a new topic but I noticed the other day in battery consumption that with flight mode on, wi-fi, gps and NFS disabled. The consumption in system services showed consumption on mobile network from total 51%, IDLE system and small CPU consumption.
It turns out that the mobile network still works in flight mode on GraphenOS?
- Edited
Before the topic sinks into oblivion ……
We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.
Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?
What are the implications if hey remain on ?
araviyski Good afternoon, didn't want to create a new topic but I noticed the other day in battery consumption that with flight mode on, wi-fi, gps and NFS disabled. The consumption in system services showed consumption on mobile network from total 51%, IDLE system and small CPU consumption.
It turns out that the mobile network still works in flight mode on GraphenOS?
I have a vague sense that in GrapheneOS the battery stats are meaningful only between full charges. If I have that right, then the experiment would be:
- Enable airplane mode
- Charge phone up to 100% (when it shows as "Charged")
- Unplug phone while remaining in airplane mode
- Discharge battery significantly (probably at least 20%)
- Review battery consumption figures
Blastoidea We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.
Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?
Regarding the cellular radio, yes:
https://grapheneos.org/faq#cellular-tracking
Activating airplane mode will fully disable the cellular radio transmit and receive capabilities
Regarding other radios, I can't say it is definitive, but I'm 99.9999% certain "disabled" means neither transmitting nor receiving.
- Edited
Blastoidea Before the topic sinks into oblivion ……
We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.
Is that what we read? A source was not cited.
What's on the GrapheneOS web site is "Activating airplane mode will fully disable the cellular radio transmit and receive capabilities".
Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?
What are the implications if [they] remain on ?
Most modern radios use a single oscillator for receiving and transmitting (and the receive path and the transmit path may well share other components, such as mixers and filters). Turning that kind of radio off means that both reception and transmission are off.
Here is an arbitrary article about the cellular modem hardware in an arbitrary Pixel: An examination of the 5G radio in Google Pixel 6 Pro, including this block diagram: https://www.techinsights.com/sites/default/files/2021-12/blog-blockdiagram.jpg. It shows a main modem chip and two band-specific radio chips. If the main modem chip is off, then there will be no cellular reception or cellular transmission on either frequency band -- which aligns exactly with the language on the GrapheneOS site.
Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?
I think there is a serious philosophical question here, namely what various people are willing to regard as a "definitive answer".
Clearly, for some people, the language on the GrapheneOS web site does not count as a "definitive answer". That's fine; everybody is free to decide what sort of answer to accept.
But for me a big question is: If the language on the GrapheneOS web site is not "definitive", what would count as "definitive"?
As I have written before (not just in this thread!), I think the next level down would be hiring an RF engineer, or going to a university lab with RF test equipment, or locating an amateur radio operator with microwave test equipment. Such a person, working from public technical details of the RF modem, will be able to reliably detect whether the modem is or is not running at any given moment. It would then be possible to enter airplane mode and monitor the phone for some amount of time.
But how much monitoring would be "definitive"? One hour? A day? A month? In theory the cellular modem could be designed to self-activate every 37 days!
Also, it would be necessary to repeat the experiment for each device model, and arguably to re-run the experiment for each model every time there is a new firmware release.
So... just what would count as a "definitive answer"? Again, different people can have different standards for that. And it would be great if some member of the GrapheneOS community either did a solid examination or hired somebody to do one (even if it were just one device and just one afternoon).
But if an "overwhelmingly definitive" answer is not possible, which I suspect it isn't, then probably most people will end up having to settle for a "pretty good" answer. Perhaps the answer already on the GrapheneOS web site is close enough? But if not, I encourage people to consider:
- Exactly what kind of answer would be better than the answer that is already there?
- What steps can the community take toward an answer like that, assuming the GrapheneOS developers are busy developing GrapheneOS (and also taking into account that people keep expressing skepticism about the statements already made by the GrapheneOS developers)?
Thanks to all who responded.
13 days later
Blastoidea I trust you are doing okay? Hope to see more of you around.
de0u
I hate to sound contrarian, but I think “are the receivers shut off in airplane mode?” is a pretty straightforward question, with a simple “yes” or “no” answer.
This is getting circular and redundant, so I will desist.
- Edited
Blastoidea I hate to sound contrarian, but I think “are the receivers shut off in airplane mode?” is a pretty straightforward question, with a simple “yes” or “no” answer.
The answer on the GrapheneOS web site is "Activating airplane mode will fully disable the cellular radio transmit and receive capabilities, which will prevent your phone from being reached from the cellular network". "Fully disable receive capabilities" means that cellular reception will not happen.
As previously documented in this thread (de0u), in a modern cellular modem there aren't "receivers" as (Edit: discrete, separable) things. So no answer about "the receivers" can be answered in a meaningful way. It is as if the question were "Are the unicorns asleep in airplane mode?". There aren't any unicorns in a modern cellular modem. So I don't think anybody can answer whether the unicorns are asleep or not, not even to provide a "simple yes or no answer".
heh..
this is one of those topics which has "existed from the start".
have watched people put phones in fridges along time ago..
(almost knocking myself out with a face palm heh)
one word; Schematics.
Technical diagrams exist for a reason..
In this context - they are not 'trade secret' IP..
Progressing development of, anything really - doesn't go very far (or well) without collaboration - especially in the context of Electrical Engineering..
Just like the unicorn reference (that was a good one, btw)..
There is a middle ground between source code, and finding someone who doesn't just have specific high end equipment, but also an actual understanding of how to utilise it properly.
(very much including an ability to accurately read the data, in this context)
(also, have an image of 'ghost hunters' in my mind currently..?)
The very term 'hacking' has its origins in this exact arena;
Disassembling a physical device in order to learn and understand how it and its components work. :)