X-Post from r/linux: An electrical engineers opinion on the Librem 5

I believe I read somewhere that optionally you could choose between a SIM and a micro SD or 2 micro SD if you didn’t want / need the SIM

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You did but I think it was just someone’s future fantasy, not functionality available now. Maybe this: Primary drive: Dual SD cards in RAID 0

So you can take the modem out but you can’t realistically use that M.2 slot for anything else. (That’s not the SIM slot though, which is different but related.)

You can take out the M.2 card that holds the cellular modem, and put in something else, but that M.2 slot is probably only wired for USB (not PCIe), and it also might involve changing some code in the kernel to allow it. This is a question for the Purism engineers to answer.


No, that’s a different idea to what was in my head… I vaguely feel like it was maybe something Todd said in one of TLG’s videos… I’m skimming them now to try and find it shrug if I was wrong, thank you kieren and amosbatto for clearing up the complexities for me

edit: just re-watched the video and he didn’t mention it where I thought he did, so I now have no idea where the idea got into my head :stuck_out_tongue:


@tommes, here are two links to information about MDM9607.LE.2.2 modem firmware that IMO are worth of mentioning (as you already pointed out):

And IZat is probably there as part of Qualcomm® Trusted Execution Environment.

Just need to wait some news from Purism about these issues. I think it’s really too complex for us.
If there are some issues some people can probably help them. This planet is big and some smart people help other for create an open source world and increase privacy :wink:

I am not Verizon customer, but according to this good news and to this bad news how it is possible that the very same firmware from Verizon once supports voice and in second scenario not, even though it is about the same firmware for the very same parent module? Basically I just wanted to link to those for your awareness as it looks like that (might be) EG06-A exists (on the particular market) as Telematics version and EM06-A as non-Telematics (Data-only) version. Just hypothetical question here, as I don’t understand, is it about EG06/EM06 modules for Verizon having some voice supportive chip (hardware) difference or just about disabling voice on M.2 card using software (and perhaps some preferable doctrinal rules)?
Secondly (and maybe somehow bothering), I like to point to Sierra Wireless AR7592 as this brings us to other modules that are just like AR7592: EMEA - AR7594, China - AR7596, Japan, Korea, Australia - AR7598. Which kind of glue do I need to put those on M.2 card? Epoxy for developers, even though I don’t posses mandatory certificate? And all of this leads me to finding (for myself) that there might exist some similarities when selecting modem module for L5 or Linux-based TCU (telematics control unit), similar development challenges, not sure and just guessing, @Tatatirci don’t get me serious on this one. But still some hopes I might keep alive, if nobody objects with some arguments why Sierra Wireless AR modules cannot be an option if eventually put by experts on M.2 card.

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This is more of a general question regarding electrical or electronic engineering from the point of how an electric engineer uses physics theory. How much of the physics, as in Standard Quantum Mechanics, is used in designing a hardware component? Is that used at all, or just referred to, or is it something that is only at the back of the mind just in case something cannot be handled using plain old trial and error steps as in classical physics as opposed to the physics that concerns wave-particle duality, uncertainty principle, entanglement, tunnelling, and then SQM theory is looked at?

I am asking this because whenever I bring up the topic of using physics theory to design parts for, say the Purism devices, I get flack that the topic is inappropriate for the thread I am on. So, is there a more appropriate thread that I can discuss such things?

Even though this is not an relevant answer, but I guess that bringing your subject matter opinion/knowledge under Round Table (your own thread) should be fine.

I have never heard of quantum physics being a consideration in board-level electrical designs. The quantum stuff all takes place on the integrated circuits. The smaller the IC manufacturing process, the more quantum physics are involved. As things get smaller, quantum physics breaks some otherwise good electrical designs and makes new things happen that can be used to improve the design that would not be possible on a physically larger circuit. When you buy the chip to put it in to your board-level design, all of that has been established. All you need to do is to read the accompanying data sheet and count on the chip doing what the data sheet says it will do. Quantum physics plays a big part in how the chip functions (and thus, how the board-level application should function). But the board-level designers never have to consider the quantum mechanics issues. Quite simply, the chip always just does what the IC manufacturer says it will do when it is placed in to a board-level application. Board level designers never have to think of quantum mechanics.


Thanks. Will try that “my own thread” under Round Table.

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This issue of quantum mechanics is also a different issue from the issues of radio wave propagation and antennas. At the frequencies we’re working with, the wavelength is very small. But the same rules of physics apply whether the wavelength is miles in size or in the nano-meter range. The only thing that changes are the physical constraints of what is practical to do to accomplish what is needed for the antenna to work well. For example, in an AM brodcast receiver, the antenna would be a few hundred meters in length. But that is not practical for the average person to have. So they coil a long-enough wire up to create an inductive loaded antenna to get an impedance match between transmitter tower and receiving radio and call it good enough. Even if most of the signal is lost, enough gets through to make things work. In a cell phone you have the opposite situation. The antenna has to be to big to catch enough of the signal to work, and capacitive loading is probably needed to provide an impedance match between transmitted signal and received signal. A lot of the signal is probably lost in the process. In any radio system, the antenna makes or breaks the system. Typically, the antenna gain is more important than how much power is transmitted.

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That is more like the kind of info I need, to continue confirming my conclusions for or against, about what SQM is capable of being used for. What I really want, if you can get on my thread “Kazmroz Science” on Round Table, is to see what exactly Standard Quantum Mechanics has been used for as in using SQM as a guide in direct engineering design application and not just what it was used to try and explain after something was already designed by the use of regular trial and error engineering methods done without recourse to SQM.