April 1, 2020

Cell Phones

I have been using a cell phone (like most of the so called civilized world) for several years now. I have always intended to learn more about the technology involved and collect some notes .... right here. But I have yet to do much.

Carriers

I have always used Verizon and been entirely satisfied with their service. There seems to be some validity to their claims to have a reliable network. Note that there are two "schemes" of cell phone transmission and encoding: They are incompatible, and a phone designed to work on a CDMA network may be hardware incompatible with a GSM network. Apple is the only maker I know of that sells phones that can work on either network -- though this may depend on the specific model number. The carriers have various stupid rules also that may limit your ability to change from one carrier to another, though this is always in a state of flux.

My Phones

Android tips

To move an APP from device storage to the SD card -- go to Settings, More, App manager. This gives you a list of your apps. Visit each one, it should have a button that says "Move to SD card" (sometimes this is greyed out).

Getting photos from an Android phone to linux

The MTP protocol seems to be the thing. On my Fedora 30 system, I do this:
su
dnf install simple-mtpfs
Fooling around with it:
simple-mtpfs  mountpoint [options] (this is the usage message)
simple-mtpfs -h (gives help)
simple-mtpfs -l (lists devices)
With my Samsung S4 connected via a USB cable, I get:
simple-mtpfs -l
1: SamsungGalaxy models (MTP)
The github page for this gives better documentation than the usage message. Source is completely misleading and optional. If you only have one possible device (like I do), you ignore that and just supply a mount point as in:
cd
mkdir mtp
simple-mtpfs ./mtp
....
fusermount -u ./mtp
Note the "fusermount" command to unmount the device. The simple-mtpfs software works with "fuser", which is a driver that supports a user filesystem, for better or worse.

If you had multiple devices (which seems highly unlikely, but who knows, maybe you want to copy files from one phone to another or something), you would use:

simple-mtpfs --device 1 ./mtp
But never mind all of this, the simple command works and I see stuff mounted under ./mtp -- and no need in my case to fiddle any settings on my phone or answer dialogs. There was a long delay waiting for my phone show up and my Fedora desktop briefly showed a useless icon about a Verizon phone.

The trick now is finding my photos (which is what I want in this case) in the mounted directory structure. There are two directories, "Phone" and "Card". Pictures does not have what I want. However each of these has a DCIM directory.

I like to have any commands I won't remember after a week in a Makefile. Then I can just go to a directory, find a Makefile there, look at it, and be back on the air without hassle. So I set up this simple Makefile:

# mount and unmount phone

list:
	simple-mtpfs -l

mount:
	simple-mtpfs /home/tom/Phone/mtp

umount:
	fusermount -u /home/tom/Phone/mtp

pull:
	rsync -av mtp/Phone/DCIM/Camera/ Camera
So, all my phone related stuff (including the mount point) is in the Phone directory on my linux machine.

Note that I added a "make pull" command to pull any new photos off of my phone and maintain a mirror of my phone photos on my linux machine.

So now the scheme to pull photos off my phone is:

-- connect the phone with a USB cable
cd Phone
make mount
make pull
make umount

Have any comments? Questions? Drop me a line!

Tom's Cell Phones / tom@mmto.org