Newbie-to-cellular questions

Wireless & IoT Cellular
1

I am looking at doing a remote teaching station. I do volunteer tutoring, and with five COVID-19 comorbidities, showing up at a school is contraindicated. What I want to do is use a RasPi 4 (which I have several of in various memory sizes, including 2, 4 and 8GB versions). I am planning to use the HQ Raspi camera to watch what the student is doing, and a conventional USB webcam for “face-to-face”. Some questions have been answered; for example, you state that T-Mobile LTE is supported. Ideally, this will give me the bandwidth I need to use the camera.

I want to build a system that does not require any action on the part of the student; I work with 3rd and 4th grade students. And during those times I am not tutoring, other tutors, similarly vulnerable, will be able to use it. I want to use stock parts so that many of these stations could be easily built and placed. I also want them to be easy for tutors who are computer-aware, but not computer experts, to be easily connect to these stations and use them.

One suggestion that was made was to use an Android telephone as my remote hi-res camera (no zoom, focus, or aperture control), and use a conventional webcam to view and communicate with the student. This may be equally difficult, but suggestions are welcome. In addition, I plan to equip the RasPi with a conventional HDMI screen, and use whiteboard software of some sort (the selections are quite plentiful, and include iPad/iPencil interfaces, Windows/Mac/Wacom selections, etc. Again, any suggestions would be welcome) so I can draw things for the student (I tutor math).

In addition to the video, I will need to control a several-axis camera (6DOF: polar coordinate position angle, tilt, pan, zoom, focus and aperture). My thought is to use SMS messages for this. I also need to send video, and of course, two-way voice.

My current image is the following, and I do not have answers for most of the questions because I have no experience in cellular, so I am hoping someone can point me to relevant documentation or tutorials:

  • From my desktop, I establish communication with the remote cell phone (but how?)

  • - When the RasPi recognizes the incoming call, it answers the call (how?)
  • - The RasPi activates the USB webcam and microphone to talk to the student (how?)
  • - When requested, the video input will come from the HQ PiCam, which can be moved (theta, tilt, pan) and adjusted (zoom, focus, and aperture) to examine what the student is working on.
  • - I am thinking that the command path for video selection and overhead camera motion would be by SMS messages.
  • - The video will be displayed on my 31" desktop screen.

    • Possible answers: use Skype to place the call. Use another service to place the call. Use a browser on RasPi to access the Skype Web interface.

    Keep in mind that I am one person, with nearly six decades of experience as a programmer, but there is still only one of me. Any hints, examples, tutorials, existing solutions, etc. that will let one person build this in a couple months will be greatly appreciated.

    If anyone wants to help with this (I plan to release everything I do as CC-BY-SA-NC), please let me know, so we can set up some kind of discussion platform to callaborate on this. And, of course, keeping everything on github.

    2

    I have now pretty thoroughly read the hookup guide, but I am left with more questions than I had before I started.

    My goal is to code this in Python, and the dominant Python seems to be CircuitPython with the Blinka library package from Adafruit. So, while there is C/C++ support, has anyone done anything about a Python support, best of all, CircuitPython support?

    All the examples assume I’m connected to an Arduino Uno R3; my preference would be to have only the RasPi4 connected, in which case the question is how to connect. The observation about the USB connection serving this purpose presumes that I have a way to communicate via USB to this device. Suggestions on how to do this would be appreciated.

    I was pleased to see that socket communication is supported; I used to teach socket programing, so I can use this instead of SMS messages. Using it for video would also work, all I need is a camera-to-socket subroutine, which I would rather not have to write myself. Having video compression might pay off well, especially given the memory and speed of the RasPi4. Suggestions welcome.

    3

    I think you might be overthinking this…

    Why not just a WiFi connection? Why does it have to be cellular?

    Why not just use a chromebook (or other smart device) and google meet (they are relatively user friendly)?

    Unless you need to watch what the students are doing on the desktop (screen sharing), wouldn’t any smartphone and/or computer with a camera work. You can easily log in from 2 devices (or single computer… use a private/incognito browser tab for your “second” device) with a single account and have both your screen shared and a camera in use at the same time, just mute one of the accounts. I volunteer with kids building projects, we seem to get by with only screen sharing pretty well.

    4

    Because I have to assume WiFi is unavailable. That is not an option. If I had WiFi, I would not have to ask how to use cellular. I have no WiFi, or wired, Internet connectivity, and no way to negotiate its availability. It is not the world I want to live in, but it is the world I have to live in. I need an answer that works within the (unpleasant) constraints I have, not a suggestion to make the world reasonable. That ain’t gonna happen. I am trying to find an answer that works, not one that would work only if the constraints I have no control over were changed.

    Here’s a simple scenario: my student is working, NOT on a computer, on a card table in the middle of a ten-acre cornfield, and the only technology available is a cell tower at the edge of the cornfield, and a small gasoline-powered generator that is giving me 120VAC, 60Hz, at 5A. That’s what I’ve got. Solutions that require high-bandwidth Internet or WiFi will not work because these two pieces of technology do not exist in the context in which I have to solve the problem, nor can they be conjured into existence by wishful thinking. If I had them available, life would be easier. Assume that tomorrow I will be in a wheat field ten miles away, in sight of a cell tower, and still no high-bandwidth Internet or WiFi.

    I don’t like it, but it’s what I’ve got, and I want a working solution.

    Oh, yes, there can be no screen sharing because there is no screen for them to share. They are not using a computer, which I believe I carefully explained. You can’t solve the problem I have by defining it to be a different problem.

    5

    That constraint wasn’t specifically defined… which is why I asked about using WiFi.

    Additionally, you mentioned using Skype… which is a high bandwidth service. Any streaming video service will require a significant amount of bandwidth; therefore, video streaming is probably not an option for you.

    Possible answers: use Skype to place the call.

    From the information you have given, this is the best I can suggest:

  • - Have the child send you a picture of what they have done (with a cellphone).
  • - Make edits or corrections for them, on the picture.
  • - Send the picture with the edits to the child and walk them through it over the phone.

    • However, if you are able to “Skype” and don’t actually have limited bandwidth… I was trying to hint at using a Chromebook (or other cheap smart device) instead of reinventing video conferencing with a Raspberry Pi.

    I am not a teacher, but in my opinion… having a kid walk out to the middle of a small cornfield, kind of sounds like a ridiculous learning environment. Wouldn’t it be preferable for them to learn within their home? Additionally, I am not sure that student would have any bandwidth or cell service problems if they are sitting 320 ft. away from a cell tower (assuming that it is a square plot).

    Anyhow, maybe someone else will have more useful suggestions than me.

    6

    Maybe get a 4G or 5G WiFi hotspot and connect to that?

    7

    You said the students are at a school in the OP:

    I do volunteer tutoring, and with five COVID-19 comorbidities, showing up at a school is contraindicated.

    I'm sure there some schools without wifi but now it's in a cornfield for some reason?

    You said there isn’t a screen to share after describing whiteboard utilities and video chat. All in all, it sounds like OP simply needs a laptop or tablet with cellular data.

    8

    I picked the cornfield because it is an easy analogy. It emphasizes the unavailability of megabit network and wifi.

    I have been in Skype meetings using my iPhone 4G LTE without any problems, so as long as I can get the camera data to a socket, I am not expecting bandwidth problems. Getting permission to be a non-school employee with access to a k-5 internet and WiFi puts me squarely in the model of teaching in a cornfield. I have been told, flatly, that I will never get permission to have that connectivity.

    I was sure that my absence of mentioning internet, wired or wireless, and focusing on how to do it with cellular, would have made it apparent that I needed a cellular-based solution.

    Last week I had to be out of the house during a zoom meeting. Like the Skype meetings, bandwidth did not seem to be a problem using 4G LTE. So all I need is suitable software. Asking students to take pictures is just not going to work.

    Also, many of my students are on the wrong side of the “digital divide”, and while they might be at home, from the viewpoint of Internet connectivity they are in a cornfield. Our local telephone and cable companies are doing their best to ameliorate this problem, but I want my solution to be usable no matter what connectivity they have available. As such, it falls into the “doing well by doing good” domain. I had a successful career. If my cellular connectivity cost goes up $20/mo, I won’t even notice. But if it cost my student’s family $20/mo, somebody goes without meals or medication. That’s Reality.

    9

    I think something like this is what you need.

    https://www.amazon.com/Alcatel-Unlocked … %3D&sr=8-6

    10

    Am struggling with something similar, a situation where wifi/internet is much less common than cellular networks. Thus, am trying to develop a cellular solution for sensor monitoring. Presently evaluating https://www.sparkfun.com/products/14997 via a T-Mobile SIM. Using 00 Example I can connect. Using 01 Example I can send out a message but it never arrives.

    After uncommenting the debug outputs in the library’s sendCommandWithResponse function, I see that the command goes out ok but is reflected back corrupted. Ultimately, an “unknown response” is generated with an empty response message.

    Only using the on-board antenna for now because it is not clear exactly how to modify the board to accept the external antenna.

    Any constructive input is welcome.