Hey helpful folks. A few months ago I was lucky enough to get lots of help through this forum for a simple project i was attempting, to help me learn more about the world of 21st century electronics, but also to be something useful for my colleagues at school.
The project was a great success, and i will get a detailed write up done soon so others can make it too, but in the mean time I have a new idea for something useful for teachers (not me personally, i am lucky i rarely find myself in dangerous situations) and would like to get an understanding if it is something that is possible.
Sometimes, teachers find themselves in dangerous or difficult situations, be it a violent parent or student, or perhaps an emergency medical situation and you can’t leave someone’s side to get help.
What i was hoping to get some input into, is if it is possible to make a name badge(for example), that also has an emergency button that sends a message to someone in admin with GPS details, that way the teacher always has access to the device. (having a way of converting the gps into a class room number is another issue i will worry about later)
Given most public schools have very strict rules around connecting to their wifi, I was wondering if this is the sort of device that could be made using LoRa. I have no experience with it, but its low power and long range features might make it ideal. Have a gateway in admin, and all the badges can send a signal to that gateway via a button that transmits the location of the badge, the gateway then either forwards that to another device that a deputy has or some other way of getting the message to who needs it.
So yeah, is LoRa something that would work for this project? is it possible to make something small enough?
Any ideas, advice, links etc. would be much appreciated as i start down another rabbit hole. Maybe LoRa isnt needed at all and it can be done simply another way, i am open to any ideas that can help me get started.
It’s a great project, not wanting to put a damper on it, but, if you are doing it for the experience, great, but there are commercial products that do same thing, but with a commercial robustness.
In my experience, using hobby based Arduino or other parts mean that they are only of a hobby based grade or nature.
Great for hobbyists, or tinkering, but not for something that anyone would rely on in a potential life or death situation.
So yes, in theory LoRa would work, but constant connectivity in a brick and concrete environment might be challenging and you would probably need all the devices to form a ‘mesh’ to get good coverage. This means all teachers having them.
GPS wont be ideal as it wont pinpoint a location within a building, however potentially the mesh network could do some form of rudimentary location lock.
Power will be interesting depending on what modules you end up using, as in the size and weight of the device vs battery life.
You would also need some form of protection against accidental triggering, and lastly there would need to be a way to secure the mesh network to only allowed devices, the last thing that you would want would be to have a bad actor get control of the network and either trigger false alarms or block real ones.
Thanks for the prompt reply. I am certain there are commercial products out there that would be more reliable, what i am attempting to do is introduce an idea. if i come to my boss with a product and a big price tag i will be ignored. If i come to my boss with some cool thing one of the staff has made, it might lead to experimentation and eventually investing the money in the quality product. That is a big win in my book. So i am looking at it in two ways, i will learn a tonne of new stuff, but with any luck, i will stimulate a conversation that might lead to improved safety of students and staff. I will start exploring the mesh stuff now as that gives me something to go on.
Thanks again for such a quick reply!
No worries, that makes sense.
In my experience in making a wireless lighting controller for photography, I went a LONG way down the road of building and coding a system to end up dumping it because I couldnt get the wireless connection to be reliable.
Sometimes it would work hundreds of meters away and other times it would not connect when sitting right next to each on the workbench.
More than not it simply didnt work.
I was using the RF24 modules and not LoRa though, so maybe there would be some difference there.
My elderly mother in law has a tag she wears around her neck, press the button if she is in trouble. It links to a device connected to the landline phone which calls a number. The system is called Vital Call if I remember right.
For the radio link it might be worth looking at how it works. The radius would be a normal size house and yard. In your situation receivers could be mounted appropriate distances from classrooms to cover the whole school.
It wouldn’t have to be too complex, one way transmission, something like a garage door opener that sends a code. The code indicates which teacher is in trouble. LoRa would be too complex in my opinion.
Great tip, i will investigate and see what i can find out. Thanks!
Lora might work well as it’s designed for reasonably long-range simple messages but one downside is that it can be tricky to set up and not really designed for communications that require an acknowledgment that a message was received. Something running on the ISM band may be more suitable if you need the system to acknowledge back to the badge that the distress call has been received.
I’d recommend taking a look at the Feather form factor microcontrollers and featherwing accessory boards. They come in both Lora and ISM band varieties and should be very expandable to include a display if needed just by stacking one on top.
The RFM69 modules came to mind as a potential option and we have units from SparkFun and Adafruit with excellent guides that covers how to set them up.
I looked through your original post and the various comments.
Your project brief has some merit but maybe in a different environment.
Logically IoT devices such as the one you described would be on its own virtual Access Point and then through a vlan. This not only maintains network security but also makes it easier to manage.
GPS is always a challenge when inside - using a beacon system say using Bluetooth to triangulate/present an accurate location could help, but there are also creative solutions to use Wifi signal strength to get an idea of where the person is.
A solution I would honestly go for would be for teachers/staff to use their own phones. Add each teacher’s device as a client with its own extension. Utilize the existing wifi network for connectivity and have the teachers install a SIP client (VoIP) on their phone/device. When they are within the school’s network it connects through it and if out of Wifi range it will use their mobile signal.
When a staff member phones in using their mobile SIP client then it is prioritized over other inbound numbers. Additionally, it enables direct person-to-person communications. A teacher ringing the emergency extension would (if all was configured as such) to ring multiple numbers at once, or ring an alarm, or induce a special tone to notify the other end that the call coming through is very urgent.
An application your concept might consider is that of Childcare centres, aged care.