Range detecting sensors

Question

I'm doing a project on college bus management. Whenever the bus is at a minimum distance of 5 km(say) away from the student whom the bus has to pickup, it should send him an alert message that the bus will reach his stop with in few minutes so that the student becomes aware of the bus coming and wouldn't miss the bus. This also saves time of students who wait for long for the bus. So I need information regarding the sensor that detects the registered users within the range of 5 km(say) and sends them an alert message.

Instructorman · Answer

Sounds like GPS sensors would be a logical choice.

dougw · Answer

This can be done strictly with smart phones that have GPS - they could either continuously see where the bus is on google maps (minimal software) or they could be alerted when it gets close.

Another way is to use FRS - the bus would change its channel when entering a new zone and key the ringer which would alert any FRS radio in the area on that channel.

Another interesting way would be to use GPS and LoRa, although I don't know how many messages are allowed.

It would be interesting to run a mesh network like Zigbee to connect all the students and the bus. You could use NFC to indicate when one got on the bus.

Instructorman · Answer

Could you provide more detail on the scope and budget for your project? An alternative might be an omnidirectional beacon on the bus with a roughly 5 km range that is detected by receivers carried by students, but there will be issues with uniformity of range in an urban environment (I am assuming an urban environment for now). Also, it would be fairly involved to determine direction and speed of travel, so the bus could be within 5 km of a student, but running back and forth along a network of streets without getting any closer, make arrival estimates very difficult. GPS may be the most cost effective and reliable approach. Many GPS receivers are available for around $20 a piece. An app based solution could also be built around the GPS receiver already found in many smart phones. Many cities are equipping local buses with GPS and uploading real time location data to open data portals that allow tracking of bus locations.

Range detecting sensors

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