Radio Communication - Project Feasability

Projects General Guidance
1

Hello everyone !

I need some help with a school project. I want to know if its feasable, and know what are the restricting

factors.

The project consists of attaching a transmitter to some object (a bike for exemple), and determining,

using a receiver, if you are getting closer or further from the object. I want to use two arduinos as the

receiver and transmitter, and they would communicate using a radio signal. It would be preferable if the

modules and antennas are small (about the size of your hand). The transmitter's range must be at least

60m in the city area. To determine if the modules are getting closer or further, the receiver would be connected to

a screen and display a nuimber that increases if you get closer or decreases if you get further away. Do you guys

think this is achievable, and what could be the restrictions and difficulties? What are some modules and

componnents we could use in a 200$ range and with very little knowledge in electronics and arduinos.

All help will be appreciated,

Thank you,

Fabrice Michel

2

Sounds feasible.

60 meters?

NRF24L01.

Search GPS.

3

60m along a street is no problem.
60m across a city block is very hard.
60m in an open park is easy
60m across dense park foliage may be impossible.
So: start by defining "city area" better.
Distance by radio waves is hard; you have to look into time of flight measurements. Signal strength is useless for this application. ToF may not work well at such short distances either. Most reliable may be to get a GPS receiver on both sides, take position, and communicate that position between the two nodes. Calculate distance based on it.
GPS gives 2-3m accuracy with clear view of the sky though between tall city blocks it may be 100m off or more due to reflections. In low rise environments (as in 10, 15 storey housing) I normally don't experience such issues.
GPS assisted by mobile phone towers as I have on my phone works great also between high-rise (40+ storey blocks) and even remarkably well indoors/underground.

4

To my mind the only practical way to detect distance is using a GPS receiver at each vehicle. However for GPS to work the receivers need a very good view of the sky which may be difficult if streets have tall buildings or tall trees.

It is just not possible to detect position with wireless signal strength - there have been dozens of Forum questions about it.

...R

5

FabriceMichel:
What are some modules and componnents we could use in a 200$ range and with very little knowledge in electronics and arduinos.

There is a device that will do this, the Semtech SX1280 LoRa device, it has a ranging capability. It measures distance by recording the time of flight of a packet exchange and it would have the range you need.

Under good line of sight conditions I have used the SX1280 to measure distances up to 85km.

However the SX1280 is less good (accurate) at very short distances of 60m or so, but should still give a reasonable far or near result.

Read about it here;