hey all,
I’m about to embark on my first project with a micro python board, i want to make a device that can measure distance from a source (ideally radio) so when its within say 3-4 meters from the source it will have a function, the source will be a second micro python device as a transmitter, i’m wanting to know if or how i can measure signal strength.
Thanks in advance !
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If you use Pico W boards and one is setup as a Access Point you can read the RSSI with the other.
Typically this is reported as a -dbm level. But there are many other factors that affect radio signals and the dbm level may not be a clear indication of distance apart.
Is it necessary to use radio, laser, IR or ultrasonic would be better indicators of distance.
Regards
Jim
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hey Jim,
Perfect! so i could use one of the Pico W boards as a slave to a micro python v1.1, or is there a better way ? I’m planning on having the receiver a micro python v1.1 board as it has the functionality I need.
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Assume this is the board you are talking about. It does not have WiFi as far as I can tell from the web page description. You would need to add a WiFi board in your project.
Regards
Jim
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Hi Arlo,
As Jim has suggested have you considered using other means of distance measurement? Physically speaking, you can use the measured latency of the transmission due to propagation delay in order to get an approximate ‘range’ (I’m avoiding the word distance here because it’ll be very difficult if not impossible to do so at a close distance) this is basically how GPS works at a high level (you can also use signal strength, but due to how the inverse square law combined with antenna transmission topology gets very complicated very quickly)
But even still, with the extreme precision of their clocks, you still get fairly low accuracy even at the distance from the surface to low-earth orbit.
I’d highly suggest looking into optical distance measurement, either with a camera and spaced fiducials separated at a fixed length from each other or a laser distance sensor. Some more clever systems even use image-recognition
It’s huge overkill for what you’re describing, but I thought it’d be a good excuse to bring this up that Liam is a huge fan of (also enables object recognition, etc.):
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Hi Bryce
At about 300 Million metres/second good luck with that over 3 - 4 metres. For a start you would have to know precisely when the TX transmitted. As suggested above a small dedicated Time of Flight system which has been specifically designed for such short distances or ultrasonic systems would be the go.
Cheers Bob
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Oh yes, you’d need to be measuring down to fractions of a nanosecond to get anything remotely representing any kind of precision 
That’s what I’d meant by impossible. Optical, ToF, or ultrasonic depending on the context of the system are likely the best options depending on the requirements.
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