Is there a ready made sensor that will detect people walking on gravel by the sound of the gravel crunching under foot.
Sensor for the sound of people walking on gravel
- Thread starter bernardgreen
- Start date
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Big dog !
trouble is these days they'll steal the dog as well
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What if it's attached to the geese ? 
How about testing a glass break detector attached to a small sheet of metal under a layer of the stones?
I know it's tuned to specific frequencies, but someone walking on the gravel will give it quite a lot of vibration.
Wouldn't be difficult to try.
I know it's tuned to specific frequencies, but someone walking on the gravel will give it quite a lot of vibration.
Wouldn't be difficult to try.
Is it just your intention to be aware of an intruder’s presence?
Or,
To let them know you know of their presence.
Or,
To let them know you know of their presence.
Cannot go into detali but the requirement is to be aware of people leaving the property.
I will pass on the suggestion of a glass break sensor. So far the two leading options are
[1] bury microphonic cable ( the type that is used to monitor fences ) in the gravel. Setting the detector to react on the sound of gravel would be easy ( if the manufacturers are to be believed) but the life time of the cable would be short when sharp edges of gravel are pressed into it by the weight of vehicles.
[2] a parabolic microphone "looking" at the area of interest and some basic audio processing.
I will pass on the suggestion of a glass break sensor. So far the two leading options are
[1] bury microphonic cable ( the type that is used to monitor fences ) in the gravel. Setting the detector to react on the sound of gravel would be easy ( if the manufacturers are to be believed) but the life time of the cable would be short when sharp edges of gravel are pressed into it by the weight of vehicles.
[2] a parabolic microphone "looking" at the area of interest and some basic audio processing.
Yes, but needs to be "discrete" .
Would the microphonic cable work inside some steel conduit? If so, it would (a) last longer and (b) be easy to replace. The conduit could zig-zag across the path to improve the chances of it being stepped on.
I think that the acousic break glass detector won't work because it is listening for a "THUMP" first...
I think that the acousic break glass detector won't work because it is listening for a "THUMP" first...
you want to determine someone leaving the property by the noise the gravel makes when walked upon.
You cant use beams between any points?
seen fibre optic cable sensor as far as I can tell the light traveling down the cable gets distorted by the pressure applied to any given point, no idea if that's cost effective mind or whether it be suitable. (google search)
You cant use beams between any points?
seen fibre optic cable sensor as far as I can tell the light traveling down the cable gets distorted by the pressure applied to any given point, no idea if that's cost effective mind or whether it be suitable. (google search)
The present set up is using beams. They are often maliciously blocked to so as render them as good as useless at providing a reliable indication that someone has left the establishment. Crunching gravel after a beam break would confirm that the beam break was due to someone leaving and not just another malicious false alarm.
It is a bit of a catch 22 . If the gravel was smooth rounded pebbles ( sea washed with no sharp edges ) then microphone cable laid under a membrane under the gravlel would probably not get damaged but that gravel does not make much noise when walked on.
Some experiments are being set up for this weekend.
It is a bit of a catch 22 . If the gravel was smooth rounded pebbles ( sea washed with no sharp edges ) then microphone cable laid under a membrane under the gravlel would probably not get damaged but that gravel does not make much noise when walked on.
Some experiments are being set up for this weekend.
Experimental results are good.
Subject to a bit more investigation the solution apears to be that microphones will fitted into some of the illuminated bollards around the gravelled area. An audio whizz kid has confirmed he can create a software package to analyse the audio to distinguish between ambient noise, rain on gravel and feet on gravel. He apparently demonstrated a prototype of this software to the client's satisifaction. He is also fairly certain that he will be able to further process the sounds from the microphones and from that tell where abouts on the gravel the person is walking.
Subject to a bit more investigation the solution apears to be that microphones will fitted into some of the illuminated bollards around the gravelled area. An audio whizz kid has confirmed he can create a software package to analyse the audio to distinguish between ambient noise, rain on gravel and feet on gravel. He apparently demonstrated a prototype of this software to the client's satisifaction. He is also fairly certain that he will be able to further process the sounds from the microphones and from that tell where abouts on the gravel the person is walking.
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