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Author Topic: Detecting an aussie postman.  (Read 1247 times)
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In Aus the postman rides a moped, all standard issue.

I originally thought of placing a sensor and an atmel processor into the mail box at the end of the drive way and run a 15 meter cable or use solar power and a radio transmitter to detect the lid of the box being lifted up....

But now i'm wondering if a microphone and a narrow band pass filter might be a better option, and mount the mic just outside... is this possible to detect moped (med - high pitch whining from these mopeds)
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Or  maybe a photoresistor to detect an increase in light from opening the lid?
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What if he shoves the letter into the slot? Then the lid won't open.
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A light sensor wouldn't false when other similar frequencies occur also.  Our postie (I thought they all did) rides a Honda CT110 which is similar to an ag bike they also sell that I've riden.  The exhaust note is higher and a bigger engine'd bike but I wonder if it would false register other traffic in your audio setup which wouldn't be ideal.

Is there a light sensor available that can trigger an interrupt so you can keep the microcontroller in deep sleep until it's needed?  If so, and you have a mailbox that opens to the sun so that's an option, you could run it solar with a small battery for sure.

Cheers !
Geoff
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In Aus the postman rides a moped, all standard issue.

I originally thought of placing a sensor and an atmel processor into the mail box at the end of the drive way and run a 15 meter cable or use solar power and a radio transmitter to detect the lid of the box being lifted up....
Why not just a microswitch to detect the lid being raised? You can connect it to a buzzer/bell inside your house to tell you when the postman has been. KISS!
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In Aus the postman rides a moped, all standard issue.

I originally thought of placing a sensor and an atmel processor into the mail box at the end of the drive way and run a 15 meter cable or use solar power and a radio transmitter to detect the lid of the box being lifted up....
Why not just a microswitch to detect the lid being raised? You can connect it to a buzzer/bell inside your house to tell you when the postman has been. KISS!



because sometimes the lid never gets raised!
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How about iR LED in the mailbox lid, sensor on the floor.  Every 10mins your microcontroller wakes from a deep sleep and turns on the light; if it can't see it you've got mail.  Or a broken LED.  But you do have a situation to attend to smiley

Geoff
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How about iR LED in the mailbox lid, sensor on the floor.  Every 10mins your microcontroller wakes from a deep sleep and turns on the light; if it can't see it you've got mail.  Or a broken LED.  But you do have a situation to attend to smiley

Geoff

Wont the IR be saturated by natural sunlight? (since there's a gap large enough to stick a magazine in) ..
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My Aussie postie wears bright yellow (for safety) and I have thought about detecting this with OpenCV webcam. This way, I can tell if the postie pasted regardless of whether mail was dropped off or not. I've tried a Bluetooth transmitter solution and thought about modifying the existing mailbox but there are various types of packages and letters sizes and shapes that may not be picked up by just one sensor. So ideally, I would have to get a new mail box and modify that but I think it would be better as an open source project.

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How about iR LED in the mailbox lid, sensor on the floor...

Wont the IR be saturated by natural sunlight? (since there's a gap large enough to stick a magazine in) ..
Both yes, but more usefully, no.  Typically you'd not have the LED just turning on and flooding the mailbox with light - rather, you'd pulse it at a known frequency using the same method iR remote controls in your sunlit lounge room avoid being overwhelmed.  Additionally, using iR will mean that your mailbox doesn't draw the attention of curious onlookers when it flashes every 10mins in the dark.

There are heaps of articles online to describe how to implement this, for example this one from Sparkfun

Cheers ! Geoff
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But now i'm wondering if a microphone and a narrow band pass filter might be a better option

Nah. It will fail to detect, give false positives, etc.

A switch is orders of magnitude more reliable.

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But now i'm wondering if a microphone and a narrow band pass filter might be a better option

Nah. It will fail to detect, give false positives, etc.

A switch is orders of magnitude more reliable.



Well it's not outside the realms, even if it meant sampling it with say a due and if that's not up to the job sampling it and uploading to a sever ...  on second thoughts
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How about a short range PIR detector mounted on the mailbox?
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You could put one of these in the back end of the mailbox - wire to the house. Your postman would love it on those dark and cloudy days.
http://www.ebay.com.au/itm/8-LED-Light-Lamp-PIR-Auto-Sensor-Motion-Detector-Wireless-Infrared-Home-Outdoor-/400487486470
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I guess modifications to postie are out of the question?
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