Detect mobile phone or pager?
I'm working on my first project using a Propeller CPU. I need to use a mobile phone or pager to trigger the Prop to do some actions (I plan to make two calls in less than XX seconds as the trigger). I had hoped to use a Piezo Film Vibra Tab Mass to detect a mobile phone or pager which was in vibrate mode, but now that I have the sensor in hand I seriously doubt that this can work, as it seems to require quite a significant displacement of the sensor before it is detected by the Prop.
The device will be at an airport, which means there are ocassional other loud sounds that should not be detected. The mobile phone or pager will be in an enclosure, so it is possible that I could detect the light from the display as the unit wakes up when it is called.
I hope to get some advice on some other sensor that could be used to detect a call to a mobile phone or pager. Ideally, the chosen sensor would be low cost and easily interfaced to a Prop. Extra points if it is one of the sensors in the Propeller Education Kit, as I already have those in hand. I don't know enough about the capabilities of those sensors to know if any of them might be suitable.
Thanks for any advice.
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Kevin Horton
Ottawa, Canada
The device will be at an airport, which means there are ocassional other loud sounds that should not be detected. The mobile phone or pager will be in an enclosure, so it is possible that I could detect the light from the display as the unit wakes up when it is called.
I hope to get some advice on some other sensor that could be used to detect a call to a mobile phone or pager. Ideally, the chosen sensor would be low cost and easily interfaced to a Prop. Extra points if it is one of the sensors in the Propeller Education Kit, as I already have those in hand. I don't know enough about the capabilities of those sensors to know if any of them might be suitable.
Thanks for any advice.
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Kevin Horton
Ottawa, Canada
Comments
As an alternative there are GSM modules, which should be able to interface directly to the micro.
For instance www.gsm-modem.de/gsm-module.html.
I suspect this option may be more expensive than I am hoping for though. GSM service is still fairly expensive in Canada. I can get a pay-as-you-go CDMA account for $100/year, but I can't find GSM service for anywhere close to that price.
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Kevin Horton
Ottawa, Canada
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- Stephen
Leon
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Amateur radio callsign: G1HSM
-Phil
I own a light aircraft, which I built in my garage and basement. This aircraft has an expensive 200 hp air-cooled engine. I live in Canada, where it is quite cold in the winter. In order to protect the health of this very expensive aircraft engine, I use an electric heater to warm it up somewhat in cold temperatures before I start it. I don't want to run the heater full time, as that can cause internal condensation which can cause corrosion. It takes the heater two to three hours to warm the engine up sufficiently before I can go flying. I want a way to remotely turn on the heater, so the aircraft can be ready to go when I get to the airport.
I bought a Prop, and an SSR, and this weekend I wired and tested the high voltage side of things. I did a proof of concept where I demonstrated that the Prop can control the SSR. I have the software specs fairly well defined, and I will start writing the Spin code tonight. Now I need to sort out how I will get the ON and OFF signals to the Prop.
You can learn more about my Van's RV-8 aircraft project on my web site (Intro Page).
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Kevin Horton
Ottawa, Canada
As it happens, my Propeller Education kit includes two Parallax 350-00009 VT935G-B photoresistors. I used an elastic band to hold one of them flush against the display of my cell phone, and drove it from 5v. I cobbled together a proof of concept test, and found that I needed 50K of resistance to get the detection threshold in the right place. I'll probably rework things a bit to drive it from 3.3v, which means I'll need a bit less resistance to get the threshold just so. I'll fiddle with it a bit more tomorrow.
This looks like a workable detection solution - thanks Jon Williams.
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Kevin Horton
Ottawa, Canada
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- Stephen
Otherwise, why not use a DTMF ringtone to trigger?
Rich H
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The Simple Servo Tester, a kit from Gadget Gangster.
It's a Reiff standard system, with cylinder bands and an oil sump pad. I've seen so much conflicting info on the risks of leaving it on full time that I am hesitant to go down that road. If there is a problem, at best it leads to a very expensive overhaul, and at worst it leads to engine failure which could be fatal if it happens at the wrong place.
Neat idea, My hangar mate is interested in the same thing for his aircraft. If I used DTMF tones, we could use one system to control two relays, and use DTMF tones to control which relay was controlled by any given call. I'll see whether any of the cheap phones I am considering purchasing has auto answer.
I'd love to find a way to get some feedback that the system has switched ON. My prototype works great whenever I test it, but it failed to work twice in actual service. It was quite frustrating to arrive at the hangar, expecting the engine to be nice and toasty, and find that it was stone cold. Grr.
I've found pointers to sending SMS via GSM phones, but all the cheap phones up here in Canada are CDMA.
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Kevin Horton
Ottawa, Canada