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Remote sensor, advice needed

Greetings, I am planning a project that involves a remote sensor (eg, temp) that sits idle but has to send an alert when the trigger goes off. The requirements are:

- Low power: has to be able to remain idle for about 1 week if needed.

- Has to transmit over wireless from across town (Atlanta, 30min drive or so).

- In the fufture, has to be able to send an image from a camera. BW is fine 640x480 is also fine.

- Form factor has to be as small as possibe, and does not have to be weatherproof since it will be inside.

I have been looking at gprs or something similar. I do not have enough experience with these systems although I have built many electronic/FPGA projects in the past.

Does anyone have any insights or advice about this? Any kind of info would be helpful, eg, which microcontroller would you use, is gprs the way to go in the US or is there another RF solution? Subscriber fees, if needed, are not a big issue if it works reliably and well. The reason I say gprs is because I do not know how far does RF reach.

Thank you for your time and help.

A
Reply to
amerdsp
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Which country will this device be in at deployment ?

If its the USA, there are a few cell phone modems that can do this job.

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If you want to do this on the cheap, using an off the self cell phone, there is no interface available on US cell phones. Unless you want to use a laptop as your embedded system.

Good Luck

donald

Reply to
Donald

Certainly it is possible to make a radio that transmits reliably over

30km, but as you guessed, the FCC won't allow it without a permit.

If it is really near Atlanta, the phone company should be able to run a line to the location. Then you could get rid of both power problem and communications problem at once.

-Le Chaud Lapin-

Reply to
Le Chaud Lapin

Unfortunately, I am unable to connect a land line to the location since it changes every so often. The unit has to be portable as well, so low power is also key.

I am starting to get convinced that cellphone data is the only way to go with this.

What small power supplies do people use on par with a 9V battery, size and performance? I mention 9V because its the only one I know. All my previous projects had a bench power supply. This is the first time I have to consider the limited amount of power. Do you think a 9V would be enough for the cell phone module, microcontroller for about 1 week? I understand that during inactivity, all will be in standby low power mode, unless a trigger happens.

Thank you all for the good information.

A
Reply to
amerdsp

Don't get out much, eh . ;-)

Which module are you thinking of using ???

The GM862-PCS Key features:

  • 17mA average stand-by, 3.5mA in low-power mode * 250mA average operating current * Data, Voice, SMS, and Fax * Data speeds up to 57.6kbps * Supply voltage : 3.4-4.2V * CMOS Camera Capable * MMCX Antenna Connector * Extensive datasheets and forum support

Supply is 3.4 to 4.2 volts with an operating current of 250 ma.

I should work. but as always, try it out a few times for deploying in the field.

donald

PS: I have not used this module. Like any other design, read the data sheets and evaluate the possibilities. Then be ready to be wrong.

Reply to
Donald

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