GPS to cell phone output somehow ???

**mbaratta** · 05-17-2004, 12:37 AM

Here goes:

(refer to diagram)

How to use it:

Set phone to vibrate. Add 12v. Leave for crooks.
When car is stolen, call or text lojack phone #.
lojack replies to predetermined phone # or email with coordinates.
Administer capital punishment to crook.

How I think it could work:

(If you don't already know, A phone vibrates by a unevenly weighted motor spinning. Power is applied to the motor, and it spins.)

Phone is opened and the motor is removed. The leads (possibly needing amplification) are then ran through the coil of a relay.

When phone is called or texted, phone thinks it's vibrating. Instead it closes the contacts on the relay.

When the relay is closed, it allows 12v to reach a pin on the microcontroller.

Micro... is constantly looking for voltage on that pin. When voltage is present, micro.. gets coordinates from gps dongle. (how?).

micro is preprogrammed with a phone # or email address, and the code to write a text message and send it.

Micro is connected to the phone where the data cable does. It's like serial, I think.

micro runs code, sends text.

Like I said earlier, I'm not a programmer, but I know a little.

I know a few websites that let you send a text message through the website.
So there is code to do it. I don't know how one would "port" the code to be stamp (or etc)friendly.

Zorro has done amazing things with phonecontrol. Including sending text messages. Maybe he can help with that part.

I also have no idea how one would get the coordinates from the gps.

I currently don't use gps, so I have 2 questions.

Can one gps dongle be used for this idea and normal direction finding, or two?

Does the gps have to be in sight? Will kinda hamper the secrecy of the device.

Thanks

Mike

**Ricky327** · 05-17-2004, 12:54 AM

When phone is called or texted, phone thinks it's vibrating. Instead it closes the contacts on the relay.

When the relay is closed, it allows 12v to reach a pin on the microcontroller.

No need for a relay. The controller can check if theres a voltage present on the wire that spin the vibrator motor.

When voltage is present, micro.. gets coordinates from gps dongle. (how?).

The controller can be programmed to read off the NMEA sentences from the GPS...This is in serial format normally running at 4800 baud.

Does the gps have to be in sight? Will kinda hamper the secrecy of the device.

No...it can be hidden under the dashboard as signals can still go through plastics.

If the phone can be controlled via its serial connection then it is so much easier. Such as picking up the phone, dialling a number and sending text all being controlled by the serial ports perhaps.

I need more info

EDIT :

Yup it is possible to answer, dial, and text via the serial port.

http://gatling.ikk.sztaki.hu/~kissg/gsm/at+c.html

Time to look more deeper into those AT commands

**spectrrr** · 05-17-2004, 02:44 AM

Originally Posted by gadget

Have you looked at the TinyTrak3 device? That sounds a lot like what we are talking about. It converts GPS NEMA serial data into packet radio data (for HAM radios) but I have been told it will not work for cell phones because the D/A converter and hardware of the cell phone will not pick up and transmit tones correctly at the speeds and tones at least that unit transmits (HAM packet data at 300 or 1200 baud).

I want one of those TinyTrak units, but I just want it to output like morse code or something.

Maybe we could find or build a voice recorder type device to transmit stored sound clips. (You record the numbers 0-9, west, east, north south, MPH...) into a couple dozen seperate memory locations on a chip. You grab the header line of the serial data out of the GPS once every 2 minutes and then character by character you have it <== IT being this basic stamp/wav storage/playback device like on those picture frames play each coresponding memory location into the phone's mic wires of the hands free kit.

So the line "... 109.12345 W 39.12345 N..." plays the sound clips stored in memory location "one, zero, nine, point, one..." and you hear yourself over the phone reading the position.

Later as more 911 call centers turn on their cell phone GPS tracking, we could just hide an old cell phone in the car, then 911 could call the cell phone (set to silent mode, auto answer) and they can get the location of a GPS enabled phone. SOME of the 911 centers in my area have this, but it's been slow to get them online. Heck I guess you could leave it on speakerphone so when 911 does call, if the badguy is in the car, they will know the police are tracking and talking to him through some hidden phone he can't find.

ahh, not quite sure where I saw it (maybe on these boards), but I'm sure i saw a guide somewhere for using the tinytrak with the cell phone.

all you have to do is use the cell phone headset plug to input the audio output from the tinytrak, and then set the prepaid cell on autoanswer. on your end, you have output the audio from your phone into your computer, and the computer decodes the HAM radio packets and spits out all the fun data to assist you in killing, err, i mean locating the guy who took your car.

I know its doable, even if it takes a simple converter for the packet data.... i'll try to find the link for you. sure seems like the easiest route.

**Ricky327** · 05-17-2004, 07:06 AM

all you have to do is use the cell phone headset plug to input the audio output from the tinytrak, and then set the prepaid cell on autoanswer.

Problem is...as been said the tinytrak cant work with mobile phones. It look like the bandwidth of the phone audio is too narrow to work with 4800 baud rate. I read on the net somewhere that the maximum frequency the mobile phone can handle is only up to 5KHz...not sure about the lower limit.

I was thinking :

A PIC is programmed to take in the 4800 baud rate from the GPS. Since most GPS unit repeat itself once every second, the PIC will take in 1 second worth of data. The data is then stored temporarily and then retransmitted as tone throught the micophone input of the phone at a lower baud rate, 110 perhaps? whatever the maximum the phone can handle.

The receiving end decode the tones then reconvert the 110 back to standard 4800 bauds for the PC to plot the locations. The same data are represented again until new one are received, this is done to fill in the missing data to satisfy the 4800 baud rate . In effect the GPS locations is only updated 4800 / 110 = once every 44 seconds...which is still workable to find where your car had gone

So it work something like this :

You ring the tracking phone and it answer automatically. (Set to autoanswer, not sure if this is true for all phones)

Then the unit work as follow :

GPS ---> [4800 to 110 baud translator] ---> [FSK tone generator] --->[Tracking mobile phone]
.
.
.
[Your phone] ---> [FSK decoder]---> [110 to 4800 baud translator]--->[PC]

As can be seen the idea is not to hard to implement using the PIC microcontollers.

The FSK can be done through software or hardware as all it does is generate a different tone for '1' or '0', 1200Hz for '0' and 2400Hz for '1' lets say. The FSK decoder can also be done through software or hardware...software solution is much better for encoder and decoder as this reduce the hardware cost.

Although the GPS update rate is slow but the idea should work with cheap phones, no need for phones with built in modem or it being data enabled. An old pay-as-you-go type of phone with no credit can be used as long as data can be transmitted successfully. The tracking unit is only activated when you ring its number.

A much neater solution is of course to use phones that can be controlled via serial ports. Been checking it last night...so much things can be done to it. The biggest problem is programming the PIC to take advantage all of whats possible with data enabled phones.

**SAScooby** · 05-17-2004, 08:25 AM

hi all

Try these links lots of the headaches been solved already

http://www.pimall.com/nais/tracking.html

http://www.securitystores.com/cgi-bin/specs.cgi?1235

http://www.gpsanywhere.com/

http://www.thespystore.com/gps-usa.htm

some seem expensive, maybe some one should buy one and hack it open to find out how it was built and then re-engineer it to our purposes ?

the little GPS mouse looks a lot like the ebay type

**Ricky327** · 05-18-2004, 07:16 AM

Its too expensive to buy one. Trying to find out how they work can still be hard...what if they use some specialised controller, customised...stuff you can never buy.

I dont think theres much into it, it just a matter of programming the controller.

Here I found a link including the source code :

http://www.parallax.com/html_pages/r..._gps_track.asp

http://www.maxim-ic.com/appnotes.cfm...te_number/1790

Im not too sure if its complete but I think the bare minium codes are there to get started. Ill like to try it but I dont have the tools for it...any one?

I just think BASIC stamp is too expensive for what they are, so im still doing more research on AT commands, NMEA sentences and PICs USART.

**gadget** · 05-18-2004, 09:20 AM

WOW, thanks for all the great links people! There are a couple existing units that I really like and feel the price is very fair for what they do. That $199 unit at gpsanywhere looks interesting, but sounds like it's still kind of on the drawing board. Some of those other ones look like a good deal, and it's worth my time to just pick one of those up rather than try and make my own.

**Magpie** · 05-18-2004, 09:35 AM

Take a look at the following link:

http://www.gpss.co.uk/chase2.htm

This guy has created a free GPS software called GPSS. Along with this he describes vehicle tracking using a GPS receiver and mobile phone. His pages are of poor quality but this is made up by some stunning software.

I would recommend starting at his home page and working from there. I have not worked out yet what exactly he used to make this work but looks promising.

**Ricky327** · 05-18-2004, 09:39 AM

It says

Updated 0800 Tuesday 4th July 2000

**Magpie** · 05-18-2004, 09:48 AM

I guess that page was.

The rest of his site is fairly up-to-date. He is working on a project for tracking bottles thrown out to sea. Kind of a message in a bottle thing..

See http://www.gpss.co.uk/bottle.htm