Greetings, I am just starting to learn about this. I am in the midst of a microcontroller project that I would like to have telemetry capabilities. I do not know much about telemetry and what choices/options are avaialable. The device would be used across town and I would like it to be able to send data back to me. It would also be nice if I can probe it to report some data as well.
Any leads about this? Where do I start looking? Any links, books reference?
If this is the wrong newsgroup, please let me know.
and take a look at all the neat stuff you can get. Communications distance is a major deciding factor.
That narrows things down nicely. ;-)
I'm thinking that GSM cellular may be something you could use. If you already have a cellular phone that uses a SIM card, then you're half way there. Check this out:
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If you can do python, then you will really like this for only ten dollars more:
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Look for information on M2M (machine-to-machine) communications.
In the UK most GSM services have both voice and data, although data usually has to be enabled separately. There are some resellers who can provide data only, but they can be difficult to find. You probably have similar arrangements where you are.
I'm using Siemens M20 and TC35i GSM modem terminals for a prototype system transmitting GPS position data to a central PC via the cellular and PSTN networks. The GPS and GSM units are interfaced by a small MCU board using a 16F88 PIC with two RS-232 ports.
In the UK there are at least 4 networks that will cover any area. There are also some specialist ones. SO I am very sure you will be able to get a "data only" type link out of one of them. Though what it costs is anyone's guess.
I have no idea of what it is like in Atlanta.
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It's just a prototype system at the moment. The final system will be powered from vehicle battery so the consumption won't matter very much, unless the client wants battery back-up. A similar system I designed for use with a people counter was normally powered from a mains supply, with a sealed lead-acid battery back-up supply. That would power it for some days.
Cell phones often have a connector at the bottom and host software that allows the phone be used as a "modem".
Can you buy a "data-only" modem? The Sony-Ericsson job we use at work does both very nicely (and it's automotive rated). The only problem we find is that S-E keep changing their roadmap so that, by the time we get the project through approvals the modem is at EOL.
So have I. Mind you, I'm doing it in Australia, where the situation is rather more controlled. ;-)
Geoff
--
Geoff Field
Professional Geek,
Amateur Stage-Levelling Gauge
Yes, Europe and Australia ( and the middle east ) have these.
OK,
I worked for a company (6 years ago) who tried using GPS and Cell phones.
After 6 months tring to talk with the cell phone people, we found that the cell phones sold in the USA have the modem functions disabled. ( disabled meaning that a simple serial port will not talk to it)
Some cell phones have cables so you can connect to a computer. Well the drivers for your PC talk non-modem control codes.
ATDT1231234567 does not work.
Getting messages from a cell phone with a SMS messages does not work.
With the fear in this country about remote control bombs, etc, you can NOT use an off the shelf cell phone and a micro serial port.
Will not work.
We ended up using a CDPD modem for that project. Now CDPD is defunct. Company is gone too.
I doubt anyone knows of a regular cell phone that can be purchased off the shelf anywhere in the US that has a regular serial port and AT command set ?
If anyone does know, they will not post here. Face it, fear of the gvmt is strong here.
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These cell phone modems do not have audio, just data.
It has nothing to do with fear, triggering things, etc. It has to do with *money* as does just about everything here. US cellphone companies want to encourage you to subscribe to their expensive data services, rather than making do with a cheap voice plan and a laptop.
Heh, I have my tinfoil hat on, I have nothing to fear 8^)
Read the description more carefully, these do have voice capability. Spark Fun also offers a data-only version, but apparently these just have defective voice circuitry...
The Siemens M20 and TC35i modems have voice and data. I've got a handset that is made for them.
GPRS is another option for telemetry that is available with the newer modems. It has the advantage that it is always 'on', and one pays for the amount of data transferred instead of paying for the time one is connected. It also provides direct access to data via the Web.
Does anyone have any recommendation cellular CDMA/GSM modem that can be embedded and that will work in the US? It seems finding a cellular modem in the US is more difficult than what I thought it would be.
Maybe I am not sure what to look for. I found some modems but they are huge and I am not sure if they work directly with a microcontroller.
Also, the remark from Donald that it will not work in the US worries me and I am not sure I understand why. I know cars have telemetry that is wireless, how do they do it?
1- GSM/GPRS modems for embedded applications available in the US I presume. Are they not?
2 - If so, how does one go about making them work with cell phone companies?
I know they are simple questions but I am just started learning about all this?
1- GSM/GPRS modems for embedded applications available in the US I presume. Are they not?
2 - If so, how does one go about making them work with cell phone companies?
I know they are simple questions but I am just started learning about all this.
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