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tobdec
08-13-2011, 06:24 PM
What kind of range does the xbee have? Can it be moded to say a mile or so range?

Ron Czapala
08-13-2011, 06:41 PM
What kind of range does the xbee have? Can it be moded to say a mile or so range?

You can find out many details on the Digi site.

Parallax also has documentation at http://www.parallax.com/go/xbee

The series 1 info is here:

http://www.digi.com/products/wireless-wired-embedded-solutions/zigbee-rf-modules/point-multipoint-rfmodules/xbee-series1-module#models

A lot depends on the antenna used and external factors - buildings, line-of-sight, etc

Duane Degn
08-13-2011, 07:08 PM
I'm going to bet it would be easier (and probably cheaper) to buy a more powerful transceiver than to mod an XBee.

I have a couple of the long range XBees (XSC). They're probably good for a mile in an open area but a block (unit of measure in a city) of houses is enough to block (disrupt) their signal in my neighborhood.

Digi also make Xtend radios. Those are more powerful than their XSC radios.

Duane

tobdec
08-13-2011, 09:09 PM
I'm going to bet it would be easier (and probably cheaper) to buy a more powerful transceiver than to mod an XBee.

I have a couple of the long range XBees (XSC). They're probably good for a mile in an open area but a block (unit of measure in a city) of houses is enough to block (disrupt) their signal in my neighborhood.

Digi also make Xtend radios. Those are more powerful than their XSC radios.

Duane

Well I pretty much agree with duane after reading the specs. The xbee zb pro has a los of 2 miles but only 300 ft in urban area. I suppose I could always use a 2.4 ghz repeater for better range but it would be bulky and very expensive. Would a high gain 2.4 ghz antenna help at all bc its only a 60mw signal? My goal is to control a long range rov rover. I rly dont care if its by computer of a descent aircraft r/c system. The only real advantage of the xbee is being able to monitor battery voltage and such. Any suggestions or input? I know I can get long range transceivers but how well will they actualy work? I want at least a mile in urban areas.

Duane Degn
08-13-2011, 10:07 PM
Have you considered using a cell phone?

I know SparkFun sells modules that should be easier to hack than a normal cell phone.

I'm actually in middle of hacking a cheap prepaid phone now. I can have the Propeller chip send text messages with it but I don't known how to access received messages from it with the Prop (yet). So for now my cell phone/ Prop is a send only device.

Another project I'm working on (panic buttons) uses Nordic nRF24L01+ modules for communication. Even if one module can't communicate directly with one of the other modules, it can still get the message through by hopping from transceiver to transceiver until the message reaches its destination.

I believe lower frequency radio signal travel farther given the same power of transmitter. You might want to look at 900MHz (or lower) systems. The XSC XBees use a 900MHz signal.

Duane

SRLM
08-14-2011, 02:24 AM
My non scientific experimentation with the 2.4GHz XBeePro wire antenna modules found that I could get reasonable data communication through 4 inside walls in an urban area with moderate contention for 2.4GHz bandwidth for a total distance of about 15 meters.

tobdec
08-14-2011, 03:43 AM
I allready considered cell phones....only hitch is hacking cell phones is border line of getting a nice visit from our friends at the FBI. That being said I have considered a low frequency (around 850 mhz) transmissions for my RC control. Another option i'm going to look into is with the local haam radio nutjob, hes a little crazy but if anyone can make ham radio operate in such a fashion he can. That would by all means give me the range needed....and even more. If the ham radio thing works out my rover could literaly be deployable newhere that would give a 3g signal for my cameras. Im starting a pretty massive project on this robot soon. I have some parts done i'll probably post a build log soon. Thanks for the input guys!

tobdec
08-14-2011, 03:48 AM
o btw duane a little input on your cell phone hack. This is what I would do. Set the cellphone to auto display txt messages. Then set it to vibrate. Run a lead from the vibration circuitry to a pull-up circuit on an input. When the input goes 1 tell another input to send a high to an op-amp circuit that will activate a solid state relay on the enter key. From there you can export the data to the propeller. Maybe you allready knew all that but if it helps lemme know.

Gadgetman
08-14-2011, 09:18 AM
If the cell-phone has a serial interface, there are AT commands that can be used to read out anything.

Lots of good stuff here:
http://www.control.com.sg/at_commands_sms.aspx

but the best way to use a cell-phone is to use them as normal modems to send a stream of control data continuously.
(you may want to switch to GPRS or something if yo want to transmit video back to the controller, though)

Duane Degn
08-14-2011, 06:27 PM
My cell phone does not have a serial interface (at least that I can find). It's a cheap prepaid phone.

I can control all the buttons with nine relays. One of the nine is used for the power button and the other eight are used two at a time to simulate button presses of the other keys.

It's a lot of fun to hear all the clicks as it sends a text message. The fastest I could get the button presses, before the message was garbled, was 10 Hz.

My current program requires the message to be stored in a buffer in the DAT section of the program. I'm working on adding keyboard support so the messages can be created on the fly.

Duane

tobdec
08-14-2011, 07:48 PM
Well heres what I was considering. Forget a phone alltogether and somehow use one of those prepaid 3g usb cards to do all my data transmissions. The only issue is its all usb so I would probably have to put a micro-atx board on my rover. That would eat sooo much power...even the smaller ones. Now if I could get my hands on a modern 3g enabled phone with a serial port.....now were cookin with gas! And duane sounds like you allready have my idea in place, from what gadgetman said also sounds like unfortunatly you may need a different phone to make it anywhere near easy to interfaace. If anybody needs phones I have a buddy that runs a local used phone buy here sell here kinda thing so I can get dam near any carrier cheap! My manager at the pc shop also has about 50 brand new verizon phones from like 8 years ago. Basicly when verizon droped radioshack he just kept um now hes liquidating so if anybody wants anything please let me know.