Xbee Pro long range made affordable until end of February 2009

Looking for telemetry transmission hardware, I came across following offer made by Digi (ex-MaxStream):

XBee-PRO 868 OEM Development Kit w/ 2 XBee-PRO modules


Apparently, the kit is available for a promotional price of only 99 USD until end of February 2009.

The package contains following:
(1) XBee-PRO 868 w/ RPSMA Connector
(1) XBee-PRO 868 w/ Wire Whip antenna
(1) RS-232 Development Boards
(1) USB Development Board
(1) RS-232 serial Cable
(1) USB Cable
(1) 868 MHz RPSMA Antenna
(1) Power Adapter
(1) 9V Battery & Clip
Various Adapters

This 868 MHz short range device has software selectable transmission power (1 mW (0 dBm) to 315 mW (+25 dBm)).
RF data rate is 24 Kbps (10% of duty cycle).
Incredible Outdoor/RF Line-of-Sight Range up to 25 miles (40 km) with dipole antenna.
Serial data rate of 1.2 Kbps to 230.4 Kbps.
It needs 3.0 – 3.6 VDC power supply and transmitter burns 500 mA typical at 3.3V (800 mA max), receiver only 65 mA typical.

Apparently, for the moment it is ETSI approved for Europe (without special license), but no FCC approval yet for the US.

I think of it as a must have... Can't wait for the Swiss reseller to send me my quote to confirm my order.

More infos on Digi web site.

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I've now found a "solution" for this, but it will kick up the duty cycle above the allowed 10% (not a bad thing in everyones eyes).

I wrote a small program which just basically simulates sending servo position update packets via the XBee 868 to a receiver unit. What I tried out now is to simply reset the modem and wait for a small moment before retransmitting data, between every full update packet.
Of course this is not optimal, it should not reset so often etc, but I did it like this to test the theory with minimal work.

And it works like clockwork, but it does have a delay between payloads and thus is slower than it would be without the reset and delay. So I will work on an optimal transmit loop count between resets based on my payload, and anyone else could do the same.

To reset the modem connect a cable between the RST pin on the adafruit module and one of the digital pins on the Arduino/ArduPilot.

Then just simply add this:
in void setup()
pinMode(resetPin,OUTPUT);
digitalWrite(resetPin,HIGH);//set the RST pin high, low will reset the module

And then in the loop code with apropriate counter (you can find this out easily if you transmit a same size payload every time, otherwise make it low enough to be safe - otherwise use response ACK packet timeout to activate)
delay(TXdelay);//wait for data to transmit
digitalWrite(resetPin,LOW);//press reset
delay(RSTactiveDelay);//spec minimum is 100us to register
digitalWrite(resetPin,HIGH);//release
delay(RSTrecoverDelay);//wait for XBee to initialize

Of course you'll need to tune your variables for your particular application, and define them.
Great job Noth666
I was searching how to hack this 6 minutes wall :)
Thank you !
Which adapter board are you currently using? I am concerned about the maximum current.

Is the XtreamBee board any better than the Adafruit?
Hello,
has there been any progress with this duty cycle issue with the 868:s? Has anyone tested the "solution" by Noth666?
Does it work reliably?
HI Kim,
I don't think there can be much more progress with the duty cycle problem other than resetting the device from time to time as it's a restriction imposed due to the frequency it uses. I personally have not tested the exact solution posted by noth666 because I fly using PIC32 but process I use is exactly the same and it works just fine. If I'm only using one way comms for servo control then my Lipo's run out long before the duty cycle is ever a problem @ 9600bps so I leave resetting off. I have had a good 12 months of flying with these modules alone (no standard TX) and have never had a crash caused by duty cycle problem so it seems reliable enough. the only modification I did use was to fit a small heat sink on the chip, I could never decide it if actually made much of a difference with the power I had it set too but fitting one is never a bad idea.

Regards,
James
Which would be the reset "pin" on the XtreamBee Adapter?
http://store.diydrones.com/product_p/br-0015-01.htm
I looked pretty well at the markings on the adapter but there is no RESET or RST pin...

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