2.4 GHz telemetry kit
ArduCopter & ArduPilot Mega telemetry kit utilizes the 2.4 GHz Xbee Pro 2.4 GHz 63mw modules; this is the kit for use in the UK, EU and other parts of the world where the 900 MHz Xbee’s can’t be used due to mobile phones using the same frequency.
The 2.4 GHz telemetry kit supports two way communication with the mission waypoint read and write functions in both Michael Oborne's Mission planner and HappyKillmore’s GCS on both the latest APM and ACM codes. This means no more USB cables & landings to connect the ArduPilot to a laptop in the field, you are able to view live telemetry data as your airframe progress through the mission, you can also load a new mission on the "fly" while your UAV circles above you and then execute that new mission without having to land! The range of operation has been tested out to half a mile with no loss in connection, connection has been found to drop off at 3/4 of a mile.
Included in the kit are all the items you need to have a fully functioning telemetry system:
Please note, the kit is now only supplied with a USB lead for use on the GCS Xtream Bee, not the FTDI Cable listed, this is because the adapter board is now a USB and not FTDI connection, there is no need to solder any jumpers / bridge any connections on the USB Xtream Bee, only the solder jumper / bridge needs to be applied to the airframe Xtreambee.
The Telemetry kits need to be supplied with a maximum of 5 volts, if you go over 5 volts you will damage the xbee units! This damage will not be covered under warranty.
The kits is available two forms:
Either as a pre soldered, fully programmed and tested kit, so they are completely plug and play or in a self built kit, for those of you who like to build your own.
Build the Xtream Bee’s:
The XtreamBee boards need to be built, this involves some soldering and is not complicated if you are experienced with soldering, however a word of warning here, when soldering the female headers, don’t use too much solder! The male pins of the Xbee modules will not fit into the female headers if any excess solder runs down inside the holes on the PCB, it fills the female headers with solder, this is not good!
When the soldering of the female header connections is complete you will have to solder the connection pins for the FTDI / telemetry cable to the APM and the computer. To enable the to way communication in the GCS’s you will need to hold the CTS line high, this is done with a solder bridge from the VIN line to CTS line. This modification is required on only the air side XtreamBee board.
When you have completed the soldering of the XtreamBee boards you need to set both slide switches to the master mode, you can now add the first Xbee module to the XtreamBee, you will see that there is an white outline of the Xbee on the board for orientation, please ensure you select the correct orientation to save the XBee unit from being damaged!
Before adding any power to the board make sure that the Antenna on the RPSMA Xbee is attached and screwed all the way on, powering the unit without the antenna being fitted or incorrectly fitted will cause the unit to fail!
Install the Xbee’s and Program:
You will need to program the Xbees using the USB Xtream Bee board. Program the whip antenna Xbee first and then the RPSMA Xbee. When the Xbee's are fitted to the XtreamBee boards the antenna has to be connected (RPSMA only) before powering the board using the supplied USB cable. You can also do this using an FTDI cable if you have one, however one is not required. To program both board you can use the USB Xtream Bee board. Image below is for FTDI cable use.
The Xbee Pro 2.4 GHz 63Mw units come set at a data rate of 9600, this needs to be changed to the higher rate of 57600. To do this you will need to use a free program called X-CTU
Down Load Here:
In "PC Settings" select the comport that the XBee is connected to, then go to the tab marked "Modem Configuration". Always select the update firmware option, click "Read", change the rate in the box shown above and then click "Write".
When you have changed the rate on the first board, remove the first Xtream Bee and switch over with the other, program the second one in the same way and to the same rate as the first.
The set up of the Xbee’s are now completed!
Adding the Telemetry to APM:
On the APM you will see that there is a total of four connection ports marked "Teleport", (if you don't have the male pins to solder to the teleport for fitting the telemetry cable they can be found here) which will need to be connected to the airframe part of the telemetry kit. There are two pins for the power and two for the communication. Once again if you look at the XtreamBee you will see there is a “5v+”, “GND”, “In” and “OUT”. With the supplied APM telemetry cable you will find one end has 4 connections and the other has 5, the 4 goes onto the APM and 5 onto the XtreamBee, match the two ends to the corresponding pins and the APM is ready to send telemetry data to the GCS.
How to get the data:
To start using the telemetry, power the APM first which will power the airframe Xbee, power the GCS Xbee second, then load the Mission Planner or HK’s GCS select the correct comport and speed (57600) and click connect. You will now have your telemetry up and running!
Always select disconnect in the GCS before removing power from either of the units, I have found that on odd occasions if you just unplug one unit / switch the power off without disconnecting in the GCS you can lock a unit, this is easy to solve by reprogramming the XBee again, but to avoid it reverse the connection process.
Use of 2.4 GHz Radio and Telemetry together:
This kit has been tested both in the field and in a lab environment to check for any clashes or interference between the RX/TX of the radio equipment operating on the same frequency as the Xbee’s, no conflicts have been found to exist.
The Xbee units on power up look at the frequencies available in the channel they have assigned, they will then select the one which has the least amount of noise, this is called DSSS in the world of Xbee’s, the DSSS operates in a very similar way to that of the 2.4 GHz radios with frequency hopping, which means we can fly more than one aircraft at a time and still use the same 2.4 GHz band as the pilot standing right next to us.
The field tests conducted were first with the radio on “range Check” which is a very low power setting, the Xbee was set to full power and placed on top of the RX and APM, the TX was taken to the minimum recommended distance and some way beyond, at which point there was still a solid lock and smooth operation of all the connected servos.
The second field test was conducted in a wide open space, where once again the Xbee was set to full power and was left on top of the APM and RX, the TX was in normal “flight Power” mode and was taken to approx 1.3 miles away with line of sight, there was no loss of connection to the servos, they still operated as if there was not a telemetry kit working right next to the RX.
The radio I used throughout all of the field testing was a Futaba T7C, I have also released three full test kits to customers to try with additional radio equipment, all non Futaba, some of the radios tested were $60 specials while others were top end systems, all tests conducted have proven to be successful with no loss in control at any time and easy to use telemetry from the box.
This kit has now been on sale for over 12 months and no issues with any radio systems has been found.
While no concerns or issues have been identified with the telemetry kit and the radio systems when tested in the field or lab, it's highly recommend that a “range check” be carried out before committing to flight, if you can maintain a solid RX / TX lock at lowered powers on the ground beyond the minimum distance recommended then flight should not be an issue.