I'm thrilled to report that my radio kit arrived and it works well. Andreas is likewise happy with his kit.
Writeup here:
http://eastbay-rc.blogspot.com/2012/04/review-3dr-900mhz-radio.html
Fixing the air unit network id:
http://eastbay-rc.blogspot.com/2012/04/setting-network-address-on-3dr-air.html
Thanks 3DR, Tridge, and everybody else that worked in producing this unit!
Comments
My 433mhz arrived a midweek. Works like a charm - minimal configuration, well implemented into mission controller and solid range. I tested it between a friends and my own house, connecting it well over 1km away with very rough terrain, several heavy tree lines and a forest between. Certainly no Line of sight here. Gave just over 20% reception with stock antenna at 20db. Great work 3DR!
@John,
The log actually shows 5% packet loss. The problem is that the mission planner is mis-reporting the packet loss when using the 3DR radios. That happens because the radios inject MAVLink packets into the stream with a different component ID then the aircraft. The planner doesn't know that, and thinks the packets are from the plane, so when it looks at the sequence numbers it thinks there has been lots of packet loss.
I'll talk to Michael about fixing this.
Cheers, Tridge
@Dennis,
The only way to tell is to look at the EEPROM settings for the frequency. You can do that in mission planner, or using a terminal program with ATI5.
Cheers, Tridge
Just received two pair of these beauties yesterday, one pair 433 mhz (two air radios, to use one as a ground ftdi style) and one 915 mhz. The problem I have is determining which of the air radios is 433 and which is 915. I've looked the boards over pretty well but can't determine which is which. Any help will be appreciated, and if the answer is just plug them in and see, I would like to be a little more certain before I power mine up. Both pair came in the same box so no help there.
Thanks in advance for any help
Dennis
@ Andrew
Heres a link to the TLOG: https://www.dropbox.com/s/a56mp35fs3r7y2m/2012-04-23%2007-36-03.tlog
@John,
With that much margin you should be getting excellent link quality. Can you post a tlog?
My only guess as to what may be wrong is you may be running an older ArduPlane/ArduCopter version that didn't support the flow control that the 3DR radios use. The default settings on the 3DR radios oversubscribe the link, so unless you have a current APM/ACM version then you may get some packet corruption if you try to send more telemetry data than the link can support. With the newer APM firmwares it will auto-adjust the rates to suit the link.
Cheers, Tridge
These radios work fawless. I put a bigger antenna on the groundstation and it improved range to a least 3miles I was still geting apm function. I will try 4 miles today.
@Andrew How are you able to extract the RSSI data from the TLOG outside of APM Planner?
@Robert Could you post a picture of your box?
I just did my first flight with the 3DR radios today and at 390m with a clear LOS I was getting a 13dB margin on my ground radio and 17 dB margin on the remote radio with a 60% link quality on the APM HUD. With the XBee I had before I was able to get a 99% link out to 1000m before I ran out of clear LOS room. My first thought is my aerial antenna placement it a little to close to other electronics, the XBee had a little more room.
Hi Robert,
The basic answer is that we don't know for sure. I haven't noticed any difference in APM behaviour between using an Xbee and using a 3DR radio, but that doesn't mean there isn't a noise problem, it just means its small enough that I haven't noticed it.
Seppo did some RF analysis of the 3DR radio prototypes and they were fine, so we were fairly confident they were OK.
One difference with the XBeePro900 is that the 3DR 900 can put out twice the power (100mW versus 50mW). So if you have something sensitive to 900MHz then you could potentially get more interference, but the simple answer to that is to lower the power output of the 3DR radio. The 3DR radio has better receive sensitivity then the XbeePro900 so you should be able to get better range even with lower power. I've done a lot of my testing at very lower power levels (down to below 2mW).
A think a bigger issue is the radio being affected by noise from the rest of the plane, rather than the APM being affected by the radio. See the graph I posted above showing bad noise on our 3m Mugin.
Cheers, Tridge
So do these things radiate less noise than the Xbee does into the airborne electronics?
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