3DR 433 Mhz Radio's
Post date: 04-Oct-2012 11:34:09
So I tried my old XBEE 868Mhz Unit I got in 2009 for my Paparazzi unit ...It works , BUT got a 10% duty cycle , thus works 6 min out of every hour ...really useless ! but point proven ..I could get Telemetry in the APM , although be it for only six minutes ..
So after Speaking to the guys on South African DIY Drones User Group I decided to get the 3DR unit ...
Some comments from the Group ... (Click Here to See All)Ettiene :That kit is excellent and is what I use. If you play around with the data rates and output power you can get quite far, though I have never reached it's max range with the settings I use now. I'll have a look at the ranges that I get, but it's easily over 1km (I fly a plane though, not a quad)Graham :433 will get longer range and as mentioned they really do work well, I have also not yet flown out of range.433 is legal as long as you don't exceed 10mW (http://www.info.gov.za/view/DownloadFileAction?id=145878)
Nicolas: A friend and I have been using the 3DR 433mhz telemetry here in South Africa since their release earlier in the year without fault. We have even connected them from our respective houses which are 1.8km apart and performed a firmware update at this range (albeit a VERY slow one). In addition our houses are not in what one would call line of sight!!!
So I ordered the kit from NetRam , not the cheapest , but one day delivery (free) ..so if I had ordered this from 3DR the price plus shipping would have been more or less the same ...and I would have to wait a month +- :~(
..... and it Arrived here early this morning ...
Everything seems to be there ...http://code.google.com/p/ardupilot-mega/wiki/3DRadio
The 3DR Radios have 2 status LEDs, one red and one green. The meaning of the different LED states is as follows:
- green LED blinking - searching for another radio
- green LED solid - link is established with another radio
- red LED flashing - transmitting data
- red LED solid - in firmware update mode
Choosing the air data rate
The key parameter that controls the range of your radios is the AIR_SPEED. The default is 64 (which is 64kbps) will give you a range of over a kilometre with small omni antennas. The lower you set the AIR_SPEED the longer your range, although lowering the AIR_SPEED also lowers how much data you can send over the link.
The radio firmware can only support 13 possible air date rates, which are 2, 4, 8, 16, 19, 24, 32, 48, 64, 96, 128, 192 and 250.
What air data rate you choose will depend on the following factors
- what range you need
- what data rate you will be sending
- whether you primarily send in one direction, or both
- whether you have ECC enabled
- whether you have an APM firmware with adaptive flow control
For most telemetry applications you will primarily be sending data mostly in one direction, from the aircraft to the ground station. For most people, the amount of data sent from the ground station to the aircraft is small, just an occasional control packet plus heartbeat packets.