Servers by jDrones

Lora telemetry module with pixhawk


(Artem Skorsky) #1

I am wondering, is there anybody managed to integrate lora module to pixhawk as a telemetry module?

I am investigating SX1280 module, looks very interesting, high data rate , and 2.4Ghz looks like it might be a very good , and cheap alternative for RF900 modules


(James Pattison) #2

One of the Partners has a 433MHz lora transceiver (http://ardupilot.org/copter/docs/common-telemetry-robsense-swarmlink.html) but I’m not aware of anyone using lora at 2.4GHz. I’d be interested to see what kind of data rates vs range is achievable.


(Artem Skorsky) #3

SX1280 has -102 sensitivity at 253kbps and -109 sensitivity at 150kbps in high sensitivity mode.

specs looks very nice, I tink i can make it work with pixhawk autopilots, (small 2.4Gz radio module), i just ordered to test


(Artem Skorsky) #4

I have manged to make lora SX1280 module work on Pixhawk. I will make more distance tests and will share. I used STM32 nucle board on both end. now I am making small pcb with sm32 chip to make the module plug and play to pixhawk autopilots. stay tune , tests coming soon)


(Kenny Trussell) #5

@Artem_Skorsky, I have use 915MHz LoRa modules from Adafruit for RTCM communication between base and rover RTK GPS units. I am interested in what you have done here with telemetry. I may wish to try it at some point in the future. I am interested in your distance tests. Thanks for sharing as you have data to share!


(NS) #6

A cheap (AU $12.89) LoRa 915MHz SX1276 is also available here https://www.aliexpress.com/item/Original-CDSENET-2pcs-E44-TTL-100-20dBm-long-range-3km-SX1276-915MHz-LoRa-RF-Transceiver-Module/32791688496.html?spm=2114.search0104.3.176.20b91638G2kEmF&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10068_10130_10547_319_317_10548_10696_453_10084_454_10083_433_10618_431_10307_537_536_10131_10902_10132_10133_10059_10884_10887_321_322_10103,searchweb201603_45,ppcSwitch_0&algo_expid=069a3d2c-df03-49d9-97e4-ad291ee92bc9-26&algo_pvid=069a3d2c-df03-49d9-97e4-ad291ee92bc9&transAbTest=ae803_4


(Maksimpiriyev) #7

@ktrussell for RTCM packages I believe you need to have data transfer latency less than 1ms.
wit LoRa low latency means high speed and not far far aways.
250Kbps is the highest speed which you can achieve less than 1ms latency
and it reaches distance between 3-6km depending on the rover altitude


(Maksimpiriyev) #8

@Noli_Sicad 2.4Ghz has some advantages over 915Mhz like the global coverage, small antenna requirement,
At 250Kbps SX1276 has receiver sensitivity -95 which is worse than WiFi

Note that LoRa has half-duplex physical layer but we also have implemented soft Full-Duplex driver to work the way telemetry works, only read/write from the serial port is enough to send and receive data.


(Maksimpiriyev) #9

@ktrussell also you can reach 10-20km range if you favor to use high latency but long distance range


(Kenny Trussell) #10

The Adafruit LoRa Feather modules (https://www.adafruit.com/product/3178) are working well for RTCM. I have them set up with the default bandwidth and other settings (Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol). My base GPS sends a burst of RTCM protocol packets once per second out its serial port. I had to do a lot of experimenting with the code on the LoRa modules to capture the serial stream and then transmit it. I first tried capturing each RTCM packet on the packet boundaries and transmitting, but there were so many small packets that the overhead of LoRa caused the packets to fall behind. I ended up just capturing 200 bytes at a time, ignoring the packetization and sending until all bytes are sent. It is working well.

I would expect telemetry transmissions would be much more intensive - AND two-way.


(Kenny Trussell) #11

I should add that my application is a mower, not a flying machine. I have not pushed the range but I have 100% RTK at up to 3000 feet with a few trees in the path.


(Artem Skorsky) #12

Hi,
I would like to share what i have done so far with LoRa drone telemetry module project.
Here is a short video shows LoRa 2.4Ghz module used in full duplex and sending / receiving MavLink data . On this demo, I used 2 Stm32 Nucle dev board and Lychee drone computer.
Lychee gets MavLink data from Cube flight controller and send through USB and sends to stm32 board. Software witten inside stm32 sends data in full duplex mode by using LoRa 2.4Ghz module and sends to other module wich is connected to the PC.

More tests, range test will come soon.


(Kenny Trussell) #13

Artemis @Artem_Skorsky, thank you for sharing. Looks good!


(Artem Skorsky) #14

So far i have made a small PCB for Lora module with STM32 chip and USB /uart connector to connect easily to autopilot. Also added LED indicators to show the signal strength. Going to test now, will update with tests soon. Cheers )


(Kenny Trussell) #15

Very nice. Looking forward to hearing more.


(ppoirier) #16

Always exciting to see a new technology being tested on the platform.
Will follow progress on range, noise immunity and interference with WIFI & RC.
Keep on the good work.


(Artem Skorsky) #17

As Lora uses CHIRP spread spectrum, it shouldnt be interrfereed wth WiFi an Rc, will make more tests)