I just finished the test of our new opensource long range system modules.
This modules 3th generation and i guess i should design 4th generation before publishing them.
I'm using RFM22B radio modules and ATMEGA328P chips on Rx and Tx.
Rx modules including 8 channel servo ports and RS232 for telemetry uplink
Tx modules including PPM-Input for analog servo control and RS232 for Computer based controls and Telemetry downlink.
System range will be around 4-5km.
Firmware Upgradeable over RS232.
Ground tests was unbelievable, it's working around 500 meters into the city (after 20+ concrete building)
I will share the flight test results, sources and schematics soon.
If you have any idea about design and inputs, please share with me before 4th generation's production..
Thanks for reading
Melih
Comments
Thanks for your work on this.
"Safe: We follow the current interpretation of the FAA guidelines on small UAVs. Recreational use (non-commerical), under 400 ft altitude, line of sight, "pilot in the loop" and onboard safety systems that always allow for manual control in the case of malfunction. We're building experimental platforms that demonstrate autonomy and the capacity to do real useful UAV work, but we test them in controlled settings. If you want to fly miles out of sight or map cities, we're going to assume you've got the proper FAA clearance or we don't want to know about it."
I was looking at these modules too, but a bit aware about the tricky integration. There is the RFM12BP with +27dBm too. What about that? With +20dBm ist still a 10% duty cycle restriction?
I always wait this day, when someone will show that the currently LRS systems are way overpriced, and I am sure there is no competition between them, given how they all keep the prices so high.
The total cost of manufacturing this system is under $30, the modules are $6 each, and the others components can't be more than $15.
Based on the modules specs, of 17dB power ad -118dB sensitivity, 2dB stock antennas, and 15dB fade margin, at 433Mhz you should be able to reach 77km, at 868 half this distance.
So, I think your 4-5 km estimation is way too conservative.
The RFM22B modules are ideal for this purpose. I like the fact that they can be programmed to operate in either the 400 MHz band or the 900 MHz band. +20 dBm is sufficient tx power for this purpose.
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