iacoreHello Fedi. Do you know a SDR-RTL / radio community?
boost welcome
makary
Matt Panaro@iacore I've been using SDRs for a long time, now; but I'm pretty much just doing it by myself. I've read several online forums, but I don't think I've ever interacted in realtime with someone else with/regarding SDRs. Is there particular/specific information you're looking for?
@eigen how to use programs like stl_433 . their man page are scarce -- contain little info as to how to use it . i would like to find a community.
@iacore sorry, did you mean Rtl_433? I use that all the time/have contributed code to it. If you have any questions about it, I can probably help; but not so much with connecting you to other people
@iacore are you in the US, and looking to scan approximately 902-928 MHz ?
Ok, I'm gonna include the below instructions because I think you'll find them helpful, even though rtl_433 doesn't support LoRa (also look for references to other SDR software that does):
https://github.com/merbanan/rtl_433/issues/2745
https://github.com/merbanan/rtl_433/issues/1939
https://github.com/merbanan/rtl_433/issues/1657
(I'm assuming the SDR dongle has a 2Mhz bandwidth).
rtl_433 can be invoked in analysis mode (pass `-A -R 0` on the command line [`-R` is to specify a number of a known/recognized device)
Unfortunately, it only accepts center-frequencies as well, not entire ranges: so you'll have to tell it to search the middle of each band in the entire range: `-f 903M -f 905M -f 907M …`
To only scan each of those for a set amount of time (let's say 3 seconds), pass `-H 3`
so, the invocation will look something like,
`rtl_433 -A -R 0 _h 3 -f 903M -f 905M…`
seems like Lora is a giant waste of time compared to ASK/PSK/FSK (forget which is which)
This program is too old to be build by CMake on my machine.
https://github.com/hexameron/rtl-sdrangelove/tree/master/plugins/channel/lora
Gary 
Simon Greenwood
Ed W8EMV 
the RTL-SDR weblog has a good steady stream of interesting posts, and a well indexed archive
also the "Signal Identification Wiki" can be helpful to pick out a signal by ear / by eye on the waterfall
https://www.sigidwiki.com/wiki/Signal_Identification_Guide
I will second @M0YNG recommendation of rtl_433 as an ISM band scanning tool, but the closer to know to what you're trying to find the easier it is to recommend a specific tool.
@w8emv @M0YNG
rtl_433 -A -f 923M returns a lot of signals. How do I see the CSS chirp thing Lora has in a graphical interface?It looks like bertrik from the Revspace hacker space documented how to do this, complete with data sheets, patents, and code:
https://revspace.nl/DecodingLora
Please note that LoRa itself has a lot of options, some of which require wider bandwidth than the RTL-SDR can decode.
There is a lot more info in this graduate-level class lab on LoRa Modulation
great! the biggest question was how far down the rabbit hole to lead you before some of the mysteries became evident
looks like there's an even more recent writeup here with a Defcon talk and some slides + code from #allanrbo
