lots of good information in Tom’s response. The answer depends on what your goal is. A fully integrated LoRa APRS network bridged/routed to a standard AX.25 network would be a challenge. Doable, but certainly not trivial. If the goal is to use LoRa to import data from the oft-maligned “dumb tracker” or some sort of sensor for display in xastir, the problem is a bit simpler.
I haven’t used LoRa, but I have used Xbee 900MHz data radios in a way that sounds similar toy what you are describing. These xbee radios are point-to-point or broadcast. I configure dumb trackers (for tracking rockets) in broadcast mode, and the code is written to time-slot the transmissions to avoid collisions. The digital side of the radio is a simple serial interface. The tracker prints a TNC2 format string to the radio, which is received by the ground station radio and transmitted via RS232 to an xastir port configured as a "serial TNC”. The TNC2 format has the advantage of being human readable, so I can hand a radio+usb/rs232 adapter to a student with a windows laptop and a simple terminal program, and they can easily see the coordinates in the position report. Not as nice as a map, but in the past everyone had HyperTerm on a windows laptop, and putty is a free substitute. It is also possible to use multiple receivers, e.g. a simple dipole on one receiver and a yogi on another, to allow for different distances. This is helpful since the distance can change quite quickly during a rocket’s flight. Getting this data retransmitted (digipeated) is problematic because digi software is not designed to accept TNC2 format packets for multiple legitimate reasons. In my attempt to accomplish this I experimented with modifying the code of a popular digi software package whose name escapes me at the moment. The modification was not as simple as I understood the author to imply, and I lost the hardware where that code lived. If you are starting from the ground up and have digipeating to an AX.25 network as a requirement, I’d probably use a KISS mode packet. If you requirements, like mine, are a bit simpler, TNC2 may do the job. -Jason > On Jul 23, 2021, at 11:17 AM, Kristoff <[email protected]> wrote: > > Hi all, > > > A quick question. > > A few people in our local radioclub have become interested in aprs over lora, > mainly using the LilyGo T-beam devices. This is in essence an ESP32 running > arduino-code + a 'lora32' module (which is a clone of of the sx1276). > I have been tinkering with the kit, mainly using micropython to get to > understand the sx1276 chip. > > So, > If I would would want to use that device as an interface for xastir, what > would be the most easy way to do this? > > I guess just use the serial interface and create some kind of "bridge" > between the serial packets and the Lora "air-interface"? > > What is the difference between the "Serial TNC", "Serial KISS TNC" and the > "Serial Multi-Port KISS TNC"? > Where can I find the documentation for this? > > Or does this already exist? > > > Note, I am on linux (of course :-) ) > > > > > BTW. > I have been discussion with a fellow ham on the use of 'UART pass-through' > devices on LoRa. These are very simple, once they are configured, you just > send data and receive data as it is a transparent serial path, ... except > that it is 'multicast'. > > What would be the best way to connect this kind of device to xastir? > > > Many thanks in advance. > > Kristoff - on1arf > > _______________________________________________ > Xastir-dev mailing list > [email protected] > http://xastir.org/mailman/listinfo/xastir-dev _______________________________________________ Xastir-dev mailing list [email protected] http://xastir.org/mailman/listinfo/xastir-dev
